Sample records for coli population structure
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Characterizing spatial structure of sediment E. coli populations to inform sampling design.
Piorkowski, Gregory S; Jamieson, Rob C; Hansen, Lisbeth Truelstrup; Bezanson, Greg S; Yost, Chris K
2014-01-01
Escherichia coli can persist in streambed sediments and influence water quality monitoring programs through their resuspension into overlying waters. This study examined the spatial patterns in E. coli concentration and population structure within streambed morphological features during baseflow and following stormflow to inform sampling strategies for representative characterization of E. coli populations within a stream reach. E. coli concentrations in bed sediments were significantly different (p = 0.002) among monitoring sites during baseflow, and significant interactive effects (p = 0.002) occurred among monitoring sites and morphological features following stormflow. Least absolute shrinkage and selection operator (LASSO) regression revealed that water velocity and effective particle size (D 10) explained E. coli concentration during baseflow, whereas sediment organic carbon, water velocity and median particle diameter (D 50) were important explanatory variables following stormflow. Principle Coordinate Analysis illustrated the site-scale differences in sediment E. coli populations between disconnected stream segments. Also, E. coli populations were similar among depositional features within a reach, but differed in relation to high velocity features (e.g., riffles). Canonical correspondence analysis resolved that E. coli population structure was primarily explained by spatial (26.9–31.7 %) over environmental variables (9.2–13.1 %). Spatial autocorrelation existed among monitoring sites and morphological features for both sampling events, and gradients in mean particle diameter and water velocity influenced E. coli population structure for the baseflow and stormflow sampling events, respectively. Representative characterization of streambed E. coli requires sampling of depositional and high velocity environments to accommodate strain selectivity among these features owing to sediment and water velocity heterogeneity.
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Jang, Jeonghwan; Di, Doris Y W; Han, Dukki; Unno, Tatsuya; Lee, Jeom-Ho; Sadowsky, Michael J; Hur, Hor-Gil
2015-11-01
Although Escherichia coli has been used as an indicator to examine fecal contamination of aquatic environment, it also has been reported to become naturalized to secondary habitats, including soil, water and beach sand. A total of 2880 E. coli isolates obtained from surface water and sediment samples from the Yeongsan River in 2013 were genotyped by using the horizontal fluorophore-enhanced rep-PCR DNA fingerprinting technique. Although different E. coli genotypic groups were observed between surface water and sediments in the dry season, they were mingled and undifferentiated from each other in the rainy season. This indicates that there are frequent sediment resuspension events in the river basin. Moreover, the genotypic composition of the E. coli population in the Yeongsan River basin changes over months and years, implying that genotypic structure of E. coli populations dynamically fluctuates in the river environment. Consequently, our data suggests that the use of E. coli libraries for fecal source tracking needs to be reassessed to account for the changing structure of riverine E. coli populations. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Badgley, Brian D; Ferguson, John; Vanden Heuvel, Amy; Kleinheinz, Gregory T; McDermott, Colleen M; Sandrin, Todd R; Kinzelman, Julie; Junion, Emily A; Byappanahalli, Muruleedhara N; Whitman, Richard L; Sadowsky, Michael J
2011-01-01
High concentrations of Escherichia coli in mats of Cladophora in the Great Lakes have raised concern over the continued use of this bacterium as an indicator of microbial water quality. Determining the impacts of these environmentally abundant E. coli, however, necessitates a better understanding of their ecology. In this study, the population structure of 4285 Cladophora-borne E. coli isolates, obtained over multiple three day periods from Lake Michigan Cladophora mats in 2007-2009, was examined by using DNA fingerprint analyses. In contrast to previous studies that have been done using isolates from attached Cladophora obtained over large time scales and distances, the extensive sampling done here on free-floating mats over successive days at multiple sites provided a large dataset that allowed for a detailed examination of changes in population structure over a wide range of spatial and temporal scales. While Cladophora-borne E. coli populations were highly diverse and consisted of many unique isolates, multiple clonal groups were also present and accounted for approximately 33% of all isolates examined. Patterns in population structure were also evident. At the broadest scales, E. coli populations showed some temporal clustering when examined by year, but did not show good spatial distinction among sites. E. coli population structure also showed significant patterns at much finer temporal scales. Populations were distinct on an individual mat basis at a given site, and on individual days within a single mat. Results of these studies indicate that Cladophora-borne E. coli populations consist of a mixture of stable, and possibly naturalized, strains that persist during the life of the mat, and more unique, transient strains that can change over rapid time scales. It is clear that further study of microbial processes at fine spatial and temporal scales is needed, and that caution must be taken when interpolating short term microbial dynamics from results obtained from weekly or monthly samples. Copyright © 2010 Elsevier Ltd. All rights reserved.
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Badgley, B.D.; Ferguson, J.; Heuvel, A.V.; Kleinheinz, G.T.; McDermott, C.M.; Sandrin, T.R.; Kinzelman, J.; Junion, E.A.; Byappanahalli, M.N.; Whitman, R.L.; Sadowsky, M.J.
2011-01-01
High concentrations of Escherichia coli in mats of Cladophora in the Great Lakes have raised concern over the continued use of this bacterium as an indicator of microbial water quality. Determining the impacts of these environmentally abundant E. coli, however, necessitates a better understanding of their ecology. In this study, the population structure of 4285 Cladophora-borne E. coli isolates, obtained over multiple three day periods from Lake Michigan Cladophora mats in 2007-2009, was examined by using DNA fingerprint analyses. In contrast to previous studies that have been done using isolates from attached Cladophora obtained over large time scales and distances, the extensive sampling done here on free-floating mats over successive days at multiple sites provided a large dataset that allowed for a detailed examination of changes in population structure over a wide range of spatial and temporal scales. While Cladophora-borne E. coli populations were highly diverse and consisted of many unique isolates, multiple clonal groups were also present and accounted for approximately 33% of all isolates examined. Patterns in population structure were also evident. At the broadest scales, E. coli populations showed some temporal clustering when examined by year, but did not show good spatial distinction among sites. E. coli population structure also showed significant patterns at much finer temporal scales. Populations were distinct on an individual mat basis at a given site, and on individual days within a single mat. Results of these studies indicate that Cladophora-borne E. coli populations consist of a mixture of stable, and possibly naturalized, strains that persist during the life of the mat, and more unique, transient strains that can change over rapid time scales. It is clear that further study of microbial processes at fine spatial and temporal scales is needed, and that caution must be taken when interpolating short term microbial dynamics from results obtained from weekly or monthly samples.
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Ecological and genetic determinants of plasmid distribution in Escherichia coli.
Medaney, Frances; Ellis, Richard J; Raymond, Ben
2016-11-01
Bacterial plasmids are important carriers of virulence and antibiotic resistance genes. Nevertheless, little is known of the determinants of plasmid distribution in bacterial populations. Here the factors affecting the diversity and distribution of the large plasmids of Escherichia coli were explored in cattle grazing on semi-natural grassland, a set of populations with low frequencies of antibiotic resistance genes. Critically, the population genetic structure of bacterial hosts was chararacterized. This revealed structured E. coli populations with high diversity between sites and individuals but low diversity within cattle hosts. Plasmid profiles, however, varied considerably within the same E. coli genotype. Both ecological and genetic factors affected plasmid distribution: plasmid profiles were affected by site, E. coli diversity, E. coli genotype and the presence of other large plasmids. Notably 3/26 E. coli serotypes accounted for half the observed plasmid-free isolates indicating that within species variation can substantially affect carriage of the major conjugative plasmids. The observed population structure suggest that most of the opportunities for within species plasmid transfer occur between different individuals of the same genotype and support recent experimental work indicating that plasmid-host coevolution, and epistatic interactions on fitness costs are likely to be important in determining occupancy. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.
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The population structure of Escherichia coli isolated from subtropical and temperate soils.
Byappanahalli, Muruleedhara N; Yan, Tao; Hamilton, Matthew J; Ishii, Satoshi; Fujioka, Roger S; Whitman, Richard L; Sadowsky, Michael J
2012-02-15
While genotypically-distinct naturalized Escherichia coli strains have been shown to occur in riparian soils of Lake Michigan and Lake Superior watersheds, comparative analyses of E. coli populations in diverse soils across a range of geographic and climatic conditions have not been investigated. The main objectives of this study were to: (a) examine the population structure and genetic relatedness of E. coli isolates collected from different soil types on a tropical island (Hawaii), and (b) determine if E. coli populations from Hawaii and temperate soils (Indiana, Minnesota) shared similar genotypes that may be reflective of biome-related soil conditions. DNA fingerprint and multivariate statistical analyses were used to examine the population structure and genotypic characteristics of the E. coli isolates. About 33% (98 of 293) of the E. coli from different soil types and locations on the island of Oahu, Hawaii, had unique DNA fingerprints, indicating that these bacteria were relatively diverse; the Shannon diversity index for the population was 4.03. Nearly 60% (171 of 293) of the E. coli isolates from Hawaii clustered into two major groups and the rest, with two or more isolates, fell into one of 22 smaller groups, or individual lineages. Multivariate analysis of variance of 89, 21, and 106 unique E. coli DNA fingerprints for Hawaii, Indiana, and Minnesota soils, respectively, showed that isolates formed tight cohesive groups, clustering mainly by location. However, there were several instances of clonal isolates being shared between geographically different locations. Thus, while nearly identical E. coli strains were shared between disparate climatologically- and geographically-distinct locations, a vast majority of the soil E. coli strains were genotypically diverse and were likely derived from separate lineages. This supports the hypothesis that these bacteria are not unique and multiple genotypes can readily adapt to become part of the soil autochthonous microflora. Copyright © 2012 Elsevier B.V. All rights reserved.
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The population structure of Escherichia coli isolated from subtropical and temperate soils
Byappanahalli, Muruleedhara N.; Yan, Tao; Hamilton, Matthew J.; Ishii, Satoshi; Fujioka, Roger S.; Whitman, Richard L.; Sadowsky, Michael J.
2012-01-01
While genotypically-distinct naturalized Escherichia coli strains have been shown to occur in riparian soils of Lake Michigan and Lake Superior watersheds, comparative analyses of E. coli populations in diverse soils across a range of geographic and climatic conditions have not been investigated. The main objectives of this study were to: (a) examine the population structure and genetic relatedness of E. coli isolates collected from different soil types on a tropical island (Hawaii), and (b) determine if E. coli populations from Hawaii and temperate soils (Indiana, Minnesota) shared similar genotypes that may be reflective of biome-related soil conditions. DNA fingerprint and multivariate statistical analyses were used to examine the population structure and genotypic characteristics of the E. coli isolates. About 33% (98 of 293) of the E. coli from different soil types and locations on the island of Oahu, Hawaii, had unique DNA fingerprints, indicating that these bacteria were relatively diverse; the Shannon diversity index for the population was 4.03. Nearly 60% (171 of 293) of the E. coli isolates from Hawaii clustered into two major groups and the rest, with two or more isolates, fell into one of 22 smaller groups, or individual lineages. Multivariate analysis of variance of 89, 21, and 106 unique E. coli DNA fingerprints for Hawaii, Indiana, and Minnesota soils, respectively, showed that isolates formed tight cohesive groups, clustering mainly by location. However, there were several instances of clonal isolates being shared between geographically different locations. Thus, while nearly identical E. coli strains were shared between disparate climatologically- and geographically-distinct locations, a vast majority of the soil E. coli strains were genotypically diverse and were likely derived from separate lineages. This supports the hypothesis that these bacteria are not unique and multiple genotypes can readily adapt to become part of the soil autochthonous microflora.
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Chattaway, Marie Anne; Jenkins, Claire; Rajendram, Dunstan; Cravioto, Alejandro; Talukder, Kaisar Ali; Dallman, Tim; Underwood, Anthony; Platt, Steve; Okeke, Iruka N; Wain, John
2014-01-01
Enteroaggregative E. coli (EAEC) is an established diarrhoeagenic pathotype. The association with virulence gene content and ability to cause disease has been studied but little is known about the population structure of EAEC and how this pathotype evolved. Analysis by Multi Locus Sequence Typing of 564 EAEC isolates from cases and controls in Bangladesh, Nigeria and the UK spanning the past 29 years, revealed multiple successful lineages of EAEC. The population structure of EAEC indicates some clusters are statistically associated with disease or carriage, further highlighting the heterogeneous nature of this group of organisms. Different clusters have evolved independently as a result of both mutational and recombination events; the EAEC phenotype is distributed throughout the population of E. coli.
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Chiyo, Patrick I.; Grieneisen, Laura E.; Wittemyer, George; Moss, Cynthia J.; Lee, Phyllis C.; Douglas-Hamilton, Iain; Archie, Elizabeth A.
2014-01-01
Social structure is proposed to influence the transmission of both directly and environmentally transmitted infectious agents. However in natural populations, many other factors also influence transmission, including variation in individual susceptibility and aspects of the environment that promote or inhibit exposure to infection. We used a population genetic approach to investigate the effects of social structure, environment, and host traits on the transmission of Escherichia coli infecting two populations of wild elephants: one in Amboseli National Park and another in Samburu National Reserve, Kenya. If E. coli transmission is strongly influenced by elephant social structure, E. coli infecting elephants from the same social group should be genetically more similar than E. coli sampled from members of different social groups. However, we found no support for this prediction. Instead, E. coli was panmictic across social groups, and transmission patterns were largely dominated by habitat and host traits. For instance, habitat overlap between elephant social groups predicted E. coli genetic similarity, but only in the relatively drier habitat of Samburu, and not in Amboseli, where the habitat contains large, permanent swamps. In terms of host traits, adult males were infected with more diverse haplotypes, and males were slightly more likely to harbor strains with higher pathogenic potential, as compared to adult females. In addition, elephants from similar birth cohorts were infected with genetically more similar E. coli than elephants more disparate in age. This age-structured transmission may be driven by temporal shifts in genetic structure of E. coli in the environment and the effects of age on bacterial colonization. Together, our results support the idea that, in elephants, social structure often will not exhibit strong effects on the transmission of generalist, fecal-oral transmitted bacteria. We discuss our results in the context of social, environmental, and host-related factors that influence transmission patterns. PMID:24705319
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Chiyo, Patrick I; Grieneisen, Laura E; Wittemyer, George; Moss, Cynthia J; Lee, Phyllis C; Douglas-Hamilton, Iain; Archie, Elizabeth A
2014-01-01
Social structure is proposed to influence the transmission of both directly and environmentally transmitted infectious agents. However in natural populations, many other factors also influence transmission, including variation in individual susceptibility and aspects of the environment that promote or inhibit exposure to infection. We used a population genetic approach to investigate the effects of social structure, environment, and host traits on the transmission of Escherichia coli infecting two populations of wild elephants: one in Amboseli National Park and another in Samburu National Reserve, Kenya. If E. coli transmission is strongly influenced by elephant social structure, E. coli infecting elephants from the same social group should be genetically more similar than E. coli sampled from members of different social groups. However, we found no support for this prediction. Instead, E. coli was panmictic across social groups, and transmission patterns were largely dominated by habitat and host traits. For instance, habitat overlap between elephant social groups predicted E. coli genetic similarity, but only in the relatively drier habitat of Samburu, and not in Amboseli, where the habitat contains large, permanent swamps. In terms of host traits, adult males were infected with more diverse haplotypes, and males were slightly more likely to harbor strains with higher pathogenic potential, as compared to adult females. In addition, elephants from similar birth cohorts were infected with genetically more similar E. coli than elephants more disparate in age. This age-structured transmission may be driven by temporal shifts in genetic structure of E. coli in the environment and the effects of age on bacterial colonization. Together, our results support the idea that, in elephants, social structure often will not exhibit strong effects on the transmission of generalist, fecal-oral transmitted bacteria. We discuss our results in the context of social, environmental, and host-related factors that influence transmission patterns.
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Khafipour, E; Plaizier, J C; Aikman, P C; Krause, D O
2011-01-01
Previous studies indicated that only subacute ruminal acidosis (SARA), induced by feeding a high-grain diet, is associated with an inflammatory response and increased abundance of Escherichia coli in the rumen. We hypothesized that ruminal E. coli in grain pellet-induced SARA carried virulence factors that potentially contribute to the immune activation during SARA. One hundred twenty-nine E. coli isolates were cultured from the rumens of 8 cows (4 animals per treatment) in which SARA had been nutritionally induced by feeding a high-grain diet (GPI-SARA) or a diet containing alfalfa pellets (API-SARA). The population structure of the E. coli was evaluated with the ABD genotyping system and repetitive sequence-based (rep)-PCR fingerprinting. Twenty-five virulence factors were evaluated with PCR. Escherichia coli numbers were higher in the GPI-SARA treatment than in the API-SARA treatment. The genetic structure of the E. coli was significantly different between SARA challenge models. Isolates from GPI-control (46%), API-control (70%), and API-SARA (53%) were closely related and fell into one cluster, whereas isolates from GPI-SARA (54%) grouped separately. The ABD typing indicated a shift from an A-type E. coli population to a B1-type population only due to GPI-SARA. Of the 25 virulence factors tested, curli fiber genes were highly associated with GPI. Curli fibers were first identified in E. coli mastitis isolates and are potent virulence factors that induce a range of immune responses. Results suggest that under low rumen pH conditions induced by a grain diet, there is a burst in the number of E. coli with virulence genes that can take advantage of these rumen conditions to trigger an inflammatory response. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
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Massot, Méril; Couffignal, Camille; Clermont, Olivier; D'Humières, Camille; Chatel, Jérémie; Plault, Nicolas; Andremont, Antoine; Caron, Alexandre; Mentré, France; Denamur, Erick
2017-07-01
To get insights into the temporal pattern of commensal Escherichia coli populations, we sampled the feces of four healthy cows from the same herd in the Hwange District of Zimbabwe daily over 25 days. The cows had not received antibiotic treatment during the previous 3 months. We performed viable E. coli counts and characterized the 326 isolates originating from the 98 stool samples at a clonal level, screened them for stx and eae genes, and tested them for their antibiotic susceptibilities. We observed that E. coli counts and dominant clones were different among cows, and very few clones were shared. No clone was shared by three or four cows. Clone richness and evenness were not different between cows. Within each host, the variability in the E. coli count was evidenced between days, and no clone was found to be dominant during the entire sampling period, suggesting the existence of clonal interference. Dominant clones tended to persist longer than subdominant ones and were mainly from phylogenetic groups A and B1. Five E. coli clones were found to contain both the stx 1 and stx 2 genes, representing 6.3% of the studied isolates. All cows harbored at least one Shiga toxin-producing E. coli (STEC) strain. Resistance to tetracycline, penicillins, trimethoprim, and sulfonamides was rare and observed in three clones that were shed at low levels in two cows. This study highlights the fact that the commensal E. coli population, including the STEC population, is host specific, is highly dynamic over a short time frame, and rarely carries antibiotic resistance determinants in the absence of antibiotic treatment. IMPORTANCE The literature about the dynamics of commensal Escherichia coli populations is very scarce. Over 25 days, we followed the total E. coli counts daily and characterized the sampled clones in the feces of four cows from the same herd living in the Hwange District of Zimbabwe. This study deals with the day-to-day dynamics of both quantitative and qualitative aspects of E. coli commensal populations, with a focus on both Shiga toxin-producing E. coli and antibiotic-resistant E. coli strains. We show that the structure of these commensal populations was highly specific to the host, even though the cows ate and roamed together, and was highly dynamic between days. Such data are of importance to understand the ecological forces that drive the dynamics of the emergence of E. coli clones of particular interest within the gastrointestinal tract and their transmission between hosts. Copyright © 2017 American Society for Microbiology.
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Popova, L Iu; Lutskaia, N I; Bogucharov, A A; Bril'kov, A V; Pechurkin, N S
1992-01-01
The populational structure of the Escherichia coli strain Z905 containing the recombinant plasmid with the phenotype AprLux+ was studied in chemostat. It was shown that the stability of the ratio of plasmid containing cells and cells without plasmids depends in the first place on the presence of the selective factor (ampicillin) in the medium and on the sources of carbon and energy limiting growth.
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NASA Astrophysics Data System (ADS)
Fabienne, P.; Mehdy, R.; Massei, N.; Clermont, O.; Denamur, E.; Berthe, T.
2011-12-01
Escherichia coli (E. coli) is a commensal bacterium of the gastro-intestinal tract of human and vertebrate animals, even if the aquatic environment could be considered as a secondary habitat. During turbids events consecutive to the rainfall, E.coli are released from manure and feces in karstic hydrosystem with different settling velocities, related to their association to particles. In water, survival of E. coli, was dependant to the grazing by protozoans and their ability to overcome environmental stress. In these conditions, viable but non culturable (VNC) population of E. coli, could be observed. The aim of this study was to investigate, in a small well characterized rural karstic watershed (i) the structure of E. coli population based on the survival ability, the distribution in four main phylo-groups (A, B1, B2, D), and the phenotypic characteristics, (ii) the fate and the distribution of viable non culturable E. coli according their settling velocities, from surface water to groundwater. For this purpose we combined microbiology and hydrology approaches, and solid phase cytometry (ChemScan°RDI) methodology was performed to numbered VNC E. coli. The distribution in the four main E. coli phylo-groups (A, B1, B2, D) shown that the E. coli population structure was modified not only by the hydrological conditions but also the use of the watershed (presence of cattle). Survival abilities of E. coli strains based on microcosm experiments, vary from 2 days to at least 14 days. Characterization of E. coli was performed by studying specific traits present in host-associated strains (virulence factors, antibiotic resistance) and those that could be involved in water persistence (growth temperature substrate range, biofilm formation and grazing by protozoa). Three major clusters of strains were defined by using a correspondence factor analysis. In water characterized by high level of fecal contamination a first cluster of E. coli strains was related to A and B2 phylo-group, presented a multiple-antibiotic-resistance profile, and had low survival abilities in water. In slightly contaminated water, E. coli strains were persistent in water, sensitive to antibiotics, and able to develop at low temperature (from 7°C to 20°C) and to degrade macromolecules. In the same karstic hydrosystem, whatever the hydrological conditions, a population of E. coli in VNC state was observed, even in dry period where VNC E. coli raised to 96% of the total viable E. coli population. The distribution of the E. coli VNC population according to their settling velocity varies along the transfer between the swallow hole to the spring. Thus rapid flow inside karstic aquifer supports the culturability of E. coli. In contrast, in during low-flow period with slow transport of contaminant, E. coli lose their culturability but could maintained inside in VNC state in such hydrosystem.
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Population structure of Cladophora-borne Escherichia coli in nearshore water of Lake Michigan.
Byappanahalli, Muruleedhara N; Whitman, Richard L; Shively, Dawn A; Ferguson, John; Ishii, Satoshi; Sadowsky, Michael J
2007-08-01
We previously reported that the macrophytic green alga Cladophora harbors high densities (up to 10(6) colony-forming units/g dry weight) of the fecal indicator bacteria, Escherichia coli and enterococci, in shoreline waters of Lake Michigan. However, the population structure and genetic relatedness of Cladophora-borne indicator bacteria remain poorly understood. In this study, 835 E. coli isolates were collected from Cladophora tufts (mats) growing on rocks from a breakwater located within the Indiana Dunes National Lakeshore in northwest Indiana. The horizontal fluorophore enhanced rep-PCR (HFERP) DNA fingerprinting technique was used to determine the genetic relatedness of the isolates to each other and to those in a library of E. coli DNA fingerprints. While the E. coli isolates from Cladophora showed a high degree of genetic relatedness (92% similarity), in most cases, however, the isolates were genetically distinct. The Shannon diversity index for the population was very high (5.39). Both spatial and temporal influences contributed to the genetic diversity. There was a strong association of isolate genotypes by location (79% and 80% for lake- and ditch-side samplings, respectively), and isolates collected from 2002 were distinctly different from those obtained in 2003. Cladophora-borne E. coli isolates represented a unique group, which was distinct from other E. coli isolates in the DNA fingerprint library tested. Taken together, these results indicate that E. coli strains associated with Cladophora may be a recurring source of indicator bacteria to the nearshore beach.
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USDA-ARS?s Scientific Manuscript database
Shiga toxin-producing Escherichia coli (STEC) serotype O145 is one of the major non-O157 serotypes associated with severe human disease. Here we examined the genetic diversity, population structure, virulence potential, and antibiotic resistance profile of environmental O145 strains isolated from a ...
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Population structure of Cladophora-borne Escherichia coli in nearshore water of Lake Michigan
Byappanahalli, M.N.; Whitman, R.L.; Shively, D.A.; Ferguson, J.; Ishii, S.; Sadowsky, M.J.
2007-01-01
We previously reported that the macrophytic green alga Cladophora harbors high densities (up to 106 colony-forming units/g dry weight) of the fecal indicator bacteria,Escherichia coli and enterococci, in shoreline waters of Lake Michigan. However, the population structure and genetic relatedness of Cladophora-borne indicator bacteria remain poorly understood. In this study, 835 E. coli isolates were collected fromCladophora tufts (mats) growing on rocks from a breakwater located within the Indiana Dunes National Lakeshore in northwest Indiana. The horizontal fluorophore enhanced rep-PCR (HFERP) DNA fingerprinting technique was used to determine the genetic relatedness of the isolates to each other and to those in a library of E. coli DNA fingerprints. While the E. coli isolates from Cladophora showed a high degree of genetic relatedness (⩾92% similarity), in most cases, however, the isolates were genetically distinct. The Shannon diversity index for the population was very high (5.39). Both spatial and temporal influences contributed to the genetic diversity. There was a strong association of isolate genotypes by location (79% and 80% for lake- and ditch-side samplings, respectively), and isolates collected from 2002 were distinctly different from those obtained in 2003. Cladophora-borne E. coli isolates represented a unique group, which was distinct from other E. coli isolates in the DNA fingerprint library tested. Taken together, these results indicate that E. coli strains associated with Cladophora may be a recurring source of indicator bacteria to the nearshore beach.
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Byappanahalli, M.N.; Whitman, R.L.; Shively, D.A.; Sadowsky, M.J.; Ishii, S.
2006-01-01
The common occurrence of Escherichia coli in temperate soils has previously been reported, however, there are few studies to date to characterize its source, distribution, persistent capability and genetic diversity. In this study, undisturbed, forest soils within six randomly selected 0.5 m2 exclosure plots (covered by netting of 2.3 mm2 mesh size) were monitored from March to October 2003 for E. coli in order to describe its numerical and population characteristics. Culturable E. coli occurred in 88% of the samples collected, with overall mean counts of 16 MPN g-1, ranging from <1 to 1657 (n = 66). Escherichia coli counts did not correlate with substrate moisture content, air, or soil temperatures, suggesting that seasonality were not a strong factor in population density control. Mean E. coli counts in soil samples (n = 60) were significantly higher inside than immediately outside the exclosures; E. coli distribution within the exclosures was patchy. Repetitive extragenic palindromic polymerase chain reaction (Rep-PCR) demonstrated genetic heterogeneity of E. coli within and among exclosure sites, and the soil strains were genetically distinct from animal (E. coli) strains tested (i.e. gulls, terns, deer and most geese). These results suggest that E. coli can occur and persist for extended periods in undisturbed temperate forest soils independent of recent allochthonous input and season, and that the soil E. coli populations formed a cohesive phylogenetic group in comparison to the set of fecal strains with which they were compared. Thus, in assessing E. coli sources within a stream, it is important to differentiate background soil loadings from inputs derived from animal and human fecal contamination. ?? 2005 Society for Applied Microbiology and Blackwell Publishing Ltd.
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The Evolution of Campylobacter jejuni and Campylobacter coli
Sheppard, Samuel K.; Maiden, Martin C.J.
2015-01-01
The global significance of Campylobacter jejuni and Campylobacter coli as gastrointestinal human pathogens has motivated numerous studies to characterize their population biology and evolution. These bacteria are a common component of the intestinal microbiota of numerous bird and mammal species and cause disease in humans, typically via consumption of contaminated meat products, especially poultry meat. Sequence-based molecular typing methods, such as multilocus sequence typing (MLST) and whole genome sequencing (WGS), have been instructive for understanding the epidemiology and evolution of these bacteria and how phenotypic variation relates to the high degree of genetic structuring in C. coli and C. jejuni populations. Here, we describe aspects of the relatively short history of coevolution between humans and pathogenic Campylobacter, by reviewing research investigating how mutation and lateral or horizontal gene transfer (LGT or HGT, respectively) interact to create the observed population structure. These genetic changes occur in a complex fitness landscape with divergent ecologies, including multiple host species, which can lead to rapid adaptation, for example, through frame-shift mutations that alter gene expression or the acquisition of novel genetic elements by HGT. Recombination is a particularly strong evolutionary force in Campylobacter, leading to the emergence of new lineages and even large-scale genome-wide interspecies introgression between C. jejuni and C. coli. The increasing availability of large genome datasets is enhancing understanding of Campylobacter evolution through the application of methods, such as genome-wide association studies, but MLST-derived clonal complex designations remain a useful method for describing population structure. PMID:26101080
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Stedt, Johan; Bengtsson, Stina; Porczak, Aleksandra; Granholm, Susanne; González-Acuña, Daniel; Olsen, Björn; Bonnedahl, Jonas; Drobni, Mirva
2013-01-01
We investigated the general level of antibiotic resistance with further analysis of extended-spectrum beta-lactamase (ESBL) prevalence, as well as the population structure of E. coli in fecal flora of humans and Franklin’s gulls (Leucophaeus pipixcan) in central parts of Chile. We found a surprisingly high carriage rate of ESBL-producing E. coli among the gulls 112/372 (30.1%) as compared to the human population 6/49 (12.2%.) Several of the E. coli sequence types (STs) identified in birds have previously been reported as Multi Drug Resistant (MDR) human pathogens including the ability to produce ESBLs. This means that not only commensal flora is shared between birds and humans but also STs with pathogenic potential. Given the migratory behavior of Franklin’s gulls, they and other migratory species, may be a part of ESBL dissemination in the environment and over great geographic distances. Apart from keeping the antibiotic use low, breaking the transmission chains between the environment and humans must be a priority to hinder the dissemination of resistance. PMID:24098774
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Analysis of evolutionary patterns of genes in campylobacter jejuni and C. coli
USDA-ARS?s Scientific Manuscript database
Background: In order to investigate the population genetics structure of thermophilic Campylobacter spp., we extracted a set of 1029 core gene families (CGF) from 25 sequenced genomes of C. jejuni, C. coli and C. lari. Based on these CGFs we employed different approaches to reveal the evolutionary ...
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Petit, Fabienne; Clermont, Olivier; Delannoy, Sabine; Servais, Pierre; Gourmelon, Michèle; Fach, Patrick; Oberlé, Kenny; Fournier, Matthieu; Denamur, Erick; Berthe, Thierry
2017-01-01
The aim of this study was to investigate the diversity of the Escherichia coli population, focusing on the occurrence of pathogenic E. coli, in surface water draining a rural catchment. Two sampling campaigns were carried out in similar hydrological conditions (wet period, low flow) along a river continuum, characterized by two opposite density gradients of animals (cattle and wild animals) and human populations. While the abundance of E. coli slightly increased along the river continuum, the abundance of both human and ruminant-associated Bacteroidales markers, as well as the number of E. coli multi-resistant to antibiotics, evidenced a fecal contamination originating from animals at upstream rural sites, and from humans at downstream urban sites. A strong spatial modification of the structure of the E. coli population was observed. At the upstream site close to a forest, a higher abundance of the B2 phylogroup and Escherichia clade strains were observed. At the pasture upstream site, a greater proportion of both E and B1 phylogroups was detected, therefore suggesting a fecal contamination of mainly bovine origin. Conversely, in downstream urban sites, A, D, and F phylogroups were more abundant. To assess the occurrence of intestinal pathogenic strains, virulence factors [afaD, stx1, stx2, eltB (LT), estA (ST), ipaH, bfpA, eae, aaiC and aatA] were screened among 651 E. coli isolates. Intestinal pathogenic strains STEC O174:H21 (stx2) and EHEC O26:H11 (eae, stx1) were isolated in water and sediments close to the pasture site. In contrast, in the downstream urban site aEPEC/EAEC and DAEC of human origin, as well as extra-intestinal pathogenic E. coli belonging to clonal group A of D phylogroup, were sampled. Even if the estimated input of STEC (Shiga toxin-producing E. coli) – released in water at the upstream pasture site – at the downstream site was low, we show that STEC could persist in sediment. These results show that, the run-off of small cattle farms contributed, as much as the wastewater effluent, in the dissemination of pathogenic E. coli in both water and sediments, even if the microbiological quality of the water was good or to average quality according to the French water index. PMID:28458656
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NASA Astrophysics Data System (ADS)
Popova, L. Yu.; Kargatova, T. V.; Ganusova, E. E.; Lobova, T. I.; Boyandin, A. N.; Mogilnaya, O. A.; Pechurkin, N. S.
Populations of Escherichia coli Z905/pPHL7, a transgenic microorganism, were heterogenic in the expression of plasmid genes when adapting to the conditions of water microcosms of various mineralization levels and structure of microbial community. This TM has formed two subpopulations (ampicillin-resistant and ampicillin-sensitive) in every microcosm. Irrespective of mineralization level of a microcosm, when E. coli Z905/pPHL7 alone was introduced, the ampicillin-resistant subpopulation prevailed, while introduction of the TM together with indigenous bacteria led to the dominance of the ampicillin-sensitive subpopulation. A high level of lux gene expression maintained longer in the freshwater microcosms than in sterile saline lake water microcosms. A horizontal gene transfer has been revealed between the jointly introduced TM and Micrococcus sp. 9/pSH1 in microcosms with the Lake Shira sterile water.
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NASA Astrophysics Data System (ADS)
Petit, F.; Ratajczak, M.; Massei, N.; Lafite, R.; Clermont, O.; Denamur, E.; Berthe, T.
2012-12-01
The karst aquifers are particularly vulnerable to contamination by faecal pathogens mainly during rainfall event. In groundwater, the fate of E. coli is dependent on their ability to overcome environmental stresses and on their association with particles. Moreover, some strains can survive leading to the emergence of a sub-population of E. coli which failed to grow on laboratory media, while they were still alive thus designated as viable but non culturable (VNC). The aim of this study was to investigate (i) the structure of culturable E. coli population based on the survival ability, the distribution in four main phylo-groups (A, B1, B2, D) and the phenotypic characteristics; and, (ii) the fate of culturable and VNC E. coli, according to their settling velocities. This work was carried out on a karstic workshop-site for which the microbial quality of water was impaired related to livestock density and septic tanks overflows. Particles characterisation was performed by estimation of their settling velocities combined with electronic microscopy observation, and solid phase cytometry (ChemScan®RDI) was carried out to quantify the viable E. coli, and thus VNC E. coli. In the karst, different populations of E. coli were coexisting related to their survival, their culturability, and their association to particles. At the sinkhole, during a rainfall event with pasture, E. coli rapidly losing their culturability after 2 days have been more frequently isolated. These isolates are mainly multiresistant to antibiotics and harbor several virulence factors. In the same time, a population of VNC E. coli (79%), associated to the "non settleable particles" (settling velocities ranging between 10-5 to 10-2 mm.s-1), mainly corresponding to colloids and organic or organo-mineral microflocs was injected in the karst system, probably corresponding to the runoff of attached-bacteria originating from cowpats. Once in the karst, the relative contribution of culturable and VNC E. coli associated to "non settleable" particles, decreased from the sinkhole to the spring. In contrast in dry period while the turbidity and the contamination by culturable E. coli is low, the three populations of viable, culturable and VNC E. coli are introduced in the karst. Within the population of culturable E. coli, persistent strains mainly belonging to B1 phylogroup and growing at 7°C were introduced in karst aquifer. At the spring, whatever the class of particles up to 96% of viable cells were in VNC state suggesting that a physiological change occurred within aquifer, independently of the association of E. coli with particles. At the well, the pumping of the water induced an input of resident VNC E. coli consecutively to a resuspension of particles previously settled within the karstic network, during a past turbid event.
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USDA-ARS?s Scientific Manuscript database
Introduction: Produce surface structures vary and complicate decontamination treatments for reducing attached bacteria. Purpose: The objective of this study on survival and recovery of injured population of Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes on cantaloupe rind surfaces...
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Lu, Haixia; Zhu, Junli; Li, Jianrong; Chen, Jinru
2015-06-01
Contaminated leafy green vegetables have been linked to several outbreaks of human gastrointestinal infections. Antimicrobial interventions that are adoptable by the fresh produce industry for control of pathogen contamination are in great demand. This study was undertaken to evaluate the efficacy of sustained active packaging on control of Escherichia coli O157:H7 and total aerobic bacteria on lettuce. Commercial Iceberg lettuce was inoculated with a 3-strain mixture of E. coli O157:H7 at 10(2) or 10(4) CFU/g. The contaminated lettuce and un-inoculated controls were placed respectively in 5 different active packaging structures. Traditional, nonactive packaging structure was included as controls. Packaged lettuce was stored at 4, 10, or 22 °C for 3 wk and sampled weekly for the population of E. coli O157:H7 and total aerobic bacteria. Results showed that packaging structures with ClO2 generator, CO2 generator, or one of the O2 scavengers effectively controlled the growth of E. coli O157:H7 and total aerobic bacteria under all storage conditions. Packaging structure with the ClO2 generator was most effective and no E. coli O157:H7 was detected in samples packaged in this structure except for those that were inoculated with 4 log CFU/g of E. coli O157:H7 and stored at 22 °C. Packaging structures with an oxygen scavenger and the allyl isothiocyanate generator were mostly ineffective in control of the growth of the bacteria on Iceberg lettuce. The research suggests that some of the packaging structures evaluated in the study can be used to control the presence of foodborne pathogens on leafy green vegetables. © 2015 Institute of Food Technologists®
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Cytotoxic Effect Associated with Overexpression of QNR Proteins in Escherichia coli.
Machuca, Jesús; Diaz de Alba, Paula; Recacha, Esther; Pascual, Álvaro; Rodriguez-Martinez, José Manuel
2017-10-01
The objective was to evaluate the cytotoxic effect associated with overexpression of multiple Qnr-like plasmid-mediated quinolone resistance (PMQR) mechanisms in Escherichia coli. Coding regions of different PMQR genes (qnrA1, qnrB1, qnrC, qnrD1, qnrS1, and qepA2) and efsqnr were cloned into pET29a(+) vector and overexpressed in E. coli BL21. E. coli BL21 with and without an empty pET29a(+) vector were used as controls. The cytotoxic effect associated with PMQR mechanism overexpression was determined by transmission electron microscopy and viability assays. Overexpressed qnr genes produced loss of bacterial viability in the range of 77-97% compared with the controls, comparable with loss of viability associated with EfsQnr overexpression (97%). No loss of viability was observed in E. coli overexpressing QepA2. In transmission electron microscopy assays, signs of cytotoxicity were observed in E. coli cells overexpressing EfsQnr and Qnr proteins (30-45% of the bacterial population showed morphological changes). Morphological changes were observed in less than 5% of bacterial populations from the control strains and E. coli overexpressing QepA2. Overexpression of qnr genes produces a cytotoxic cellular and structural effect in E. coli, the magnitude of which varies depending on the family of Qnr proteins.
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NASA Technical Reports Server (NTRS)
Popova, L. Yu; Kargatova, T. V.; Ganusova, E. E.; Lobova, T. I.; Boyandin, A. N.; Mogilnaya, O. A.; Pechurkin, N. S.
2005-01-01
Populations of Escherichia coli Z905/pPHL7, a transgenic microorganism, were heterogenic in the expression of plasmid genes when adapting to the conditions of water microcosms of various mineralization levels and structure of microbial community. This TM has formed two subpopulations (ampicillin-resistant and ampicillin-sensitive) in every microcosm. Irrespective of mineralization level of a microcosm, when E. coli Z905/pPHL7 alone was introduced, the ampicillin-resistant subpopulation prevailed, while introduction of the TM together with indigenous bacteria led to the dominance of the ampicillin-sensitive subpopulation. A high level of lux gene expression maintained longer in the freshwater microcosms than in sterile saline lake water microcosms. A horizontal gene transfer has been revealed between the jointly introduced TM and Micrococcus sp. 9/pSH1 in microcosms with the Lake Shira sterile water. c2005 COSPAR. Published by Elsevier Ltd. All rights reserved.
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Rödiger, Stefan; Kramer, Toni; Frömmel, Ulrike; Weinreich, Jörg; Roggenbuck, Dirk; Guenther, Sebastian; Schaufler, Katharina; Schröder, Christian; Schierack, Peter
2015-09-01
We report the population structure and dynamics of one Escherichia coli population of wild mallard ducks in their natural environment over four winter seasons, following the characterization of 100 isolates each consecutive season. Macro-restriction analysis was used to define isolates variously as multi- or 1-year pulsed-field gel electrophoresis (PFGE) types. Isolates were characterized genotypically based on virulence-associated genes (VAGs), phylogenetic markers, and phenotypically based on haemolytic activity, antimicrobial resistance, adhesion to epithelial cells, microcin production, motility and carbohydrate metabolism. Only 12 out of 220 PFGE types were detectable over more than one winter, and classified as multi-year PFGE types. There was a dramatic change of PFGE types within two winter seasons. Nevertheless, the genetic pool (VAGs) and antimicrobial resistance pattern remained remarkably stable. The high diversity and dynamics of this E. coli population were also demonstrated by the occurrence of PFGE subtypes and differences between isolates of one PFGE type (based on VAGs, antimicrobial resistance and adhesion rates). Multi- and 1-year PFGE types differed in antimicrobial resistance, VAGs and adhesion. Other parameters were not prominent colonization factors. In conclusion, the high diversity, dynamics and stable genetic pool of an E. coli population seem to enable their successful colonization of host animal population over time. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.
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Mazumder, Asit
2014-01-01
Escherichia coli isolates (n = 658) obtained from drinking water intakes of Comox Lake (2011 to 2013) were screened for the following virulence genes (VGs): stx1 and stx2 (Shiga toxin-producing E. coli [STEC]), eae and the adherence factor (EAF) gene (enteropathogenic E. coli [EPEC]), heat-stable (ST) enterotoxin (variants STh and STp) and heat-labile enterotoxin (LT) genes (enterotoxigenic E. coli [ETEC]), and ipaH (enteroinvasive E. coli [EIEC]). The only genes detected were eae and stx2, which were carried by 37.69% (n = 248) of the isolates. Only eae was harbored by 26.74% (n = 176) of the isolates, representing potential atypical EPEC strains, while only stx2 was detected in 10.33% (n = 68) of the isolates, indicating potential STEC strains. Moreover, four isolates were positive for both the stx2 and eae genes, representing potential EHEC strains. The prevalence of VGs (eae or stx2) was significantly (P < 0.0001) higher in the fall season, and multiple genes (eae plus stx2) were detected only in fall. Repetitive element palindromic PCR (rep-PCR) fingerprint analysis of 658 E. coli isolates identified 335 unique fingerprints, with an overall Shannon diversity (H′) index of 3.653. Diversity varied among seasons over the years, with relatively higher diversity during fall. Multivariate analysis of variance (MANOVA) revealed that the majority of the fingerprints showed a tendency to cluster according to year, season, and month. Taken together, the results indicated that the diversity and population structure of E. coli fluctuate on a temporal scale, reflecting the presence of diverse host sources and their behavior over time in the watershed. Furthermore, the occurrence of potentially pathogenic E. coli strains in the drinking water intakes highlights the risk to human health associated with direct and indirect consumption of untreated surface water. PMID:25548059
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Grinberg, Alex; Midwinter, Anne C.; Marshall, Jonathan C.; Collins-Emerson, Julie M.; French, Nigel P.
2016-01-01
ABSTRACT Campylobacteriosis is one of the most important foodborne diseases worldwide and a significant health burden in New Zealand. Campylobacter jejuni is the predominant species worldwide, accounting for approximately 90% of human cases, followed by Campylobacter coli. Most studies in New Zealand have focused on C. jejuni; hence, the impact of C. coli strains on human health is not well understood. The aim of this study was to genotype C. coli isolates collected in the Manawatu region of New Zealand from clinical cases, fresh poultry meat, ruminant feces, and environmental water sources, between 2005 and 2014, to study their population structure and estimate the contribution of each source to the burden of human disease. Campylobacter isolates were identified by PCR and typed by multilocus sequence typing. C. coli accounted for 2.9% (n = 47/1,601) of Campylobacter isolates from human clinical cases, 9.6% (n = 108/1,123) from poultry, 13.4% (n = 49/364) from ruminants, and 6.4% (n = 11/171) from water. Molecular subtyping revealed 27 different sequence types (STs), of which 18 belonged to clonal complex ST-828. ST-1581 was the most prevalent C. coli sequence type isolated from both human cases (n = 12/47) and poultry (n = 44/110). When classified using cladistics, all sequence types belonged to clade 1 except ST-7774, which belonged to clade 2. ST-854, ST-1590, and ST-4009 were isolated only from human cases and fresh poultry, while ST-3232 was isolated only from human cases and ruminant sources. Modeling indicated ruminants and poultry as the main sources of C. coli human infection. IMPORTANCE We performed a molecular epidemiological study of Campylobacter coli infection in New Zealand, one of few such studies globally. This study analyzed the population genetic structure of the bacterium and included a probabilistic source attribution model covering different animal and water sources. The results are discussed in a global context. PMID:27208097
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Pringle, Shelly L; Palmer, Kelli L; McLean, Robert J C
2017-01-01
Escherichia coli lives in the gastrointestinal tract and elsewhere, where it coexists within a mixed population. Indole production enables E. coli to grow with other gram-negative bacteria as indole inhibits N-acyl-homoserine lactone (AHL) quorum regulation. We investigated whether E. coli indole production enhanced competition with gram-positive Enterococcus faecalis, wherein quorum signaling is mediated by small peptides. During planktonic co-culture with E. faecalis, the fitness and population density of E. coli tnaA mutants (unable to produce indole) equaled or surpassed that of E. coli wt. During biofilm growth, the fitness of both populations of E. coli stabilized around 100 %, whereas the fitness of E. faecalis declined over time to 85-90 %, suggesting that biofilm and planktonic populations have different competition strategies. Media supplementation with indole removed the competitive advantage of E. coli tnaA in planktonic populations but enhanced it in biofilm populations. E. coli wt and tnaA showed similar growth in Luria-Bertani (LB) broth. However, E. coli growth was inhibited in the presence of filter-sterilized spent LB from E. faecalis, with inhibition being enhanced by indole. Similarly, there was also an inhibition of E. faecalis growth by proteinaceous components (likely bacteriocins) from spent culture media from both E. coli strains. We conclude that E. coli indole production is not a universal competition strategy, but rather works against gram-negative, AHL-producing bacteria.
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Zhang, Wei; Zhu, Yao-Hong; Zhou, Dong; Wu, Qiong; Song, Dan; Dicksved, Johan; Wang, Jiu-Feng
2017-02-01
Structural disruption of the gut microbiota and impaired goblet cell function are collateral etiologic factors in enteric diseases. Low, moderate, or high doses of a Bacillus licheniformis-B. subtilis mixture (BLS mix) were orally administered to piglets of genotype MUC4 that are supposed to be F4-expressing enterotoxigenic Escherichia coli strain (F4 + ETEC) F4ab/ac receptor negative (i.e., MUC4-resistant piglets) for 1 week before F4 + ETEC challenge. The luminal contents were collected from the mucosa of the colon on day 8 after F4 + ETEC challenge. The BLS mix attenuated E. coli-induced expansion of Bacteroides uniformis, Eubacterium eligens, Acetanaerobacterium, and Sporobacter populations. Clostridium and Turicibacter populations increased following F4 + ETEC challenge in pigs pretreated with low-dose BLS mix. Lactobacillus gasseri and Lactobacillus salivarius populations increased after administration of BLS mix during E. coli infection. The beneficial effects of BLS mix were due in part to the expansion of certain Clostridium, Lactobacillus, and Turicibacter populations, with a corresponding increase in the number of goblet cells in the ileum via upregulated Atoh1 expression, in turn increasing MUC2 production and thus preserving the mucus barrier and enhancing host defenses against enteropathogenic bacteria. However, excessive BLS mix consumption may increase the risk for enteritis, partly through disruption of colonic microbial ecology, characterized by expansion of Proteobacteria and impaired goblet cell function in the ileum. Our findings suggest that oral administration of BLS mix reprograms the gut microbiota and enhances goblet cell function to ameliorate enteritis. The present study is important for improving our understanding of the protective role of probiotics against Escherichia coli infection in piglets. Structural disruption of the gut microbiota and impaired goblet cell function are collateral etiologic factors in enteric diseases. In this study, low, moderate, or high doses of a Bacillus licheniformis-B. subtilis mixture (BLS mix) were orally administered to MUC4-resistant piglets for 1 week before the F4-expressing ETEC strain (F4 + ETEC) challenge. Our findings suggest that oral administration of BLS mix reprograms the gut microbiota and enhances goblet cell function to ameliorate enteritis. Copyright © 2017 American Society for Microbiology.
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Zhang, Wei; Zhou, Dong; Wu, Qiong; Song, Dan; Dicksved, Johan; Wang, Jiu-Feng
2016-01-01
ABSTRACT Structural disruption of the gut microbiota and impaired goblet cell function are collateral etiologic factors in enteric diseases. Low, moderate, or high doses of a Bacillus licheniformis-B. subtilis mixture (BLS mix) were orally administered to piglets of genotype MUC4 that are supposed to be F4-expressing enterotoxigenic Escherichia coli strain (F4+ ETEC) F4ab/ac receptor negative (i.e., MUC4-resistant piglets) for 1 week before F4+ ETEC challenge. The luminal contents were collected from the mucosa of the colon on day 8 after F4+ ETEC challenge. The BLS mix attenuated E. coli-induced expansion of Bacteroides uniformis, Eubacterium eligens, Acetanaerobacterium, and Sporobacter populations. Clostridium and Turicibacter populations increased following F4+ ETEC challenge in pigs pretreated with low-dose BLS mix. Lactobacillus gasseri and Lactobacillus salivarius populations increased after administration of BLS mix during E. coli infection. The beneficial effects of BLS mix were due in part to the expansion of certain Clostridium, Lactobacillus, and Turicibacter populations, with a corresponding increase in the number of goblet cells in the ileum via upregulated Atoh1 expression, in turn increasing MUC2 production and thus preserving the mucus barrier and enhancing host defenses against enteropathogenic bacteria. However, excessive BLS mix consumption may increase the risk for enteritis, partly through disruption of colonic microbial ecology, characterized by expansion of Proteobacteria and impaired goblet cell function in the ileum. Our findings suggest that oral administration of BLS mix reprograms the gut microbiota and enhances goblet cell function to ameliorate enteritis. IMPORTANCE The present study is important for improving our understanding of the protective role of probiotics against Escherichia coli infection in piglets. Structural disruption of the gut microbiota and impaired goblet cell function are collateral etiologic factors in enteric diseases. In this study, low, moderate, or high doses of a Bacillus licheniformis-B. subtilis mixture (BLS mix) were orally administered to MUC4-resistant piglets for 1 week before the F4-expressing ETEC strain (F4+ ETEC) challenge. Our findings suggest that oral administration of BLS mix reprograms the gut microbiota and enhances goblet cell function to ameliorate enteritis. PMID:27881419
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Perini, L; Quero, G M; García, E Serrano; Luna, G M
2015-12-15
Despite its worldwide importance as fecal indicator in aquatic systems, little is known about the diversity of Escherichia coli in the environment and the factors driving its spatial distribution. The city of Venice (Italy), lying at the forefront of a large European lagoon, is an ideal site to study the mechanisms driving the fate of fecal bacteria, due to the huge fluxes of tourists, the city's unique architecture (causing poor efficiency of sewages treatment), and the long branching network of canals crossing the city. We summarize the results of a multi-year investigation to study the temporal dynamics of E. coli around the city, describe the population structure (by assigning isolates to their phylogenetic group) and the genotypic diversity, and explore the role of environmental factors in determining its variability. E. coli abundance in water was highly variable, ranging from being undetectable up to 10(4) Colony Forming Units (CFU) per 100 ml. Abundance did not display significant relationships with the water physico-chemical variables. The analysis of the population structure showed the presence of all known phylogroups, including extra-intestinal and potentially pathogenic ones. The genotypic diversity was very high, as likely consequence of the heterogeneous input of fecal bacteria from the city, and showed site-specific patterns. Intensive sampling during the tidal fluctuations highlighted the prominent role of tides, rather than environmental variables, as source of spatial variation, with a more evident influence in water than sediments. These results, the first providing information on the genetic properties, spatial heterogeneity and influence of tides on E. coli populations around Venice, have implications to manage the fecal pollution, and the associated waterborne disease risks, in coastal cities lying in front of lagoons and semi-enclosed basins. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Oteo, Jesús; González-López, Juan José; Ortega, Adriana; Quintero-Zárate, J Natalia; Bou, Germán; Cercenado, Emilia; Conejo, María Carmen; Martínez-Martínez, Luis; Navarro, Ferran; Oliver, Antonio; Bartolomé, Rosa M; Campos, José
2014-07-01
In a previous prospective multicenter study in Spain, we found that OXA-1 and inhibitor-resistant TEM (IRT) β-lactamases constitute the most common plasmid-borne mechanisms of genuine amoxicillin-clavulanate (AMC) resistance in Escherichia coli. In the present study, we investigated the population structure and virulence traits of clinical AMC-resistant E. coli strains expressing OXA-1 or IRT and compared these traits to those in a control group of clinical AMC-susceptible E. coli isolates. All OXA-1-producing (n = 67) and IRT-producing (n = 45) isolates were matched by geographical and temporal origin to the AMC-susceptible control set (n = 56). We performed multilocus sequence typing and phylogenetic group characterization for each isolate and then studied the isolates for the presence of 49 virulence factors (VFs) by PCR and sequencing. The most prevalent clone detected was distinct for each group: group C isolates of sequence type (ST) 88 (C/ST88) were the most common in OXA-1 producers, B2/ST131 isolates were the most common in IRT producers, and B2/ST73 isolates were the most common in AMC-susceptible isolates. The median numbers of isolates per ST were 3.72 in OXA-1 producers, 2.04 in IRT producers, and 1.69 in AMC-susceptible isolates; the proportions of STs represented by one unique isolate in each group were 19.4%, 31.1%, and 48.2%, respectively. The sum of all VFs detected, calculated as a virulence score, was significantly higher in AMC-susceptible isolates than OXA-1 and IRT producers (means, 12.5 versus 8.3 and 8.2, respectively). Our findings suggest that IRT- and OXA-1-producing E. coli isolates resistant to AMC have a different and less diverse population structure than AMC-susceptible clinical E. coli isolates. The AMC-susceptible population also contains more VFs than AMC-resistant isolates. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
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Evans, D G; Silver, R P; Evans, D J; Chase, D G; Gorbach, S L
1975-01-01
An enterotoxin-producing strain of Escherichia coli isolated from a case of cholera-like diarrhea (E. coli strain H-10407) was found to possess a surface-associated colonization factor. Colonization was manifested as the ability of small inocula (10(5) bacteria) to attain large (10(9)) populations in the infant rabbit intestine with a concomitant diarrheal response. A laboratory-passed derivative of E. coli H-10407, designated H-10407-P, failed to exhibit an increase in population in the infant rabbit and also failed to induce diarrhea. Cell-free culture supernatant fluids of E. coli H-10407 and H-10407-P produced equivalent enterotoxic responses in infant and in adult rabbits. Specific anti-colonization factor antiserum was produced by adsorbing hyperimmune anti-H-10407 serum with both heat-killed and living cells E. coli H-10407-P. This specific adsorbed serum protected infant rabbits from challenge with living E. coli H-10407 although the serum did not possess bactericidal activity. The anti-colonization factor serum did not agglutinate a strain of E. coli K-12 possessing the K88 colonization factor peculiar to E. coli enterotoxigenic for swine. By electron microscopy it was demonstrated that E. coli H-10407, but not H10407-, possessed pilus-like surface structures which agglutinated with the specific adsorbed (anti-colonization factor) antiserum. E. coli H-10407 possessed three species of plasmid deoxyribonucleic acid, measuring 60 X 10(6), 42 X 10(6), and 3.7 X 10(6) daltons, respectively. E. coli H-10407-P possessed only the 42 X 10(6)- and the 3.7 X 10(6)-dalton plasmid species. Spontaneous loss of the specific H-10407 surface-associated antigen was accompanied by loss of the 60 X 10(6)-dalton species of plasmid deoxyribonucleic acid and loss of colonizing ability. Thus, it is concluded that the E. coli colonization factor described here is a virulence factor which may play an important and possibly essential role in naturally occurring E. coli enterotoxic diarrhea in man. Images PMID:1100526
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Evans, D G; Silver, R P; Evans, D J; Chase, D G; Gorbach, S L
1975-09-01
An enterotoxin-producing strain of Escherichia coli isolated from a case of cholera-like diarrhea (E. coli strain H-10407) was found to possess a surface-associated colonization factor. Colonization was manifested as the ability of small inocula (10(5) bacteria) to attain large (10(9)) populations in the infant rabbit intestine with a concomitant diarrheal response. A laboratory-passed derivative of E. coli H-10407, designated H-10407-P, failed to exhibit an increase in population in the infant rabbit and also failed to induce diarrhea. Cell-free culture supernatant fluids of E. coli H-10407 and H-10407-P produced equivalent enterotoxic responses in infant and in adult rabbits. Specific anti-colonization factor antiserum was produced by adsorbing hyperimmune anti-H-10407 serum with both heat-killed and living cells E. coli H-10407-P. This specific adsorbed serum protected infant rabbits from challenge with living E. coli H-10407 although the serum did not possess bactericidal activity. The anti-colonization factor serum did not agglutinate a strain of E. coli K-12 possessing the K88 colonization factor peculiar to E. coli enterotoxigenic for swine. By electron microscopy it was demonstrated that E. coli H-10407, but not H10407-, possessed pilus-like surface structures which agglutinated with the specific adsorbed (anti-colonization factor) antiserum. E. coli H-10407 possessed three species of plasmid deoxyribonucleic acid, measuring 60 X 10(6), 42 X 10(6), and 3.7 X 10(6) daltons, respectively. E. coli H-10407-P possessed only the 42 X 10(6)- and the 3.7 X 10(6)-dalton plasmid species. Spontaneous loss of the specific H-10407 surface-associated antigen was accompanied by loss of the 60 X 10(6)-dalton species of plasmid deoxyribonucleic acid and loss of colonizing ability. Thus, it is concluded that the E. coli colonization factor described here is a virulence factor which may play an important and possibly essential role in naturally occurring E. coli enterotoxic diarrhea in man.
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Whitman, R.L.; Przybyla-Kelly, K.; Shively, D.A.; Nevers, M.B.; Byappanahalli, M.N.
2008-01-01
Reducing fecal indicator bacteria, such as Escherichia coli (E. coli), in streams is important for many downstream areas. E. coli concentrations within streams may be reduced by intervening ponds or wetlands through a number of physical and biological means. A section of Dunes Creek, a small coastal stream of southern Lake Michigan, was impounded and studied for 30??months from pre-through post-construction of the experimental pond. E. coli reduction became more predictable and effective with pond age. E. coli followed the hydrograph and increased several-fold during both rainfall and snowmelt events. Seasonally, the pond was more effective at reducing E. coli during summer than winter. Late summer, non-solar reduction or inactivation of E. coli in the pond was estimated at 72% and solar inactivation at 26%. E. coli DNA fingerprinting demonstrated that the winter population was genetically more homogeneous than the summer population. Detection of FRNA coliphages suggests that there was fecal contamination during heavy rain events. An understanding of how environmental factors interact with E. coli populations is important for assessing anticipated contaminant loading and the reduction of indicator bacteria in downstream reaches. ?? 2007.
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Almeida, Carina; Azevedo, Nuno F; Santos, Sílvio; Keevil, Charles W; Vieira, Maria J
2011-03-29
Our current understanding of biofilms indicates that these structures are typically composed of many different microbial species. However, the lack of reliable techniques for the discrimination of each population has meant that studies focusing on multi-species biofilms are scarce and typically generate qualitative rather than quantitative data. We employ peptide nucleic acid fluorescence in situ hybridization (PNA FISH) methods to quantify and visualize mixed biofilm populations. As a case study, we present the characterization of Salmonella enterica/Listeria monocytogenes/Escherichia coli single, dual and tri-species biofilms in seven different support materials. Ex-situ, we were able to monitor quantitatively the populations of ∼56 mixed species biofilms up to 48 h, regardless of the support material. In situ, a correct quantification remained more elusive, but a qualitative understanding of biofilm structure and composition is clearly possible by confocal laser scanning microscopy (CLSM) at least up to 192 h. Combining the data obtained from PNA FISH/CLSM with data from other established techniques and from calculated microbial parameters, we were able to develop a model for this tri-species biofilm. The higher growth rate and exopolymer production ability of E. coli probably led this microorganism to outcompete the other two [average cell numbers (cells/cm(2)) for 48 h biofilm: E. coli 2,1 × 10(8) (± 2,4 × 10(7)); L. monocytogenes 6,8 × 10(7) (± 9,4 × 10(6)); and S. enterica 1,4 × 10(6) (± 4,1 × 10(5))]. This overgrowth was confirmed by CSLM, with two well-defined layers being easily identified: the top one with E. coli, and the bottom one with mixed regions of L. monocytogenes and S. enterica. While PNA FISH has been described previously for the qualitative study of biofilm populations, the present investigation demonstrates that it can also be used for the accurate quantification and spatial distribution of species in polymicrobial communities. Thus, it facilitates the understanding of interspecies interactions and how these are affected by changes in the surrounding environment.
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Keeling, Carisa; Niebuhr, Steven E; Acuff, Gary R; Dickson, James S
2009-04-01
Five Escherichia coli biotype I isolates were compared with E. coli O157:H7 under four common meat processing conditions. The processes that were evaluated were freezing, refrigerating, fermentation, and thermal inactivation. For each study, at least one surrogate organism was not statistically different when compared with E. coli O157:H7. However, the four studies did not consistently show the same isolate as having this agreement. The three studies that involved temperature as a method of controlling or reducing the E. coli population all had at least one possible surrogate in common. In the fermentation study, only one isolate (BAA-1429) showed no statistical difference when compared with E. coli O157:H7. However, the population reductions that were observed indicated the isolates BAA-1427 and BAA-1431 would overestimate the surviving E. coli O157:H7 population in a fermented summer sausage. When all of the data from all of the surrogates were examined, it was found that isolates BAA-1427, BAA-1429, and BAA-1430 would be good surrogates for all four of the processes that were examined in this study. There was no statistical difference noted between these three isolates and E. coli O157:H7 in the refrigeration study. These isolates resulted in smaller population reductions than did E. coli O157:H7 in the frozen, fermentation, and thermal inactivation studies. This would indicate that these isolates would overpredict the E. coli O157:H7 population in these three instances. This overprediction results in an additional margin of safety when using E. coli biotype 1 as a surrogate.
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Genetic Structure of Natural Populations of Escherichia coli in Wild Hosts on Different Continents
Souza, Valeria; Rocha, Martha; Valera, Aldo; Eguiarte, Luis E.
1999-01-01
Current knowledge of genotypic and phenotypic diversity in the species Escherichia coli is based almost entirely on strains recovered from humans or zoo animals. In this study, we analyzed a collection of 202 strains obtained from 81 mammalian species representing 39 families and 14 orders in Australia and the Americas, as well as several reference strains; we also included a strain from a reptile and 10 from different families of birds collected in Mexico. The strains were characterized genotypically by multilocus enzyme electrophoresis (MLEE) and phenotypically by patterns of sugar utilization, antibiotic resistance, and plasmid profile. MLEE analysis yielded an estimated genetic diversity (H) of 0.682 for 11 loci. The observed genetic diversity in this sample is the greatest yet reported for E. coli. However, this genetic diversity is not randomly distributed; geographic effects and host taxonomic group accounted for most of the genetic differentiation. The genetic relationship among the strains showed that they are more associated by origin and host order than is expected by chance. In a dendrogram, the ancestral cluster includes primarily strains from Australia and ECOR strains from groups B and C. The most differentiated E. coli in our analysis are strains from Mexican carnivores and strains from humans, including those in the ECOR group A. The kinds and numbers of sugars utilized by the strains varied by host taxonomic group and country of origin. Strains isolated from bats were found to exploit the greatest range of sugars, while those from primates utilized the fewest. Toxins are more frequent in strains from rodents from both continents than in any other taxonomic group. Strains from Mexican wild mammals were, on average, as resistant to antibiotics as strains from humans in cities. On average, the Australian strains presented a lower antibiotic resistance than the Mexican strains. However, strains recovered from hosts in cities carried significantly more plasmids than did strains isolated from wild mammals. Previous studies have shown that natural populations of E. coli harbor an extensive genetic diversity that is organized in a limited number of clones. However, knowledge of this worldwide bacterium has been limited. Here, we suggest that the strains from a wide range of wild hosts from different regions of the world are organized in an ecotypic structure where adaptation to the host plays an important role in the population structure. PMID:10427022
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Impact of enumeration method on diversity of Escherichia coli genotypes isolated from surface water.
Martin, E C; Gentry, T J
2016-11-01
There are numerous regulatory-approved Escherichia coli enumeration methods, but it is not known whether differences in media composition and incubation conditions impact the diversity of E. coli populations detected by these methods. A study was conducted to determine if three standard water quality assessments, Colilert ® , USEPA Method 1603, (modified mTEC) and USEPA Method 1604 (MI), detect different populations of E. coli. Samples were collected from six watersheds and analysed using the three enumeration approaches followed by E. coli isolation and genotyping. Results indicated that the three methods generally produced similar enumeration data across the sites, although there were some differences on a site-by-site basis. The Colilert ® method consistently generated the least diverse collection of E. coli genotypes as compared to modified mTEC and MI, with those two methods being roughly equal to each other. Although the three media assessed in this study were designed to enumerate E. coli, the differences in the media composition, incubation temperature, and growth platform appear to have a strong selective influence on the populations of E. coli isolated. This study suggests that standardized methods of enumeration and isolation may be warranted if researchers intend to obtain individual E. coli isolates for further characterization. This study characterized the impact of three USEPA-approved Escherichia coli enumeration methods on observed E. coli population diversity in surface water samples. Results indicated that these methods produced similar E. coli enumeration data but were more variable in the diversity of E. coli genotypes observed. Although the three methods enumerate the same species, differences in media composition, growth platform, and incubation temperature likely contribute to the selection of different cultivable populations of E. coli, and thus caution should be used when implementing these methods interchangeably for downstream applications which require cultivated isolates. © 2016 The Society for Applied Microbiology.
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Williamson, Deborah A; Lim, Alwin; Wiles, Siouxsie; Roberts, Sally A; Freeman, Joshua T
2013-08-21
Escherichia coli is a major human pathogen, both in community and healthcare settings. To date however, relatively few studies have defined the population burden of E. coli bloodstream infections. Such information is important in informing strategies around treatment and prevention of these serious infections. Against this background, we performed a retrospective, population-based observational study of all cases of E. coli bacteremia in patients presenting to our hospital between January 2005 and December 2011. Auckland District Health Board is a tertiary-level, university-affiliated institution serving a population of approximately 500,000, within a larger metropolitan population of 1.4 million. We identified all patients with an episode of bloodstream infection due to E. coli over the study period. A unique episode was defined as the first positive E. coli blood culture taken from the same patient within a thirty-day period. Standard definitions were used to classify episodes into community- or healthcare-associated E. coli bacteremia. Demographic information was obtained for all patients, including: age; gender; ethnicity; length of stay (days); requirement for intensive care admission and all-cause, in-patient mortality. A total of 1507 patients had a unique episode of E. coli bacteremia over the study period. The overall average annual incidence of E. coli bacteremia was 52 per 100,000 population, and was highest in the under one year and over 65-year age groups. When stratified by ethnicity, rates were highest in Pacific Peoples and Māori (83 and 62 per 100,000 population respectively). The incidence of community-onset E. coli bacteremia increased significantly over the study period. The overall in-hospital mortality rate was 9% (135/1507), and was significantly higher in patients who had a hospital-onset E. coli bacteremia. Our work provides valuable baseline data on the incidence of E. coli bacteremia in our locale. The incidence was higher that that described from other developed countries, with significant demographic variation, most notably in ethnic-specific incidence rates. Future work should assess the possible reasons for this disparity.
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2013-01-01
Background Escherichia coli is a major human pathogen, both in community and healthcare settings. To date however, relatively few studies have defined the population burden of E. coli bloodstream infections. Such information is important in informing strategies around treatment and prevention of these serious infections. Against this background, we performed a retrospective, population-based observational study of all cases of E. coli bacteremia in patients presenting to our hospital between January 2005 and December 2011. Methods Auckland District Health Board is a tertiary-level, university-affiliated institution serving a population of approximately 500,000, within a larger metropolitan population of 1.4 million. We identified all patients with an episode of bloodstream infection due to E. coli over the study period. A unique episode was defined as the first positive E. coli blood culture taken from the same patient within a thirty-day period. Standard definitions were used to classify episodes into community- or healthcare-associated E. coli bacteremia. Demographic information was obtained for all patients, including: age; gender; ethnicity; length of stay (days); requirement for intensive care admission and all-cause, in-patient mortality. Results A total of 1507 patients had a unique episode of E. coli bacteremia over the study period. The overall average annual incidence of E. coli bacteremia was 52 per 100,000 population, and was highest in the under one year and over 65-year age groups. When stratified by ethnicity, rates were highest in Pacific Peoples and Māori (83 and 62 per 100,000 population respectively). The incidence of community-onset E. coli bacteremia increased significantly over the study period. The overall in-hospital mortality rate was 9% (135/1507), and was significantly higher in patients who had a hospital-onset E. coli bacteremia. Conclusions Our work provides valuable baseline data on the incidence of E. coli bacteremia in our locale. The incidence was higher that that described from other developed countries, with significant demographic variation, most notably in ethnic-specific incidence rates. Future work should assess the possible reasons for this disparity. PMID:23964864
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Balasubramaniam, Krishna; Beisner, Brianne; Guan, Jiahui; Vandeleest, Jessica; Fushing, Hsieh; Atwill, Edward; McCowan, Brenda
2018-01-01
In group-living animals, heterogeneity in individuals' social connections may mediate the sharing of microbial infectious agents. In this regard, the genetic relatedness of individuals' commensal gut bacterium Escherichia coli may be ideal to assess the potential for pathogen transmission through animal social networks. Here we use microbial phylogenetics and population genetics approaches, as well as host social network reconstruction, to assess evidence for the contact-mediated sharing of E. coli among three groups of captively housed rhesus macaques ( Macaca mulatta ), at multiple organizational scales. For each group, behavioral data on grooming, huddling, and aggressive interactions collected for a six-week period were used to reconstruct social network communities via the Data Cloud Geometry (DCG) clustering algorithm. Further, an E. coli isolate was biochemically confirmed and genotypically fingerprinted from fecal swabs collected from each macaque. Population genetics approaches revealed that Group Membership, in comparison to intrinsic attributes like age, sex, and/or matriline membership of individuals, accounted for the highest proportion of variance in E. coli genotypic similarity. Social network approaches revealed that such sharing was evident at the community-level rather than the dyadic level. Specifically, although we found no links between dyadic E. coli similarity and social contact frequencies, similarity was significantly greater among macaques within the same social network communities compared to those across different communities. Moreover, tests for one of our study-groups confirmed that E. coli isolated from macaque rectal swabs were more genotypically similar to each other than they were to isolates from environmentally deposited feces. In summary, our results suggest that among frequently interacting, spatially constrained macaques with complex social relationships, microbial sharing via fecal-oral, social contact-mediated routes may depend on both individuals' direct connections and on secondary network pathways that define community structure. They lend support to the hypothesis that social network communities may act as bottlenecks to contain the spread of infectious agents, thereby encouraging disease control strategies to focus on multiple organizational scales. Future directions includeincreasing microbial sampling effort per individual to better-detect dyadic transmission events, and assessments of the co-evolutionary links between sociality, infectious agent risk, and host immune function.
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Anaerobically Grown Escherichia coli Has an Enhanced Mutation Rate and Distinct Mutational Spectra
Shewaramani, Sonal; Finn, Thomas J.; Kassen, Rees; Rainey, Paul B.
2017-01-01
Oxidative stress is a major cause of mutation but little is known about how growth in the absence of oxygen impacts the rate and spectrum of mutations. We employed long-term mutation accumulation experiments to directly measure the rates and spectra of spontaneous mutation events in Escherichia coli populations propagated under aerobic and anaerobic conditions. To detect mutations, whole genome sequencing was coupled with methods of analysis sufficient to identify a broad range of mutational classes, including structural variants (SVs) generated by movement of repetitive elements. The anaerobically grown populations displayed a mutation rate nearly twice that of the aerobic populations, showed distinct asymmetric mutational strand biases, and greater insertion element activity. Consistent with mutation rate and spectra observations, genes for transposition and recombination repair associated with SVs were up-regulated during anaerobic growth. Together, these results define differences in mutational spectra affecting the evolution of facultative anaerobes. PMID:28103245
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Maier, Bruce R.; Hentges, David J.
1972-01-01
Germfree mice were associated with selected species of human intestinal bacteria and then challenged with a streptomycin-resistant Shigella flexneri strain. Antagonism against Shigella was most pronounced in mice associated with Escherichia coli and least pronounced in mice associated with Bacteroides fragilis. A moderate degree of antagonism could be demonstrated in mice associated with either Streptococcus faecalis or Bifidobacterium adolescentis. Shigella persisted in the cecal contents of E. coli-associated mice at very low, stable levels. Shigella populations were reduced to levels below detection in the ceca of mice diassociated with E. coli and Bacteroides. Upon subsequent administration of streptomycin, Bacteroides disappeared from the ceca. The E. coli population was greatly reduced, and Shigella reappeared at very high population levels as an apparent recombinant which resembled E. coli biochemically. A streptomycin-resistant E. coli population subsequently emerged and became dominant in the ceca. Shigella concomitantly declined to levels below detection. PMID:4631914
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Matamoros, Sébastien; van Hattem, Jarne M; Arcilla, Maris S; Willemse, Niels; Melles, Damian C; Penders, John; Vinh, Trung Nguyen; Thi Hoa, Ngo; de Jong, Menno D; Schultsz, Constance
2017-11-10
To understand the dynamics behind the worldwide spread of the mcr-1 gene, we determined the population structure of Escherichia coli and of mobile genetic elements (MGEs) carrying the mcr-1 gene. After a systematic review of the literature we included 65 E. coli whole genome sequences (WGS), adding 6 recently sequenced travel related isolates, and 312 MLST profiles. We included 219 MGEs described in 7 Enterobacteriaceae species isolated from human, animal and environmental samples. Despite a high overall diversity, 2 lineages were observed in the E. coli population that may function as reservoirs of the mcr-1 gene, the largest of which was linked to ST10, a sequence type known for its ubiquity in human faecal samples and in food samples. No genotypic clustering by geographical origin or isolation source was observed. Amongst a total of 13 plasmid incompatibility types, the IncI2, IncX4 and IncHI2 plasmids accounted for more than 90% of MGEs carrying the mcr-1 gene. We observed significant geographical clustering with regional spread of IncHI2 plasmids in Europe and IncI2 in Asia. These findings point towards promiscuous spread of the mcr-1 gene by efficient horizontal gene transfer dominated by a limited number of plasmid incompatibility types.
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Analysis of co-evolving genes in campylobacter jejuni and C. coli
USDA-ARS?s Scientific Manuscript database
Background: The population structure of Campylobacter has been frequently studied by MLST, for which fragments of housekeeping genes are compared. We wished to determine if the used MLST genes are representative of the complete genome. Methods: A set of 1029 core gene families (CGF) was identifie...
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Laing, Chad R; Buchanan, Cody; Taboada, Eduardo N; Zhang, Yongxiang; Karmali, Mohamed A; Thomas, James E; Gannon, Victor Pj
2009-06-29
Many approaches have been used to study the evolution, population structure and genetic diversity of Escherichia coli O157:H7; however, observations made with different genotyping systems are not easily relatable to each other. Three genetic lineages of E. coli O157:H7 designated I, II and I/II have been identified using octamer-based genome scanning and microarray comparative genomic hybridization (mCGH). Each lineage contains significant phenotypic differences, with lineage I strains being the most commonly associated with human infections. Similarly, a clade of hyper-virulent O157:H7 strains implicated in the 2006 spinach and lettuce outbreaks has been defined using single-nucleotide polymorphism (SNP) typing. In this study an in silico comparison of six different genotyping approaches was performed on 19 E. coli genome sequences from 17 O157:H7 strains and single O145:NM and K12 MG1655 strains to provide an overall picture of diversity of the E. coli O157:H7 population, and to compare genotyping methods for O157:H7 strains. In silico determination of lineage, Shiga-toxin bacteriophage integration site, comparative genomic fingerprint, mCGH profile, novel region distribution profile, SNP type and multi-locus variable number tandem repeat analysis type was performed and a supernetwork based on the combination of these methods was produced. This supernetwork showed three distinct clusters of strains that were O157:H7 lineage-specific, with the SNP-based hyper-virulent clade 8 synonymous with O157:H7 lineage I/II. Lineage I/II/clade 8 strains clustered closest on the supernetwork to E. coli K12 and E. coli O55:H7, O145:NM and sorbitol-fermenting O157 strains. The results of this study highlight the similarities in relationships derived from multi-locus genome sampling methods and suggest a "common genotyping language" may be devised for population genetics and epidemiological studies. Future genotyping methods should provide data that can be stored centrally and accessed locally in an easily transferable, informative and extensible format based on comparative genomic analyses.
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Semanchek, J J; Golden, D A; Williams, R C
1999-03-01
The effect of atmospheric composition and storage temperature on growth and survival of uninjured and sublethally heat-injured Escherichia coli O157:H7, inoculated onto brain heart infusion agar containing 0.3% beef extract (BEM), was determined. BEM plates were packaged in barrier bags in air, 100% CO2, 100% N2, 20% CO2: 80% N2, and vacuum and were stored at 4, 10, and 37 degrees C for up to 20 days. Package atmosphere and inoculum status (i.e., uninjured or heat-injured) influenced (P < 0.01) growth and survival of E. coli O157:H7 stored at all test temperatures. Growth of heat-injured E. coli O157:H7 was slower (P < 0.01) than uninjured E. coli O157:H7 stored at 37 degrees C. At 37 degrees C, uninjured E. coli O157:H7 reached stationary phase growth earlier than heat-injured populations. Uninjured E. coli O157:H7 grew during 10 days of storage at 10 degrees C, while heat-injured populations declined during 20 days of storage at 10 degrees C. Uninjured E. coli O157:H7 stored at 10 degrees C reached stationary phase growth within approximately 10 days in all packaging atmospheres except CO2. Populations of uninjured and heat-injured E. coli O157:H7 declined throughout storage for 20 days at 4 degrees C. Survival of uninjured populations stored at 4 degrees C, as well as heat-injured populations stored at 4 and 10 degrees C, was enhanced in CO2 atmosphere. Survival of heat-injured E. coli O157:H7 at 4 and 10 degrees C was not different (P > 0.05). Uninjured and heat-injured E. coli O157:H7 are able to survive at low temperatures in the modified atmospheres used in this study.
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Chromosomal changes during experimental evolution in laboratory populations of Escherichia coli.
Bergthorsson, U; Ochman, H
1999-02-01
Short-term rates of chromosome evolution were analyzed in experimental populations of Escherichia coli B that had been propagated for 2,000 generations under four thermal regimens. Chromosome alterations were monitored in 24 independent populations by pulsed-field gel electrophoresis of DNA treated with five rare-cutting restriction enzymes. A total of 11 changes, 8 affecting chromosome size and 3 altering restriction sites, were observed in these populations, with none occurring in strains cultured at 37 degreesC. Considering the changes detected in these experimental populations, the rate of chromosome alteration of E. coli is estimated to be half of that observed in experimental populations of yeast.
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Environmental Escherichia coli: Ecology and public health implications - A review
Jang, Jeonghwan; Hur, Hor-Gil; Sadowsky, Michael J.; Byappanahalli, Muruleedhara; Yan, Tao; Ishii, Satoshi
2017-01-01
Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae. The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through feces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent fecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extra-intestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a fecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics provide the diversity and complexity of E. coli strains in various environments, affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments in regards to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia. The impact of environmental E. coli on water quality and public health is also discussed.
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Sokurenko, E V; Courtney, H S; Maslow, J; Siitonen, A; Hasty, D L
1995-01-01
Type 1 fimbriae are heteropolymeric surface organelles responsible for the D-mannose-sensitive (MS) adhesion of Escherichia coli. We recently reported that variation of receptor specificity of type 1 fimbriae can result solely from minor alterations in the structure of the gene for the FimH adhesin subunit. To further study the relationship between allelic variation of the fimH gene and adhesive properties of type 1 fimbriae, the fimH genes from five additional strains were cloned and used to complement the FimH deletion in E. coli KB18. When the parental and recombinant strains were tested for adhesion to immobilized mannan, a wide quantitative range in the ability of bacteria to adhere was noted. The differences in adhesion do not appear to be due to differences in the levels of fimbriation or relative levels of incorporation of FimH, because these parameters were similar in low-adhesion and high-adhesion strains. The nucleotide sequence for each of the fimH genes was determined. Analysis of deduced FimH sequences allowed identification of two sequence homology groups, based on the presence of Asn-70 and Ser-78 or Ser-70 and Asn-78 residues. The consensus sequences for each group conferred very low adhesion activity, and this low-adhesion phenotype predominated among a group of 43 fecal isolates. Strains isolated from a different host niche, the urinary tract, expressed type 1 fimbriae that conferred an increased level of adhesion. The results presented here strongly suggest that the quantitative variations in MS adhesion are due primarily to structural differences in the FimH adhesin. The observed differences in MS adhesion among populations of E. coli isolated from different host niches call attention to the possibility that phenotypic variants of FimH may play a functional role in populations dynamics. PMID:7601831
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Distribution of Diverse Escherichia coli between Cattle and Pasture.
NandaKafle, Gitanjali; Seale, Tarren; Flint, Toby; Nepal, Madhav; Venter, Stephanus N; Brözel, Volker S
2017-09-27
Escherichia coli is widely considered to not survive for extended periods outside the intestines of warm-blooded animals; however, recent studies demonstrated that E. coli strains maintain populations in soil and water without any known fecal contamination. The objective of this study was to investigate whether the niche partitioning of E. coli occurs between cattle and their pasture. We attempted to clarify whether E. coli from bovine feces differs phenotypically and genotypically from isolates maintaining a population in pasture soil over winter. Soil, bovine fecal, and run-off samples were collected before and after the introduction of cattle to the pasture. Isolates (363) were genotyped by uidA and mutS sequences and phylogrouping, and evaluated for curli formation (Rough, Dry, And Red, or RDAR). Three types of clusters emerged, viz. bovine-associated, clusters devoid of cattle isolates and representing isolates endemic to the pasture environment, and clusters with both. All isolates clustered with strains of E. coli sensu stricto, distinct from the cryptic species Clades I, III, IV, and V. Pasture soil endemic and bovine fecal populations had very different phylogroup distributions, indicating niche partitioning. The soil endemic population was largely comprised of phylogroup B1 and had a higher average RDAR score than other isolates. These results indicate the existence of environmental E. coli strains that are phylogenetically distinct from bovine fecal isolates, and that have the ability to maintain populations in the soil environment.
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Effect of high flow events on spatiotemporal variation of E. coli concentrations in creek sediments
USDA-ARS?s Scientific Manuscript database
Sediments can harbor large populations of Escherichia coli often times in greater amounts than the overlying water column. Resuspension of sediments during storm events causes the release of E. coli which drastically changes microbial water quality metrics. It is not well known how populations of E....
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CRISPR-based herd immunity can limit phage epidemics in bacterial populations
Geyrhofer, Lukas; Barton, Nicholas H
2018-01-01
Herd immunity, a process in which resistant individuals limit the spread of a pathogen among susceptible hosts has been extensively studied in eukaryotes. Even though bacteria have evolved multiple immune systems against their phage pathogens, herd immunity in bacteria remains unexplored. Here we experimentally demonstrate that herd immunity arises during phage epidemics in structured and unstructured Escherichia coli populations consisting of differing frequencies of susceptible and resistant cells harboring CRISPR immunity. In addition, we develop a mathematical model that quantifies how herd immunity is affected by spatial population structure, bacterial growth rate, and phage replication rate. Using our model we infer a general epidemiological rule describing the relative speed of an epidemic in partially resistant spatially structured populations. Our experimental and theoretical findings indicate that herd immunity may be important in bacterial communities, allowing for stable coexistence of bacteria and their phages and the maintenance of polymorphism in bacterial immunity. PMID:29521625
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Beisner, Brianne; Guan, Jiahui; Vandeleest, Jessica; Fushing, Hsieh; Atwill, Edward; McCowan, Brenda
2018-01-01
In group-living animals, heterogeneity in individuals’ social connections may mediate the sharing of microbial infectious agents. In this regard, the genetic relatedness of individuals’ commensal gut bacterium Escherichia coli may be ideal to assess the potential for pathogen transmission through animal social networks. Here we use microbial phylogenetics and population genetics approaches, as well as host social network reconstruction, to assess evidence for the contact-mediated sharing of E. coli among three groups of captively housed rhesus macaques (Macaca mulatta), at multiple organizational scales. For each group, behavioral data on grooming, huddling, and aggressive interactions collected for a six-week period were used to reconstruct social network communities via the Data Cloud Geometry (DCG) clustering algorithm. Further, an E. coli isolate was biochemically confirmed and genotypically fingerprinted from fecal swabs collected from each macaque. Population genetics approaches revealed that Group Membership, in comparison to intrinsic attributes like age, sex, and/or matriline membership of individuals, accounted for the highest proportion of variance in E. coli genotypic similarity. Social network approaches revealed that such sharing was evident at the community-level rather than the dyadic level. Specifically, although we found no links between dyadic E. coli similarity and social contact frequencies, similarity was significantly greater among macaques within the same social network communities compared to those across different communities. Moreover, tests for one of our study-groups confirmed that E. coli isolated from macaque rectal swabs were more genotypically similar to each other than they were to isolates from environmentally deposited feces. In summary, our results suggest that among frequently interacting, spatially constrained macaques with complex social relationships, microbial sharing via fecal-oral, social contact-mediated routes may depend on both individuals’ direct connections and on secondary network pathways that define community structure. They lend support to the hypothesis that social network communities may act as bottlenecks to contain the spread of infectious agents, thereby encouraging disease control strategies to focus on multiple organizational scales. Future directions includeincreasing microbial sampling effort per individual to better-detect dyadic transmission events, and assessments of the co-evolutionary links between sociality, infectious agent risk, and host immune function. PMID:29372120
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Eo, Yumi; Ma, Xiaochu; Stephens, Kristina; Jeong, Migyeong; Bentley, William E.
2018-01-01
Quorum sensing (QS), a bacterial process that regulates population-scale behavior, is mediated by small signaling molecules, called autoinducers (AIs), that are secreted and perceived, modulating a “collective” phenotype. Because the autoinducer AI-2 is secreted by a wide variety of bacterial species, its “perception” cues bacterial behavior. This response is mediated by the lsr (LuxS-regulated) operon that includes the AI-2 transporter LsrACDB and the kinase LsrK. We report that HPr, a phosphocarrier protein central to the sugar phosphotransferase system of Escherichia coli, copurifies with LsrK. Cocrystal structures of an LsrK/HPr complex were determined, and the effects of HPr and phosphorylated HPr on LsrK activity were assessed. LsrK activity is inhibited when bound to HPr, revealing new linkages between QS activity and sugar metabolism. These findings help shed new light on the abilities of bacteria to rapidly respond to changing nutrient levels at the population scale. They also suggest new means of manipulating QS activity among bacteria and within various niches. PMID:29868643
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Experimental evidence of the role of pores on movement and distribution of bacteria in soil
NASA Astrophysics Data System (ADS)
Kravchenko, Alexandra N.; Rose, Joan B.; Marsh, Terence L.; Guber, Andrey K.
2014-05-01
It has been generally recognized that micro-scale heterogeneity in soil environments can have a substantial effect on movement, fate, and survival of soil microorganisms. However, only recently the development of tools for micro-scale soil analyses, including X-ray computed micro-tomography (μ-CT), enabled quantitative analyses of these effects. The long-term goal of our work is to explore how differences in micro-scale characteristics of pore structures influence movement, spatial distribution patterns, and activities of soil microorganisms. Using X-ray μ-CT we found that differences in land use and management practices lead to development of contrasting patterns in pore size-distributions within intact soil aggregates. Then our experiments with Escherichia coli added to intact soil aggregates demonstrated that the differences in pore structures can lead to substantial differences in bacteria redistribution and movement within the aggregates. Specifically, we observed more uniform E.coli redistribution in aggregates with homogeneously spread pores, while heterogeneous pore structures resulted in heterogeneous E.coli patterns. Water flow driven by capillary forces through intact aggregate pores appeared to be the main contributor to the movement patterns of the introduced bacteria. Influence of pore structure on E.coli distribution within the aggregates further continued after the aggregates were subjected to saturated water flow. E. coli's resumed movement with saturated water flow and subsequent redistribution within the soil matrix was influenced by porosity, abundance of medium and large pores, pore tortuosity, and flow rates, indicating that greater flow accompanied by less convoluted pores facilitated E. coli transport within the intra-aggregate space. We also found that intra-aggregate heterogeneity of pore structures can have an effect on spatial distribution patterns of indigenous microbial populations. Preliminary analysis showed that in aggregates from an organic agricultural system with cover crops, characterized by greater intra-aggregate pore heterogeneity, bacteria of Actinobacteria and Firmicutes groups were more abundant in presence of large as compared to small pores. In contrast, no differences were observed in the aggregates from conventionally managed soil, overall characterized by homogeneous intra-aggregate pore patterns. Further research efforts are being directed towards quantification of the pore structure effects on activities and community composition of soil microorganisms.
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Distribution of Diverse Escherichia coli between Cattle and Pasture
NandaKafle, Gitanjali; Seale, Tarren; Flint, Toby; Nepal, Madhav; Venter, Stephanus N.; Brözel, Volker S.
2017-01-01
Escherichia coli is widely considered to not survive for extended periods outside the intestines of warm-blooded animals; however, recent studies demonstrated that E. coli strains maintain populations in soil and water without any known fecal contamination. The objective of this study was to investigate whether the niche partitioning of E. coli occurs between cattle and their pasture. We attempted to clarify whether E. coli from bovine feces differs phenotypically and genotypically from isolates maintaining a population in pasture soil over winter. Soil, bovine fecal, and run-off samples were collected before and after the introduction of cattle to the pasture. Isolates (363) were genotyped by uidA and mutS sequences and phylogrouping, and evaluated for curli formation (Rough, Dry, And Red, or RDAR). Three types of clusters emerged, viz. bovine-associated, clusters devoid of cattle isolates and representing isolates endemic to the pasture environment, and clusters with both. All isolates clustered with strains of E. coli sensu stricto, distinct from the cryptic species Clades I, III, IV, and V. Pasture soil endemic and bovine fecal populations had very different phylogroup distributions, indicating niche partitioning. The soil endemic population was largely comprised of phylogroup B1 and had a higher average RDAR score than other isolates. These results indicate the existence of environmental E. coli strains that are phylogenetically distinct from bovine fecal isolates, and that have the ability to maintain populations in the soil environment. PMID:28747587
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Sterilization by Cooling in Isochoric Conditions: The Case of Escherichia coli
Salinas-Almaguer, Samuel; Angulo-Sherman, Abril; Sierra-Valdez, Francisco Javier; Mercado-Uribe, Hilda
2015-01-01
High hydrostatic pressure (HHP) affects the structure, metabolism and survival of micro-organisms including bacteria. For this reason HHP is a promising treatment in the food industry. The aim of this work is to evaluate the effect of high pressure, under isochoric cooling conditions, on Escherichia coli, where such high pressure develops due to the fact water cannot expand. We combine survival curves obtained by spectrophotometry and images of atomic force microscopy in this study. Our results show that cooling at -20 and -30°C leads to a partial destruction of a Escherichia coli population. However, cooling at -15°C causes a total extermination of bacteria. This intriguing result is explained by the phase diagram of water. In the first case, the simultaneous formation of ice III and ice Ih crystals provides a safe environment for bacteria. In the second case (-15°C) Escherichia coli remains in a metastable and amorphous free-of-crystals liquid subjected to high pressure. Our work is the first experimental study carried out to inactivate Escherichia coli under isochoric cooling conditions. Unlike HHP, which is based on the application of an external load to augment the pressure, this technique only requires cooling. The method could be used for annihilation of other Escherichia coli strains and perhaps other micro-organisms. PMID:26480032
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Ingle, Danielle J; Valcanis, Mary; Kuzevski, Alex; Tauschek, Marija; Inouye, Michael; Stinear, Tim; Levine, Myron M; Robins-Browne, Roy M; Holt, Kathryn E
2016-07-01
The lipopolysaccharide (O) and flagellar (H) surface antigens of Escherichia coli are targets for serotyping that have traditionally been used to identify pathogenic lineages. These surface antigens are important for the survival of E. coli within mammalian hosts. However, traditional serotyping has several limitations, and public health reference laboratories are increasingly moving towards whole genome sequencing (WGS) to characterize bacterial isolates. Here we present a method to rapidly and accurately serotype E. coli isolates from raw, short read WGS data. Our approach bypasses the need for de novo genome assembly by directly screening WGS reads against a curated database of alleles linked to known and novel E. coli O-groups and H-types (the EcOH database) using the software package srst2. We validated the approach by comparing in silico results for 197 enteropathogenic E. coli isolates with those obtained by serological phenotyping in an independent laboratory. We then demonstrated the utility of our method to characterize isolates in public health and clinical settings, and to explore the genetic diversity of >1500 E. coli genomes from multiple sources. Importantly, we showed that transfer of O- and H-antigen loci between E. coli chromosomal backbones is common, with little evidence of constraints by host or pathotype, suggesting that E. coli ' strain space' may be virtually unlimited, even within specific pathotypes. Our findings show that serotyping is most useful when used in combination with strain genotyping to characterize microevolution events within an inferred population structure.
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Wang, Liyun; Keatch, Robert; Zhao, Qi; Wright, John A; Bryant, Clare E; Redmann, Anna L; Terentjev, Eugene M
2018-01-12
Biofilm formation on abiotic surfaces in food and medical industry can cause severe contamination and infection, yet how biological and physical factors determine cellular architecture of early biofilms and bacterial behavior of the constituent cells remains largely unknown. In this study we examine the specific role of type-I fimbriae in nascent stages of biofilm formation and the response of micro-colonies to environmental flow shear at single-cell resolution. The results show that type-I fimbriae are not required for reversible adhesion from plankton, but critical for irreversible adhesion of Escherichia coli ( E.coli ) MG1655 forming biofilms on polyethylene terephthalate (PET) surfaces. Besides establishing a firm cell-surface contact, the irreversible adhesion seems necessary to initiate the proliferation of E.coli on the surface. After application of shear stress, bacterial retention is dominated by the 3D architecture of colonies independent of the population and the multi-layered structure could protect the embedded cells from being insulted by fluid shear, while cell membrane permeability mainly depends on the biofilm population and the duration time of the shear stress. Importance Bacterial biofilms could lead to severe contamination problems in medical devices and food processing equipment. However, biofilms are usually studied at a rough macroscopic level, thus little is known about how individual bacterial behavior within biofilms and multicellular architecture are influenced by bacterial appendages (e.g. pili/fimbriae) and environmental factors during early biofilm formation. We apply Confocal Laser Scanning Microscopy (CLSM) to visualize E.coli micro-colonies at single-cell resolution. Our findings suggest that type-I fimbriae are vital to the initiation of bacterial proliferation on surfaces and that the responses of biofilm architecture and cell membrane permeability of constituent bacteria to fluid shear stress are different, which are respectively regulated by the 3D morphology and the population of micro-colonies. Copyright © 2018 American Society for Microbiology.
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Dying for Good: Virus-Bacterium Biofilm Co-evolution Enhances Environmental Fitness
DOE Office of Scientific and Technical Information (OSTI.GOV)
Jin, Hongjun; Squier, Thomas C.; Long, Philip E.
Commonly used in biotechnology applications, filamentous M13 phage are non-lytic viruses that infect E. coli and other bacteria, with the potential to promote horizontal gene transfer in natural populations with synthetic biology implications for engineering community systems. Using the E. coli strain TG1, we have investigated how a selective pressure involving elevated levels of toxic chromate, mimicking that found in some superfund sites, alters population dynamics following infection with either wild-type M13 phage or an M13-phage encoding a chromate reductase (Gh-ChrR) capable of the reductive immobilization of chromate (ie, M13-phageGh-ChrR). In the absence of a selective pressure, M13-phage infection resultsmore » in a reduction in bacterial growth rate; in comparison, in the presence of chromate there are substantial increases in both cellular killing and biomass formation following infection of E. coli strain TG1with M13-phageGh-ChrR that is dependent on chromate-reductase activity. These results are discussed in terms of community structures that facilitate lateral gene transfer of beneficial traits that enhance phage replication, infectivity, and stability against environmental change.« less
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Environmental Escherichia coli: ecology and public health implications-a review.
Jang, J; Hur, H-G; Sadowsky, M J; Byappanahalli, M N; Yan, T; Ishii, S
2017-09-01
Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae. The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through faeces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent faecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extraintestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a faecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics revealed the diversity and complexity of E. coli strains in various environments, which are affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments with regard to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia. The impact of environmental E. coli on water quality and public health is also discussed. © 2017 The Society for Applied Microbiology.
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Bok, Ewa; Mazurek, Justyna; Stosik, Michał; Wojciech, Magdalena; Baldy-Chudzik, Katarzyna
2015-01-19
Cattle is a reservoir of potentially pathogenic E. coli, bacteria that can represent a significant threat to public health, hence it is crucial to monitor the prevalence of the genetic determinants of virulence and antimicrobial resistance among the E. coli population. The aim of this study was the analysis of the phylogenetic structure, distribution of virulence factors (VFs) and prevalence of antimicrobial resistance among E. coli isolated from two groups of healthy cattle: 50 cows housed in the conventional barn (147 isolates) and 42 cows living on the ecological pasture (118 isolates). The phylogenetic analysis, identification of VFs and antimicrobial resistance genes were based on either multiplex or simplex PCR. The antimicrobial susceptibilities of E. coli were examined using the broth microdilution method. Two statistical approaches were used to analyse the results obtained for two groups of cattle. The relations between the dependent (VFs profiles, antibiotics) and the independent variables were described using the two models. The mixed logit model was used to characterise the prevalence of the analysed factors in the sets of isolates. The univariate logistic regression model was used to characterise the prevalence of these factors in particular animals. Given each model, the odds ratio (OR) and the 95% confidence interval for the population were estimated. The phylogroup B1 was predominant among isolates from beef cattle, while the phylogroups A, B1 and D occurred with equal frequency among isolates from dairy cattle. The frequency of VFs-positive isolates was significantly higher among isolates from beef cattle. E. coli from dairy cattle revealed significantly higher resistance to antibiotics. Some of the tested resistance genes were present among isolates from dairy cattle. Our study showed that the habitat and diet may affect the genetic diversity of commensal E. coli in the cattle. The results suggest that the ecological pasture habitat is related to the increased spreading rate of the VFs, while the barn habitat is characterised by the higher levels of antimicrobial resistance among E. coli.
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Bok, Ewa; Mazurek, Justyna; Stosik, Michał; Wojciech, Magdalena; Baldy-Chudzik, Katarzyna
2015-01-01
Cattle is a reservoir of potentially pathogenic E. coli, bacteria that can represent a significant threat to public health, hence it is crucial to monitor the prevalence of the genetic determinants of virulence and antimicrobial resistance among the E. coli population. The aim of this study was the analysis of the phylogenetic structure, distribution of virulence factors (VFs) and prevalence of antimicrobial resistance among E. coli isolated from two groups of healthy cattle: 50 cows housed in the conventional barn (147 isolates) and 42 cows living on the ecological pasture (118 isolates). The phylogenetic analysis, identification of VFs and antimicrobial resistance genes were based on either multiplex or simplex PCR. The antimicrobial susceptibilities of E. coli were examined using the broth microdilution method. Two statistical approaches were used to analyse the results obtained for two groups of cattle. The relations between the dependent (VFs profiles, antibiotics) and the independent variables were described using the two models. The mixed logit model was used to characterise the prevalence of the analysed factors in the sets of isolates. The univariate logistic regression model was used to characterise the prevalence of these factors in particular animals. Given each model, the odds ratio (OR) and the 95% confidence interval for the population were estimated. The phylogroup B1 was predominant among isolates from beef cattle, while the phylogroups A, B1 and D occurred with equal frequency among isolates from dairy cattle. The frequency of VFs-positive isolates was significantly higher among isolates from beef cattle. E. coli from dairy cattle revealed significantly higher resistance to antibiotics. Some of the tested resistance genes were present among isolates from dairy cattle. Our study showed that the habitat and diet may affect the genetic diversity of commensal E. coli in the cattle. The results suggest that the ecological pasture habitat is related to the increased spreading rate of the VFs, while the barn habitat is characterised by the higher levels of antimicrobial resistance among E. coli. PMID:25607605
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Diarrheagenic Escherichia coli in Children from Costa Rica
Pérez, Cristian; Gómez-Duarte, Oscar G.; Arias, María L.
2010-01-01
More than 5,000 diarrheal cases per year receive medical care at the National Children's Hospital of Costa Rica, and nearly 5% of them require hospitalization. A total of 173 Escherichia coli strains isolated from children with diarrhea were characterized at the molecular, serologic, and phenotypic level. Multiplex and duplex polymerase chain reactions were used to detect the six categories of diarrheagenic E. coli. Thirty percent (n = 52) of the strains were positive, indicating a high prevalence among the pediatric population. Enteropathogenic E. coli and enteroinvasive E. coli pathotypes were the most prevalent (21% and 19%, respectively). Pathogenic strains were distributed among the four E. coli phylogenetic groups A, B1, B2, and D, with groups A and B1 the most commonly found. This study used molecular typing to evaluate the prevalence of diarrheagenic E. coli reported in Costa Rica and demonstrated the importance of these pathotypes in the pediatric population. PMID:20682870
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Echeverria, P; Mejia, P A; Duangmani, C
1981-01-01
Hostesses and restaurant employees in the Philippines were studied to determine whether an increased use of antibiotics was associated with a higher point prevalence of enterotoxigenic Escherichia coli. Of 1,030 hostesses and 628 restaurant employees, 28 and 4%, respectively, said that they had taken antibiotics within a week of being cultured (P less than 0.001). Of hostesses and restaurant employees, 10% (103 of 1,030) and 2% (14 of 628), respectively, had antibiotics detectable in their urine (P less than 0.001). Enterotoxigenic E. coli strains were isolated from 1.2% (12 of 1,030) of hostesses and 1.7% (11 of 628) of restaurant employees. In both populations, enterotoxigenic E. coli strains were never found in subjects who had antibacterial activity in their urine. Although resistance to two or more antibiotics was found more frequently in E. coli isolated from hostesses than in that isolated from restaurant workers (48 versus 33%; P less than 0.01), antibiotic selective pressure did not increase the prevalence of enterotoxigenic E. coli in these two populations. PMID:6751218
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Echeverria, P; Mejia, P A; Duangmani, C
1981-02-01
Hostesses and restaurant employees in the Philippines were studied to determine whether an increased use of antibiotics was associated with a higher point prevalence of enterotoxigenic Escherichia coli. Of 1,030 hostesses and 628 restaurant employees, 28 and 4%, respectively, said that they had taken antibiotics within a week of being cultured (P less than 0.001). Of hostesses and restaurant employees, 10% (103 of 1,030) and 2% (14 of 628), respectively, had antibiotics detectable in their urine (P less than 0.001). Enterotoxigenic E. coli strains were isolated from 1.2% (12 of 1,030) of hostesses and 1.7% (11 of 628) of restaurant employees. In both populations, enterotoxigenic E. coli strains were never found in subjects who had antibacterial activity in their urine. Although resistance to two or more antibiotics was found more frequently in E. coli isolated from hostesses than in that isolated from restaurant workers (48 versus 33%; P less than 0.01), antibiotic selective pressure did not increase the prevalence of enterotoxigenic E. coli in these two populations.
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Ukuku, Dike O; Mukhopadhyay, Sudarsan; Onwulata, Charles
2013-01-01
Previously, we reported inactivation of Escherichia coli populations in corn product (CP) and whey protein product (WPP) extruded at different temperatures. However, information on the effect of storage temperatures on injured bacterial populations was not addressed. In this study, the effect of storage temperatures on the survival and recovery of thermal death time (TDT) disks and extrusion injured E. coli populations in CP and WPP was investigated. CP and WPP inoculated with E. coli bacteria at 7.8 log(10) CFU/g were conveyed separately into the extruder with a series 6300 digital type T-35 twin screw volumetric feeder set at a speed of 600 rpm and extruded at 35°C, 55°C, 75°C, and 95°C, or thermally treated with TDT disks submerged into water bath set at 35°C, 55°C, 75°C, and 95°C for 120 s. Populations of surviving bacteria including injured cells in all treated samples were determined immediately and every day for 5 days, and up to 10 days for untreated samples during storage at 5°C, 10°C, and 23°C. TDT disks treatment at 35°C and 55°C did not cause significant changes in the population of the surviving bacteria including injured populations. Extrusion treatment at 35°C and 55°C led to significant (p<0.05) reduction of E. coli populations in WPP as opposed to CP. The injured populations among the surviving E. coli cells in CP and WPP extruded at all temperatures tested were inactivated during storage. Population of E. coli inactivated in samples extruded at 75°C was significantly (p<0.05) different than 55°C during storage. Percent injured population could not be determined in samples extruded at 95°C due to absence of colony forming units on the agar plates. The results of this study showed that further inactivation of the injured populations occurred during storage at 5°C for 5 days suggesting the need for immediate storage of 75°C extruded CP and WPP at 5°C for at least 24 h to enhance their microbial safety.
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Tomás-Callejas, Alejandro; López-Velasco, Gabriela; Camacho, Alex B; Artés, Francisco; Artés-Hernández, Francisco; Suslow, Trevor V
2011-12-02
Escherichia coli O157:H7 has been associated in multiple outbreaks linked to the consumption of whole produce and fresh-cut leafy vegetables. However, plant-based foods had not been traditionally recognized as a host for enteric pathogens until the elevated incidence of produce-related outbreaks became apparent. The survival dynamics of two cocktails of generic E. coli (environmental water, plant and soil isolates) and E. coli O157:H7 within the phyllosphere of Mizuna, Red Chard and Tatsoi during their production, harvest, minimal processing, packaging and storage over two greenhouse production cycles were studied. Genotyping of applied generic E. coli strains to evaluate their comparative survival and relative abundance in the phyllosphere by REP-PCR is also reported. The Mizuna, Red Chard and Tatsoi shoots were grown under standard greenhouse conditions and fertility management. Both E. coli cocktails were spray-inoculated separately and determined to result in an initial mean population density of log 4.2 CFU/cm². Leaves were harvested as mini-greens approximating commercial maturity, minimally processed in a model washing system treated with 3 mg/L of ClO₂ and stored for 7 days at 5 °C. Rapid decline of generic E. coli and E. coli O157:H7 populations was observed for all plant types regardless of the leaf age at the time of inoculation and the irrigation type across both seasonal growth cycle trials. The decline rate of the surviving populations for the fall season was slower than for the summer season. The minimal processing with 3 mg/L of ClO₂ was not sufficient to fully disinfect the inoculated leaves prior to packaging and refrigerated storage. Viable populations of E. coli and E. coli O157:H7 were confirmed throughout storage, including the final time point at the end of acceptable visual leaf quality. In this study, the ability of low populations of E. coli to survive during production and postharvest operations in selected mini-greens has been demonstrated. However, further field-based trials are needed to expand understanding of the post-contamination fate of enteric bacterial pathogens on leafy vegetables. In summary, this research work provides baseline data upon which to develop food safety preventive control guidance during the production and minimal processing of these crops. Copyright © 2011 Elsevier B.V. All rights reserved.
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Sterilization effects of atmospheric cold plasma brush
NASA Astrophysics Data System (ADS)
Yu, Q. S.; Huang, C.; Hsieh, F.-H.; Huff, H.; Duan, Yixiang
2006-01-01
This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0×104-1.0×105 Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and/or Ar +O2 plasmas. A complete kill of the Micrococcus luteus required about 3 min argon plasma exposures. With oxygen addition into the argon plasma gas streams, a complete kill of the bacteria needed only less than 1 min plasma exposure for Micrococcus luteus and about 2 min exposure for Escherichia coli. The plasma treatment effects on the different bacteria cell structures were examined using scanning electron microscopy.
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ESBL-producing Escherichia coli in Swedish gulls-A case of environmental pollution from humans?
Atterby, Clara; Börjesson, Stefan; Ny, Sofia; Järhult, Josef D; Byfors, Sara; Bonnedahl, Jonas
2017-01-01
ESBL-producing bacteria are present in wildlife and the environment might serve as a resistance reservoir. Wild gulls have been described as frequent carriers of ESBL-producing E. coli strains with genotypic characteristics similar to strains found in humans. Therefore, potential dissemination of antibiotic resistance genes and bacteria between the human population and wildlife need to be further investigated. Occurrence and characterization of ESBL-producing E. coli in Swedish wild gulls were assessed and compared to isolates from humans, livestock and surface water collected in the same country and similar time-period. Occurrence of ESBL-producing E. coli in Swedish gulls is about three times higher in gulls compared to Swedish community carriers (17% versus 5%) and the genetic characteristics of the ESBL-producing E. coli population in Swedish wild gulls and Swedish human are similar. ESBL-plasmids IncF- and IncI1-type carrying ESBL-genes blaCTX-M-15 or blaCTX-M-14 were most common in isolates from both gulls and humans, but there was limited evidence of clonal transmission. Isolates from Swedish surface water harbored similar genetic characteristics, which highlights surface waters as potential dissemination routes between wildlife and the human population. Even in a low-prevalence country such as Sweden, the occurrence of ESBL producing E. coli in wild gulls and the human population appears to be connected and the occurrence of ESBL-producing E. coli in Swedish gulls is likely a case of environmental pollution.
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Janisiewicz, W. J.; Conway, W. S.; Brown, M. W.; Sapers, G. M.; Fratamico, P.; Buchanan, R. L.
1999-01-01
Pathogenic Escherichia coli O157:H7, as well as nonpathogenic strains ATCC 11775 and ATCC 23716, grew exponentially in wounds on Golden Delicious apple fruit. The exponential growth occurred over a longer time period on fruit inoculated with a lower concentration of the bacterium than on fruit inoculated with a higher concentration. The bacterium reached the maximum population supported in the wounds regardless of the initial inoculum concentrations. Populations of E. coli O157:H7 in various concentrations of sterilized apple juice and unsterilized cider declined over time and declined more quickly in diluted juice and cider. The decline was greater in the unsterilized cider than in juice, which may have resulted from the interaction of E. coli O157:H7 with natural populations of yeasts that increased with time. Experiments on the transmission of E. coli by fruit flies, collected from a compost pile of decaying apples and peaches, were conducted with strain F-11775, a fluorescent transformant of nonpathogenic E. coli ATCC 11775. Fruit flies were easily contaminated externally and internally with E. coli F-11775 after contact with the bacterium source. The flies transmitted this bacterium to uncontaminated apple wounds, resulting in a high incidence of contaminated wounds. Populations of the bacterium in apple wounds increased significantly during the first 48 h after transmission. Further studies under commercial conditions are necessary to confirm these findings. PMID:9872751
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ESBL-producing Escherichia coli in Swedish gulls—A case of environmental pollution from humans?
Atterby, Clara; Ny, Sofia; Järhult, Josef D.; Byfors, Sara; Bonnedahl, Jonas
2017-01-01
ESBL-producing bacteria are present in wildlife and the environment might serve as a resistance reservoir. Wild gulls have been described as frequent carriers of ESBL-producing E. coli strains with genotypic characteristics similar to strains found in humans. Therefore, potential dissemination of antibiotic resistance genes and bacteria between the human population and wildlife need to be further investigated. Occurrence and characterization of ESBL-producing E. coli in Swedish wild gulls were assessed and compared to isolates from humans, livestock and surface water collected in the same country and similar time-period. Occurrence of ESBL-producing E. coli in Swedish gulls is about three times higher in gulls compared to Swedish community carriers (17% versus 5%) and the genetic characteristics of the ESBL-producing E. coli population in Swedish wild gulls and Swedish human are similar. ESBL-plasmids IncF- and IncI1-type carrying ESBL-genes blaCTX-M-15 or blaCTX-M-14 were most common in isolates from both gulls and humans, but there was limited evidence of clonal transmission. Isolates from Swedish surface water harbored similar genetic characteristics, which highlights surface waters as potential dissemination routes between wildlife and the human population. Even in a low-prevalence country such as Sweden, the occurrence of ESBL producing E. coli in wild gulls and the human population appears to be connected and the occurrence of ESBL-producing E. coli in Swedish gulls is likely a case of environmental pollution. PMID:29284053
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Cultural and environmental factors affecting the longevity of Escherichia coli in Histosols.
Tate, R L
1978-05-01
The survival of Escherichia coli in organic soils (Histosols) was examined. The death rate of this organism in Pahokee muck was less than that observed in Pompano fine sand. The number of viable E. coli cells found in the muck was approximately threefold greater than that found in the sand following 8 days of incubation. The initial population of the coliform affected the death rate. The rate of loss of viability varied 100-fold when the population size decreased from 2.5 x 10(7) to 3.4 x 10(4). Other factors affecting the viability of E. coli in muck were aerobic versus anaerobic growth of the organism and moist versus flooded conditions in the soil. The greatest survival of the coliform was noted with anaerobically grown cells amended to flooded soil. That the observed decrease in E. coli viability in soil was the result of biotic factors was demonstrated with amendment of sterile soil with E. coli. When 1.1 x 10(5) bacteria per g of soil were added to sterile muck, a population of 3.0 x 10(7) organisms per g of soil developed over a 10-day period. The role of the protozoa in eradication of the coliform from the muck was indicated by a sixfold increase in the protozoan population in natural soil amended with E. coli. Higher organic matter content in a Histosol compared with a mineral soil resulted in an increased survival of the fecal coliforms. Biotic factors are instrumental in the decline in coliform populations, but the potential for growth of the coliform in the organic soil could extend the survival of the organism.
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Cultural and Environmental Factors Affecting the Longevity of Escherichia coli in Histosols †
Tate, Robert L.
1978-01-01
The survival of Escherichia coli in organic soils (Histosols) was examined. The death rate of this organism in Pahokee muck was less than that observed in Pompano fine sand. The number of viable E. coli cells found in the muck was approximately threefold greater than that found in the sand following 8 days of incubation. The initial population of the coliform affected the death rate. The rate of loss of viability varied 100-fold when the population size decreased from 2.5 × 107 to 3.4 × 104. Other factors affecting the viability of E. coli in muck were aerobic versus anaerobic growth of the organism and moist versus flooded conditions in the soil. The greatest survival of the coliform was noted with anaerobically grown cells amended to flooded soil. That the observed decrease in E. coli viability in soil was the result of biotic factors was demonstrated with amendment of sterile soil with E. coli. When 1.1 × 105 bacteria per g of soil were added to sterile muck, a population of 3.0 × 107 organisms per g of soil developed over a 10-day period. The role of the protozoa in eradication of the coliform from the muck was indicated by a sixfold increase in the protozoan population in natural soil amended with E. coli. Higher organic matter content in a Histosol compared with a mineral soil resulted in an increased survival of the fecal coliforms. Biotic factors are instrumental in the decline in coliform populations, but the potential for growth of the coliform in the organic soil could extend the survival of the organism. PMID:350158
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Sequential establishment of stripe patterns in an expanding cell population.
Liu, Chenli; Fu, Xiongfei; Liu, Lizhong; Ren, Xiaojing; Chau, Carlos K L; Li, Sihong; Xiang, Lu; Zeng, Hualing; Chen, Guanhua; Tang, Lei-Han; Lenz, Peter; Cui, Xiaodong; Huang, Wei; Hwa, Terence; Huang, Jian-Dong
2011-10-14
Periodic stripe patterns are ubiquitous in living organisms, yet the underlying developmental processes are complex and difficult to disentangle. We describe a synthetic genetic circuit that couples cell density and motility. This system enabled programmed Escherichia coli cells to form periodic stripes of high and low cell densities sequentially and autonomously. Theoretical and experimental analyses reveal that the spatial structure arises from a recurrent aggregation process at the front of the continuously expanding cell population. The number of stripes formed could be tuned by modulating the basal expression of a single gene. The results establish motility control as a simple route to establishing recurrent structures without requiring an extrinsic pacemaker.
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McEgan, Rachel; Danyluk, Michelle D
2015-05-01
This study evaluated the efficacy of aqueous (aQUAT) and isopropyl alcohol-based quaternary ammonium (ipQUAT) sanitizers for reducing Salmonella spp., Escherichia coli O157:H7, or Listeria monocytogenes populations on peanut and pistachio shell pieces. Inoculated nutshells were mixed with QUAT sanitizers, water, or 70% ethanol and enumerated immediately or after incubation at 30 °C for 48 h. None of the treatments had any immediate effect on Salmonella or E. coli O157:H7 populations on the peanut or pistachio shells. L. monocytogenes populations declined immediately on the peanut and pistachio shells treated with aQUAT or ipQUAT. After incubation, Salmonella and E. coli O157:H7 populations increased significantly on the water- or aQUAT-treated peanut and pistachio shells. L. monocytogenes populations also increased significantly on the water- or aQUAT-treated peanut shells, but levels did not change on the water-treated pistachio shells and levels were just above the limit of detection on the aQUAT-treated pistachio shells. After treatment with ipQUAT and 48-h incubation, Salmonella and E. coli O157:H7 populations decreased to or below the limit of detection on both shell types; L. monocytogenes populations remained at or below the limit of detection on both shell types. Copyright © 2014 Elsevier Ltd. All rights reserved.
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USDA-ARS?s Scientific Manuscript database
In a previous study, we reported viability loss of Escherichia coli populations in corn (CP) and whey protein products (WPP) extruded at different temperatures. However, information on the effect of storage temperatures on injured bacterial populations was not addressed. The objective of this study ...
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Nanocomposite copolymer thin-film sensor for detection of escherichia coli
NASA Astrophysics Data System (ADS)
Mathur, Prafull; Misra, S. C. K.; Yadav, Maneesha; Bawa, S. S.; Gupta, A. K.
2006-01-01
The majority of human diseases associated with microbial contaminated water are infectious in nature and the associated pathogen includes bacteria, fungi, viruses and protozoa. Water contaminated with bacteria can cause a number of food-borne and water-borne diseases. The waterborne transmission is highly effective means of spreading infectious agents to a large portion of population; this includes water and milk too. Waterborne infections are recognized as resulting either from ingestion of contaminated water or ice, food items, which have, came into contact with microbial contaminated water (occurring through bathing and recreational activities) etc. The detection of E. coli in food and water is normally carried out by culturing methods, which normally take 3-6 days, These methods are complicated and time-consuming in spite of their correctness, and cannot easily meet inspection demands on E. coli. Hence, an establishment of rapid detection methods for E. coli is strongly required. We have developed highly sensitive and cost effective solid sate sensors prepared from vacuum evaporated thin films of nanocomposite copolymer detection of presence of E. coli vapors in the air within 20 seconds. These sensors operate at room temperature. The preparation, optical, electrical, and structural characterization and behavioral acceptance test on the microorganism sensing properties of these sensors are reported here.
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High dietary zinc feeding promotes persistence of multi-resistant E. coli in the swine gut.
Ciesinski, Lisa; Guenther, Sebastian; Pieper, Robert; Kalisch, Martin; Bednorz, Carmen; Wieler, Lothar H
2018-01-01
High levels of zinc oxide are used frequently as feed additive in pigs to improve gut health and growth performance and are still suggested as an alternative to antimicrobial growth promoters. However, we have recently described an increase of multi-resistant E. coli in association to zinc feeding in piglets. This previous study focused on clonal diversity of E. coli, observing the effect on multi-resistant strains by chance. To shed further light into this highly important topic and falsify our previous findings, we performed a zinc pig feeding trial where we specifically focused on in-depth analysis of antimicrobial resistant E. coli. Under controlled experimental conditions, piglets were randomly allocated to a high dietary zinc (zinc group) and a background zinc feeding group (control group). At different ages samples were taken from feces, digesta, and mucosa and absolute E. coli numbers were determined. A total of 2665 E. coli isolates were than phenotypically tested for antimicrobial resistance and results were confirmed by minimum inhibitory concentration testing for random samples. In piglets fed with high dietary zinc, we detected a substantial increase of multi-resistant E. coli in all gut habitats tested, ranging from 28.9-30.2% multi-resistant E. coli compared to 5.8-14.0% in the control group. This increase was independent of the total number of E. coli. Interestingly, the total amount of the E. coli population decreased over time. Thus, the increase of the multi-resistant E. coli populations seems to be linked with persistence of the resistant population, caused by the influence of high dietary zinc feeding. In conclusion, these findings corroborate our previous report linking high dietary zinc feeding of piglets with the occurrence of antimicrobial resistant E. coli and therefore question the feeding of high dietary zinc oxide as alternative to antimicrobial growth promoters.
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High dietary zinc feeding promotes persistence of multi-resistant E. coli in the swine gut
Guenther, Sebastian; Pieper, Robert; Kalisch, Martin; Bednorz, Carmen; Wieler, Lothar H.
2018-01-01
High levels of zinc oxide are used frequently as feed additive in pigs to improve gut health and growth performance and are still suggested as an alternative to antimicrobial growth promoters. However, we have recently described an increase of multi-resistant E. coli in association to zinc feeding in piglets. This previous study focused on clonal diversity of E. coli, observing the effect on multi-resistant strains by chance. To shed further light into this highly important topic and falsify our previous findings, we performed a zinc pig feeding trial where we specifically focused on in-depth analysis of antimicrobial resistant E. coli. Under controlled experimental conditions, piglets were randomly allocated to a high dietary zinc (zinc group) and a background zinc feeding group (control group). At different ages samples were taken from feces, digesta, and mucosa and absolute E. coli numbers were determined. A total of 2665 E. coli isolates were than phenotypically tested for antimicrobial resistance and results were confirmed by minimum inhibitory concentration testing for random samples. In piglets fed with high dietary zinc, we detected a substantial increase of multi-resistant E. coli in all gut habitats tested, ranging from 28.9–30.2% multi-resistant E. coli compared to 5.8–14.0% in the control group. This increase was independent of the total number of E. coli. Interestingly, the total amount of the E. coli population decreased over time. Thus, the increase of the multi-resistant E. coli populations seems to be linked with persistence of the resistant population, caused by the influence of high dietary zinc feeding. In conclusion, these findings corroborate our previous report linking high dietary zinc feeding of piglets with the occurrence of antimicrobial resistant E. coli and therefore question the feeding of high dietary zinc oxide as alternative to antimicrobial growth promoters. PMID:29373597
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van Vliet, Simon; Hol, Felix J H; Weenink, Tim; Galajda, Peter; Keymer, Juan E
2014-05-07
Bacterial habitats, such as soil and the gut, are structured at the micrometer scale. Important aspects of microbial life in such spatial ecosystems are migration and colonization. Here we explore the colonization of a structured ecosystem by two neutrally labeled strains of Escherichia coli. Using time-lapse microscopy we studied the colonization of one-dimensional arrays of habitat patches linked by connectors, which were invaded by the two E. coli strains from opposite sides. The two strains colonize a habitat from opposite sides by a series of traveling waves followed by an expansion front. When population waves collide, they branch into a continuing traveling wave, a reflected wave and a stationary population. When the two strains invade the landscape from opposite sides, they remain segregated in space and often one population will displace the other from most of the habitat. However, when the strains are co-cultured before entering the habitats, they colonize the habitat together and do not separate spatially. Using physically separated, but diffusionally coupled, habitats we show that colonization waves and expansion fronts interact trough diffusible molecules, and not by direct competition for space. Furthermore, we found that colonization outcome is influenced by a culture's history, as the culture with the longest doubling time in bulk conditions tends to take over the largest fraction of the habitat. Finally, we observed that population distributions in parallel habitats located on the same device and inoculated with cells from the same overnight culture are significantly more similar to each other than to patterns in identical habitats located on different devices inoculated with cells from different overnight cultures, even tough all cultures were started from the same -80°C frozen stock. We found that the colonization of spatially structure habitats by two interacting populations can lead to the formation of complex, but reproducible, spatiotemporal patterns. Furthermore, we showed that chemical interactions between two populations cause them to remain spatially segregated while they compete for habitat space. Finally, we observed that growth properties in bulk conditions correlate with the outcome of habitat colonization. Together, our data show the crucial roles of chemical interactions between populations and a culture's history in determining the outcome of habitat colonization.
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2014-01-01
Background Bacterial habitats, such as soil and the gut, are structured at the micrometer scale. Important aspects of microbial life in such spatial ecosystems are migration and colonization. Here we explore the colonization of a structured ecosystem by two neutrally labeled strains of Escherichia coli. Using time-lapse microscopy we studied the colonization of one-dimensional arrays of habitat patches linked by connectors, which were invaded by the two E. coli strains from opposite sides. Results The two strains colonize a habitat from opposite sides by a series of traveling waves followed by an expansion front. When population waves collide, they branch into a continuing traveling wave, a reflected wave and a stationary population. When the two strains invade the landscape from opposite sides, they remain segregated in space and often one population will displace the other from most of the habitat. However, when the strains are co-cultured before entering the habitats, they colonize the habitat together and do not separate spatially. Using physically separated, but diffusionally coupled, habitats we show that colonization waves and expansion fronts interact trough diffusible molecules, and not by direct competition for space. Furthermore, we found that colonization outcome is influenced by a culture’s history, as the culture with the longest doubling time in bulk conditions tends to take over the largest fraction of the habitat. Finally, we observed that population distributions in parallel habitats located on the same device and inoculated with cells from the same overnight culture are significantly more similar to each other than to patterns in identical habitats located on different devices inoculated with cells from different overnight cultures, even tough all cultures were started from the same −80°C frozen stock. Conclusions We found that the colonization of spatially structure habitats by two interacting populations can lead to the formation of complex, but reproducible, spatiotemporal patterns. Furthermore, we showed that chemical interactions between two populations cause them to remain spatially segregated while they compete for habitat space. Finally, we observed that growth properties in bulk conditions correlate with the outcome of habitat colonization. Together, our data show the crucial roles of chemical interactions between populations and a culture’s history in determining the outcome of habitat colonization. PMID:24884963
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Nguyen, Thao P; Friedrich, Loretta M; Danyluk, Michelle D
2014-07-01
Strawberries and blueberries harvested at or near full-ripe maturity tend to be less firm and more susceptible to bruising during harvest and transport. The objective of this research was to determine the fate of Escherichia coli O157:H7 and Salmonella on bruised and intact surfaces of whole strawberries and blueberries at shipping (2°C) and retail display (15.5°C) temperatures. Strawberries and blueberries were either purchased from a supermarket or were harvested immediately prior to use; they were bruised using established protocols, were spot inoculated, and were incubated at 2 and 15.5°C. Strawberries, subjected to modified atmospheres, were further transferred to bags and were sealed in with an initial atmosphere of ca. 10% CO2 and 5% O2. Strawberries were sampled at 0, 2, 5, and 24 h and on days 3 and 7; blueberries were sampled on days 0, 1, 3, and 7. After stomaching, samples were enumerated on nonselective and selective media, and populations were recorded as log CFU per berry. At both storage temperatures, population declines for both E. coli O157:H7 and Salmonella were seen under all conditions for strawberries. At 2 ± 2°C, E. coli O157:H7 and Salmonella populations on blueberries declined over 7 days under all conditions. At 15.5 ± 2°C, E. coli O157:H7 populations declined; however, Salmonella populations initially declined but increased to populations near or above initial populations over 7 days on blueberries. No overall significant differences were observed between bruised and intact treatments or between the two maturity levels for strawberries and blueberries. Modified atmospheric conditions did not affect the behavior of E. coli O157:H7 and Salmonella on strawberries at both temperatures. This research indicates that E. coli O157:H7 and Salmonella do not grow on strawberries at shipping or retail display temperatures, even when they are harvested at a maturity prone to bruising; however, Salmonella growth may occur on bruised full ripe blueberries under retail display temperatures.
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Yang, S E; Chou, C C
2000-07-01
Growth and survival of Escherichia coli O157:H7 and Listeria monocytogenes in steamed eggs and scrambled eggs held at different temperatures (5, 18, 22, 37, 55, and 60 degrees C) were investigated in the present study. Among the holding temperatures tested, both pathogens multiplied best at 37 degrees C followed by 22, 18, and 5 degrees C. In general, E. coli O157:H7 grew better in the egg products than L. monocytogenes did at all the storage temperatures tested except at 5 degrees C. E. coli O157:H7 did not grow in steamed eggs and scrambled eggs held at 5 degrees C. L. monocytogenes showed a slight population increase of approximately 0.6 to 0.9 log CFU/g in these egg products at the end of the 36-h storage period at 5 degrees C. The population of both pathogens detected in the egg products was affected by the initial population, holding temperature, and length of the holding period. It was also noted that L. monocytogenes was more susceptible than E. coli O157:H7 in steamed eggs held at 60 degrees C. After holding at 60 degrees C for 1 h, no detectable viable cells of L. monocytogenes with a population reduction of 5.4 log CFU/g was observed in steamed eggs, whereas a lower population reduction of only approximately 0.5 log CFU/ml was noted for E. coli O157:H7.
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Nelson, M; Jones, S H; Edwards, C; Ellis, J C
2008-08-19
Due to their opportunistic and gregarious nature, gulls may be important reservoirs and vectors for anthropogenically derived fecal pathogens in coastal areas. We used ribotyping, a genotypic bacterial source tracking method, to compare populations of Escherichia coli among herring gulls Larus argentatus, great black-backed gulls L. marinus, wastewater, and landfill trash in New Hampshire and Maine, USA. Concentrations of E. coli in gull feces varied widely among individuals, but were generally high (6.0 x 10(1) to 2.5 x 10(9) g(-1) wet weight). Of 39 E. coli isolates from L. argentatus, 67% had banding patterns that were > or = 90% similar to those from wastewater and trash, whereas only 39% of 36 L. marinus isolates exhibited > or = 90% similarity to these sources. Strains of E. coli from gulls matched (> or = 90% similarity) more strains from wastewater (39% matching) than from trash (15% matching). E. coli isolates from L. marinus feces exhibited a greater diversity of banding patterns than did isolates from L. argentatus. There were more unique E. coli banding patterns in trash samples than in wastewater, and higher diversity indices in the former compared to the latter. These findings suggest that both species of gulls, especially L. argentatus, obtain fecal bacteria from wastewater and landfill trash, which they may transport to recreational beaches and waters. Our results also indicate that E. coli populations may vary widely between gull species, and between the anthropogenic habitats that they frequent, i.e. landfills and wastewater treatment facilities.
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Gross, Gabriele; Wildner, Jessica; Schonewille, Arjan; Rademaker, Jan L. W.; van der Meer, Roelof; Snel, Johannes
2008-01-01
Application of phytohemagglutinin (PHA) in weaning feed has been suggested to stimulate intestinal epithelium maturation. In this study, PHA strongly affected the fecal bacterial population structure of rats. Escherichia coli overgrowth was not prevented by probiotic mannose-adhering Lactobacillus plantarum 299v. Therefore, use of PHA in weaning feed deserves careful evaluation. PMID:18606805
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Porous media augmented with biochar for the retention of E. coli
NASA Astrophysics Data System (ADS)
Kolotouros, Christos A.; Manariotis, Ioannis D.; Karapanagioti, Hrissi K.
2016-04-01
A significant number of epidemic outbreaks has been attributed to waterborne fecal-borne pathogenic microorganisms from contaminated ground water. The transport of pathogenic microorganisms in groundwater is controlled by physical and chemical soil properties like soil structure, texture, percent water saturation, soil ionic strength, pore-size distribution, soil and solution pH, soil surface charge, and concentration of organic carbon in solution. Biochar can increase soil productivity by improving both chemical and physical soil properties. The mixing of biochar into soils may stimulate microbial population and activate dormant soil microorganisms. Furthermore, the application of biochar into soil affects the mobility of microorganisms by altering the physical and chemical properties of the soil, and by retaining the microorganisms on the biochar surface. The aim of this study was to investigate the effect of biochar mixing into soil on the transport of Escherichia coli in saturated porous media. Initially, batch experiments were conducted at two different ionic strengths (1 and 150 mM KCl) and at varying E. coli concentrations in order to evaluate the retention of E. coli on biochar in aqueous solutions. Kinetic analysis was conducted, and three isotherm models were employed to analyze the experimental data. Column experiments were also conducted in saturated sand columns augmented with different biochar contents, in order to examine the effect of biochar on the retention of E. coli. The Langmuir model fitted better the retention experimental data, compared to Freundlich and Tempkin models. The retention of E. coli was enhanced at lower ionic strength. Finally, biochar-augmented sand columns were more capable in retaining E. coli than pure sand columns.
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Lytic bacteriophages reduce Escherichia coli O157
Ferguson, Sean; Roberts, Cheryl; Handy, Eric; Sharma, Manan
2013-01-01
The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield™) or a control (phosphate buffered saline, PBS) was applied to lettuce by either; (1) immersion of lettuce in 500 ml of EcoShield™ 8.3 log PFU/ml or 9.8 log PFU/ml for up to 2 min before inoculation with E. coli O157:H7; (2) spray-application of EcoShield™ (9.3 log PFU/ml) to lettuce after inoculation with E. coli O157:H7 (4.10 CFU/cm2) following exposure to 50 μg/ml chlorine for 30 sec. After immersion studies, lettuce was spot-inoculated with E. coli O157:H7 (2.38 CFU/cm2). Phage-treated, inoculated lettuce pieces were stored at 4°C for and analyzed for E. coli O157:H7 populations for up to 7 d. Immersion of lettuce in 9.8 log PFU/ml EcoShield™ for 2 min significantly (p < 0.05) reduced E. coli O157:H7 populations after 24 h when stored at 4°C compared with controls. Immersion of lettuce in suspensions containing high concentrations of EcoShield™ (9.8 log PFU/ml) resulted in the deposition of high concentrations (7.8 log log PFU/cm2) of bacteriophages on the surface of fresh cut lettuce, potentially contributing to the efficacy of the lytic phages on lettuce. Spraying phages on to inoculated fresh cut lettuce after being washed in hypochlorite solution was significantly more effective in reducing E. coli O157:H7 populations (2.22 log CFU/cm2) on day 0 compared with control treatments (4.10 log CFU/cm2). Both immersion and spray treatments provided protection from E. coli O157:H7 contamination on lettuce, but spray application of lytic bacteriophages to lettuce was more effective in immediately reducing E. coli O157:H7 populations fresh cut lettuce. PMID:23819106
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Xu, Yong; Dugat-Bony, Eric; Zaheer, Rahat; Selinger, Lorna; Barbieri, Ruth; Munns, Krysty; McAllister, Tim A; Selinger, L Brent
2014-01-01
Escherichia coli O157:H7 is a major foodborne human pathogen causing disease worldwide. Cattle are a major reservoir for this pathogen and those that shed E. coli O157:H7 at >104 CFU/g feces have been termed "super-shedders". A rich microbial community inhabits the mammalian intestinal tract, but it is not known if the structure of this community differs between super-shedder cattle and their non-shedding pen mates. We hypothesized that the super-shedder state is a result of an intestinal dysbiosis of the microbial community and that a "normal" microbiota prevents E. coli O157:H7 from reaching super-shedding levels. To address this question, we applied 454 pyrosequencing of bacterial 16S rRNA genes to characterize fecal bacterial communities from 11 super-shedders and 11 contemporary pen mates negative for E. coli O157:H7. The dataset was analyzed by using five independent clustering methods to minimize potential biases and to increase confidence in the results. Our analyses collectively indicated significant variations in microbiome composition between super-shedding and non-shedding cattle. Super-shedders exhibited higher bacterial richness and diversity than non-shedders. Furthermore, seventy-two operational taxonomic units, mostly belonging to Firmicutes and Bacteroidetes phyla, were identified showing differential abundance between these two groups of cattle. The operational taxonomic unit affiliation provides new insight into bacterial populations that are present in feces arising from super-shedders of E. coli O157:H7.
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Clarification of the recovery mechanism of Escherichia coli after hydrostatic pressure treatment
NASA Astrophysics Data System (ADS)
Ohshima, Shuto; Nomura, Kazuki; Iwahashi, Hitoshi
2013-06-01
High hydrostatic pressure (HP) technology has gained more attention as a non-thermal food pasteurization technology. Recently, a limitation of the HP technology was reported by Koseki and Yamamoto [Recovery of Escherichia coli ATCC 25922 in phosphate buffered saline after treatment with high hydrostatic pressure. Int. J. Food Microbiol. 2006;110:108-111], who completely recovered Escherichia coli species after HP treatment. We investigated the recovery mechanism of E. coli after HP treatment. The cells were treated with 200-300 MPa at 0-25°C for 24 h. The HP-treated E. coli was recovered in phosphate-buffered saline (PBS) during 120 h of incubation at 25°C, confirming the results reported by them. However, E. coli did not grow in PBS but grew with inactivated cells in PBS. In addition, the results of our "population size experiments" demonstrated that the recovery of E. coli cells depended on both the degree of pressure and the population size. These results suggest that some portion of cells recovered from the damage and then grew by using inactivated cells.
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Limayem, Alya; Martin, Elizabeth M
2014-01-01
Antibiotics are frequently used in agricultural systems to promote livestock health and to control bacterial contaminants. Given the upsurge of the resistant fecal indicator bacteria (FIB) in the surface waters, a novel statistical method namely, microbial risk assessment (MRA) was performed, to evaluate the probability of infection by resistant FIB on populations exposed to recreational waters. Diarrheagenic Escherichia coli, except E. coli O157:H7, were selected for their prevalence in aquatic ecosystem. A comparative study between a typical E. coli pathway and a case scenario aggravated by antibiotic use has been performed via Crystal Ball® software in an effort to analyze a set of available inputs provided by the US institutions including E. coli concentrations in US Great Lakes through using random sampling and probability distributions. Results from forecasting a possible worst-case scenario dose-response, accounted for an approximate 50% chance for 20% of the exposed human populations to be infected by recreational water in the U.S. However, in a typical scenario, there is a 50% chance of infection for only 1% of the exposed human populations. The uncertain variable, E. coli concentration accounted for approximately 92.1% in a typical scenario as the major contributing factor of the dose-response model. Resistant FIB in recreational waters that are exacerbated by a low dose of antibiotic pollutants would increase the adverse health effects in exposed human populations by 10 fold.
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Stanford, K; Bach, S J; Stephens, T P; McAllister, T A
2010-12-01
The effects of rumen protozoal populations on ruminal populations and fecal shedding of Escherichia coli O157:H7 were evaluated by using specifically faunated sheep. Nine fauna-free sheep (three animals per treatment) were inoculated with Dasytricha spp. (DAS sheep); with mixed population A (PopA) comprising Entodinium spp., Isotricha spp., Diplodinium spp., and Polyplastron spp.; or with mixed population B (PopB) comprising Entodinium spp., Isotricha spp., Dasytricha spp., and Epidinium spp.; six sheep were maintained fauna-free (FF sheep) to serve as controls. Sheep were fed barley silage-based diets, and treatment groups were housed in isolated rooms. Sheep were inoculated orally with 10(10) CFU of a four-strain mixture of nalidixic acid-resistant E. coli O157:H7. Samples of ruminal fluid and feces were collected over 77 days. Polyplastron spp. were detected in only one sheep in PopA, and Dasytricha spp. were detected only once within the PopB cohort. Sheep in the DAS group were 2.03 times more likely (P < 0.001) to shed E. coli O157:H7 than were those in the other three treatments, whereas the PopB sheep were less likely (0.65; P < 0.05) to shed this bacterium. The likelihood of harboring ruminal E. coli O157:H7 also tended (P = 0.06) to be higher in DAS and was lower (P < 0.01) in FF than in other cohorts. Possibly, Dasytricha spp. had a hosting effect, and Epidinium spp. had a predatory relationship, with E. coli O157:H7. Additional study into predator-prey and hosting relationships among rumen protozoa and E. coli O157:H7 is warranted.
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Keskinen, Lindsey A; Burke, Angela; Annous, Bassam A
2009-06-30
This study compared the efficacy of chlorine (20-200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20-200 ppm chlorite ion concentration, Sanova), and aqueous chlorine dioxide (20-200 ppm chlorite ion concentration, TriNova) washes in reducing populations of Escherichia coli O157:H7 on artificially inoculated lettuce. Fresh-cut leaves of Romaine or Iceberg lettuce were inoculated by immersion in water containing E. coli O157:H7 (8 log CFU/ml) for 5 min and dried in a salad spinner. Leaves (25 g) were then washed for 2 min, immediately or following 24 h of storage at 4 degrees C. The washing treatments containing chlorite ion concentrations of 100 and 200 ppm were the most effective against E. coli O157:H7 populations on Iceberg lettuce, with log reductions as high as 1.25 log CFU/g and 1.05 log CFU/g for TriNova and Sanova wash treatments, respectively. All other wash treatments resulted in population reductions of less than 1 log CFU/g. Chlorine (200 ppm), TriNova, Sanova, and acidic electrolyzed water were all equally effective against E. coli O157:H7 on Romaine, with log reductions of approximately 1 log CFU/g. The 20 ppm chlorine wash was as effective as the deionized water wash in reducing populations of E. coli O157:H7 on Romaine and Iceberg lettuce. Scanning electron microscopy indicated that E. coli O157:H7 that was incorporated into biofilms or located in damage lettuce tissue remained on the lettuce leaf, while individual cells on undamaged leaf surfaces were more likely to be washed away.
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Results of a 6-month survey of stool cultures for Escherichia coli O157:H7.
Marshall, W F; McLimans, C A; Yu, P K; Allerberger, F J; Van Scoy, R E; Anhalt, J P
1990-06-01
Escherichia coli O157:H7 is a recently recognized enteric pathogen that causes acute hemorrhagic colitis. Although the infection is usually self-limited, it may be complicated by hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. At our institution, stool specimens are now routinely cultured for this organism. To determine the prevalence of E. coli O157:H7-associated diarrhea in our patient population, we surveyed all submitted stool cultures for 6 months for this organism. Specimens were screened for non-sorbitol fermenting E. coli and confirmed by slide-agglutination and immobilization testing. Of 2,164 specimens, 10 yielded E. coli O157:H7. It was the fourth most common bacterial stool pathogen found. Bloody diarrhea and abdominal pain were the most common symptoms of the infected patients. E. coli O157:H7 causes sporadic infections in our patient population and should be considered in the differential diagnosis of acute hemorrhagic colitis.
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Campos, Ana Carolina C.; Andrade, Nathália L.; Ferdous, Mithila; Chlebowicz, Monika A.; Santos, Carla C.; Correal, Julio C. D.; Lo Ten Foe, Jerome R.; Rosa, Ana Cláudia P.; Damasco, Paulo V.; Friedrich, Alex W.; Rossen, John W. A.
2018-01-01
Urinary tract infections (UTIs) are often caused by Escherichia coli. Their increasing resistance to broad-spectrum antibiotics challenges the treatment of UTIs. Whereas, E. coli ST131 is often multidrug resistant (MDR), ST69 remains susceptible to antibiotics such as cephalosporins. Both STs are commonly linked to community and nosocomial infections. E. coli phylogenetic groups B2 and D are associated with virulence and resistance profiles making them more pathogenic. Little is known about the population structure of E. coli isolates obtained from urine samples of hospitalized patients in Brazil. Therefore, we characterized E. coli isolated from urine samples of patients hospitalized at the university and three private hospitals in Rio de Janeiro, using whole genome sequencing. A high prevalence of E. coli ST131 and ST69 was found, but other lineages, namely ST73, ST648, ST405, and ST10 were also detected. Interestingly, isolates could be divided into two groups based on their antibiotic susceptibility. Isolates belonging to ST131, ST648, and ST405 showed a high resistance rate to all antibiotic classes tested, whereas isolates belonging to ST10, ST73, ST69 were in general susceptible to the antibiotics tested. Additionally, most ST69 isolates, normally resistant to aminoglycosides, were susceptible to this antibiotic in our population. The majority of ST131 isolates were ESBL-producing and belonged to serotype O25:H4 and the H30-R subclone. Previous studies showed that this subclone is often associated with more complicated UTIs, most likely due to their high resistance rate to different antibiotic classes. Sequenced isolates could be classified into five phylogenetic groups of which B2, D, and F showed higher resistance rates than groups A and B1. No significant difference for the predicted virulence genes scores was found for isolates belonging to ST131, ST648, ST405, and ST69. In contrast, the phylogenetic groups B2, D and F showed a higher predictive virulence score compared to phylogenetic groups A and B1. In conclusion, despite the diversity of E. coli isolates causing UTIs, clonal groups O25:H4-B2-ST131 H30-R, O1:H6-B2-ST648, and O102:H6-D-ST405 were the most prevalent. The emergence of highly virulent and MDR E. coli in Brazil is of high concern and requires more attention from the health authorities. PMID:29503639
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Campos, Ana Carolina C; Andrade, Nathália L; Ferdous, Mithila; Chlebowicz, Monika A; Santos, Carla C; Correal, Julio C D; Lo Ten Foe, Jerome R; Rosa, Ana Cláudia P; Damasco, Paulo V; Friedrich, Alex W; Rossen, John W A
2018-01-01
Urinary tract infections (UTIs) are often caused by Escherichia coli . Their increasing resistance to broad-spectrum antibiotics challenges the treatment of UTIs. Whereas, E. coli ST131 is often multidrug resistant (MDR), ST69 remains susceptible to antibiotics such as cephalosporins. Both STs are commonly linked to community and nosocomial infections. E. coli phylogenetic groups B2 and D are associated with virulence and resistance profiles making them more pathogenic. Little is known about the population structure of E. coli isolates obtained from urine samples of hospitalized patients in Brazil. Therefore, we characterized E. coli isolated from urine samples of patients hospitalized at the university and three private hospitals in Rio de Janeiro, using whole genome sequencing. A high prevalence of E. coli ST131 and ST69 was found, but other lineages, namely ST73, ST648, ST405, and ST10 were also detected. Interestingly, isolates could be divided into two groups based on their antibiotic susceptibility. Isolates belonging to ST131, ST648, and ST405 showed a high resistance rate to all antibiotic classes tested, whereas isolates belonging to ST10, ST73, ST69 were in general susceptible to the antibiotics tested. Additionally, most ST69 isolates, normally resistant to aminoglycosides, were susceptible to this antibiotic in our population. The majority of ST131 isolates were ESBL-producing and belonged to serotype O25:H4 and the H30-R subclone. Previous studies showed that this subclone is often associated with more complicated UTIs, most likely due to their high resistance rate to different antibiotic classes. Sequenced isolates could be classified into five phylogenetic groups of which B2, D, and F showed higher resistance rates than groups A and B1. No significant difference for the predicted virulence genes scores was found for isolates belonging to ST131, ST648, ST405, and ST69. In contrast, the phylogenetic groups B2, D and F showed a higher predictive virulence score compared to phylogenetic groups A and B1. In conclusion, despite the diversity of E. coli isolates causing UTIs, clonal groups O25:H4-B2-ST131 H30-R, O1:H6-B2-ST648, and O102:H6-D-ST405 were the most prevalent. The emergence of highly virulent and MDR E. coli in Brazil is of high concern and requires more attention from the health authorities.
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USDA-ARS?s Scientific Manuscript database
The use of ultrasound to enhance the efficacy of selected sanitizers in reduction of Escherichia coli O157:H7 populations on spinach was investigated. Spot-inoculated spinach samples were treated with water, chlorine, acidified sodium chlorite (ASC), peroxyacetic acid (POAA), and acidic electrolyzed...
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Langendorf, Christopher G.; Key, Trevor L. G.; Fenalti, Gustavo; Kan, Wan-Ting; Buckle, Ashley M.; Caradoc-Davies, Tom; Tuck, Kellie L.; Law, Ruby H. P.; Whisstock, James C.
2010-01-01
Background In mammals succinic semialdehyde dehydrogenase (SSADH) plays an essential role in the metabolism of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) to succinic acid (SA). Deficiency of SSADH in humans results in elevated levels of GABA and γ-Hydroxybutyric acid (GHB), which leads to psychomotor retardation, muscular hypotonia, non-progressive ataxia and seizures. In Escherichia coli, two genetically distinct forms of SSADHs had been described that are essential for preventing accumulation of toxic levels of succinic semialdehyde (SSA) in cells. Methodology/Principal Findings Here we structurally characterise SSADH encoded by the E coli gabD gene by X-ray crystallographic studies and compare these data with the structure of human SSADH. In the E. coli SSADH structure, electron density for the complete NADP+ cofactor in the binding sites is clearly evident; these data in particular revealing how the nicotinamide ring of the cofactor is positioned in each active site. Conclusions/Significance Our structural data suggest that a deletion of three amino acids in E. coli SSADH permits this enzyme to use NADP+, whereas in contrast the human enzyme utilises NAD+. Furthermore, the structure of E. coli SSADH gives additional insight into human mutations that result in disease. PMID:20174634
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Inactivation of Escherichia coli O157:H7 attached to spinach harvester blade using bacteriophage.
Patel, Jitendra; Sharma, Manan; Millner, Patricia; Calaway, Todd; Singh, Manpreet
2011-04-01
Outbreaks associated with leafy greens have focused attention on the transfer of human pathogens to these commodities during harvest with commercial equipment. Attachment of Escherichia coli O157:H7 on new or rusty spinach harvester blades immersed in spinach extract or 10% tryptic soy broth (TSB) was investigated. Bacteriophages specific for E. coli O157:H7 were evaluated to kill cells attached to blade. A cocktail of five nalidixic acid-resistant E. coli O157:H7 isolates was transferred to 25 mL of spinach extract or 10% TSB. A piece of sterilized spinach harvester blade (2×1") was placed in above spinach extract or 10% TSB and incubated at room (22 °C) or dynamic (30 °C day, 20 °C night) temperatures. E. coli O157:H7 populations attached to blade during incubation in spinach extract or 10% TSB were determined. When inoculated at 1 log CFU/mL, E. coli O157:H7 attachment to blades after 24 and 48 h incubation at dynamic temperature (6.09 and 6.37 log CFU/mL) was significantly higher than when incubated at 22 °C (4.84 and 5.68 log CFU/mL), respectively. After 48 h incubation, two blades were sprayed on each side with a cocktail of E. coli O157-specific bacteriophages before scraping the blade, and subsequent plating on Sorbitol MacConkey media-nalidixic acid. Application of bacteriophages reduced E. coli O157:H7 populations by 4.5 log CFU on blades after 2 h of phage treatment. Our study demonstrates that E. coli O157:H7 can attach to and proliferate on spinach harvester blades under static and dynamic temperature conditions, and bacteriophages are able to reduce E. coli O157:H7 populations adhered to blades. © Mary Ann Liebert, Inc.
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Xiao, Zhenlei; Bauchan, Gary; Nichols-Russell, Lydia; Luo, Yaguang; Wang, Qin; Nou, Xiangwu
2015-10-01
Radish (Raphanus sativus var. longipinnatus) microgreens were produced from seeds inoculated with Escherichia coli O157:H7 by using peat moss-based soil-substitute and hydroponic production systems. E. coli populations on the edible and inedible parts of harvested microgreen plants (7 days postseeding) and in growth medium were examined. E. coli O157:H7 was shown to survive and proliferate significantly during microgreen growth in both production systems, with a higher level in the hydroponic production system. At the initial seed inoculation level of 3.7 log CFU/g, E. coli O157:H7 populations on the edible part of microgreen plants reached 2.3 and 2.1 log CFU/g (overhead irrigation and bottom irrigation, respectively) for microgreens from the soil-substitute production system and reached 5.7 log CFU/g for those hydroponically grown. At a higher initial inoculation of 5.6 log CFU/g seeds, the corresponding E. coli O157:H7 populations on the edible parts of microgreens grown in these production systems were 3.4, 3.6, and 5.3 log CFU/g, respectively. Examination of the spatial distribution of bacterial cells on different parts of microgreen plants showed that contaminated seeds led to systematic contamination of whole plants, including both edible and inedible parts, and seed coats remained the focal point of E. coli O157:H7 survival and growth throughout the period of microgreen production.
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Bhattacharya, A; Nsonwu, O; Johnson, A P; Hope, R
2018-03-01
Escherichia coli bacteraemia rates have been increasing in England. Using the national mandatory surveillance data for E. coli bacteraemia from 2012/13 to 2016/17, we aimed to estimate the incidence of E. coli bacteraemia and 30-day all-cause case fatality rate (CFR) by 2020/21 in the absence of new interventions to reduce infection rates. After controlling for age, sex, and hospital versus community-onset of infection, it is estimated that the incidence of E. coli bacteraemia will be 90.5 (95% PI: 89.8-91.3) per 100,000 population (N = 50,663), with an associated CFR of 11.5 (95% PI: 11.2-11.8) per 100,000 population (N = 6554), by 2020/21. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.
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Escherichia coli DNA polymerase I can disrupt G-quadruplex structures during DNA replication.
Teng, Fang-Yuan; Hou, Xi-Miao; Fan, San-Hong; Rety, Stephane; Dou, Shuo-Xing; Xi, Xu-Guang
2017-12-01
Non-canonical four-stranded G-quadruplex (G4) DNA structures can form in G-rich sequences that are widely distributed throughout the genome. The presence of G4 structures can impair DNA replication by hindering the progress of replicative polymerases (Pols), and failure to resolve these structures can lead to genetic instability. In the present study, we combined different approaches to address the question of whether and how Escherichia coli Pol I resolves G4 obstacles during DNA replication and/or repair. We found that E. coli Pol I-catalyzed DNA synthesis could be arrested by G4 structures at low protein concentrations and the degree of inhibition was strongly dependent on the stability of the G4 structures. Interestingly, at high protein concentrations, E. coli Pol I was able to overcome some kinds of G4 obstacles without the involvement of other molecules and could achieve complete replication of G4 DNA. Mechanistic studies suggested that multiple Pol I proteins might be implicated in G4 unfolding, and the disruption of G4 structures requires energy derived from dNTP hydrolysis. The present work not only reveals an unrealized function of E. coli Pol I, but also presents a possible mechanism by which G4 structures can be resolved during DNA replication and/or repair in E. coli. © 2017 Federation of European Biochemical Societies.
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Jang, Hyein; Matthews, Karl R
2018-04-01
This study aimed to determine the influence of bacterial surface polysaccharides (cellulose, colanic acid, and lipopolysaccharide; LPS) on the colonization or survival of Escherichia coli O157:H7 on plants and the plant defense response. Survival of E. coli O157:H7 were evaluated on Arabidopsis thaliana and romaine lettuce as a model plant and an edible crop (leafy vegetable), respectively. The population of the wild-type strain of E. coli O157:H7 on Arabidopsis plants and lettuce was significantly (P < 0.05) greater compared with the colanic acid-deficient and LPS-truncated mutants on day 1 and day 5 post-inoculation. This result indicates that colanic acid and LPS structures may contribute to the ability of bacterial survival or persistence on plants. The wild-type strain of E. coli O157:H7 produced approximately twice the amount (P < 0.05) of capsular polysaccharide (CPS) than the colanic acid and LPS-truncated mutants. The significantly lower production of CPS was associated with significantly greater (2-fold) expression of pathogenesis-related gene (PR1) compared with the wild-type and cellulose-deficient mutant (P < 0.05). Collectively, the results of this study may suggest that specific surface polysaccharides of E. coli O157:H7 differentially induce the plant defense response, consequently affecting the survival of the human pathogen on plants. The survival and persistence of E. coli O157:H7 was similar on Arabidopsis and lettuce regardless of day post-inoculation. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Proliferation of Escherichia coli O157:H7 in soil and hydroponic microgreen production systems
USDA-ARS?s Scientific Manuscript database
Radish (Raphanus sativus var. longipinnatus) microgreens were produced from seeds inoculated with Escherichia coli O157: H7 using soil substitute and hydroponic production systems. E. coli populations on the edible and inedible parts of harvested microgreen plants and in growth medium were examined....
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Oyen, David; Fenwick, R Bryn; Aoto, Phillip C; Stanfield, Robyn L; Wilson, Ian A; Dyson, H Jane; Wright, Peter E
2017-08-16
The rate-determining step in the catalytic cycle of E. coli dihydrofolate reductase is tetrahydrofolate (THF) product release, which can occur via an allosteric or an intrinsic pathway. The allosteric pathway, which becomes accessible when the reduced cofactor NADPH is bound, involves transient sampling of a higher energy conformational state, greatly increasing the product dissociation rate as compared to the intrinsic pathway that obtains when NADPH is absent. Although the kinetics of this process are known, the enzyme structure and the THF product conformation in the transiently formed excited state remain elusive. Here, we use side-chain proton NMR relaxation dispersion measurements, X-ray crystallography, and structure-based chemical shift predictions to explore the structural basis of allosteric product release. In the excited state of the E:THF:NADPH product release complex, the reduced nicotinamide ring of the cofactor transiently enters the active site where it displaces the pterin ring of the THF product. The p-aminobenzoyl-l-glutamate tail of THF remains weakly bound in a widened binding cleft. Thus, through transient entry of the nicotinamide ring into the active site, the NADPH cofactor remodels the enzyme structure and the conformation of the THF to form a weakly populated excited state that is poised for rapid product release.
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Wanjugi, P; Fox, G A; Harwood, V J
2016-10-01
Nutrient levels, competition from autochthonous microorganisms, and protozoan predation may all influence survival of fecal microorganisms as they transition from the gastrointestinal tract to aquatic habitats. Although Escherichia coli is an important indicator of waterborne pathogens, the effects of environmental stressors on its survival in aquatic environments remain poorly understood. We manipulated organic nutrient, predation, and competition levels in outdoor microcosms containing natural river water, sediments, and microbial populations to determine their relative contribution to E. coli survival. The activities of predator (protozoa) and competitor (indigenous bacteria) populations were inhibited by adding cycloheximide or kanamycin. We developed a statistical model of E. coli density over time that fits with the data under all experimental conditions. Predation and competition had significant negative effects on E. coli survival, while higher nutrient levels increased survival. Among the main effects, predation accounted for the greatest variation (40 %) compared with nutrients (25 %) or competition (15 %). The highest nutrient level mitigated the effect of predation on E. coli survival. Thus, elevated organic nutrients may disproportionately enhance the survival of E. coli, and potentially that of other enteric bacteria, in aquatic habitats.
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Zaheer, Rahat; Selinger, Lorna; Barbieri, Ruth; Munns, Krysty; McAllister, Tim A.; Selinger, L. Brent
2014-01-01
Escherichia coli O157:H7 is a major foodborne human pathogen causing disease worldwide. Cattle are a major reservoir for this pathogen and those that shed E. coli O157:H7 at >104 CFU/g feces have been termed “super-shedders”. A rich microbial community inhabits the mammalian intestinal tract, but it is not known if the structure of this community differs between super-shedder cattle and their non-shedding pen mates. We hypothesized that the super-shedder state is a result of an intestinal dysbiosis of the microbial community and that a “normal” microbiota prevents E. coli O157:H7 from reaching super-shedding levels. To address this question, we applied 454 pyrosequencing of bacterial 16S rRNA genes to characterize fecal bacterial communities from 11 super-shedders and 11 contemporary pen mates negative for E. coli O157:H7. The dataset was analyzed by using five independent clustering methods to minimize potential biases and to increase confidence in the results. Our analyses collectively indicated significant variations in microbiome composition between super-shedding and non-shedding cattle. Super-shedders exhibited higher bacterial richness and diversity than non-shedders. Furthermore, seventy-two operational taxonomic units, mostly belonging to Firmicutes and Bacteroidetes phyla, were identified showing differential abundance between these two groups of cattle. The operational taxonomic unit affiliation provides new insight into bacterial populations that are present in feces arising from super-shedders of E. coli O157:H7. PMID:24858731
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Shashkov, Alexander S; Wang, Min; Turdymuratov, Eldar M; Hu, Shaohui; Arbatsky, Nikolay P; Guo, Xi; Wang, Lei; Knirel, Yuriy A
2015-03-02
O-Antigen (O-polysaccharide) variation is the basis for bacterial serotyping and is important in bacterial virulence and niche adaptation. In this work, we present structural and genetic evidences for close relationships between the O-antigens of the Cronobacter spp. and Escherichia coli. Cronobacter sakazakii G2594 (serotype O4) and Cronobacter malonaticus G3864 (serotype O1) are structurally related to those of E. coli O103 and O29, respectively, and some other members of the Enterobacteriaceae family differing in the patterns of lateral glucosylation (C. sakazakii G2594) or O-acetylation (C. malonaticus G3864). The O-antigen gene clusters of the corresponding Cronobacter and E. coli strains contain the same genes with high-level similarity, and the structural differences within both O-antigen pairs were suggested to be due to modification genes carried by prophages. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Smati, Mounira; Clermont, Olivier; Bleibtreu, Alexandre; Fourreau, Frédéric; David, Anthony; Daubié, Anne-Sophie; Hignard, Cécile; Loison, Odile; Picard, Bertrand; Denamur, Erick
2015-08-01
The primary habitat of the Escherichia coli species is the gut of warm-blooded vertebrates. The E. coli species is structured into four main phylogenetic groups A, B1, B2, and D. We estimated the relative proportions of these phylogroups in the feces of 137 wild and domesticated animals with various diets living in the Ile de France (Paris) region by real-time PCR. We distinguished three main clusters characterized by a particular abundance of two or more phylogroups within the E. coli animal commensal populations, which we called "enterocolitypes" by analogy with the enterotypes defined in the human gut microbiota at the genus level. These enterocolitypes were characterized by a dominant (>50%) B2, B1, or A phylogroup and were associated with different host species, diets, and habitats: wild and herbivorous species (wild rabbits and deer), domesticated herbivorous species (domesticated rabbits, horses, sheep, and cows), and omnivorous species (boar, pigs, and chickens), respectively. By analyzing retrospectively the data obtained using the same approach from 98 healthy humans living in Ile de France (Smati et al. 2013, Appl. Environ. Microbiol. 79, 5005-5012), we identified a specific human enterocolitype characterized by the dominant and/or exclusive (>90%) presence of phylogroup B2. We then compared B2 strains isolated from animals and humans, and revealed that human and animal strains differ regarding O-type and B2 subgroup. Moreover, two genes, sfa/foc and clbQ, were associated with the exclusive character of strains, observed only in humans. In conclusion, a complex network of interactions exists at several levels (genus and intra-species) within the intestinal microbiota. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.
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Lutterodt, G; Basnet, M; Foppen, J W A; Uhlenbrook, S
2009-02-01
Bacteria properties play an important role in the transport of bacteria in groundwater, but their role, especially for longer transport distances (>0.5 m) has not been studied. Thereto, we studied the effects of cell surface hydrophobicity, outer surface potential (OSP), cell sphericity, motility, and Ag43 protein expression on the outer cell surface for a number of E. coli strains, obtained from the environment on their transport behavior in columns of saturated quartz sand of 5 m height in two solutions: demineralized (DI) water and artificial groundwater (AGW). In DI water, sticking efficiencies ranged between 0.1 and 0.4 at the column inlet, and then decreased with transport distance to 0.02-0.2. In AGW, sticking efficiencies were on average 1log-unit higher than those in DI (water). Bacteria motility and Ag43 expression affected attachment with a (high) statistical significance. In contrast, hydrophobicity, OSP and cell sphericity did not significantly correlate with sticking efficiency. However, for transport distances more than 0.33 m, the correlation between sticking efficiency, Ag43 expression, and motility became insignificant. We concluded that Ag43 and motility played an important role in E. coli attachment to quartz grain surfaces, and that the transport distance dependent sticking efficiency reductions were caused by motility and Ag43 expression variations within a population. The implication of our findings is that less motile bacteria with little or no Ag43 expression may travel longer distances once they enter groundwater environments. In future studies, the possible effect of bacteria surface structures, like fimbriae, pili and surface proteins on bacteria attachment need to be considered more systematically in order to arrive at more meaningful inter-population comparisons of the transport behavior of E. coli strains in aquifers.
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Comparative ecology of Escherichia coli in endangered Australian sea lion (Neophoca cinerea) pups.
Fulham, Mariel; Power, Michelle; Gray, Rachael
2018-05-04
The dissemination of human-associated bacteria into the marine environment has the potential to expose wildlife populations to atypical microbes that can alter the composition of the gut microbiome or act as pathogens. The objective of the study was to determine whether endangered Australian sea lion (Neophoca cinerea) pups from two South Australian colonies, Seal Bay, Kangaroo Island and Dangerous Reef, Spencer Gulf, have been colonised by human-associated Escherichia coli. Faecal samples (n = 111) were collected to isolate E. coli, and molecular screening was applied to assign E. coli isolates (n = 94) to phylotypes and detect class 1 integrons; mobile genetic elements that confer resistance to antimicrobial agents. E. coli phylotype distribution and frequency differed significantly between colonies with phylotypes B2 and D being the most abundant at Seal Bay, Kangaroo Island (55% and 7%) and Dangerous Reef, Spencer Gulf (36% and 49%), respectively. This study reports the first case of antimicrobial resistant E. coli in free-ranging Australian sea lions through the identification of class 1 integrons from an individual pup at Seal Bay. A significant relationship between phylotype and total white cell count (WCC) was identified, with significantly higher WCC seen in pups with human-associated phylotypes at Dangerous Reef. The difference in phylotype distribution and presence of human-associated E. coli suggests that proximity to human populations can influence sea lion gut microbiota. The identification of antimicrobial resistance in a free-ranging pinniped population provides crucial information concerning anthropogenic influences in the marine environment. Copyright © 2018 Elsevier B.V. All rights reserved.
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Café au lait macules and juvénile polyps.
Pacheco, Theresa R; Scatena, Lisa S; Hoffenberg, Edward J; Gralla, Jane; Lee, Lela A
2007-01-01
Several hereditary and nonhereditary gastrointestinal tract polyposis syndromes exhibit extra-intestinal manifestations, including cutaneous findings. However, a lack of information exists regarding cutaneous features of juvenile polyposis. Our objective was to document the prevalence of cutaneous hyperpigmented lesions in children with juvenile polyposis coli or juvenile polyposis coli and their first degree relatives.Children seen in the gastroenterology practice at The Children's Hospital in Denver, Colorado with polyps (juvenile polyposis coli, sporadic juvenile polyps, and familial adenomatous polyposis coli) and their first degree relatives were invited to participate in the study. A comprehensive skin examination was performed on those who consented to participate. We found that 8 of 14 patients (eight with juvenile polyposis coli, four with juvenile polyposis, and two with familial adenomatous polyposis coli) had at least one café-au-lait macule, compared with three of 27 relatives (p=0.003).The prevalence of at least one café-au-lait macule in our patients (8/14 or 57.1%, CI: 28.9–82.3%) was significantly higher than the general population prevalence of 28.5% (p=0.023). However, if the two patients with familial adenomatous polyposis coli were excluded, the comparison with the general population prevalence did not reach statistical significance (p=0.095). The prevalence of multiple cafe´-au-lait macules in our patients (4/14 or 28.6%; CI:8.4–58.1%) was significantly higher than the general population prevalence of 5.2% (p ¼ 0.005). A notable finding was the presence of multiple café -au-lait macules in 4 of 12 juvenile polyposis coli/juvenile polyposis patients.Two patients with juvenile polyposis coli also had lentigines. In this selected case series, we observed single or multiple café-au-lait macules in a high proportion of children with the three types of polyps. Further studies are needed to assess a possible common pathway for hamartomatous polypsand café-au-lait macules.
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RNase P cleaves transient structures in some riboswitches.
Altman, Sidney; Wesolowski, Donna; Guerrier-Takada, Cecilia; Li, Yong
2005-08-09
RNase P from Escherichia coli cleaves the coenzyme B12 riboswitch from E. coli and a similar one from Bacillus subtilis. The cleavage sites do not occur in any recognizable structure, as judged from theoretical schemes that have been drawn for these 5' UTRs. However, it is possible to draw a scheme that is a good representation of the E. coli cleavage site for RNase P and for the cleavage site in B. subtilis. These data indicate that transient structures are important in RNase P cleavage and in riboswitch function. Coenzyme B12 has a small inhibitory effect on E. coli RNase P cleavage of the E. coli riboswitch. Both E. coli RNase P and a partially purified RNase P from Aspergillus nidulans mycelia succeeded in cleaving a putative arginine riboswitch from A. nidulans. The cleavage site may be a representative of another model substrate for eukaryotic RNase P. This 5' UTR controls splicing of the arginase mRNA in A. nidulans. Four other riboswitches in E. coli were not cleaved by RNase P under the conditions tested.
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RNase P cleaves transient structures in some riboswitches
Altman, Sidney; Wesolowski, Donna; Guerrier-Takada, Cecilia; Li, Yong
2005-01-01
RNase P from Escherichia coli cleaves the coenzyme B12 riboswitch from E. coli and a similar one from Bacillus subtilis. The cleavage sites do not occur in any recognizable structure, as judged from theoretical schemes that have been drawn for these 5′ UTRs. However, it is possible to draw a scheme that is a good representation of the E. coli cleavage site for RNase P and for the cleavage site in B. subtilis. These data indicate that transient structures are important in RNase P cleavage and in riboswitch function. Coenzyme B12 has a small inhibitory effect on E. coli RNase P cleavage of the E. coli riboswitch. Both E. coli RNase P and a partially purified RNase P from Aspergillus nidulans mycelia succeeded in cleaving a putative arginine riboswitch from A. nidulans. The cleavage site may be a representative of another model substrate for eukaryotic RNase P. This 5′ UTR controls splicing of the arginase mRNA in A. nidulans. Four other riboswitches in E. coli were not cleaved by RNase P under the conditions tested. PMID:16061811
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How does the cladoceran Daphnia pulex affect the fate of Escherichia coli in water?
Burnet, Jean-Baptiste; Faraj, Tarek; Cauchie, Henry-Michel; Joaquim-Justo, Célia; Servais, Pierre; Prévost, Michèle; Dorner, Sarah M.
2017-01-01
The faecal indicator Escherichia coli plays a central role in water quality assessment and monitoring. It is therefore essential to understand its fate under various environmental constraints such as predation by bacterivorous zooplankton. Whereas most studies have examined how protozooplankton communities (heterotrophic nanoflagellates and ciliates) affect the fate of E. coli in water, the capacity of metazooplankton to control the faecal indicator remains poorly understood. In this study, we investigated how the common filter-feeding cladoceran, Daphnia pulex, affects the fate of E. coli under different experimental conditions. Daphnia ingested E. coli and increased its loss rates in water, but the latter rates decreased from 1.65 d-1 to 0.62 d-1 after a 1,000-fold reduction in E. coli initial concentrations, due to lower probability of encounter between Daphnia and E. coli. The combined use of culture and PMA qPCR (viability-qPCR) demonstrated that exposure to Daphnia did not result into the formation of viable but non-culturable E. coli cells. In lake water, a significant part of E. coli population loss was associated with matrix-related factors, most likely due to predation by other bacterivorous biota and/or bacterial competition. However, when exposing E. coli to a D. pulex gradient (from 0 to 65 ind.L-1), we observed an increasing impact of Daphnia on E. coli loss rates, which reached 0.47 d-1 in presence of 65 ind.L-1. Our results suggest that the filter-feeder can exert a non-negligible predation pressure on E. coli, especially during seasonal Daphnia population peaks. Similar trials using other Daphnia species as well as stressed E. coli cells will increase our knowledge on the capacity of this widespread zooplankter to control E. coli in freshwater resources. Based on our results, we strongly advocate the use of natural matrices to study these biotic interactions in order to avoid overestimation of Daphnia impact. PMID:28178322
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How does the cladoceran Daphnia pulex affect the fate of Escherichia coli in water?
Burnet, Jean-Baptiste; Faraj, Tarek; Cauchie, Henry-Michel; Joaquim-Justo, Célia; Servais, Pierre; Prévost, Michèle; Dorner, Sarah M
2017-01-01
The faecal indicator Escherichia coli plays a central role in water quality assessment and monitoring. It is therefore essential to understand its fate under various environmental constraints such as predation by bacterivorous zooplankton. Whereas most studies have examined how protozooplankton communities (heterotrophic nanoflagellates and ciliates) affect the fate of E. coli in water, the capacity of metazooplankton to control the faecal indicator remains poorly understood. In this study, we investigated how the common filter-feeding cladoceran, Daphnia pulex, affects the fate of E. coli under different experimental conditions. Daphnia ingested E. coli and increased its loss rates in water, but the latter rates decreased from 1.65 d-1 to 0.62 d-1 after a 1,000-fold reduction in E. coli initial concentrations, due to lower probability of encounter between Daphnia and E. coli. The combined use of culture and PMA qPCR (viability-qPCR) demonstrated that exposure to Daphnia did not result into the formation of viable but non-culturable E. coli cells. In lake water, a significant part of E. coli population loss was associated with matrix-related factors, most likely due to predation by other bacterivorous biota and/or bacterial competition. However, when exposing E. coli to a D. pulex gradient (from 0 to 65 ind.L-1), we observed an increasing impact of Daphnia on E. coli loss rates, which reached 0.47 d-1 in presence of 65 ind.L-1. Our results suggest that the filter-feeder can exert a non-negligible predation pressure on E. coli, especially during seasonal Daphnia population peaks. Similar trials using other Daphnia species as well as stressed E. coli cells will increase our knowledge on the capacity of this widespread zooplankter to control E. coli in freshwater resources. Based on our results, we strongly advocate the use of natural matrices to study these biotic interactions in order to avoid overestimation of Daphnia impact.
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A Structural Study of Escherichia coli Cells Using an In Situ Liquid Chamber TEM Technology.
Wang, Yibing; Chen, Xin; Cao, Hongliang; Deng, Chao; Cao, Xiaodan; Wang, Ping
2015-01-01
Studying cell microstructures and their behaviors under living conditions has been a challenging subject in microbiology. In this work, in situ liquid chamber TEM was used to study structures of Escherichia coli cells in aqueous solutions at a nanometer-scale resolution. Most of the cells remained intact under electron beam irradiation, and nanoscale structures were observed during the TEM imaging. The analysis revealed structures of pili surrounding the E. coli cells; the movements of the pili in the liquid were also observed during the in situ tests. This technology also allowed the observation of features of the nucleoid in the E. coli cells. Overall, in situ TEM can be applied as a valuable tool to study real-time microscopic structures and processes in microbial cells residing in native aqueous solutions.
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Sundqvist, Martin; Granholm, Susanne; Naseer, Umaer; Rydén, Patrik; Brolund, Alma; Sundsfjord, Arnfinn; Kahlmeter, Gunnar; Johansson, Anders
2014-12-01
A 2-year prospective intervention on the prescription of trimethoprim reduced the use by 85% in a health care region with 178,000 inhabitants. Here, we performed before-and-after analyses of the within-population distribution of trimethoprim resistance in Escherichia coli. Phylogenetic and population genetic methods were applied to multilocus sequence typing data of 548 consecutively collected E. coli isolates from clinical urinary specimens. Results were analyzed in relation to antibiotic susceptibility and the presence and genomic location of different trimethoprim resistance gene classes. A total of 163 E. coli sequence types (STs) were identified, of which 68 were previously undescribed. The isolates fell into one of three distinct genetic clusters designated BAPS 1 (E. coli phylogroup B2), BAPS 2 (phylogroup A and B1), and BAPS 3 (phylogroup D), each with a similar frequency before and after the intervention. BAPS 2 and BAPS 3 were positively and BAPS 1 was negatively associated with trimethoprim resistance (odds ratios of 1.97, 3.17, and 0.26, respectively). In before-and-after analyses, trimethoprim resistance frequency increased in BAPS 1 and decreased in BAPS 2. Resistance to antibiotics other than trimethoprim increased in BAPS 2. Analysis of the genomic location of different trimethoprim resistance genes in isolates of ST69, ST58, and ST73 identified multiple independent acquisition events in isolates of the same ST. The results show that despite a stable overall resistance frequency in E. coli before and after the intervention, marked within-population changes occurred. A decrease of resistance in one major genetic cluster was masked by a reciprocal increase in another major cluster. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
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Sundqvist, Martin; Granholm, Susanne; Naseer, Umaer; Rydén, Patrik; Brolund, Alma; Sundsfjord, Arnfinn; Kahlmeter, Gunnar
2014-01-01
A 2-year prospective intervention on the prescription of trimethoprim reduced the use by 85% in a health care region with 178,000 inhabitants. Here, we performed before-and-after analyses of the within-population distribution of trimethoprim resistance in Escherichia coli. Phylogenetic and population genetic methods were applied to multilocus sequence typing data of 548 consecutively collected E. coli isolates from clinical urinary specimens. Results were analyzed in relation to antibiotic susceptibility and the presence and genomic location of different trimethoprim resistance gene classes. A total of 163 E. coli sequence types (STs) were identified, of which 68 were previously undescribed. The isolates fell into one of three distinct genetic clusters designated BAPS 1 (E. coli phylogroup B2), BAPS 2 (phylogroup A and B1), and BAPS 3 (phylogroup D), each with a similar frequency before and after the intervention. BAPS 2 and BAPS 3 were positively and BAPS 1 was negatively associated with trimethoprim resistance (odds ratios of 1.97, 3.17, and 0.26, respectively). In before-and-after analyses, trimethoprim resistance frequency increased in BAPS 1 and decreased in BAPS 2. Resistance to antibiotics other than trimethoprim increased in BAPS 2. Analysis of the genomic location of different trimethoprim resistance genes in isolates of ST69, ST58, and ST73 identified multiple independent acquisition events in isolates of the same ST. The results show that despite a stable overall resistance frequency in E. coli before and after the intervention, marked within-population changes occurred. A decrease of resistance in one major genetic cluster was masked by a reciprocal increase in another major cluster. PMID:25288078
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Johnson, Timothy J.; Logue, Catherine M.; Johnson, James R.; Kuskowski, Michael A.; Sherwood, Julie S.; Barnes, H. John; DebRoy, Chitrita; Wannemuehler, Yvonne M.; Obata-Yasuoka, Mana; Spanjaard, Lodewijk
2012-01-01
Abstract The emergence of plasmid-mediated multidrug resistance (MDR) among enteric bacteria presents a serious challenge to the treatment of bacterial infections in humans and animals. Recent studies suggest that avian Escherichia coli commonly possess the ability to resist multiple antimicrobial agents, and might serve as reservoirs of MDR for human extraintestinal pathogenic Escherichia coli (ExPEC) and commensal E. coli populations. We determined antimicrobial susceptibility profiles for 2202 human and avian E. coli isolates, then sought for associations among resistance profile, plasmid content, virulence factor profile, and phylogenetic group. Avian-source isolates harbored greater proportions of MDR than their human counterparts, and avian ExPEC had higher proportions of MDR than did avian commensal E. coli. MDR was significantly associated with possession of the IncA/C, IncP1-α, IncF, and IncI1 plasmid types. Overall, inferred virulence potential did not correlate with drug susceptibility phenotype. However, certain virulence genes were positively associated with MDR, including ireA, ibeA, fyuA, cvaC, iss, iutA, iha, and afa. According to the total dataset, isolates segregated significantly according to host species and clinical status, thus suggesting that avian and human ExPEC and commensal E. coli represent four distinct populations with limited overlap. These findings suggest that in extraintestinal E. coli, MDR is most commonly associated with plasmids, and that these plasmids are frequently found among avian-source E. coli from poultry production systems. PMID:21988401
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Tarifa, M C; Lozano, J E; Brugnoni, L I
2015-02-01
The objective of this study was to determine the interactions between common spoilage yeast, Candida tropicalis, isolated from ultrafiltration membranes, and Escherichia coli O157:H7 and Salmonella sp. on stainless steel surfaces. Single and dual-species attachment assays were performed on stainless steel at 25°C using apple juice as culture medium. The growth of Salmonella sp. rose when it was co-cultivated with C. tropicalis in dual biofilms at 16 and 24 h; the same effect was observed for E. coli O157:H7 at 24 h. The colonization of C. tropicalis on stainless steel surfaces was reduced when it was co-cultivated with both pathogenic bacteria, reducing C. tropicalis population by at least 1.0 log unit. Visualization by SEM demonstrated that E. coli O157:H7 and Salmonella sp. adhere closely to hyphal elements using anchorage structures to attach to the surface and other cells. These results suggest a route for potential increased survival of pathogens in juice processing environments. These support the notion that the species involved interact in mixed yeast-bacteria communities favouring the development of bacteria over yeast. This study support the plausibility that pathogen interactions with strong biofilm forming members of spoilage microbiota, such as C. tropicalis, might play an important role for the survival and dissemination of E. coli O157:H7 and Salmonella sp. in food-processing environments. © 2014 The Society for Applied Microbiology.
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Guenther, Sebastian; Ewers, Christa; Wieler, Lothar H.
2011-01-01
Wildlife is normally not exposed to clinically used antimicrobial agents but can acquire antimicrobial resistant bacteria through contact with humans, domesticated animals and the environment, where water polluted with feces seems to be the most important vector. Escherichia coli, an ubiquitous commensal bacterial species colonizing the intestinal tract of mammals and birds, is also found in the environment. Extended-spectrum beta-lactamases producing E. coli (ESBL-E. coli) represent a major problem in human and veterinary medicine, particular in nosocomial infections. Additionally an onset of community-acquired ESBL-E. coli infections and an emergence in livestock farming has been observed in recent years, suggesting a successful transmission as well as persistence of ESBL-E. coli strains outside clinical settings. Another parallel worldwide phenomenon is the spread of ESBL-E. coli into the environment beyond human and domesticated animal populations, and this seems to be directly influenced by antibiotic practice. This might be a collateral consequence of the community-onset of ESBL-E. coli infections but can result (a) in a subsequent colonization of wild animal populations which can turn into an infectious source or even a reservoir of ESBL-E. coli, (b) in a contribution of wildlife to the spread and transmission of ESBL-E. coli into fragile environmental niches, (c) in new putative infection cycles between wildlife, domesticated animals and humans, and (d) in problems in the medical treatment of wildlife. This review aims to summarize the current knowledge on ESBL-E. coli in wildlife, in turn underlining the need for more large scale investigations, in particular sentinel studies to monitor the impact of multiresistant bacteria on wildlife. PMID:22203818
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Kozak, Gosia K; Pearl, David L; Parkman, Julia; Reid-Smith, Richard J; Deckert, Anne; Boerlin, Patrick
2009-09-01
Sulfonamide-resistant Escherichia coli and Salmonella isolates from pigs and chickens in Ontario and Québec were screened for sul1, sul2, and sul3 by PCR. Each sul gene was distributed differently across populations, with a significant difference between distribution in commensal E. coli and Salmonella isolates and sul3 restricted mainly to porcine E. coli isolates.
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Kozak, Gosia K.; Pearl, David L.; Parkman, Julia; Reid-Smith, Richard J.; Deckert, Anne; Boerlin, Patrick
2009-01-01
Sulfonamide-resistant Escherichia coli and Salmonella isolates from pigs and chickens in Ontario and Québec were screened for sul1, sul2, and sul3 by PCR. Each sul gene was distributed differently across populations, with a significant difference between distribution in commensal E. coli and Salmonella isolates and sul3 restricted mainly to porcine E. coli isolates. PMID:19633109
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Jones, C D R; Hunter, C; Williams, A P; Strachan, N J C; Cross, P
2011-10-01
This research compared public opinions about Escherichia coli O157 (an increasing environmental hazard associated with livestock) in two farming areas with contrasting incidence of E. coli O157 disease. A questionnaire was administered in rural Grampian (10·8 cases/100,000 population per year) and North Wales (2·5 cases/100,000 population per year). Awareness was highest among farmers in Grampian (91%) and lowest among visitors to both areas (28%). Respondents were more likely to indicate vomiting (76%) than bloody diarrhoea (48%) as a common symptom. Undercooked meat and contact with farm animal faeces were identified by 60% of all respondents as risk factors who described 'basic hygiene' for risk reduction indoors. Visitors view E. coli O157 as a food hazard, not an environmental hazard that produces vomiting not dysentery. Efforts to reduce human infections in livestock farming areas could be improved with proximate reminders for visitors of the environmental pathway of E. coli O157 infection.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Svintradze, David V.; Virginia Commonwealth University, Richmond, VA 23219-1540; Peterson, Darrell L.
Differences in OxyR regulated expression of oxidative stress genes between Escherichia coli and Porphyromonas gingivalis are explained by very minor differences in structure and amino-acid sequence of the respective oxidized and reduced OxyR regulatory domains. These differences affect OxyR quaternary structures and are predicted from model building of full length OxyR–DNA complexes to confer distinct modes of DNA binding on this transcriptional regulator. OxyR transcriptionally regulates Escherichia coli oxidative stress response genes through a reversibly reducible cysteine disulfide biosensor of cellular redox status. Structural changes induced by redox changes in these cysteines are conformationally transmitted to the dimer subunit interfaces,more » which alters dimer and tetramer interactions with DNA. In contrast to E. coli OxyR regulatory-domain structures, crystal structures of Porphyromonas gingivalis OxyR regulatory domains show minimal differences in dimer configuration on changes in cysteine disulfide redox status. This locked configuration of the P. gingivalis OxyR regulatory-domain dimer closely resembles the oxidized (activating) form of the E. coli OxyR regulatory-domain dimer. It correlates with the observed constitutive activation of some oxidative stress genes in P. gingivalis and is attributable to a single amino-acid insertion in P. gingivalis OxyR relative to E. coli OxyR. Modelling of full-length P. gingivalis, E. coli and Neisseria meningitidis OxyR–DNA complexes predicts different modes of DNA binding for the reduced and oxidized forms of each.« less
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Schlinkmann, Karola M; Hillenbrand, Matthias; Rittner, Alexander; Künz, Madeleine; Strohner, Ralf; Plückthun, Andreas
2012-09-21
To identify structural features in a G-protein-coupled receptor (GPCR) crucial for biosynthesis, stability in the membrane and stability in detergent micelles, we developed an evolutionary approach using expression in the inner membrane of Escherichia coli. From the analysis of 800,000 sequences of the rat neurotensin receptor 1, in which every amino acid had been varied to all 64 codons, we uncovered several "shift" positions, where the selected population focuses on a residue different from wild type. Here, we employed in vitro DNA recombination and a comprehensive synthetic binary library made by the Slonomics® technology, allowing us to uncover additive and synergistic effects in the structure that maximize both detergent stability and functional expression. We identified variants with >25,000 functional molecules per E. coli cell, a 50-fold increase over wild type, and observed strong coevolution of detergent stability. We arrived at receptor variants highly stable in short-chain detergents, much more so than those found by alanine scanning on the same receptor. These evolved GPCRs continue to be able to signal through the G-protein. We discuss the structural reasons for these improvements achieved through directed evolution. Copyright © 2012 Elsevier Ltd. All rights reserved.
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Nei, Daisuke; Latiful, Bari M; Enomoto, Katsuyoshi; Inatsu, Yasuhiro; Kawamoto, Shinnichi
2011-10-01
Abstract The majority of seed sprout-related outbreaks have been associated with Escherichia coli O157:H7 and Salmonella. Therefore, we aimed to find an effective method to inactivate these organisms on seeds before sprouting. Treatment with 8.7% (v/v) acetic acid at 55°C for 2-3 h reduced the population of E. coli O157:H7 and Salmonella inoculated on alfalfa (Medicago sativa L.) and radish seeds (Raphanus sativus L.) by more than 5.0 log CFU/g, and a longer treatment time completely eliminated the E. coli O157:H7 population. The E. coli O157:H7 populations were reduced to an undetectable level with a gaseous acetic acid treatment for 48 h. After enrichment, no E. coli O157:H7 were found in the alfalfa and radish seeds (25 g). However, these treatments were unable to eliminate Salmonella in both seed types. No significant difference between the germination rates of treated alfalfa seeds and control seeds was found, and germination rates greater than 95% were obtained for the radish seeds. Although chlorine washing is commonly used for seed decontamination, chlorine washing at 200 and 20,000 ppm resulted in a reduction of pathogens by less than or equal to 3 log CFU/g. Therefore, these results suggested that gaseous acetic acid is more effective than chlorine washing in controlling pathogenic bacteria on sprout seeds.
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VanderWaal, Kimberly L; Atwill, Edward R; Isbell, Lynne A; McCowan, Brenda
2014-03-01
Although network analysis has drawn considerable attention as a promising tool for disease ecology, empirical research has been hindered by limitations in detecting the occurrence of pathogen transmission (who transmitted to whom) within social networks. Using a novel approach, we utilize the genetics of a diverse microbe, Escherichia coli, to infer where direct or indirect transmission has occurred and use these data to construct transmission networks for a wild giraffe population (Giraffe camelopardalis). Individuals were considered to be a part of the same transmission chain and were interlinked in the transmission network if they shared genetic subtypes of E. coli. By using microbial genetics to quantify who transmits to whom independently from the behavioural data on who is in contact with whom, we were able to directly investigate how the structure of contact networks influences the structure of the transmission network. To distinguish between the effects of social and environmental contact on transmission dynamics, the transmission network was compared with two separate contact networks defined from the behavioural data: a social network based on association patterns, and a spatial network based on patterns of home-range overlap among individuals. We found that links in the transmission network were more likely to occur between individuals that were strongly linked in the social network. Furthermore, individuals that had more numerous connections or that occupied 'bottleneck' positions in the social network tended to occupy similar positions in the transmission network. No similar correlations were observed between the spatial and transmission networks. This indicates that an individual's social network position is predictive of transmission network position, which has implications for identifying individuals that function as super-spreaders or transmission bottlenecks in the population. These results emphasize the importance of association patterns in understanding transmission dynamics, even for environmentally transmitted microbes like E. coli. This study is the first to use microbial genetics to construct and analyse transmission networks in a wildlife population and highlights the potential utility of an approach integrating microbial genetics with network analysis. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.
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Kim, Juhui; Chung, Hyunjung; Cho, Joonil; Yoon, Kisun
2013-01-01
The aim of this study was to model the growth of nalidixic acid-resistant E. coli O157:H7 (E. coli O157:H7NR) in blanched spinach and to evaluate model performance with an independent set of data for interpolation (8.5, 13, 15 and 27 °C) and for extrapolation (broth and fresh-cut iceberg lettuce) using the ratio method and the acceptable prediction zone method. The lag time (LT), specific growth rate (SGR) and maximum population density (MPD) obtained from each primary model were modeled as a function of temperature (7, 10, 17, 24, 30, and 36 °C) using Davey, square root, and polynomial models, respectively. At 7 °C, the populations of E. coli O157:H7NR increased in tryptic soy broth with nalidixic acid (TSBN), blanched spinach and fresh-cut iceberg lettuce, while the populations of E. coli O157:H7 decreased in TSB after 118 h of LT, indicating the risk of nalidixic acid-resistant strain of E. coli O157:H7 contaminated in ready-to-eat produce at refrigerated temperature. When the LT and SGR models of blanched spinach was extended to iceberg lettuce, all relative errors (percentage of RE = 100%) were inside the acceptable prediction zone and had an acceptable Bf and Af values. Thus, it was concluded that developed secondary models for E. coli O157:H7NR in blanched spinach were suitable for use in making predictions for fresh cut iceberg lettuce, but not for static TSBN in this work. PMID:23839062
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Musicha, Patrick; Feasey, Nicholas A; Cain, Amy K; Kallonen, Teemu; Chaguza, Chrispin; Peno, Chikondi; Khonga, Margaret; Thompson, Sarah; Gray, Katherine J; Mather, Alison E; Heyderman, Robert S; Everett, Dean B; Thomson, Nicholas R; Msefula, Chisomo L
2017-06-01
Efforts to treat Escherichia coli infections are increasingly being compromised by the rapid, global spread of antimicrobial resistance (AMR). Whilst AMR in E. coli has been extensively investigated in resource-rich settings, in sub-Saharan Africa molecular patterns of AMR are not well described. In this study, we have begun to explore the population structure and molecular determinants of AMR amongst E. coli isolates from Malawi. Ninety-four E. coli isolates from patients admitted to Queen's Hospital, Malawi, were whole-genome sequenced. The isolates were selected on the basis of diversity of phenotypic resistance profiles and clinical source of isolation (blood, CSF and rectal swab). Sequence data were analysed using comparative genomics and phylogenetics. Our results revealed the presence of five clades, which were strongly associated with E. coli phylogroups A, B1, B2, D and F. We identified 43 multilocus STs, of which ST131 (14.9%) and ST12 (9.6%) were the most common. We identified 25 AMR genes. The most common ESBL gene was bla CTX-M-15 and it was present in all five phylogroups and 11 STs, and most commonly detected in ST391 (4/4 isolates), ST648 (3/3 isolates) and ST131 [3/14 (21.4%) isolates]. This study has revealed a high diversity of lineages associated with AMR, including ESBL and fluoroquinolone resistance, in Malawi. The data highlight the value of longitudinal bacteraemia surveillance coupled with detailed molecular epidemiology in all settings, including low-income settings, in describing the global epidemiology of ESBL resistance. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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Characterization of E. coli O157:H7 strains isolated from super-shedding cattle
USDA-ARS?s Scientific Manuscript database
Background: Recent reports have indicated that a small sub-population of cattle shedding high levels of Escherichia coli O157:H7 is the main source for transmission of the pathogen between animals. Cattle achieving a fecal shedding status of 104 CFU of E. coli O157:H7/gram are now referred to as su...
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Fumarate-Mediated Persistence of Escherichia coli against Antibiotics
Kim, Jun-Seob; Cho, Da-Hyeong; Heo, Paul; Jung, Suk-Chae; Park, Myungseo; Oh, Eun-Joong; Sung, Jaeyun; Kim, Pan-Jun; Lee, Suk-Chan; Lee, Dae-Hee; Lee, Sarah; Lee, Choong Hwan; Shin, Dongwoo
2016-01-01
Bacterial persisters are a small fraction of quiescent cells that survive in the presence of lethal concentrations of antibiotics. They can regrow to give rise to a new population that has the same vulnerability to the antibiotics as did the parental population. Although formation of bacterial persisters in the presence of various antibiotics has been documented, the molecular mechanisms by which these persisters tolerate the antibiotics are still controversial. We found that amplification of the fumarate reductase operon (FRD) in Escherichia coli led to a higher frequency of persister formation. The persister frequency of E. coli was increased when the cells contained elevated levels of intracellular fumarate. Genetic perturbations of the electron transport chain (ETC), a metabolite supplementation assay, and even the toxin-antitoxin-related hipA7 mutation indicated that surplus fumarate markedly elevated the E. coli persister frequency. An E. coli strain lacking succinate dehydrogenase (SDH), thereby showing a lower intracellular fumarate concentration, was killed ∼1,000-fold more effectively than the wild-type strain in the stationary phase. It appears that SDH and FRD represent a paired system that gives rise to and maintains E. coli persisters by producing and utilizing fumarate, respectively. PMID:26810657
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Antibacterial effect of lactoferricin B on Escherichia coli O157:H7 in ground beef.
Venkitanarayanan, K S; Zhao, T; Doyle, M P
1999-07-01
The antibacterial activity of lactoferricin B on enterohemorrhagic Escherichia coli O157:H7 in 1% peptone medium and ground beef was studied at 4 and 10 degrees C. In 1% peptone medium, 50 and 100 microg of lactoferricin B per ml reduced E. coli O157:H7 populations by approximately 0.7 and 2.0 log CFU/ml, respectively. Studies comparing the antibacterial effect of lactoferricin B on E. coli O157:H7 in 1% peptone at pH 5.5 and 7.2 did not reveal any significant difference (P > 0.5) at the two pH values. Lactoferricin B (100 microg/g) reduced E. coli O157:H7 population in ground beef by about 0.8 log CFU/g (P < 0.05). No significant difference (P > 0.5) was observed in the total plate count between treatment and control ground beef samples stored at 4 and 10 degrees C. The antibacterial effect of lactoferricin B on E. coli O157:H7 observed in this study is not of sufficient magnitude to merit its use in ground beef for controlling the pathogen.
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Analysis of the Genome Structure of the Nonpathogenic Probiotic Escherichia coli Strain Nissle 1917
Grozdanov, Lubomir; Raasch, Carsten; Schulze, Jürgen; Sonnenborn, Ulrich; Gottschalk, Gerhard; Hacker, Jörg; Dobrindt, Ulrich
2004-01-01
Nonpathogenic Escherichia coli strain Nissle 1917 (O6:K5:H1) is used as a probiotic agent in medicine, mainly for the treatment of various gastroenterological diseases. To gain insight on the genetic level into its properties of colonization and commensalism, this strain's genome structure has been analyzed by three approaches: (i) sequence context screening of tRNA genes as a potential indication of chromosomal integration of horizontally acquired DNA, (ii) sequence analysis of 280 kb of genomic islands (GEIs) coding for important fitness factors, and (iii) comparison of Nissle 1917 genome content with that of other E. coli strains by DNA-DNA hybridization. PCR-based screening of 324 nonpathogenic and pathogenic E. coli isolates of different origins revealed that some chromosomal regions are frequently detectable in nonpathogenic E. coli and also among extraintestinal and intestinal pathogenic strains. Many known fitness factor determinants of strain Nissle 1917 are localized on four GEIs which have been partially sequenced and analyzed. Comparison of these data with the available knowledge of the genome structure of E. coli K-12 strain MG1655 and of uropathogenic E. coli O6 strains CFT073 and 536 revealed structural similarities on the genomic level, especially between the E. coli O6 strains. The lack of defined virulence factors (i.e., alpha-hemolysin, P-fimbrial adhesins, and the semirough lipopolysaccharide phenotype) combined with the expression of fitness factors such as microcins, different iron uptake systems, adhesins, and proteases, which may support its survival and successful colonization of the human gut, most likely contributes to the probiotic character of E. coli strain Nissle 1917. PMID:15292145
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Saida, H.; Ytow, N.; Seki, H.
1998-01-01
The Gram stain method was applied to the photometric characterization of aquatic bacterial populations with a charge-coupled device camera and an image analyzer. Escherichia coli and Bacillus subtilis were used as standards of typical gram-negative and gram-positive bacteria, respectively. A mounting agent to obtain clear images of Gram-stained bacteria on Nuclepore membrane filters was developed. The bacterial stainability by the Gram stain was indicated by the Gram stain index (GSI), which was applicable not only to the dichotomous classification of bacteria but also to the characterization of cell wall structure. The GSI spectra of natural bacterial populations in water with various levels of eutrophication showed a distinct profile, suggesting possible staining specificity that indicates the presence of a particular bacterial population in the aquatic environment. PMID:9464416
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Fogarty, L.R.; Haack, S.K.; Wolcott, M.J.; Whitman, R.L.
2003-01-01
Aims: To evaluate the numbers and selected phenotypic and genotypic characteristics of the faecal indicator bacteria Escherichia coli and enterococci in gull faeces at representative Great Lakes swimming beaches in the United States. Methods and Results: E. coli and enterococci were enumerated in gull faeces by membrane filtration. E. coli genotypes (rep-PCR genomic profiles) and E. coli (Vitek?? GNI+) and enterococci (API?? rapid ID 32 Strep and resistance to streptomycin, gentamicin, vancomycin, tetracycline and ampicillin) phenotypes were determined for isolates obtained from gull faeces both early and late in the swimming season. Identical E. coli genotypes were obtained only from single gull faecal samples but most faecal samples yielded more than one genotype (median of eight genotypes for samples with 10 isolates). E. coli isolates from the same site that clustered at ???85% similarity were from the same sampling date and shared phenotypic characteristics, and at this similarity level there was population overlap between the two geographically isolated beach sites. Enterococcus API?? profiles varied with sampling date. Gull enterococci displayed wide variation in antibiotic resistance patterns, and high-level resistance to some antibiotics. Conclusions: Gull faeces could be a major contributor of E. coli (105-109 CFU g-1) and enterococci (104-108 CFU g-1) to Great Lakes recreational waters. E. coli and enterococci in gull faeces are highly variable with respect to their genotypic and phenotypic characteristics and may exhibit temporal or geographic trends in these features. Significance and Impact of the Study: The high degree of variation in genotypic or phenotypic characteristics of E. coli or enterococci populations within gull hosts will require extensive sampling for adequate characterization, and will influence methods that use these characteristics to determine faecal contamination sources for recreational waters.
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Chandrasekaran, Ramyavardhanee; Hamilton, Matthew J; Wang, Ping; Staley, Christopher; Matteson, Scott; Birr, Adam; Sadowsky, Michael J
2015-12-15
Escherichia coli is used to indicate fecal contamination in freshwater systems and is an indicator of the potential presence of human pathogens. However, naturalized E. coli strains that persist and grow in the environment confound the use of this bacterium as a fecal indicator. Here we examined the spatial and temporal distribution of E. coli in water and sediments of the Seven Mile Creek (SMC), a constructed, ephemeral watershed. E. coli concentrations showed variation by site and date, likely due to changes in temperature and rainfall. Horizontal fluorophore enhanced rep-PCR (HFERP) DNA fingerprint analyses indicated that E. coli populations were very diverse and consisted of transient and naturalized strains, which were especially prevalent in sediment. E. coli fingerprints from water and sediment collected in the same year clustered together with significant overlap, indicating exchange of strains between matrices. Isolates obtained during periods of flow, but not during non-flow conditions, clustered together regardless of sample site, indicating that transport between sites occurred. Naturalized E. coli strains were found in the SMC and strains become geographically isolated and distinct during non-flow conditions. Isolates collected during late spring to fall clustered together at each site, suggesting that temperature and growth of naturalized strains are likely factors affecting population dynamics. Results of this study show that newly introduced and naturalized E. coli strains are present in the SMC. Results of this study highlight an important concern for resource managers using this species for water quality monitoring. Copyright © 2015 Elsevier B.V. All rights reserved.
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Swinscoe, Isobel; Oliver, David M; Gilburn, Andre S; Quilliam, Richard S
2018-06-19
The sustainable management of recreational beaches is essential for minimising risk of human exposure to microbial pathogens whilst simultaneously maintaining valuable ecosystem services. Decaying seaweed on public beaches is gaining recognition as a substrate for microbial contamination, and is a potentially significant reservoir for human pathogens in close proximity to beach users. Closely associated with beds of decaying seaweed are dense populations of the seaweed fly (Coelopidae), which could influence the spatio-temporal fate of seaweed-associated human pathogens within beach environments. Replicated mesocosms containing seaweed inoculated with a bioluminescent strain of the zoonotic pathogen E. coli O157:H7, were used to determine the effects of two seaweed flies, Coelopa frigida and C. pilipes, on E. coli O157:H7 survival dynamics. Multiple generations of seaweed flies and their larvae significantly enhanced persistence of E. coli O157:H7 in simulated wrack habitats, demonstrating that both female and male C. frigida flies are capable of transferring E. coli O157:H7 between individual wrack beds and into the sand. Adult fly faeces can contain significant concentrations of E. coli O157:H7, which suggests they are capable of acting as biological vectors and bridge hosts between wrack habitats and other seaweed fly populations, and facilitate the persistence and dispersal of E. coli O157:H7 in sandy beach environments. This study provides the first evidence that seaweed fly populations inhabiting natural wrack beds contaminated with the human pathogen E. coli O157:H7 have the capacity to amplify the hazard source, and therefore potential transmission risk, to beach users exposed to seaweed and sand in the intertidal zone. The risk to public health from seaweed flies and decaying wrack beds is usually limited by human avoidance behaviour; however, seaweed fly migration and nuisance inland plagues in urban areas could increase human exposure routes beyond the beach environment. Copyright © 2018 Elsevier Ltd. All rights reserved.
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Römer, Antje; Scherz, Gesine; Reupke, Saskia; Meißner, Jessica; Wallmann, Jürgen; Kietzmann, Manfred; Kaspar, Heike
2017-12-04
In the European Union, various fluoroquinolones are authorised for the treatment of food producing animals. Each administration poses an increased risk of development and spread of antimicrobial resistance. The aim of this study was to investigate the impact of parenteral administration of enrofloxacin on the prevalence of enrofloxacin and ciprofloxacin susceptibilities in the commensal intestinal E. coli population. E. coli isolates from faeces of twelve healthy pigs were included. Six pigs were administered enrofloxacin on day 1 to 3 and after two weeks for further three days. The other pigs formed the control group. MIC values were determined. Virulence and resistance genes were detected by PCR. Phylogenetic grouping was performed by PCR. Enrofloxacin and ciprofloxacin were analysed in sedimentation samples by HPLC. Susceptibility shifts in commensal E. coli isolates were determined in both groups. Non-wildtype E. coli could be cultivated from two animals of the experimental group for the first time one week after the first administration and from one animal of the control group on day 28. The environmental load with enrofloxacin in sedimentation samples showed the highest amount between days one and five. The repeated parenteral administration of enrofloxacin to pigs resulted in rapidly increased MIC values (day 28: MIC up to 4 mg/L, day 35: MIC ≥ 32mg/L). E. coli populations of the control group in the same stable without direct contact to the experimental group were affected. The parenteral administration of enrofloxacin to piglets considerably reduced the number of the susceptible intestinal E. coli population which was replaced by E. coli strains with increased MIC values against enrofloxacin. Subsequently also pigs of the control were affected suggesting a transferability of strains from the experimental group through the environment to the control group especially as we could isolate the same PFGE strains from both pig groups and the environment.
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Kwan, Grace; Charkowski, Amy O; Barak, Jeri D
2013-02-12
Although enteric human pathogens are usually studied in the context of their animal hosts, a significant portion of their life cycle occurs on plants. Plant disease alters the phyllosphere, leading to enhanced growth of human pathogens; however, the impact of human pathogens on phytopathogen biology and plant health is largely unknown. To characterize the interaction between human pathogens and phytobacterial pathogens in the phyllosphere, we examined the interactions between Pectobacterium carotovorum subsp. carotovorum and Salmonella enterica or Escherichia coli O157:H7 with regard to bacterial populations, soft rot progression, and changes in local pH. The presence of P. carotovorum subsp. carotovorum enhanced the growth of both S. enterica and E. coli O157:H7 on leaves. However, in a microaerophilic environment, S. enterica reduced P. carotovorum subsp. carotovorum populations and soft rot progression by moderating local environmental pH. Reduced soft rot was not due to S. enterica proteolytic activity. Limitations on P. carotovorum subsp. carotovorum growth, disease progression, and pH elevation were not observed on leaves coinoculated with E. coli O157:H7 or when leaves were coinoculated with S. enterica in an aerobic environment. S. enterica also severely undermined the relationship between the phytobacterial population and disease progression of a P. carotovorum subsp. carotovorum budB mutant defective in the 2,3-butanediol pathway for acid neutralization. Our results show that S. enterica and E. coli O157:H7 interact differently with the enteric phytobacterial pathogen P. carotovorum subsp. carotovorum. S. enterica inhibition of soft rot progression may conceal a rapidly growing human pathogen population. Whereas soft rotted produce can alert consumers to the possibility of food-borne pathogens, healthy-looking produce may entice consumption of contaminated vegetables. Salmonella enterica and Escherichia coli O157:H7 may use plants to move between animal and human hosts. Their populations are higher on plants cocolonized with the common bacterial soft rot pathogen Pectobacterium carotovorum subsp. carotovorum, turning edible plants into a risk factor for human disease. We inoculated leaves with P. carotovorum subsp. carotovorum and S. enterica or E. coli O157:H7 to study the interactions between these bacteria. While P. carotovorum subsp. carotovorum enhanced the growth of both S. enterica and E. coli O157:H7, these human pathogens affected P. carotovorum subsp. carotovorum fundamentally differently. S. enterica reduced P. carotovorum subsp. carotovorum growth and acidified the environment, leading to less soft rot on leaves; E. coli O157:H7 had no such effects. As soft rot signals a food safety risk, the reduction of soft rot symptoms in the presence of S. enterica may lead consumers to eat healthy-looking but S. enterica-contaminated produce.
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Inatsu, Yasuhiro; Bari, Md Latiful; Kawasaki, Susumu; Isshiki, Kenji; Kawamoto, Shinichi
2005-02-01
Efficacy of acidified sodium chlorite for reducing the population of Escherichia coli O157:H7 pathogens on Chinese cabbage leaves was evaluated. Washing leaves with distilled water could reduce the population of E. coli O157:H7 by approximately 1.0 log CFU/g, whereas treating with acidified chlorite solution could reduce the population by 3.0 log CFU/g without changing the leaf color. A similar level of reduction was achieved by washing with sodium chlorite solution containing various organic acids. However, acidified sodium chlorite in combination with a mild heat treatment reduced the population by approximately 4.0 log CFU/g without affecting the color, but it softened the leaves. Moreover, the efficacy of the washing treatment was similar at low (4 degrees C) and room (25 degrees C) temperatures, indicating that acidified sodium chloride solution could be useful as a sanitizer for surface washing of fresh produce.
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Arana, Inés; Orruño, Maite; Seco, Carolina; Muela, Alicia; Barcina, Isabel
2008-03-01
The ability of Urografin or Percoll density gradient centrifugations to separate nonculturable subpopulations from heterogeneous Escherichia coli populations was analysed. Bacterial counts (total, active and culturable cells) and flow cytometric analyses were carried out in all recovered bands. After Urografin centrifugation, and despite the different origin of E. coli populations, a common pattern was obtained. High-density bands were formed mainly by nonculturable cells. However, the increase in cell density would not be common to all nonculturable cells, since part of this subpopulations banded in low-density zones, mixed with culturable cells. Bands obtained after Percoll centrifugation were heterogeneous and culturable and nonculturable cells were recovered along the gradient. Thus, fractionation in Urografin cannot be only attributed to changes in buoyant densities during the transition from culturable to nonculturable state. Urografin density gradients allow us to obtain enriched fractions in nonculturable subpopulations from a heterogeneous population, but working conditions should be carefully chosen to avoid Urografin toxicity.
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Survival of Escherichia coli O157:H7 in ground beef jerky assessed on two plating media.
Harrison, J A; Harrison, M A; Rose, R A
1998-01-01
Recent outbreaks of food-borne illness due to Salmonella spp. in beef jerky and Escherichia coli O157:H7 in venison jerky, coupled with the fact that a variety of preparation methods and dying procedures abound, raise concern over the safety of processed meat products made in the home. The potential of injured bacterial cells to regain the ability to cause illness is a particular threat with pathogens such as E. coli O157:H7, which is believed to have a low infectious dose. This study examined the efficacy of various methods of jerky preparation in reducing populations of E, coli O157:H7 in ground beef jerky and compared the recovery rate of E. coli O157:H7 on two selective plating media, modified sorbitol MacConkey agar (MSMA) and modified eosin methylene blue agar (MEMB). Populations of E. coli O157:H7 in both heated and unheated samples exhibited a greater decline during drying when a nitrite and salt cure mix was added during jerky preparation. When recovery of E. coli O157:H7 on MSMA and MEMB was compared, a trend toward slightly higher recovery rates with MEMB was observed. On the basis of these results, MEMB is a suitable alternative to MSMA for the recovery of E. coli O157:H7 from heated and dried meat samples similar to beef jerky.
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Ren, Xiaomeng; Zhu, Yanyan; Gamallat, Yaser; Ma, Shenhao; Chiwala, Gift; Meyiah, Abdo; Xin, Yi
2017-10-01
Our research group previously isolated and identified a strain of pathogenic Escherichia coli from clinical samples called E. coli O124 K72. The present study was aimed at determining the potential effects of E. coli O124 K72 on intestinal barrier functions and structural proteins integrity in guinea pig. Guinea pigs were grouped into three groups; control (CG); E. coli O124 K72 (E. coli); and probiotics Lactobacillus rhamnosus (LGG). Initially, we create intestinal dysbiosis by giving all animals Levofloxacin for 10days, but the control group (CG) received the same volume of saline. Then, the animals received either E. coli O124 K72 (E. coli) or Lactobacillus rhamnosus (LGG) according to their assigned group. E. coli O124 K72 treatment significantly affected colon morphology and distorted intestinal barrier function by up-regulating Claudin2 and down-regulating Occludin. In addition, E. coli upregulated the mRNA expression of MUC1, MUC2, MUC13 and MUC15. Furthermore, suspected tumor was found in the E. coli treated animals. Our results suggested that E. coli O124 K72 strain has adverse effects on intestinal barrier functions and is capable of altering integrity of structural proteins in guinea pig model while at same time it may have a role in colon carcinogenesis. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
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The evolution of antibiotic resistance in a structured host population.
Blanquart, François; Lehtinen, Sonja; Lipsitch, Marc; Fraser, Christophe
2018-06-01
The evolution of antibiotic resistance in opportunistic pathogens such as Streptococcus pneumoniae , Escherichia coli or Staphylococcus aureus is a major public health problem, as infection with resistant strains leads to prolonged hospital stay and increased risk of death. Here, we develop a new model of the evolution of antibiotic resistance in a commensal bacterial population adapting to a heterogeneous host population composed of untreated and treated hosts, and structured in different host classes with different antibiotic use. Examples of host classes include age groups and geographic locations. Explicitly modelling the antibiotic treatment reveals that the emergence of a resistant strain is favoured by more frequent but shorter antibiotic courses, and by higher transmission rates. In addition, in a structured host population, localized transmission in host classes promotes both local adaptation of the bacterial population and the global maintenance of coexistence between sensitive and resistant strains. When transmission rates are heterogeneous across host classes, resistant strains evolve more readily in core groups of transmission. These findings have implications for the better management of antibiotic resistance: reducing the rate at which individuals receive antibiotics is more effective to reduce resistance than reducing the duration of treatment. Reducing the rate of treatment in a targeted class of the host population allows greater reduction in resistance, but determining which class to target is difficult in practice. © 2018 The Authors.
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Spatial structure and nutrients promote invasion of IncP-1 plasmids in bacterial populations
Fox, Randal E; Zhong, Xue; Krone, Stephen M; Top, Eva M
2008-01-01
In spite of the importance of plasmids in bacterial adaptation, we have a poor understanding of their dynamics. It is not known if or how plasmids persist in and spread through (invade) a bacterial population when there is no selection for plasmid-encoded traits. Moreover, the differences in dynamics between spatially structured and mixed populations are poorly understood. Through a joint experimental/theoretical approach, we tested the hypothesis that self-transmissible IncP-1 plasmids can invade a bacterial population in the absence of selection when initially very rare, but only in spatially structured habitats and when nutrients are regularly replenished. Using protocols that differed in the degree of spatial structure and nutrient levels, the invasiveness of plasmid pB10 in Escherichia coli was monitored during at least 15 days, with an initial fraction of plasmid-bearing (p+) cells as low as 10−7. To further explore the mechanisms underlying plasmid dynamics, we developed a spatially explicit mathematical model. When cells were grown on filters and transferred to fresh medium daily, the p+ fraction increased to 13%, whereas almost complete invasion occurred when the population structure was disturbed daily. The plasmid was unable to invade in liquid. When carbon source levels were lower or not replenished, plasmid invasion was hampered. Simulations of the mathematical model closely matched the experimental results and produced estimates of the effects of alternative experimental parameters. This allowed us to isolate the likely mechanisms most responsible for the observations. In conclusion, spatial structure and nutrient availability can be key determinants in the invasiveness of plasmids. PMID:18528415
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Is central dogma a global property of cellular information flow?
Piras, Vincent; Tomita, Masaru; Selvarajoo, Kumar
2012-01-01
The central dogma of molecular biology has come under scrutiny in recent years. Here, we reviewed high-throughput mRNA and protein expression data of Escherichia coli, Saccharomyces cerevisiae, and several mammalian cells. At both single cell and population scales, the statistical comparisons between the entire transcriptomes and proteomes show clear correlation structures. In contrast, the pair-wise correlations of single transcripts to proteins show nullity. These data suggest that the organizing structure guiding cellular processes is observed at omics-wide scale, and not at single molecule level. The central dogma, thus, globally emerges as an average integrated flow of cellular information. PMID:23189060
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Is central dogma a global property of cellular information flow?
Piras, Vincent; Tomita, Masaru; Selvarajoo, Kumar
2012-01-01
The central dogma of molecular biology has come under scrutiny in recent years. Here, we reviewed high-throughput mRNA and protein expression data of Escherichia coli, Saccharomyces cerevisiae, and several mammalian cells. At both single cell and population scales, the statistical comparisons between the entire transcriptomes and proteomes show clear correlation structures. In contrast, the pair-wise correlations of single transcripts to proteins show nullity. These data suggest that the organizing structure guiding cellular processes is observed at omics-wide scale, and not at single molecule level. The central dogma, thus, globally emerges as an average integrated flow of cellular information.
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The functional consequences of non-genetic diversity in cellular navigation
NASA Astrophysics Data System (ADS)
Emonet, Thierry; Waite, Adam J.; Frankel, Nicholas W.; Dufour, Yann; Johnston, Jessica F.
Substantial non-genetic diversity in complex behaviors, such as chemotaxis in E. coli, has been observed for decades, but the relevance of this diversity for the population is not well understood. Here, we use microfluidics to show that non-genetic diversity leads to significant structuring of the population in space and time, which confirms predictions made by our detailed mathematical model of chemotaxis. We then use genetic tools to show that altering the expression level of a single chemotaxis protein is sufficient to alter the distribution of swimming behaviors, which directly determines the performance of a population in a gradient of attractant, a result also predicted by our model. Supported by NIH 1R01GM106189, the James S McDonnell Foundation, and the Paul Allen foundation.
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Thein, Z M; Smaranayake, Y H; Smaranayake, L P
2007-11-01
Despite the increasing recognition of the role played by mixed species biofilms in health and disease, the behavior and factors modulating these biofilms remain elusive. We therefore compared the effect of serum, two dietary sugars (sucrose and galactose) and a biocide, chlorhexidine digluconate, on a dual species biofilm (DSB) of Candida albicans and Escherichia coli and, their single species biofilm (SSB) counterparts. Both modes of biofilm growth on polystyrene plastic surfaces were quantified using a viable cell count method and visualized using confocal scanning laser microscopy (CSLM). Present data indicate that co-culture of C. albicans with varying initial concentrations of E. coli leads to a significant inhibition of yeast growth (r=-0.964; p<0.001). Parallel ultrastructural studies using CSLM and a Live/Dead stain confirmed that E. coli growth rendered blastospores and hyphal yeasts non-viable in DSB. SSB of C. albicans showed pronounced growth when its growth surface was pretreated with serum and by sugar supplements in the incubating medium (p<0.05). Intriguingly, C. albicans in DSB was more resistant to the antiseptic effect of chlorhexidine digluconate. Taken together, the current data elucidate some features of the colonization resistance offered by bacteria in mixed bacterial/fungal habitats and how such phenomena may contribute to the development of fungal superinfection during antimicrobial therapy.
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Perreten, Vincent; Boerlin, Patrick
2003-03-01
A new gene, sul3, which specifies a 263-amino-acid protein similar to a dihydropteroate synthase encoded by the 54-kb conjugative plasmid pVP440 from Escherichia coli was characterized. Expression of the cloned sul3 gene conferred resistance to sulfamethoxazole on E. coli. Two copies of the insertion element IS15Delta/26 flanked the region containing sul3. The sul3 gene was detected in one-third of the sulfonamide-resistant pathogenic E. coli isolates from pigs in Switzerland.
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Perreten, Vincent; Boerlin, Patrick
2003-01-01
A new gene, sul3, which specifies a 263-amino-acid protein similar to a dihydropteroate synthase encoded by the 54-kb conjugative plasmid pVP440 from Escherichia coli was characterized. Expression of the cloned sul3 gene conferred resistance to sulfamethoxazole on E. coli. Two copies of the insertion element IS15Δ/26 flanked the region containing sul3. The sul3 gene was detected in one-third of the sulfonamide-resistant pathogenic E. coli isolates from pigs in Switzerland. PMID:12604565
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Numbers of fecal streptococci and Escherichia coli in fresh and dry cattle, horse, and sheep manure.
Weaver, R W; Entry, J A; Graves, Alexandria
2005-10-01
Livestock are known contributors to stream pollution. Numbers of fecal streptococci and Escherichia coli in manure naturally deposited by livestock in the field are needed for activities related to bacterial source tracking and determining maximum daily bacterial loading of streams. We measured populations of fecal streptococci and E. coli in fresh and dry manure from cattle (Bos taurus L.), horses (Equus caballus L.), and sheep (Ovis aires L.) on farms in southern Idaho. Populations of indicator bacteria in dry manure were often as high as that in fresh manure from horse and sheep. There was a 2 log10 drop in the population of fecal coliform numbers in dry cattle manure from cattle in pastures but not from cattle in pens. Bacterial isolates used in source tracking should include isolates from both fresh and dry manure to better represent the bacterial source loading of streams.
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2018-01-01
Few experimental studies have examined the role that sexual recombination plays in bacterial evolution, including the effects of horizontal gene transfer on genome structure. To address this limitation, we analyzed genomes from an experiment in which Escherichia coli K-12 Hfr (high frequency recombination) donors were periodically introduced into 12 evolving populations of E. coli B and allowed to conjugate repeatedly over the course of 1000 generations. Previous analyses of the evolved strains from this experiment showed that recombination did not accelerate adaptation, despite increasing genetic variation relative to asexual controls. However, the resolution in that previous work was limited to only a few genetic markers. We sought to clarify and understand these puzzling results by sequencing complete genomes from each population. The effects of recombination were highly variable: one lineage was mostly derived from the donors, while another acquired almost no donor DNA. In most lineages, some regions showed repeated introgression and others almost none. Regions with high introgression tended to be near the donors’ origin of transfer sites. To determine whether introgressed alleles imposed a genetic load, we extended the experiment for 200 generations without recombination and sequenced whole-population samples. Beneficial alleles in the recipient populations were occasionally driven extinct by maladaptive donor-derived alleles. On balance, our analyses indicate that the plasmid-mediated recombination was sufficiently frequent to drive donor alleles to fixation without providing much, if any, selective advantage. PMID:29385126
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Mohammed, Hussni O; Stipetic, Korana; Salem, Ahmed; McDonough, Patrick; Chang, Yung Fu; Sultan, Ali
2015-10-01
Escherichia coli O157:H7, non-O157 E. coli, and Campylobacter spp. are among the top-ranked pathogens that threaten the safety of food supply systems around the world. The associated risks and predisposing factors were investigated in a dynamic animal population using a repeat-cross-sectional study design. Animal and environmental samples were collected from dairy and camel farms, chicken processing plants, and abattoirs and analyzed for the presence of these pathogens using a combination of bacterial enrichment and real-time PCR tests without culture confirmation. Data on putative risk factors were also collected and analyzed. E. coli O157:H7 was detected by PCR at higher levels in sheep and camel feces than in cattle feces (odds ratios [OR], 6.8 and 21.1, respectively). Although the genes indicating E. coli O157:H7 were detected at a relatively higher rate (4.3%) in fecal samples from dairy cattle, they were less common in milk and udder swabs from the same animals (1 and 2%, respectively). Among the food adulterants, E. coli O103 was more common in cattle fecal samples, whereas O26 was more common in sheep feces and O45 in camel feces compared with cattle (OR, 2.6 and 3.1, respectively). The occurrence of E. coli in the targeted populations differed by the type of sample and season of the year. Campylobacter jejuni and Campylobacter coli were more common in sheep and camel feces than in cattle feces. Most of the survey and surveillance of E. coli focused on serogroup O157 as a potential foodborne hazard; however, based on the PCR results, non-O157 Shiga toxin-producing E. coli serotypes appeared to be more common, and efforts should be made to include them in food safety programs.
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Plasmid Replicon Typing of Commensal and Pathogenic Escherichia coli Isolates▿
Johnson, Timothy J.; Wannemuehler, Yvonne M.; Johnson, Sara J.; Logue, Catherine M.; White, David G.; Doetkott, Curt; Nolan, Lisa K.
2007-01-01
Despite the critical role of plasmids in horizontal gene transfer, few studies have characterized plasmid relatedness among different bacterial populations. Recently, a multiplex PCR replicon typing protocol was developed for classification of plasmids occurring in members of the Enterobacteriaceae. Here, a simplified version of this replicon typing procedure which requires only three multiplex panels to identify 18 plasmid replicons is described. This method was used to screen 1,015 Escherichia coli isolates of avian, human, and poultry meat origin for plasmid replicon types. Additionally, the isolates were assessed for their content of several colicin-associated genes. Overall, a high degree of plasmid variability was observed, with 221 different profiles occurring among the 1,015 isolates examined. IncFIB plasmids were the most common type identified, regardless of the source type of E. coli. IncFIB plasmids occurred significantly more often in avian pathogenic E. coli (APEC) and retail poultry E. coli (RPEC) than in uropathogenic E. coli (UPEC) and avian and human fecal commensal E. coli isolates (AFEC and HFEC, respectively). APEC and RPEC were also significantly more likely than UPEC, HFEC, and AFEC to possess the colicin-associated genes cvaC, cbi, and/or cma in conjunction with one or more plasmid replicons. The results suggest that E. coli isolates contaminating retail poultry are notably similar to APEC with regard to plasmid profiles, with both generally containing multiple plasmid replicon types in conjunction with colicin-related genes. In contrast, UPEC and human and avian commensal E. coli isolates generally lack the plasmid replicons and colicin-related genes seen in APEC and RPEC, suggesting limited dissemination of such plasmids among these bacterial populations. PMID:17277222
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van Hoek, Angela H A M; Stalenhoef, Janneke E; van Duijkeren, Engeline; Franz, Eelco
2016-10-15
During the last decade extended-spectrum cephalosporin (ESC)-resistant Escherichia coli from food-producing animals, especially from broilers, have become a major public health concern because of the potential transmission of these resistant bacteria or their plasmid-encoded resistance genes to humans. The objective of this study was to compare ESC-resistant E. coli isolates from broilers (n=149), humans in contact with these broilers (n=44), humans in the general population (n=63), and patients with a urinary tract infection (UTI) (n=10) with respect to virulence determinants, phylogenetic groups and extended-spectrum β-lactamase (ESBL)/plasmidic-AmpC (pAmpC) genes. The most prevalent ESBL/pAmpC genes among isolates from broilers and individuals on broiler farms were bla CTX-M-1 , bla CMY-2 and bla SHV-12 . In isolates from humans in the general population bla CTX-M-1 , bla CTX-M-14 and bla CTX-M-15 were found most frequently, whereas in UTI isolates bla CTX-M-15 predominated. The marker for enteroaggregative E. coli, aggR, was only identified in a broiler and human isolates from the general population. The extraintestinal virulence genes afa and hlyD were exclusively present in human isolates in the general population and UTI isolates. Multivariate analysis, based on ESBL/pAmpC resistance genes, virulence profiles and phylogenetic groups, revealed that most UTI isolates formed a clearly distinct group. Isolates from broilers and humans associated with broiler farms clustered together. In contrast, isolates from the general population showed some overlap with the former two groups but primarily formed a separate group. These results indicate than transmission occurs between broilers and humans on broiler farms, but also indicate that the role of broilers as a source of foodborne transmission of ESC-resistant E. coli to the general population and subsequently causative agents of human urinary tract infections is likely relatively small. Copyright © 2016 Elsevier B.V. All rights reserved.
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Galindo-Méndez, Mario
Background Community acquired urinary tract infections (CaUTI) caused by strains of extended-spectrum β-lactamases (ESBL) - producing Escherichia coli, mainly by strains carrying the blaCTX-M-15 gene, is a growing phenomenon worldwide. Aim To determine the antibiotic susceptibility pattern of ESBL-producing E. coli as cause of CaUTI and to identify their molecular pattern. Methods A descriptive study was performed in the city of Oaxaca, Mexico, from where 288 strains of CaUTI-producing strains of E. coli in adults with possible UTI were isolated. The CLSI criteria was followed to determine the antimicrobial susceptibility patterns, and their molecular characterization was performed by using PCR. Results 31.3% of E. coli strains isolated in our population were ESBL producers, which presented higher levels of antibiotic resistance than those of non-producers of these enzymes. 95.6% of the studied strains were carriers of the blaCTX-M gene. Conclusions One-third of the Ca-UTI caused by E. coli in our population are caused by ESBL-producing strains, which present high levels of resistance to the antibiotics widely used in our community. This situation considerably decreases the number of antibiotics available for an empiric treatment against these infections.
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Arias, M L; Monge-Rojas, R; Chaves, C; Antillón, F
2001-06-01
Escherichia coli O157: H7 has emerged as a new pathogen and is found worldwide. We studied the effect of several storage temperatures on the survival of this bacterium in common foods from a neotropical environment (Costa Rica) because at least seven clinical cases have been reported from the country, and no epidemiological link or probable food association has been described. High (10(6)-10(8) CFU/ml) and low (10(4)-10(6) CFU/ml) populations of E. coli were inoculated (three replications) in ground meat, chopped cabbage, chicken giblets and pasteurized milk and incubated at 0, 6 and 12 degrees C for 24, 48 and 72 h. Vegetables and milk were also stored at 22 degrees C for the same periods. The E. coli O157: H7 enumeration was done according to the methodology described in the Bacteriological Analytical Manual. Populations of E. coli O157: H7 showed either an increasing or decreasing trend, according to temperature, time or food base. Our data indicate that E. coli O157: H7 is capable of surviving and growing in meat, cabbage, milk and chicken giblets; food items commonly consumed by Costa Ricans.
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Byappanahalli, M.N.; Whitman, R.L.; Shively, D.A.; Ting, W.T.E.; Tseng, C.C.; Nevers, M.B.
2006-01-01
We studied the shoreward and seasonal distribution of E. coli and enterococci in sand (at the water table) at two southern Lake Michigan beaches - Dunbar and West Beach (in Indiana). Deep, backshore sand (??? 20 m inland) was regularly sampled for 15 months during 2002-2003. E. coli counts were not significantly different in samples taken at 5-m intervals from 0-40 M inland (P = 0.25). Neither E. coli nor enterococci mean counts showed any correlation or differences between the two beaches studied. In laboratory experiments, E. coli readily grew in sand supplemented with lake plankton, suggesting that in situ E. coli growth may occur when temperature and natural organic sources are adequate. Of the 114 sand enterococci isolates tested, positive species identification was obtained for only 52 (46%), with E. faecium representing the most dominant species (92%). Genetic characterization by ribotyping revealed no distinct genotypic pattern (s) for E. coli, suggesting that the sand population was rather a mixture of numerous strains (genotypes). These findings indicate that E. coli and enterococci can occur and persist for extended periods in backshore sand at the groundwater table. Although this study was limited to two beaches of southern Lake Michigan, similar findings can be expected at other temperate freshwater beaches. The long-term persistence of these bacteria, perhaps independent of pollution events, complicates their use as indicator organisms. Further, backshore sand at the water table may act as a reservoir for these bacteria and potentially for human pathogens. ?? IWA Publishing 2006.
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Zhang, Qian
2012-01-01
Naturalized soil Escherichia coli populations need to resist common soil desiccation stress in order to inhabit soil environments. In this study, four representative soil E. coli strains and one lab strain, MG1655, were tested for desiccation resistance via die-off experiments in sterile quartz sand under a potassium acetate-induced desiccation condition. The desiccation stress caused significantly lower die-off rates of the four soil strains (0.17 to 0.40 day−1) than that of MG1655 (0.85 day−1). Cellular responses, including extracellular polymeric substance (EPS) production, exogenous glycine betaine (GB) uptake, and intracellular compatible organic solute synthesis, were quantified and compared under the desiccation and hydrated control conditions. GB uptake appeared not to be a specific desiccation response, while EPS production showed considerable variability among the E. coli strains. All E. coli strains produced more intracellular trehalose, proline, and glutamine under the desiccation condition than the hydrated control, and only the trehalose concentration exhibited a significant correlation with the desiccation-contributed die-off coefficients (Spearman's ρ = −1.0; P = 0.02). De novo trehalose synthesis was further determined for 15 E. coli strains from both soil and nonsoil sources to determine its prevalence as a specific desiccation response. Most E. coli strains (14/15) synthesized significantly more trehalose under the desiccation condition, and the soil E. coli strains produced more trehalose (106.5 ± 44.9 μmol/mg of protein [mean ± standard deviation]) than the nonsoil reference strains (32.5 ± 10.5 μmol/mg of protein). PMID:22885754
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Mittl, P. R.; Schulz, G. E.
1994-01-01
The crystal structure of the dimeric flavoenzyme glutathione reductase from Escherichia coli was determined and refined to an R-factor of 16.8% at 1.86 A resolution. The molecular 2-fold axis of the dimer is local but very close to a possible crystallographic 2-fold axis; the slight asymmetry could be rationalized from the packing contacts. The 2 crystallographically independent subunits of the dimer are virtually identical, yielding no structural clue on possible cooperativity. The structure was compared with the well-known structure of the homologous enzyme from human erythrocytes with 52% sequence identity. Significant differences were found at the dimer interface, where the human enzyme has a disulfide bridge, whereas the E. coli enzyme has an antiparallel beta-sheet connecting the subunits. The differences at the glutathione binding site and in particular a deformation caused by a Leu-Ile exchange indicate why the E. coli enzyme accepts trypanothione much better than the human enzyme. The reported structure provides a frame for explaining numerous published engineering results in detail and for guiding further ones. PMID:8061609
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NASA Astrophysics Data System (ADS)
Shih, Yu-Ling; Le, Trung; Rothfield, Lawrence
2003-06-01
The MinCDE proteins of Escherichia coli are required for proper placement of the division septum at midcell. The site selection process requires the rapid oscillatory redistribution of the proteins from pole to pole. We report that the three Min proteins are organized into extended membrane-associated coiled structures that wind around the cell between the two poles. The pole-to-pole oscillation of the proteins reflects oscillatory changes in their distribution within the coiled structure. We also report that the E. coli MreB protein, which is required for maintaining the rod shape of the cell, also forms extended coiled structures, which are similar to the MreB structures that have previously been reported in Bacillus subtilis. The MreB and MinCDE coiled arrays do not appear identical. The results suggest that at least two functionally distinct cytoskeletal-like elements are present in E. coli and that structures of this type can undergo dynamic changes that play important roles in division site placement and possibly other aspects of the life of the cell.
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Paudel, Surya; Stessl, Beatrix; Hess, Claudia; Zloch, Angelika; Hess, Michael
2016-10-07
Various information about the genetic diversity of Escherichia coli isolates from chickens are available but a detailed epidemiological investigation based upon isolates obtained from interrelated pullet and layer flocks is still missing. Therefore, in the course of a longitudinal epidemiological study on pullets and layers, 144 E. coli isolates from chickens with or without pathological lesions of the reproductive tract were serotyped and genotyped with pulsed-field gel electrophoresis (PFGE). These isolates were collected during rearing, peak and at the end of production. The actual study is the first of its kind so as to elucidate genetic relatedness among extraintestinal E. coli isolated from chickens with varying pathological conditions in interrelated layer farms/flocks at different stages of rearing. Serotyping revealed that 63.19 % of the isolates could not be assigned to any of the three serotypes tested whereas 30.55 % of the isolates belonged to serotype O1:K1, 4.86 % to O2:K1 and 1.38 % to O78:K80. After macrorestriction digest with XbaI, 91.66 % of the isolates were typeable resulting in 96 distinct PFGE profiles. Among them, five PFGE types included isolates collected from diseased chickens as well as from birds without pathological lesions. This finding shows that pathogenicity of E. coli in layers seems to be largely influenced by concurrent susceptibility factors. Furthermore, in six out of eight cases where two isolates were collected from each of eight birds, different PFGE types were found in the same or different organs of the same bird. The existence of predominant or persistent E. coli genotypes was only observed in two cases. It is concluded that extraintestinal E. coli genotypes and serotypes in pullets and layers are heterogenous and also do not maintain a single clonality within the same bird. The facts that E. coli strains did not show any definite clonal population structure based on geographical region, age of the host and pathological lesions should have relevance in further epidemiological studies and control strategies.
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Iron induces bimodal population development by Escherichia coli
DePas, William H.; Hufnagel, David A.; Lee, John S.; Blanco, Luz P.; Bernstein, Hans C.; Fisher, Steve T.; James, Garth A.; Stewart, Philip S.; Chapman, Matthew R.
2013-01-01
Bacterial biofilm formation is a complex developmental process involving cellular differentiation and the formation of intricate 3D structures. Here we demonstrate that exposure to ferric chloride triggers rugose biofilm formation by the uropathogenic Escherichia coli strain UTI89 and by enteric bacteria Citrobacter koseri and Salmonella enterica serovar typhimurium. Two unique and separable cellular populations emerge in iron-triggered, rugose biofilms. Bacteria at the air–biofilm interface express high levels of the biofilm regulator csgD, the cellulose activator adrA, and the curli subunit operon csgBAC. Bacteria in the interior of rugose biofilms express low levels of csgD and undetectable levels of matrix components curli and cellulose. Iron activation of rugose biofilms is linked to oxidative stress. Superoxide generation, either through addition of phenazine methosulfate or by deletion of sodA and sodB, stimulates rugose biofilm formation in the absence of high iron. Additionally, overexpression of Mn-superoxide dismutase, which can mitigate iron-derived reactive oxygen stress, decreases biofilm formation in a WT strain upon iron exposure. Not only does reactive oxygen stress promote rugose biofilm formation, but bacteria in the rugose biofilms display increased resistance to H2O2 toxicity. Altogether, we demonstrate that iron and superoxide stress trigger rugose biofilm formation in UTI89. Rugose biofilm development involves the elaboration of two distinct bacterial populations and increased resistance to oxidative stress. PMID:23359678
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Sharma, Gaurav K; Mahajan, Sonalika; Matura, Rakesh; Subramaniam, Saravanan; Mohapatra, Jajati K; Pattnaik, Bramhadev
2014-11-01
Differentiation of Foot-and-Mouth Disease infected from vaccinated animals is essential for effective implementation of vaccination based control programme. Detection of antibodies against 3ABC non-structural protein of FMD virus by immunodiagnostic assays provides reliable indication of FMD infection. Sero-monitoring of FMD in the large country like India is a big task where thousands of serum samples are annually screened. Currently, monoclonal or polyclonal antibodies are widely used in these immunodiagnostic assays. Considering the large population of livestock in the country, an economical and replenishable alternative of these antibodies was required. In this study, specific short chain variable fragment (scFv) antibody against 3B region of 3ABC poly-protein was developed. High level of scFv expression in Escherichia coli system was obtained by careful optimization in four different strains. Two formats of enzyme immunoassays (sandwich and competitive ELISAs) were optimized using scFv with objective to differentiate FMD infected among the vaccinated population. The assays were statistically validated by testing 2150 serum samples. Diagnostic sensitivity/specificity of sandwich and competitive ELISAs were determined by ROC method as 92.2%/95.5% and 89.5%/93.5%, respectively. This study demonstrated that scFv is a suitable alternate for immunodiagnosis of FMD on large scale. Copyright © 2014 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Ruthenburg,A.; Graybosch, D.; Huetsch, J.
DNA gyrase is unique among type II topoisomerases in that its DNA supercoiling activity is unidirectional. The C-terminal domain of the gyrase A subunit (GyrA-CTD) is required for this supercoiling bias. We report here the x-ray structure of the Escherichia coli GyrA-CTD (Protein Data Bank code 1ZI0). The E. coli GyrA-CTD adopts a circular-shaped {beta}-pinwheel fold first seen in the Borrelia burgdorferi GyrA-CTD. However, whereas the B. burgdorferi GyrA-CTD is flat, the E. coli GyrA-CTD is spiral. DNA relaxation assays reveal that the E. coli GyrA-CTD wraps DNA inducing substantial (+) superhelicity, while the B. burgdorferi GyrA-CTD introduces a moremore » modest (+) superhelicity. The observation of a superhelical spiral in the present structure and that of the Bacillus stearothermophilus ParC-CTD structure suggests unexpected similarities in substrate selectivity between gyrase and Topo IV enzymes. We propose a model wherein the right-handed ((+) solenoidal) wrapping of DNA around the E. coli GyrA-CTD enforces unidirectional (-) DNA supercoiling.« less
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General Suppression of Escherichia coli O157:H7 in Sand-Based Dairy Livestock Bedding▿ †
Westphal, Andreas; Williams, Michele L.; Baysal-Gurel, Fulya; LeJeune, Jeffrey T.; McSpadden Gardener, Brian B.
2011-01-01
Sand bedding material is frequently used in dairy operations to reduce the occurrence of mastitis and enhance cow comfort. One objective of this work was to determine if sand-based bedding also supported the microbiologically based suppression of an introduced bacterial pathogen. Bedding samples were collected in summer, fall, and winter from various locations within a dairy operation and tested for their ability to suppress introduced populations of Escherichia coli O157:H7. All sources of bedding displayed a heat-sensitive suppressiveness to the pathogen. Differences in suppressiveness were also noted between different samples at room temperature. At just 1 day postinoculation (dpi), the recycled sand bedding catalyzed up to a 1,000-fold reduction in E. coli counts, typically 10-fold greater than the reduction achieved with other substrates, depending on the sampling date. All bedding substrates were able to reduce E. coli populations by over 10,000-fold within 7 to 15 dpi, regardless of sampling date. Terminal restriction fragment length polymorphism (T-RFLP) analysis was used to identify bacterial populations potentially associated with the noted suppression of E. coli O157:H7 in sand bedding. Eleven terminal restriction fragments (TRFs) were overrepresented in paired comparisons of suppressive and nonsuppressive specimens at multiple sampling points, indicating that they may represent environmentally stable populations of pathogen-suppressing bacteria. Cloning and sequencing of these TRFs indicated that they represent a diverse subset of bacteria, belonging to the Cytophaga-Flexibacter-Bacteroidetes, Gammaproteobacteria, and Firmicutes, only a few of which have previously been identified in livestock manure. Such data indicate that microbial suppression may be harnessed to develop new options for mitigating the risk and dispersal of zoonotic bacterial pathogens on dairy farms. PMID:21257815
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Assessment of the contamination potentials of some foodborne bacteria in biofilms for food products.
Adetunji, Victoria O; Adedeji, Adeyemi O; Kwaga, Jacob
2014-09-01
To assess biofilms formed by different bacterial strains on glass slides, and changes in biofilm mass and biofilm-associated cell populations after brief contacts between biofilms and either media agar or food products. Two Listeria monocytogenes and Escherichia coli (E. coli) strains and a single Staphylococcus aureus (S. aureus) strain were inoculated separately in tryptic soy broth containing glass coupons incubated for 24, 48 or 72 h at 37 °C. The biofilms formed by individual bacterial strains and biofilm-associated cell populations were determined. Biofilms were subsequently allowed to have brief contacts (1-3 times), through gentle touching, with either agar, meat or soft white cheese (2 cm(3)). Changes in biofilm mass on glass slides and cell populations embedded in biofilms were quantified. A nonpathogenic E. coli formed more biofilms than an E. coli O157:H7 strain. Biofilms formed by S. aureus and Listeria monocytogenes were essentially similar. The biofilm mass increased as incubation time increased within 48 h of incubation and was not positively correlated with cellulose production. Biofilm mass at 48 and 72 h of incubation was not significantly different. More frequent contacts with agar or foods did not remove more biofilms or biofilm-associated cells from glass slides. More S. aureus biofilms were removed followed by Listeria and E. coli biofilms. Mean contamination of agar or food models was 0.00 to 7.65 log CFU/cm(2). Greater contaminations in cell populations were observed with S. aureus and Listeria biofilms. The results provide a clearer assessment of contaminating potential of foods that comes in contact with them. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.
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Reed-Jones, Neiunna L.; Marine, Sasha Cahn; Everts, Kathryne L.
2016-01-01
Cover crops provide several ecosystem services, but their impact on enteric bacterial survival remains unexplored. The influence of cover cropping on foodborne pathogen indicator bacteria was assessed in five cover crop/green manure systems: cereal rye, hairy vetch, crimson clover, hairy vetch-rye and crimson clover-rye mixtures, and bare ground. Cover crop plots were inoculated with Escherichia coli and Listeria innocua in the fall of 2013 and 2014 and tilled into the soil in the spring to form green manure. Soil samples were collected and the bacteria enumerated. Time was a factor for all bacterial populations studied in all fields (P < 0.001). E. coli levels declined when soil temperatures dipped to <5°C and were detected only sporadically the following spring. L. innocua diminished somewhat but persisted, independently of season. In an organic field, the cover crop was a factor for E. coli in year 1 (P = 0.004) and for L. innocua in year 2 (P = 0.011). In year 1, E. coli levels were highest in the rye and hairy vetch-rye plots. In year 2, L. innocua levels were higher in hairy vetch-rye (P = 0.01) and hairy vetch (P = 0.03) plots than in the rye plot. Bacterial populations grew (P < 0.05) or remained the same 4 weeks after green manure incorporation, although initial reductions in L. innocua numbers were observed after tilling (P < 0.05). Green manure type was a factor only for L. innocua abundance in a transitional field (P < 0.05). Overall, the impacts of cover crops/green manures on bacterial population dynamics in soil varied, being influenced by bacterial species, time from inoculation, soil temperature, rainfall, and tillage; this reveals the need for long-term studies. PMID:26729724
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Christensen, Sarah C. B.; Arvin, Erik; Nissen, Erling; Albrechtsen, Hans-Jørgen
2013-01-01
Individuals of the water louse, Asellus aquaticus, enter drinking water distribution systems in temperate parts of the world, where they establish breeding populations. We analysed populations of surface water A. aquaticus from two ponds for associated faecal indicator bacteria and assessed the risk of A. aquaticus transporting bacteria into distribution systems. Concentrations of up to two E. coli and five total coliforms·mL−1 were measured in the water and 200 E. coli and >240 total coliforms·mL−1 in the sediments of the investigated ponds. Concentrations of A. aquaticus associated bacteria never exceeded three E. coli and six total coliforms·A. aquaticus−1. During exposure to high concentrations of coliforms, concentrations reached 350 coliforms·A. aquaticus−1. A. aquaticus associated E. coli were only detected as long as E. coli were present in the water and sediment. The calculated probability of exceeding drinking water guideline values in non-disinfected systems by intrusion of A. aquaticus was low. Only in scenarios with narrow pipes and low flows, did total coliforms exceed guideline values, implying that the probability of detection by routine monitoring is also low. The study expands the knowledge base for evaluating incidents with presence of coliform indicators in drinking water by showing that intruding A. aquaticus were not important carriers of E. coli or other coliform bacteria even when emerging from faecally contaminated waters. PMID:23455399
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Oliver, David M; Bird, Clare; Burd, Emmy; Wyman, Michael
2016-09-06
The relationship between culturable counts (CFU) and quantitative PCR (qPCR) cell equivalent counts of Escherichia coli in dairy feces exposed to different environmental conditions and temperature extremes was investigated. Fecal samples were collected in summer and winter from dairy cowpats held under two treatments: field-exposed versus polytunnel-protected. A significant correlation in quantified E. coli was recorded between the qPCR and culture-based methods (r = 0.82). Evaluation of the persistence profiles of E. coli over time revealed no significant difference in the E. coli numbers determined as either CFU or gene copies during the summer for the field-exposed cowpats, whereas significantly higher counts were observed by qPCR for the polytunnel-protected cowpats, which were exposed to higher ambient temperatures. In winter, the qPCR returned significantly higher counts of E. coli for the field-exposed cowpats, thus representing a reversal of the findings from the summer sampling campaign. Results from this study suggest that with increasing time post-defecation and with the onset of challenging environmental conditions, such as extremes in temperature, culture-based counts begin to underestimate the true resilience of viable E. coli populations in livestock feces. This is important not only in the long term as the Earth changes in response to climate-change drivers but also in the short term during spells of extremely cold or hot weather.
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NASA Astrophysics Data System (ADS)
Rohmah, Y.; Rinanti, A.; Hendrawan, D. I.
2018-01-01
This study aims to determine the quality of groundwater in densely populated areas in the Pasar Minggu district, which focuses on examination of Escherichia coli bacteria as biological parameters. E.coli analysis was conducted in 3 sub-districtin the Pasar Minggu district, South Jakarta (106° 45‧0″E - 6° 15‧40″S), which included Pejaten Barat, Jati Padang and Kebagusan sub-district based on topography. The method used is Most Probable Number (MPN), referring to SNI 01-2332.1-2006. The results showed that the presence of E. coli in the highest groundwater ranged from 1100 MPN/100 ml to > 1100 MPN/100 ml, present in Pejaten Barat sub-district (06° 16‧39 "S-106° 49‧48" E) whereas the lowest number ranged from 11.5 MPN/100 ml to 23 MPN/100 ml occurred in Jati Padang sub-district (06° 17‧6 "S - 106° 49‧48" E).The correlation test results show that the amount of E.coli in ground water is affected by the distance of the septic tank to the groundwater well. The amount of E.coli contained in groundwater is also increasing, 1100 MPN/100 ml in groundwater samples at <10 m and < 20 MPN/100 ml in groundwater samples at> 15 m depth. This study provides information that topography and water flow affect the amount of E. coli.
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Christensen, Sarah C B; Arvin, Erik; Nissen, Erling; Albrechtsen, Hans-Jørgen
2013-03-01
Individuals of the water louse, Asellus aquaticus, enter drinking water distribution systems in temperate parts of the world, where they establish breeding populations. We analysed populations of surface water A. aquaticus from two ponds for associated faecal indicator bacteria and assessed the risk of A. aquaticus transporting bacteria into distribution systems. Concentrations of up to two E. coli and five total coliforms·mL-1 were measured in the water and 200 E. coli and >240 total coliforms·mL-1 in the sediments of the investigated ponds. Concentrations of A. aquaticus associated bacteria never exceeded three E. coli and six total coliforms·A. aquaticus-1. During exposure to high concentrations of coliforms, concentrations reached 350 coliforms·A. aquaticus-1. A. aquaticus associated E. coli were only detected as long as E. coli were present in the water and sediment. The calculated probability of exceeding drinking water guideline values in non-disinfected systems by intrusion of A. aquaticus was low. Only in scenarios with narrow pipes and low flows, did total coliforms exceed guideline values, implying that the probability of detection by routine monitoring is also low. The study expands the knowledge base for evaluating incidents with presence of coliform indicators in drinking water by showing that intruding A. aquaticus were not important carriers of E. coli or other coliform bacteria even when emerging from faecally contaminated waters.
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Benoit, Michael; Klaus, David
2005-01-01
Space flight has been shown to affect various bacterial growth parameters. It is proposed that weightlessness allows the cells to remain evenly distributed, consequently altering the chemical makeup of their surrounding fluid, and hence indirectly affecting their physiological behaviour. In support of this argument, ground-based studies using clinostats to partially simulate the quiescent environment attained in microgravity have generally been successful in producing bacterial growth characteristics that mimic responses reported under actual space conditions. A novel approach for evaluating the effects of reduced cell sedimentation is presented here through use of Escherichia coli cultures genetically modified to be neutrally buoyant. Since clinorotation would not (or would only minimally) affect cell distribution of this already near-colloidal cell system, it was hypothesized that the effects on final population density would be eliminated relative to a static control. Gas-vesicle-producing E. coli cultures were grown under clinostat and static conditions and the culture densities at 60 h were compared. As a control, E. coli that do not produce gas vesicles, but were otherwise identical to the experimental strain, were also grown under clinostat and static conditions. As hypothesized, no significant difference was observed in cell populations at 60 h between the clinorotated and static gas-vesicle-producing E. coli cultures, while the cells that did not produce gas vesicles showed a mean increase in population density of 10.5 % (P = 0.001). These results further suggest that the lack of cumulative cell sedimentation is the dominant effect of space flight on non-stirred, in vitro E. coli cultures.
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2017-06-01
Department of Defense (DOD) active duty (AD) service members, and the DMDC Contingency Tracking System (CTS) to determine Department of the Navy (DON...and the Department of Defense (DOD) active duty (AD) population increased above the weighted historic IR; however, all of the 2016 rates remained...infections among young, otherwise healthy, sexually active women. 5 Screening practices may also contribute to higher rates of E. coli infections among
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Sensitivity of Mixed Populations of Staphylococcus aureus and Escherichia coli to Mercurials
Stutzenberger, F. J.; Bennett, E. O.
1965-01-01
Staphylococcus aureus was found to have a higher resistance to merbromin and mercuric chloride in the presence of Escherichia coli. The protective effect of the gram-negative organism on S. aureus was due to the production of extracellular glutathione and hydrogen sulfide and to an unequal distribution of the inhibitor between the two species. S. aureus did not significantly influence the resistance of E. coli to mercurials. PMID:14339264
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Yesil, Mustafa; Kasler, David R; Huang, En; Yousef, Ahmed E
2017-07-01
Foodborne disease outbreaks associated with the consumption of fresh produce pose a threat to public health, decrease consumer confidence in minimally processed foods, and negatively impact the sales of these commodities. The aim of the study was to determine the influence of population size of inoculated pathogen on its inactivation by gaseous ozone treatment during vacuum cooling. Spinach leaves were spot inoculated with Escherichia coli O157:H7 at approximate initial populations of 10 8 , 10 7 , and 10 5 CFU/g. Inoculated leaves were vacuum cooled (28.5 inHg; 4°C) in a custom-made vessel and then were subjected to a gaseous ozone treatment under the following conditions: 1.5 g of ozone per kg of gas mixture, vessel pressure at 10 lb/in 2 gauge, 94 to 98% relative humidity, and 30 min of holding time at 9°C. Treatment of the leaves, having the aforementioned inocula, decreased E. coli populations by 0.2, 2.1, and 2.8 log CFU/g, respectively, compared with the inoculated untreated controls. Additionally, spinach leaves were inoculated at 1.4 × 10 3 CFU/g, which approximates natural contamination level, and the small populations remaining after ozone treatment were quantified using the most-probable-number (MPN) method. Vacuum and ozone sequential treatment decreased this E. coli O157:H7 population to <3 MPN/g (i.e., greater than 3-log reduction). Resulting log reductions were greater (P < 0.05) at the lower rather than the higher inoculum levels. In conclusion, treatment of spinach leaves with gaseous ozone is effective against pathogen loads comparable to those found in naturally contaminated fresh produce, but efficacy decreases as inoculum level increases.
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Barth, S A; Blome, S; Cornelis, D; Pietschmann, J; Laval, M; Maestrini, O; Geue, L; Charrier, F; Etter, E; Menge, C; Beer, M; Jori, F
2018-06-01
On the Mediterranean island of Corsica, cohabitation between sympatric domestic pigs and Eurasian wild boar (Sus scrofa) is common and widespread and can facilitate the maintenance and dissemination of several pathogens detrimental for the pig industry or human health. In this study, we monitored a population of free-ranging domestic pigs reared in extensive conditions within a 800-ha property located in Central Corsica which was frequently visited by a sympatric population of wild boar between 2013 and 2015. We used GPS collars to assess evidence of a spatially shared environment. Subsequently, we analysed by PFGE of XbaI-restricted DNA if those populations shared faecal Escherichia coli clones that would indicate contact and compared these results with those collected in a distant (separated by at least 50 km) population of wild boar used as control. Results showed that one of eight wild boars sampled in the study area shed E. coli XbaI clones identical to clones isolated from domestic pig sounders from the farm, while wild boar populations sampled in distant parts of the study area shared no identical clone with the domestic pigs monitored. Interestingly, within the sampled pigs, two identical clones were found in 2013 and in 2015, indicating a long-time persisting colonization type. Although the method of isolation of E. coli and PFGE typing of the isolates requires intensive laboratory work, it is applicable under field conditions to monitor potential infectious contacts. It also provides evidence of exchange of microorganisms between sympatric domestic pigs and wild boar populations. © 2018 Blackwell Verlag GmbH.
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Trung, Nguyen Vinh; Nhung, Hoang Ngoc; Carrique-Mas, Juan J; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James; Nhung, Nguyen Thi; Van Minh, Pham; Wagenaar, Jaap A; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi
2016-09-09
Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E. coli O104:H4 in Europe in 2011. We assessed the opportunities for E. coli carrying the aggR and stx genes to emerge in 'backyard' farms in south-east Asia. Faecal samples collected from 204 chicken farms; 204 farmers and 306 age- and gender-matched individuals not exposed to poultry farming were plated on MacConkey agar plates with and without antimicrobials being supplemented. Sweep samples obtained from MacConkey agar plates without supplemented antimicrobials were screened by multiplex PCR for the detection of the stx1, stx2 and aggR genes. One chicken farm sample each (0.5 %) contained the stx1 and the aggR gene. Eleven (2.4 %) human faecal samples contained the stx1 gene, 2 samples (0.4 %) contained stx2 gene, and 31 (6.8 %) contained the aggR gene. From 46 PCR-positive samples, 205 E. coli isolates were tested for the presence of stx1, stx2, aggR, wzx O104 and fliC H4 genes. None of the isolates simultaneously contained the four genetic markers associated with E. coli O104:H4 epidemic strain (aggR, stx2, wzx O104 and fliC H4 ). Of 34 EAEC, 64.7 % were resistant to 3(rd)-generation cephalosporins. These results indicate that in southern Vietnam, the human population is a more likely reservoir of aggR and stx gene carrying E. coli than the chicken population. However, conditions for transmission of isolates and/or genes between human and animal reservoirs resulting in the emergence of highly virulent E. coli strains are still favorable, given the nature of'backyard' farms in Vietnam.
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Genotype diversity of Escherichia coli isolates in natural waters determined by PFGE and ERIC-PCR.
Casarez, Elizabeth A; Pillai, Suresh D; Di Giovanni, George D
2007-08-01
Most library-dependent bacterial source tracking studies using Escherichia coli (E. coli) have focused on strain diversity of isolates obtained from known human and animal faecal sources for library development. In contrast, this study evaluated the genotype variation of E. coli isolated from natural surface water using pulsed field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus sequence polymerase chain reaction (ERIC-PCR) to better understand these naturally occurring populations. A total of 650 water samples were collected over a nine month period from eleven sampling stations from Lake Waco and Belton Lake in Central Texas. Of the 650 water samples collected, 412 were positive for E. coli, yielding a total of 631 E. coli isolates (1-12 isolates collected per sample). PFGE and ERIC-PCR patterns were successfully generated for 555 isolates and were compared using the curve-based Pearson's product-moment correlation coefficient. The 555 E. coli isolates represented 461 PFGE genotypes, with 84% (386/461) of the genotypes being represented by individual isolates. The remaining 75 genotypes were represented by 2-5 isolates each. Using ERIC-PCR, the 555 E. coli isolates represented 175 genotypes, with 63% (109/175) of the genotypes being represented by individual isolates. In contrast to the PFGE results, two ERIC-PCR genotypes represented 37% of the E. coli isolates, (83 and 124 isolates, respectively), and were found throughout the watersheds both spatially and temporally. Based on the PFGE genotype diversity of water isolates, there is little evidence that a small number of environmentally-adapted E. coli represent dominant populations in the studied waterbodies. However, with the lower discriminatory power technique ERIC-PCR, an opposing conclusion might have been drawn. These results emphasize the importance of considering the resolving power of the source tracking technique being used when assessing strain diversity and geographical stability.
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Sharma, Manan; Lakshman, Sudesna; Ferguson, Sean; Ingram, David T; Luo, Yaguang; Patel, Jitu
2011-05-01
Fresh-cut leafy greens contaminated with Escherichia coli O157:H7 have caused foodborne outbreaks. Packaging conditions, coupled with abusive storage temperatures of contaminated lettuce, were evaluated for their effect on the potential virulence of E. coli O157:H7. Shredded lettuce was inoculated with 5.58 and 3.98 log CFU E. coli O157:H7 per g and stored at 4 and 15°C, respectively, for up to 10 days. Lettuce was packaged under treatment A (modified atmosphere packaging conditions used for commercial fresh-cut produce, in gas-permeable film with N(2)), treatment B (near-ambient air atmospheric conditions in a gas-permeable film with microperforations), and treatment C (high-CO(2) and low-O(2) conditions in a gas-impermeable film). E. coli O157:H7 populations from each treatment were determined by enumeration of numbers on MacConkey agar containing nalidixic acid. RNA was extracted from packaged lettuce for analysis of expression of virulence factor genes stx(2), eae, ehxA, iha, and rfbE. E. coli O157:H7 populations on lettuce at 4°C under all treatments decreased, but most considerably so under treatment B over 10 days. At 15°C, E. coli O157:H7 populations increased by at least 2.76 log CFU/g under all treatments. At 15°C, expression of eae and iha was significantly greater under treatment B than it was under treatments A and C on day 3. Similarly, treatment B promoted significantly higher expression of stx(2), eae, ehxA, and rfbE genes on day 10, compared with treatments A and C at 15°C. Results indicate that storage under near-ambient air atmospheric conditions can promote higher expression levels of O157 virulence factors on lettuce, and could affect the severity of E. coli O157:H7 infections associated with leafy greens.
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2011-01-01
Background Population antimicrobial use may influence resistance emergence. Resistance is an ecological phenomenon due to potential transmissibility. We investigated spatial and temporal patterns of ciprofloxacin (CIP) population consumption related to E. coli resistance emergence and dissemination in a major Brazilian city. A total of 4,372 urinary tract infection E. coli cases, with 723 CIP resistant, were identified in 2002 from two outpatient centres. Cases were address geocoded in a digital map. Raw CIP consumption data was transformed into usage density in DDDs by CIP selling points influence zones determination. A stochastic model coupled with a Geographical Information System was applied for relating resistance and usage density and for detecting city areas of high/low resistance risk. Results E. coli CIP resistant cluster emergence was detected and significantly related to usage density at a level of 5 to 9 CIP DDDs. There were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density. Conclusions There were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density. The usage density of 5-9 CIP DDDs per 1,000 inhabitants within the same influence zone was the resistance triggering level. This level led to E. coli resistance clustering, proving that individual resistance emergence and dissemination was affected by antimicrobial population consumption. PMID:21356088
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Liu, Jinxin; Zhao, Zhe; Orfe, Lisa; Subbiah, Murugan; Call, Douglas R
2016-02-01
We determined if antibiotics residues that are excreted from treated animals can contribute to persistence of resistant bacteria in agricultural environments. Administration of ceftiofur, a third-generation cephalosporin, resulted in a ∼ 3 log increase in ceftiofur-resistant Escherichia coli found in the faeces and pen soils by day 10 (P = 0.005). This resistant population quickly subsided in faeces, but was sustained in the pen soil (∼ 4.5 log bacteria g(-1)) throughout the trial (1 month). Florfenicol treatment resulted in a similar pattern although the loss of florfenicol-resistant E. coli was slower for faeces and remained stable at ∼ 6 log bacteria g(-1) in the soil. Calves were treated in pens where eGFP-labelled E. coli were present in the bedding (∼ 2 log g(-1)) resulting in amplification of the eGFP E. coli population ∼ 2.1 log more than eGFP E. coli populations in pens with untreated calves (day 4; P < 0.005). Excreted residues accounted for > 10-fold greater contribution to the bedding reservoir compared with shedding of resistant bacteria in faeces. Treatment with therapeutic doses of ceftiofur or florfenicol resulted in 2-3 log g(-1) more bacteria than the estimated ID50 (2.83 CFU g(-1)), consistent with a soil-borne reservoir emerging after antibiotic treatment that can contribute to the long-term persistence of antibiotic resistance in animal agriculture. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.
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Escherichia coli, total coliform, and fecal coliform data were collected from two wastewater treatment facilities, a subsurface constructed wetlands, and the receiving stream. Results are presented from individual wastewater treatment process streams, final effluent and river sit...
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Super shedding of Escherichia coli O157:H7 by cattle and the impact on beef carcass contamination.
Arthur, Terrance M; Brichta-Harhay, Dayna M; Bosilevac, Joseph M; Kalchayanand, Norasak; Shackelford, Steven D; Wheeler, Tommy L; Koohmaraie, Mohammad
2010-09-01
Beef carcass contamination is a direct result of pathogen transfer from cattle hides harboring organisms such as enterohemorrhagic Escherichia coli. Hide contamination occurs from direct and indirect fecal contamination in cattle production and lairage environments. In each of these environments, individual animals shedding E. coli O157:H7 at high levels (>10(4) CFU/g of feces, hereafter referred to as "super shedders") can have a disproportionate effect on cattle hide and subsequent carcass contamination. It is not known what criteria must be met to cause an animal to shed at levels exceeding 10(4) CFU/g. Understanding the factors that play a role in super shedding will aid in minimizing or eliminating the super shedding population. Interventions that would prevent super shedding in the cattle population should reduce E. coli O157:H7 transmission in the production and lairage environments resulting in reduced risk of beef carcass contamination and a safer finished product.
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Inatsu, Yasuhiro; Ohata, Yukiko; Ananchaipattana, Chiraporn; Latiful Bari, Md; Hosotani, Yukie; Kawasaki, Susumu
2016-01-01
Fate of Escherichia coli O157 cells was evaluated when inoculated into each step after production of lightly pickled Chinese cabbage. The efficacy of surface sterilization by 100 mg/L of chlorine water for 10 min on raw leaves (6.0 log CFU/g) was 2.2 log CFU/g reduction. No meaningful change of the population of E. coli O157 (3.5 log CFU/g to 1.5 log MPN/g) contaminated into 19 kinds of products was observed. These results indicated the difficulty of estimating the viable count of the cells between contaminated on farms and further processing and storage steps. The population of E. coli O157 (3 log CFU/g to 1 log MPN/g) inoculated into the Chinese cabbage products was reduced less than 0.6 log CFU/g after 2 h-incubation at 37℃ in artificial gastric juice. Prevention from initial contamination of E. coli O157 on the ingredients of Chinese cabbage products is important to reduce the risk of food poisoning because the reduction of the bacterial counts after processing and consumption are limited.
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Byappanahalli, M.; Fujioka, R.
2004-01-01
The soil environment in Hawaii is generally characterised as sub-optimal but permissive to support the in situ growth of E. coli and enterococci. However, soil desiccation and competition for nutrients by major indigenous soil microflora have been identified as potential factors that could limit a rapid and continual growth of faecal indicator bacteria in this soil environment. Despite these limitations, the genetic capacities of E. coli and enterococci are robust enough to enable these bacteria to become established as minor populations of Hawaii's soil microflora. Although the concentrations of E. coli and enterococci may have represented a fraction of the total soil microbiota, their presence in this habitat was very significant, for two important reasons: (a) soil was a major environmental source of E. coli and enterococci, and (b) the elevated counts of these bacteria in streams that routinely exceeded the EPA standards were due to run-off from soil. As a result, E. coli and enterococci were inadequate indicators to measure the degree of faecal contamination and potential presence of sewage-borne pathogens in Hawaiian streams. ?? IWA Publishing 2004.
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Michelacci, Valeria; Bondì, Roslen; Gigliucci, Federica; Franz, Eelco; Badouei, Mahdi Askari; Schlager, Sabine; Minelli, Fabio; Tozzoli, Rosangela; Caprioli, Alfredo; Morabito, Stefano
2016-01-01
Verotoxigenic Escherichia coli infections in humans cause disease ranging from uncomplicated intestinal illnesses to bloody diarrhea and systemic sequelae, such as hemolytic uremic syndrome (HUS). Previous research indicated that pigeons may be a reservoir for a population of verotoxigenic E. coli producing the VT2f variant. We used whole-genome sequencing to characterize a set of VT2f-producing E. coli strains from human patients with diarrhea or HUS and from healthy pigeons. We describe a phage conveying the vtx2f genes and provide evidence that the strains causing milder diarrheal disease may be transmitted to humans from pigeons. The strains causing HUS could derive from VT2f phage acquisition by E. coli strains with a virulence genes asset resembling that of typical HUS-associated verotoxigenic E. coli. PMID:27584691
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Methodological comparisons for antimicrobial resistance surveillance in feedlot cattle
2013-01-01
Background The purpose of this study was to objectively compare methodological approaches that might be utilized in designing an antimicrobial resistance (AMR) surveillance program in beef feedlot cattle. Specifically, four separate comparisons were made to investigate their potential impact on estimates for prevalence of AMR. These included investigating potential differences between 2 different susceptibility testing methods (broth microdilution and disc diffusion), between 2 different target bacteria (non-type-specific E. coli [NTSEC] and Mannheimia haemolytica), between 2 strategies for sampling feces (individual samples collected per rectum and pooled samples collected from the pen floor), and between 2 strategies for determining which cattle to sample (cattle that were culture-positive for Mannheimia haemolytica and those that were culture-negative). Results Comparing two susceptibility testing methods demonstrated differences in the likelihood of detecting resistance between automated disk diffusion (BioMIC®) and broth microdilution (Sensititre®) for both E. coli and M. haemolytica. Differences were also detected when comparing resistance between two bacterial organisms within the same cattle; there was a higher likelihood of detecting resistance in E. coli than in M. haemolytica. Differences in resistance prevalence were not detected when using individual animal or composite pen sampling strategies. No differences in resistance prevalences were detected in E. coli recovered from cattle that were culture-positive for M. haemolytica compared to those that were culture-negative, suggesting that sampling strategies which targeted recovery of E. coli from M. haemolytica-positive cattle would not provide biased results. Conclusions We found that for general purposes, the susceptibility test selected for AMR surveillance must be carefully chosen considering the purpose of the surveillance since the ability to detect resistance appears to vary between these tests depending upon the population where they are applied. Continued surveillance of AMR in M. haemolytica recovered by nasopharyngeal swab is recommended if monitoring an animal health pathogen is an objective of the surveillance program as results of surveillance using fecal E. coli cannot be extrapolated to this important respiratory pathogen. If surveillance of E. coli was pursued in the same population, study populations could target animals that were culture-positive for M. haemolytica without biasing estimates for AMR in E. coli. Composite pen-floor sampling or sampling of individuals per-rectum could possibly be used interchangeably for monitoring resistance in E. coli. PMID:24144185
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Structural, electronic structure and antibacterial properties of graphene-oxide nano-sheets
NASA Astrophysics Data System (ADS)
Sharma, Aditya; Varshney, Mayora; Nanda, Sitansu Sekhar; Shin, Hyun Joon; Kim, Namdong; Yi, Dong Kee; Chae, Keun-Hwa; Ok Won, Sung
2018-04-01
Correlation between the structural/electronic structure properties and bio-activity of graphene-based materials need to be thoroughly evaluated before their commercial implementation in the health and environment precincts. To better investigate the local hybridization of sp2/sp3 orbitals of the functional groups of graphene-oxide (GO) and their execution in the antimicrobial mechanism, we exemplify the antibacterial activity of GO sheets towards the Escherichia coli bacteria (E. coli) by applying the field-emission scanning electron microscopy (FESEM), near edge X-ray absorption fine structure (NEXAFS) and scanning transmission X-ray microscope (STXM) techniques. C K-edge and O K-edge NEXAFS spectra have revealed lesser sp2 carbon atoms in the aromatic ring and attachment of functional oxygen groups at GO sheets. Entrapment of E. coli bacteria by GO sheets is evidenced by FESEM investigations and has also been corroborated by nano-scale imaging of bacteria using the STXM. Spectroscopy evidence of functional oxygen moieties with GO sheets and physiochemical entrapment of E. coli bacteria have assisted us to elaborate the mechanism of cellular oxidative stress-induced disruption of bacterial membrane.
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Structural basis for suppression of hypernegative DNA supercoiling by E. coli topoisomerase I
Tan, Kemin; Zhou, Qingxuan; Cheng, Bokun; ...
2015-10-20
Escherichia coli topoisomerase I has an essential function in preventing hypernegative supercoiling of DNA. A full length structure of E. coli topoisomerase I reported here shows how the C-terminal domains bind single-stranded DNA (ssDNA) to recognize the accumulation of negative supercoils in duplex DNA. These C-terminal domains of E. coli topoisomerase I are known to interact with RNA polymerase, and two flexible linkers within the C-terminal domains may assist in the movement of the ssDNA for the rapid removal of transcription driven negative supercoils. The structure has also unveiled for the first time how the 4-Cys zinc ribbon domain andmore » zinc ribbon-like domain bind ssDNA with primarily π -stacking interactions. Finally, this novel structure, in combination with new biochemical data, provides important insights into the mechanism of genome regulation by type IA topoisomerases that is essential for life, as well as the structures of homologous type IA TOP3α and TOP3β from higher eukaryotes that also have multiple 4-Cys zinc ribbon domains required for their physiological functions.« less
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Structure-Based Annotation of a Novel Sugar Isomerase from the Pathogenic E. coli O157:H7
DOE Office of Scientific and Technical Information (OSTI.GOV)
van Staalduinen, L.; Park, C; Yeom, S
2010-01-01
Prokaryotes can use a variety of sugars as carbon sources in order to provide a selective survival advantage. The gene z5688 found in the pathogenic Escherichia coli O157:H7 encodes a 'hypothetical' protein of unknown function. Sequence analysis identified the gene product as a putative member of the cupin superfamily of proteins, but no other functional information was known. We have determined the crystal structure of the Z5688 protein at 1.6 {angstrom} resolution and identified the protein as a novel E. coli sugar isomerase (EcSI) through overall fold analysis and secondary-structure matching. Extensive substrate screening revealed that EcSI is capable ofmore » acting on D-lyxose and D-mannose. The complex structure of EcSI with fructose allowed the identification of key active-site residues, and mutagenesis confirmed their importance. The structure of EcSI also suggested a novel mechanism for substrate binding and product release in a cupin sugar isomerase. Supplementation of a nonpathogenic E. coli strain with EcSI enabled cell growth on the rare pentose d-lyxose.« less
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Zhou, Z X; Wei, D F; Guan, Y; Zheng, A N; Zhong, J J
2010-03-01
The purpose of this study was to provide micrographic evidences for the damaged membrane structure and intracellular structure change of Escherichia coli strain 8099, induced by polyhexamethylene guanidine hydrochloride (PHMG). The bactericidal effect of PHMG on E. coli was investigated based on beta-galactosidase activity assay, fluorescein-5-isothiocyanate confocal laser scanning microscopy, field emission scanning electron microscopy and transmission electron microscopy. The results revealed that a low dose (13 microg ml(-1)) of PHMG slightly damaged the outer membrane structure of the treated bacteria and increased the permeability of the cytoplasmic membrane, while no significant damage was observed to the morphological structure of the cells. A high dose (23 microg ml(-1)) of PHMG collapsed the outer membrane structure, led to the formation of a local membrane pore across the membrane and badly damaged the internal structure of the cells. Subsequently, intracellular components were leaked followed by cell inactivation. Dose-dependent membrane disruption was the main bactericidal mechanism of PHMG. The formation of the local membrane pores was probable after exposure to a high dose (23 microg ml(-1)) of PHMG. Micrographic evidences were provided about the damaged membrane structure and intracellular structure change of E. coli. The presented information helps understand the bactericidal mechanism of PHMG by membrane damage.
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Kim, Seonhwa; Bang, Jihyun; Kim, Hoikyung; Beuchat, Larry R; Ryu, Jee-Hoon
2013-11-01
We investigated the potential use of biofilm formed by a competitive-exclusion (CE) microorganism to inactivate Escherichia coli O157:H7 on a stainless steel surface. Five microorganisms showing inhibitory activities against E. coli O157:H7 were isolated from vegetable seeds and sprouts. The microorganism with the greatest antimicrobial activity was identified as Paenibacillus polymyxa (strain T5). In tryptic soy broth (TSB), strain T5 reached a higher population at 25 °C than at 12 or 37 °C without losing inhibitory activity against E. coli O157:H7. When P. polymyxa (6 log CFU/mL) was co-cultured with E. coli O157:H7 (2, 3, 4, or 5 log CFU/mL) in TSB at 25 °C, the number of E. coli O157:H7 decreased significantly within 24h. P. polymyxa formed a biofilm on stainless steel coupons (SSCs) in TSB at 25 °C within 24h, and cells in biofilms, compared to attached cells without biofilm formation, showed significantly increased resistance to a dry environment (43% relative humidity [RH]). With the exception of an inoculum of 4 log CFU/coupon at 100% RH, upon exposure to biofilm formed by P. polymyxa on SSCs, populations of E. coli O157:H7 (2, 4, or 6 log CFU/coupon) were significantly reduced within 48 h. Most notably, when E. coli O157:H7 at 2 log CFU/coupon was applied to SSCs on which P. polymyxa biofilm had formed, it was inactivated within 1h, regardless of RH. These results will be useful when developing strategies using biofilms produced by competitive exclusion microorganisms to inactivate foodborne pathogens in food processing environments. © 2013.
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Pang, Yu-Hsin; Hung, Yen-Con
2016-07-01
Spray washing is a common sanitizing method for the fresh produce industry. The purpose of this research was to investigate the antimicrobial effect of spraying slightly acidic electrolyzed water (SAEW) and a combination of ozonated water with ultraviolet (UV) in reducing Escherichia coli O157:H7 on romaine and iceberg lettuces. Both romaine and iceberg lettuces were spot inoculated with 100 μL of a 3 strain mixture of E. coli O157:H7 to achieve an inoculum of 6 log CFU/g on lettuce. A strong antimicrobial effect was observed for the UV-ozonated water combination, which reduced the population of E. coli by 5 log CFU/g of E. coli O157:H7 on both lettuces. SAEW achieved about 5 log CFU/g reductions in the bacterial counts on romaine lettuce. However, less than 2.5 log CFU/g in the population of E. coli O157:H7 was reduced on iceberg lettuce. The difference may be due to bacteria aggregation near and within stomata for iceberg lettuce but not for romaine lettuce. The UV light treatment may stimulate the opening of the stomata for the UV-ozonated water treatment and hence achieve better bacterial inactivation than the SAEW treatment for iceberg lettuce. Our results demonstrated that the combined treatment of SAEW and UV-ozonated water in the spray washing process could more effectively reduce E. coli O157:H7 on lettuce, which in turn may help reduce incidences of E. coli O157:H7 outbreaks. © 2016 Institute of Food Technologists®
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Nowak, Kathrin; Fahr, Jakob; Weber, Natalie; Lübke-Becker, Antina; Semmler, Torsten; Weiss, Sabrina; Mombouli, Jean-Vivien; Wieler, Lothar H; Guenther, Sebastian; Leendertz, Fabian H; Ewers, Christa
2017-01-01
Bats are suspected to be a reservoir of several bacterial and viral pathogens relevant to animal and human health, but studies on Escherichia coli in these animals are sparse. We investigated the presence of E. coli in tissue samples (liver, lung and intestines) collected from 50 fruit bats of five different species (Eidolon helvum, Epomops franqueti, Hypsignathus monstrosus, Myonycteris torquata, Rousettus aegyptiacus) of two different areas in the Republic of Congo between 2009 and 2010. To assess E. coli pathotypes and phylogenetic relationships, we determined the presence of 59 virulence associated genes and multilocus sequence types (STs). Isolates were further tested for their susceptibility to several antimicrobial substances by agar disk diffusion test and for the presence of an Extended-Spectrum Beta-Lactamase phenotype. E. coli was detected in 60% of the bats analysed. The diversity of E. coli strains was very high, with 37 different STs within 40 isolates. Occasionally, we detected sequence types (e.g. ST69, ST127, and ST131) and pathotypes (e.g. ExPEC, EPEC and atypical EPEC), which are known pathogens in human and/or animal infections. Although the majority of strains were assigned to phylogenetic group B2 (46.2%), which is linked with the ExPEC pathovar, occurrence of virulence-associated genes in these strains were unexpectedly low. Due to this, and as only few of the E. coli isolates showed intermediate resistance to certain antimicrobial substances, we assume a rather naïve E. coli population, lacking contact to humans or domestic animals. Future studies featuring in depth comparative whole genome sequence analyses will provide insights into the microevolution of this interesting strain collection.
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Nowak, Kathrin; Fahr, Jakob; Weber, Natalie; Lübke-Becker, Antina; Semmler, Torsten; Weiss, Sabrina; Mombouli, Jean-Vivien; Wieler, Lothar H.; Guenther, Sebastian
2017-01-01
Bats are suspected to be a reservoir of several bacterial and viral pathogens relevant to animal and human health, but studies on Escherichia coli in these animals are sparse. We investigated the presence of E. coli in tissue samples (liver, lung and intestines) collected from 50 fruit bats of five different species (Eidolon helvum, Epomops franqueti, Hypsignathus monstrosus, Myonycteris torquata, Rousettus aegyptiacus) of two different areas in the Republic of Congo between 2009 and 2010. To assess E. coli pathotypes and phylogenetic relationships, we determined the presence of 59 virulence associated genes and multilocus sequence types (STs). Isolates were further tested for their susceptibility to several antimicrobial substances by agar disk diffusion test and for the presence of an Extended-Spectrum Beta-Lactamase phenotype. E. coli was detected in 60% of the bats analysed. The diversity of E. coli strains was very high, with 37 different STs within 40 isolates. Occasionally, we detected sequence types (e.g. ST69, ST127, and ST131) and pathotypes (e.g. ExPEC, EPEC and atypical EPEC), which are known pathogens in human and/or animal infections. Although the majority of strains were assigned to phylogenetic group B2 (46.2%), which is linked with the ExPEC pathovar, occurrence of virulence-associated genes in these strains were unexpectedly low. Due to this, and as only few of the E. coli isolates showed intermediate resistance to certain antimicrobial substances, we assume a rather naïve E. coli population, lacking contact to humans or domestic animals. Future studies featuring in depth comparative whole genome sequence analyses will provide insights into the microevolution of this interesting strain collection. PMID:28700648
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Identification of Escherichia coli and Shigella Species from Whole-Genome Sequences.
Chattaway, Marie A; Schaefer, Ulf; Tewolde, Rediat; Dallman, Timothy J; Jenkins, Claire
2017-02-01
Escherichia coli and Shigella species are closely related and genetically constitute the same species. Differentiating between these two pathogens and accurately identifying the four species of Shigella are therefore challenging. The organism-specific bioinformatics whole-genome sequencing (WGS) typing pipelines at Public Health England are dependent on the initial identification of the bacterial species by use of a kmer-based approach. Of the 1,982 Escherichia coli and Shigella sp. isolates analyzed in this study, 1,957 (98.4%) had concordant results by both traditional biochemistry and serology (TB&S) and the kmer identification (ID) derived from the WGS data. Of the 25 mismatches identified, 10 were enteroinvasive E. coli isolates that were misidentified as Shigella flexneri or S. boydii by the kmer ID, and 8 were S. flexneri isolates misidentified by TB&S as S. boydii due to nonfunctional S. flexneri O antigen biosynthesis genes. Analysis of the population structure based on multilocus sequence typing (MLST) data derived from the WGS data showed that the remaining discrepant results belonged to clonal complex 288 (CC288), comprising both S. boydii and S. dysenteriae strains. Mismatches between the TB&S and kmer ID results were explained by the close phylogenetic relationship between the two species and were resolved with reference to the MLST data. Shigella can be differentiated from E. coli and accurately identified to the species level by use of kmer comparisons and MLST. Analysis of the WGS data provided explanations for the discordant results between TB&S and WGS data, revealed the true phylogenetic relationships between different species of Shigella, and identified emerging pathoadapted lineages. © Crown copyright 2017.
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Could arsenic mitigation lead to increased diarrheal disease in Bangladesh?
NASA Astrophysics Data System (ADS)
van Geen, A.; Ahmed, K.; Akita, Y.; Alam, M.; Culligan, P.; Feighery, J.; Ferguson, A. S.; Emch, M.; Escamilla, V.; Knappett, P.; Layton, A.; Mailloux, B. J.; McKay, L. D.; Mey, J. L.; Serre, M. L.; Streatfield, P. K.; Wu, J.; Yunus, M.
2010-12-01
Could arsenic mitigation lead to increased diarrheal disease in Bangladesh? The health risks of As exposure caused by the installation of millions of shallow tubewells in the Bengal Basin are widely known but fecal contamination of groundwater in this densely populated region with poor sanitation has rarely been studied systematically. In order to examine the degree of microbial contamination of groundwater and, specifically, determine whether arsenic mitigation by switching between shallow wells might affect exposure to microbial pathogens, 125 tubewells ranging between 20 and 120 ft in depth and spanning a wide range of As concentrations were monitored monthly for the fecal indicator E. coli across 7 villages of Matlab and Araihazar, Bangladesh. Overall, the fraction of shallow wells with detectable E. coli ranged from 20% during the dry season to 70% during the monsoon. The linear relation observed between the frequency of E. coli detection in well water during the monsoon and population residing within 25 m of a well (p<0.05) indicates a link between aquifer contamination and population density that might be explained by variations in overlying fecal source strength, coupled with rapid infiltration of surface contaminants into the aquifer. Neither well depth within the 20-120 ft range nor the presence of a concrete platform at the surface had a detectable impact on E. coli levels in well water. PCR analysis of groundwater from 50 wells where E. coli was detected (i.e. >1 CFU/100 mL) indicates that 40% of the wells contained a known pathogen such as Shigella, rotavirus or pathogenic E. coli. Detection of E. coli was on average higher by two-thirds in shallow wells with up to 10 ug/L As compared to shallow wells with >50 ug/L As. This raises the possibility that the most widely applied form of As mitigation, switching to a neighboring household’s low-As well, could result in increased exposure to microbial pathogens. The inverse relation between E. coli detection frequency and groundwater As may reflect the shorter hydraulic travel time to shallow low-As aquifers compared to high-As aquifers that has been reported previously. The relevance to human health of microbial contaminants contained in groundwater in South Asia is supported by significantly higher rates of diarrheal disease in children under 5 recorded in 2000-06 in Matlab for households using a shallow low-As well compared to households using a shallow high-As well, controlling for the effects of population density, socio-economic status, and flood control.
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Gu, Hao; Liao, Yaling; Zhang, Jin; Wang, Ying; Liu, Zhiyong; Cheng, Ping; Wang, Xingyong; Zou, Quanming; Gu, Jiang
2018-01-01
Escherichia coli (E. coli) K1 causes meningitis and remains an unsolved problem in neonates, despite the application of antibiotics and supportive care. The cross-reactivity of bacterial capsular polysaccharides with human antigens hinders their application as vaccine candidates. Thus, protein antigens could be an alternative strategy for the development of an E. coli K1 vaccine. Outer membrane protein A (OmpA) of E. coli K1 is a potential vaccine candidate because of its predominant contribution to bacterial pathogenesis and sub-cellular localization. However, little progress has been made regarding the use of OmpA for this purpose due to difficulties in OmpA production. In the present study, we first investigated the immunogenicity of the four extracellular loops of OmpA. Using the structure of OmpA, we rationally designed and successfully generated the artificial protein OmpAVac, composed of connected loops from OmpA. Recombinant OmpAVac was successfully produced in E. coli BL21 and behaved as a soluble homogenous monomer in the aqueous phase. Vaccination with OmpAVac induced Th1, Th2, and Th17 immune responses and conferred effective protection in mice. In addition, OmpAVac-specific antibodies were able to mediate opsonophagocytosis and inhibit bacterial invasion, thereby conferring prophylactic protection in E. coli K1-challenged adult mice and neonatal mice. These results suggest that OmpAVac could be a good vaccine candidate for the control of E. coli K1 infection and provide an additional example of structure-based vaccine design. PMID:29876324
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Gu, Hao; Liao, Yaling; Zhang, Jin; Wang, Ying; Liu, Zhiyong; Cheng, Ping; Wang, Xingyong; Zou, Quanming; Gu, Jiang
2018-01-01
Escherichia coli ( E. coli ) K1 causes meningitis and remains an unsolved problem in neonates, despite the application of antibiotics and supportive care. The cross-reactivity of bacterial capsular polysaccharides with human antigens hinders their application as vaccine candidates. Thus, protein antigens could be an alternative strategy for the development of an E. coli K1 vaccine. Outer membrane protein A (OmpA) of E. coli K1 is a potential vaccine candidate because of its predominant contribution to bacterial pathogenesis and sub-cellular localization. However, little progress has been made regarding the use of OmpA for this purpose due to difficulties in OmpA production. In the present study, we first investigated the immunogenicity of the four extracellular loops of OmpA. Using the structure of OmpA, we rationally designed and successfully generated the artificial protein OmpAVac, composed of connected loops from OmpA. Recombinant OmpAVac was successfully produced in E. coli BL21 and behaved as a soluble homogenous monomer in the aqueous phase. Vaccination with OmpAVac induced Th1, Th2, and Th17 immune responses and conferred effective protection in mice. In addition, OmpAVac-specific antibodies were able to mediate opsonophagocytosis and inhibit bacterial invasion, thereby conferring prophylactic protection in E. coli K1-challenged adult mice and neonatal mice. These results suggest that OmpAVac could be a good vaccine candidate for the control of E. coli K1 infection and provide an additional example of structure-based vaccine design.
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The Biology of the Escherichia coli Extracellular Matrix
Hufnagel, David A.; DePas, William H.; Chapman, Matthew R.
2015-01-01
Chapter Summary Escherichia coli (E. coli) is one of the world’s best-characterized organisms, as it has been extensively studied for over a century. However, most of this work has focused on E. coli grown under laboratory conditions that do not faithfully simulate its natural environments. Therefore, the historical perspectives on E. coli physiology and life cycle are somewhat skewed toward experimental systems that feature E. coli growing logarithmically in a test tube. Typically a commensal bacterium, E. coli resides in the lower intestines of a slew of animals. Outside of the lower intestine, E. coli can adapt and survive in a very different set of environmental conditions. Biofilm formation allows E. coli to survive, and even thrive, in environments that do not support the growth of planktonic populations. E. coli can form biofilms virtually everywhere; in the bladder during a urinary tract infection, on in-dwelling medical devices, and outside of the host on plants and in the soil. The E. coli extracellular matrix, primarily composed of the protein polymer named curli and the polysaccharide cellulose, promotes adherence to organic and inorganic surfaces, and resistance to desiccation, the host immune system and other antimicrobials. The pathways that govern E. coli biofilm formation, cellulose production, and curli biogenesis will be discussed in this book chapter, which concludes with insights into the future of E. coli biofilm research and potential therapies. PMID:26185090
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Virulence factors in Escherichia coli urinary tract infection.
Johnson, J R
1991-01-01
Uropathogenic strains of Escherichia coli are characterized by the expression of distinctive bacterial properties, products, or structures referred to as virulence factors because they help the organism overcome host defenses and colonize or invade the urinary tract. Virulence factors of recognized importance in the pathogenesis of urinary tract infection (UTI) include adhesins (P fimbriae, certain other mannose-resistant adhesins, and type 1 fimbriae), the aerobactin system, hemolysin, K capsule, and resistance to serum killing. This review summarizes the virtual explosion of information regarding the epidemiology, biochemistry, mechanisms of action, and genetic basis of these urovirulence factors that has occurred in the past decade and identifies areas in need of further study. Virulence factor expression is more common among certain genetically related groups of E. coli which constitute virulent clones within the larger E. coli population. In general, the more virulence factors a strain expresses, the more severe an infection it is able to cause. Certain virulence factors specifically favor the development of pyelonephritis, others favor cystitis, and others favor asymptomatic bacteriuria. The currently defined virulence factors clearly contribute to the virulence of wild-type strains but are usually insufficient in themselves to transform an avirulent organism into a pathogen, demonstrating that other as-yet-undefined virulence properties await discovery. Virulence factor testing is a useful epidemiological and research tool but as yet has no defined clinical role. Immunological and biochemical anti-virulence factor interventions are effective in animal models of UTI and hold promise for the prevention of UTI in humans. Images PMID:1672263
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Gruss, Fabian; Hiller, Sebastian; Maier, Timm
2015-01-01
TamA is an Omp85 protein involved in autotransporter assembly in the outer membrane of Escherichia coli. It comprises a C-terminal 16-stranded transmembrane β-barrel as well as three periplasmic POTRA domains, and is a challenging target for structure determination. Here, we present a method for crystal structure determination of TamA, including recombinant expression in E. coli, detergent extraction, chromatographic purification, and bicelle crystallization in combination with seeding. As a result, crystals in space group P21212 are obtained, which diffract to 2.3 Å resolution. This protocol also serves as a template for structure determination of other outer membrane proteins, in particular of the Omp85 family.
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Jones, Randall T.; Koeltzow, Donald E.; Stocker, B. A. D.
1972-01-01
Escherichia coli K-12 ϰ971 was crossed with a smooth Salmonella typhimurium donor, HfrK6, which transfers early the ilv-linked rfa region determining lipopolysaccharide (LPS) core structure. Two ilv+ hybrids differing in their response to the LPS-specific phages FO and C21 were then crossed with S. typhimurium HfrK9, which transfers early the rfb gene cluster determining O repeat unit structure. Most recombinants selected for his+ (near rfb) were agglutinated by Salmonella factor 4 antiserum. Transfer of an F′ factor (FS400) carrying the rfb–his region of S. typhimurium to the same two ilv+ hybrids gave similar results. LPS extracted from two ilv+,his+, factor 4-positive hybrids contained abequose, the immunodominant sugar for factor 4 specificity. By contrast, his+ hybrids obtained from ϰ971 itself by similar HfrK9 and F′FS400 crosses were not agglutinated by factor 4 antiserum, indicating that the parental E. coli ϰ971 does not have the capacity to attach Salmonella O repeat units to its LPS core. It is concluded that the Salmonella rfb genes are expressed only in E. coli ϰ971 hybrids which have also acquired ilv-linked genes (presumably rfa genes affecting core structure or O-translocase ability, or both) from a S. typhimurium donor. When E. coli ϰ971 was crossed with a smooth E. coli donor, Hfr59, of serotype O8, which transfers his early, most his+ recombinants were agglutinated by E. coli O8 antiserum and lysed by the O8-specific phage, Ω8. This suggests that, although the parental E. coli K-12 strain ϰ971 cannot attach Salmonella-specific repeat units to its LPS core, it does have the capacity to attach E. coli O8-specific repeat units. PMID:4559827
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Scott-Bullard, Britteny R; Geornaras, Ifigenia; Delmore, Robert J; Woerner, Dale R; Reagan, James O; Morgan, J Bred; Belk, Keith E
2017-12-01
A study was conducted to investigate the efficacy of a sulfuric acid-sodium sulfate blend (SSS) against Escherichia coli O157:H7, non-O157 Shiga toxin-producing E. coli (STEC), Salmonella, and nonpathogenic E. coli biotype I on prerigor beef surface tissue. The suitability of using the nonpathogenic E. coli as a surrogate for in-plant validation studies was also determined by comparing the data obtained for the nonpathogenic inoculum with those for the pathogenic inocula. Prerigor beef tissue samples (10 by 10 cm) were inoculated (ca. 6 log CFU/cm 2 ) on the adipose side in a laboratory-scale spray cabinet with multistrain mixtures of E. coli O157:H7 (5 strains), non-O157 STEC (12 strains), Salmonella (6 strains), or E. coli biotype I (5 strains). Treatment parameters evaluated were two SSS pH values (1.5 and 1.0) and two spray application pressures (13 and 22 lb/in 2 ). Untreated inoculated beef tissue samples served as controls for initial bacterial populations. Overall, the SSS treatments lowered inoculated (6.1 to 6.4 log CFU/cm 2 ) bacterial populations by 0.6 to 1.5 log CFU/cm 2 (P < 0.05), depending on inoculum type and recovery medium. There were no main effects (P ≥ 0.05) of solution pH or spray application pressure when SSS was applied to samples inoculated with any of the tested E. coli inocula; however, solution pH did have a significant effect (P < 0.05) when SSS was applied to samples inoculated with Salmonella. Results indicated that the response of the nonpathogenic E. coli inoculum to the SSS treatments was similar (P ≥ 0.05) to that of the pathogenic inocula tested, making the E. coli biotype I strains viable surrogate organisms for in-plant validation of SSS efficacy on beef. The application of SSS at the tested parameters to prerigor beef surface tissue may be an effective intervention for controlling pathogens in a commercial beef harvest process.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
S Park; B Crane
2011-12-31
CheA-mediated CheB phosphorylation and the subsequent CheB-mediated demethylation of the chemoreceptors are important steps required for the bacterial chemotactic adaptation response. Although Escherichia coli CheB has been reported to interact with CheA competitively against CheY, we have observed that Thermotoga maritima CheB has no detectable CheA-binding. By determining the CheY-like domain crystal structure of T. maritima CheB, and comparing against the T. maritima CheY and Salmonella typhimurium CheB structures, we propose that the two consecutive glutamates in the {beta}4/{alpha}4 loop of T. maritima CheB that is absent in T. maritima CheY and in E. coli/S. typhimurium CheB may be onemore » factor contributing to the low CheA affinity.« less
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Zdorovenko, E L; Wang, Y; Shashkov, A S; Chen, T; Ovchinnikova, O G; Liu, B; Golomidova, A K; Babenko, V V; Letarov, A V; Knirel, Y A
2018-05-01
Glycerophosphate-containing O-specific polysaccharides (OPSs) were obtained by mild acidic degradation of lipopolysaccharides isolated from Escherichia coli type strain O81 and E. coli strain HS3-104 from horse feces. The structures of both OPSs and of the oligosaccharide derived from the strain O81 OPS by treatment with 48% HF were studied by monosaccharide analysis and one- and two-dimensional 1H- and 13C-NMR spectroscopy. Both OPSs had similar structures and differed only in the presence of a side-chain glucose residue in the strain HS3-104 OPS. The genes and the organization of the O-antigen biosynthesis gene cluster in both strains are almost identical with the exception of the gtr gene cluster responsible for glucosylations in the strain HS3-104, which is located elsewhere in the genome.
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Pathogenic Escherichia coli and food handlers in luxury hotels in Nairobi, Kenya.
Onyango, Abel O; Kenya, Eucharia U; Mbithi, John J N; Ng'ayo, Musa O
2009-11-01
The epidemiology and virulence properties of pathogenic Escherichia coli among food handlers in tourist destination hotels in Kenya are largely uncharacterized. This cross-sectional study among consenting 885 food handlers working in nine luxurious tourist hotels in Nairobi, Kenya determined the epidemiology, virulence properties, antibiotics susceptibility profiles and conjugation abilities of pathogenic Escherichia coli. Pathogenic Escherichia coli was detected among 39 (4.4%) subjects, including 1.8% enteroaggregative Escherichia coli (EAEC) harboring aggR genes, 1.2% enterotoxigenic Escherichia coli (ETEC) expressing both LT and STp toxins, 1.1% enteropathogenic Escherichia coli (EPEC) and 0.2% Shiga-like Escherichia coli (EHEC) both harboring eaeA and stx2 genes respectively. All the pathotypes had increased surface hydrophobicity. Using multivariate analyses, food handlers with loose stools were more likely to be infected with pathogenic Escherichia coli. Majority 53.8% of the pathotypes were resistant to tetracycline with 40.2% being multi-drug resistant. About 85.7% pathotypes trans-conjugated with Escherichia coli K12 F(-) NA(r) LA. The carriage of multi-drug resistant, toxin expressing pathogenic Escherichia coli by this population is of public health concern because exposure to low doses can result in infection. Screening food handlers and implementing public awareness programs is recommended as an intervention to control transmission of enteric pathogens.
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Duffy, Mary A; Hernandez-Santiago, Virginia; Orange, Gillian; Davey, Peter G; Guthrie, Bruce
2013-01-01
Background Antibiotic resistance is a growing concern and antibiotic usage the main contributing factor, but there are few studies examining antibiotic use and resistance in children. Aim To investigate the association between previous trimethoprim prescribing and resistance in urinary Escherichia coli (E. coli) isolates in children. Design and setting Retrospective, population cohort study in Tayside, Scotland. Method Multilevel modelling of linked microbiology and dispensed prescribing data for 1373 ≤16-year-olds with E. coli urinary isolates in 2004–2009, examining the association between prior trimethoprim prescription and subsequent trimethoprim resistance in people with urinary E. coli isolates. Results Trimethoprim resistance was common (26.6%, 95% confidence interval [CI] = 24.6 to 28.6). Previous trimethoprim prescription was associated with subsequent culture of trimethoprim-resistant E. coli, with more recent prescription being more strongly associated with resistance. After adjusting for the number of previous E. coli isolates and sample year, trimethoprim prescribing in the previous 84 days remained significantly associated with culturing trimethoprim-resistant E. coli (adjusted OR 4.71, 95% CI = 1.83 to 12.16 for the previous 15–28 days versus never prescribed; adjusted OR 3.16, 95% CI = 1.63 to 6.13 for the previous 29–84 days); however, associations were not statistically significant for longer periods since prior exposure. Conclusion Trimethoprim prescription has implications for future resistance in individual children, as well as at population level. Clinicians must ensure appropriateness of treatment choice and duration, and alternative antibiotics should be considered for childhood urinary tract infections if trimethoprim has been prescribed in the preceding 3 months. PMID:23540479
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Duffy, Mary A; Hernandez-Santiago, Virginia; Orange, Gillian; Davey, Peter G; Guthrie, Bruce
2013-04-01
Antibiotic resistance is a growing concern and antibiotic usage the main contributing factor, but there are few studies examining antibiotic use and resistance in children. To investigate the association between previous trimethoprim prescribing and resistance in urinary Escherichia coli (E. coli) isolates in children. Retrospective, population cohort study in Tayside, Scotland. Multilevel modelling of linked microbiology and dispensed prescribing data for 1373 ≤16-year-olds with E. coli urinary isolates in 2004-2009, examining the association between prior trimethoprim prescription and subsequent trimethoprim resistance in people with urinary E. coli isolates. Trimethoprim resistance was common (26.6%, 95% confidence interval [CI] = 24.6 to 28.6). Previous trimethoprim prescription was associated with subsequent culture of trimethoprim-resistant E. coli, with more recent prescription being more strongly associated with resistance. After adjusting for the number of previous E. coli isolates and sample year, trimethoprim prescribing in the previous 84 days remained significantly associated with culturing trimethoprim-resistant E. coli (adjusted OR 4.71, 95% CI = 1.83 to 12.16 for the previous 15-28 days versus never prescribed; adjusted OR 3.16, 95% CI = 1.63 to 6.13 for the previous 29-84 days); however, associations were not statistically significant for longer periods since prior exposure. Trimethoprim prescription has implications for future resistance in individual children, as well as at population level. Clinicians must ensure appropriateness of treatment choice and duration, and alternative antibiotics should be considered for childhood urinary tract infections if trimethoprim has been prescribed in the preceding 3 months.
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Murphy, Colleen; Reid-Smith, Richard J.; Prescott, John F.; Bonnett, Brenda N.; Poppe, Cornelis; Boerlin, Patrick; Weese, J. Scott; Janecko, Nicol; McEwen, Scott A.
2009-01-01
The prevalence and patterns of antimicrobial susceptibility of fecal Escherichia coli, Salmonella spp., extended β-lactamase producing E. coli (ESBL-E. coli), methicillin-resistant Staphylococcus aureus (MRSA), and methicillin-resistant Staphylococcus pseudintermedius (MRSP) were determined for healthy dogs (n = 188) and cats (n = 39) from veterinary hospitals in southern Ontario that had not had recent exposure to antimicrobials. The prevalence of antimicrobial resistance in E. coli was as follows: streptomycin (dogs — 17%, cats — 2%), ampicillin (dogs — 13%, cats — 4%), cephalothin (dogs — 13%, cats — < 1%), and tetracycline (dogs — 11%, cats — 2%). Eleven percent of dogs and 15% of cats had isolates that were resistant to at least 2 antimicrobials. Cephamycinase (CMY)-2 producing E. coli was cultured from 2 dogs. No Salmonella spp., ESBL-E. coli, MRSA, or MRSP isolates were recovered. The observed prevalence of resistance in commensal E. coli from this population was lower than that previously reported in companion animals, but a small percentage of dogs may be a reservoir for CMY-2 E. coli. PMID:20046603
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Mo, Solveig Sølverød; Urdahl, Anne Margrete; Madslien, Knut; Sunde, Marianne; Nesse, Live L; Slettemeås, Jannice Schau; Norström, Madelaine
2018-01-01
The objective of this study was to estimate and compare the occurrence of AMR in wild red foxes in relation to human population densities. Samples from wild red foxes (n = 528) included in the Norwegian monitoring programme on antimicrobial resistance in bacteria from food, feed and animals were included. All samples were divided into three different groups based on population density in the municipality where the foxes were hunted. Of the 528 samples included, 108 (20.5%), 328 (62.1%) and 92 (17.4%) originated from areas with low, medium and high population density, respectively. A single faecal swab was collected from each fox. All samples were plated out on a selective medium for Enterobacteriaceae for culturing followed by inclusion and susceptibility testing of one randomly selected Escherichia coli to assess the overall occurrence of AMR in the Gram-negative bacterial population. Furthermore, the samples were subjected to selective screening for detection of E. coli displaying resistance towards extended-spectrum cephalosporins and fluoroquinolones. In addition, a subset of samples (n = 387) were subjected to selective culturing to detect E. coli resistant to carbapenems and colistin, and enterococci resistant to vancomycin. Of these, 98 (25.3%), 200 (51.7%) and 89 (23.0%) originated from areas with low, medium and high population density, respectively. Overall, the occurrence of AMR in indicator E. coli from wild red foxes originating from areas with different human population densities in Norway was low to moderate (8.8%). The total occurrence of AMR was significantly higher; χ2 (1,N = 336) = 6.53, p = 0.01 in areas with high population density compared to areas with medium population density. Similarly, the occurrence of fluoroquinolone resistant E. coli isolated using selective detection methods was low in areas with low population density and more common in areas with medium or high population density. In conclusion, we found indications that occurrence of AMR in wild red foxes in Norway is associated with human population density. Foxes living in urban areas are more likely to be exposed to AMR bacteria and resistance drivers from food waste, garbage, sewage, waste water and consumption of contaminated prey compared to foxes living in remote areas. The homerange of red fox has been shown to be limited thereby the red fox constitutes a good sentinel for monitoring antimicrobial resistance in the environment. Continuous monitoring on the occurrence of AMR in different wild species, ecological niches and geographical areas can facilitate an increased understanding of the environmental burden of AMR in the environment. Such information is needed to further assess the impact for humans, and enables implementation of possible control measures for AMR in humans, animals and the environment in a true "One Health" approach.
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Cheng, Ming-Fang; Chen, Wan-Ling; Huang, I-Fei; Chen, Jung-Ren; Chiou, Yee-Hsuan; Chen, Yao-Shen; Lee, Susan Shin-Jung; Hung, Wan-Yu; Hung, Chih-Hsin; Wang, Jiun-Ling
2016-08-01
Community-acquired urinary tract infection (UTI) caused by extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is an emerging problem. Compared with urban infants, rural infants may encounter different distributions of community-acquired resistant strains and various barriers to efficient management. A retrospective survey and comparison was conducted for infants with UTI caused by ESBL-producing E. coli admitted to an urban hospital (n = 111) and a rural hospital (n = 48) in southern Taiwan from 2009 to 2012. Compared with 2009 and 2010, the total number of cases at both hospitals significantly increased in 2011 and 2012 (p < 0.001). Compared with the rural patients, the urban patients were significantly younger, and they had fewer days of fever before and after admission, fewer presentations of poor activity and poor appetite, and a lower serum creatinine level. Most of the patients had no prior history of illness, and we could not identify any significant different risk factors for acquiring ESBL-producing E. coli, such as past antimicrobial use, hospitalization, UTI, and underlying renal diseases, between the urban and rural populations. The increase in community-acquired UTI in infants caused by ESBL-producing E. coli was similar between the urban and rural populations. Our preliminary data suggest that the rural-urban disparities were probably related to easy access to health care by the urban population. ESBL complicates disease management, and the increase in the prevalence of ESBL producers is a major health concern and requires further healthy carrier and environmental surveillance.
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Erickson, Marilyn C; Liao, Jean; Payton, Alison S; Webb, Cathy C; Ma, Li; Zhang, Guodong; Flitcroft, Ian; Doyle, Michael P; Beuchat, Larry R
2013-12-01
The survival and distribution of enteric pathogens in soil and lettuce systems were investigated in response to several practices (soil amendment supplementation and reduced watering) that could be applied by home gardeners. Leaf lettuce was grown in manure compost/top soil (0:5, 1:5 or 2:5 w/w) mixtures. Escherichia coli O157:H7 or Salmonella was applied at a low or high dose (10(3) or 10(6) colony-forming units (CFU) mL(-1) ) to the soil of seedlings and mid-age plants. Supplementation of top soil with compost did not affect pathogen survival in the soil or on root surfaces, suggesting that nutrients were not a limiting factor. Salmonella populations on root surfaces were 0.7-0.8 log CFU g(-1) lower for mid-age plants compared with seedlings. E. coli O157:H7 populations on root surfaces were 0.8 log CFU g(-1) lower for mid-age plants receiving 40 mL of water compared with plants receiving 75 mL of water on alternate days. Preharvest internalization of E. coli O157:H7 and Salmonella into lettuce roots was not observed at any time. Based on the environmental conditions and high pathogen populations in soil used in this study, internalization of Salmonella or E. coli O157:H7 into lettuce roots did not occur under practices that could be encountered by inexperienced home gardeners. © 2013 Society of Chemical Industry.
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Zhi, Shuai; Banting, Graham; Li, Qiaozhi; Edge, Thomas A.; Topp, Edward; Sokurenko, Mykola; Scott, Candis; Braithwaite, Shannon; Ruecker, Norma J.; Yasui, Yutaka; McAllister, Tim; Chui, Linda
2016-01-01
ABSTRACT Escherichia coli has been proposed to have two habitats—the intestines of mammals/birds and the nonhost environment. Our goal was to assess whether certain strains of E. coli have evolved toward adaptation and survival in wastewater. Raw sewage samples from different treatment plants were subjected to chlorine stress, and ∼59% of the surviving E. coli strains were found to contain a genetic insertion element (IS30) located within the uspC-flhDC intergenic region. The positional location of the IS30 element was not observed across a library of 845 E. coli isolates collected from various animal hosts or within GenBank or whole-genome reference databases for human and animal E. coli isolates (n = 1,177). Phylogenetics clustered the IS30 element-containing wastewater E. coli isolates into a distinct clade, and biomarker analysis revealed that these wastewater isolates contained a single nucleotide polymorphism (SNP) biomarker pattern that was specific for wastewater. These isolates belonged to phylogroup A, possessed generalized stress response (RpoS) activity, and carried the locus of heat resistance, features likely relevant to nonhost environmental survival. Isolates were screened for 28 virulence genes but carried only the fimH marker. Our data suggest that wastewater contains a naturalized resident population of E. coli. We developed an endpoint PCR targeting the IS30 element within the uspC-flhDC intergenic region, and all raw sewage samples (n = 21) were positive for this marker. Conversely, the prevalence of this marker in E. coli-positive surface and groundwater samples was low (≤5%). This simple PCR assay may represent a convenient microbial source-tracking tool for identification of water samples affected by municipal wastewater. IMPORTANCE The results of this study demonstrate that some strains of E. coli appear to have evolved to become naturalized populations in the wastewater environment and possess a number of stress-related genetic elements likely important for survival in this nonhost environment. The presence of non-host-adapted strains in wastewater challenges our understanding of using E. coli as a microbial indicator of wastewater treatment performance, suggesting that the E. coli strains present in human and animal feces may be very different from those found in treated wastewater. PMID:27371583
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On Relevance of Codon Usage to Expression of Synthetic and Natural Genes in Escherichia coli
Supek, Fran; Šmuc, Tomislav
2010-01-01
A recent investigation concluded that codon bias did not affect expression of green fluorescent protein (GFP) variants in Escherichia coli, while stability of an mRNA secondary structure near the 5′ end played a dominant role. We demonstrate that combining the two variables using regression trees or support vector regression yields a biologically plausible model with better support in the GFP data set and in other experimental data: codon usage is relevant for protein levels if the 5′ mRNA structures are not strong. Natural E. coli genes had weaker 5′ mRNA structures than the examined set of GFP variants and did not exhibit a correlation between the folding free energy of 5′ mRNA structures and protein expression. PMID:20421604
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Pettengill, Emily A.; Pettengill, James B.; Binet, Rachel
As a leading cause of bacterial dysentery, Shigella represents a significant threat to public health and food safety. Related, but often overlooked, enteroinvasive Escherichia coli (EIEC) can also cause dysentery. Current typing methods have limited ability to identify and differentiate between these pathogens despite the need for rapid and accurate identification of pathogens for clinical treatment and outbreak response. We present a comprehensive phylogeny of Shigella and EIEC using whole genome sequencing of 169 samples, constituting unparalleled strain diversity, and observe a lack of monophyly between Shigella and EIEC and among Shigella taxonomic groups. The evolutionary relationships in the phylogenymore » are supported by analyses of population structure and hierarchical clustering patterns of translated gene homolog abundance. Lastly, we identified a panel of 404 single nucleotide polymorphism (SNP) markers specific to each phylogenetic cluster for more accurate identification of Shigella and EIEC. Our findings show that Shigella and EIEC are not distinct evolutionary groups within the E. coli genus and, thus, EIEC as a group is not the ancestor to Shigella. The multiple analyses presented provide evidence for reconsidering the taxonomic placement of Shigella. The SNP markers offer more discriminatory power to molecular epidemiological typing methods involving these bacterial pathogens.« less
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Pettengill, Emily A.; Pettengill, James B.; Binet, Rachel
2016-01-19
As a leading cause of bacterial dysentery, Shigella represents a significant threat to public health and food safety. Related, but often overlooked, enteroinvasive Escherichia coli (EIEC) can also cause dysentery. Current typing methods have limited ability to identify and differentiate between these pathogens despite the need for rapid and accurate identification of pathogens for clinical treatment and outbreak response. We present a comprehensive phylogeny of Shigella and EIEC using whole genome sequencing of 169 samples, constituting unparalleled strain diversity, and observe a lack of monophyly between Shigella and EIEC and among Shigella taxonomic groups. The evolutionary relationships in the phylogenymore » are supported by analyses of population structure and hierarchical clustering patterns of translated gene homolog abundance. Lastly, we identified a panel of 404 single nucleotide polymorphism (SNP) markers specific to each phylogenetic cluster for more accurate identification of Shigella and EIEC. Our findings show that Shigella and EIEC are not distinct evolutionary groups within the E. coli genus and, thus, EIEC as a group is not the ancestor to Shigella. The multiple analyses presented provide evidence for reconsidering the taxonomic placement of Shigella. The SNP markers offer more discriminatory power to molecular epidemiological typing methods involving these bacterial pathogens.« less
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Pajak, B.; De Smedt, T.; Moulin, V.; De Trez, C.; Maldonado-Lopez, R.; Vansanten, G.; Briend, E.; Urbain, J.; Leo, O.; Moser, M.
2000-01-01
Aims—To describe a new fixation and embedding method for tissue samples, immunohistowax processing, which preserves both morphology and antigen immunoreactivity, and to use this technique to investigate the role of dendritic cells in the immune response in peripheral tissues. Methods—This technique was used to stain a population of specialised antigen presenting cells (dendritic cells) that have the unique capacity to sensitise naive T cells, and therefore to induce primary immune responses. The numbers of dendritic cells in peripheral organs of mice either untreated or injected with live Escherichia coli were compared. Results—Numbers of dendritic cells were greatly decreased in heart, kidney, and intestine after the inoculation of bacteria. The numbers of dendritic cells in the lung did not seem to be affected by the injection of E coli. However, staining of lung sections revealed that some monocyte like cells acquired morphological and phenotypic features of dendritic cells, and migrated into blood vessels. Conclusions—These observations suggest that the injection of bacteria induces the activation of dendritic cells in peripheral organs, where they play the role of sentinels, and/or their movement into lymphoid organs, where T cell priming is likely to occur. Key Words: dendritic cell • Escherichia coli • immunohistochemistry PMID:10961175
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Black soldier fly (Diptera: Stratiomyidae) larvae reduce Escherichia coli in dairy manure.
Liu, Qiaolin; Tomberlin, Jeffery K; Brady, Jeff A; Sanford, Michelle R; Yu, Ziniu
2008-12-01
Escherichia coli labeled with a green fluorescent protein was inoculated into sterile dairy manure at 7.0 log cfu/g. Approximately 125 black soldier fly larvae were placed in manure inoculated and homogenized with E. coli. Manure inoculated with E. coli but without black soldier fly larvae served as the control. For the first experiment, larvae were introduced into 50, 75, 100, or 125 g sterilized dairy manure inoculated and homogenized with E. coli and stored 72 h at 27 degrees C. Black soldier fly larvae significantly reduced E. coli counts in all treatments. However, varying the amount of manure provided the black soldier fly larvae significantly affected their weight gain and their ability to reduce E. coli populations present. For the second experiment, larvae were introduced into 50 g manure inoculated with E. coli and stored for 72 h at 23, 27, 31, or 35 degrees C. Minimal bacterial growth was recorded in the control held at 35 degrees C and was excluded from the analysis. Black soldier fly larvae significantly reduced E. coli counts in manure held at remaining temperatures. Accordingly, temperature significantly influenced the ability of black soldier fly larvae to develop and reduce E. coli counts with greatest suppression occurring at 27 degrees C.
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McEgan, Rachel; Mootian, Gabriel; Goodridge, Lawrence D; Schaffner, Donald W; Danyluk, Michelle D
2013-07-01
Coliforms, Escherichia coli, and various physicochemical water characteristics have been suggested as indicators of microbial water quality or index organisms for pathogen populations. The relationship between the presence and/or concentration of Salmonella and biological, physical, or chemical indicators in Central Florida surface water samples over 12 consecutive months was explored. Samples were taken monthly for 12 months from 18 locations throughout Central Florida (n = 202). Air and water temperature, pH, oxidation-reduction potential (ORP), turbidity, and conductivity were measured. Weather data were obtained from nearby weather stations. Aerobic plate counts and most probable numbers (MPN) for Salmonella, E. coli, and coliforms were performed. Weak linear relationships existed between biological indicators (E. coli/coliforms) and Salmonella levels (R(2) < 0.1) and between physicochemical indicators and Salmonella levels (R(2) < 0.1). The average rainfall (previous day, week, and month) before sampling did not correlate well with bacterial levels. Logistic regression analysis showed that E. coli concentration can predict the probability of enumerating selected Salmonella levels. The lack of good correlations between biological indicators and Salmonella levels and between physicochemical indicators and Salmonella levels shows that the relationship between pathogens and indicators is complex. However, Escherichia coli provides a reasonable way to predict Salmonella levels in Central Florida surface water through logistic regression.
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McEgan, Rachel; Mootian, Gabriel; Goodridge, Lawrence D.; Schaffner, Donald W.
2013-01-01
Coliforms, Escherichia coli, and various physicochemical water characteristics have been suggested as indicators of microbial water quality or index organisms for pathogen populations. The relationship between the presence and/or concentration of Salmonella and biological, physical, or chemical indicators in Central Florida surface water samples over 12 consecutive months was explored. Samples were taken monthly for 12 months from 18 locations throughout Central Florida (n = 202). Air and water temperature, pH, oxidation-reduction potential (ORP), turbidity, and conductivity were measured. Weather data were obtained from nearby weather stations. Aerobic plate counts and most probable numbers (MPN) for Salmonella, E. coli, and coliforms were performed. Weak linear relationships existed between biological indicators (E. coli/coliforms) and Salmonella levels (R2 < 0.1) and between physicochemical indicators and Salmonella levels (R2 < 0.1). The average rainfall (previous day, week, and month) before sampling did not correlate well with bacterial levels. Logistic regression analysis showed that E. coli concentration can predict the probability of enumerating selected Salmonella levels. The lack of good correlations between biological indicators and Salmonella levels and between physicochemical indicators and Salmonella levels shows that the relationship between pathogens and indicators is complex. However, Escherichia coli provides a reasonable way to predict Salmonella levels in Central Florida surface water through logistic regression. PMID:23624476
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E. coli chemotaxis and super-diffusion
NASA Astrophysics Data System (ADS)
Dobnikar, Jure; Matthäus, Franziska; Jagodic, Marko
2010-03-01
The bacteria E. coli actively propel by switching between clockwise and anti-clockwise rotation of the flagella attached to their cell membranes. This results in two modes of motion: tumbling and swimming. The switching between the two modes is coupled to the ligand sensing through the chemotactic signalling pathway inside the cell. We modelled the signalling pathway and performed numerical simulations of the chemotactic motion of a large number of E. coli bacteria under various external conditions. We have shown that under certain conditions the thermal noise in the level of receptor-bound CheR (an enzyme responsible for methylation of the receptor sites) leads to super-diffusive behaviour (L'evy walk) which is advantageous for the bacterial populations in environments with scarce food. Exerting external pressure we might observe evolution of the wild-type to the super-diffusive populations.
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[EFFECT OF PULSE-PERIODIC CORONA DISCHARGE ON VIABILITY OF ESCHERICHIA COLI M17 CELLS IN BIOFILMS].
Rybalchenko, O V; Stepanova, O M; Orlova, O G; Astafiev, A M; Kudryavtsev, A A; Kapustina, V V
2015-01-01
Detection of bactericidal effect of pulse-periodic corona discharge (PPCD) on cells and biofilms of Escherichia coli M17. A gas-discharge device was created based on PPCD in air with power supply parameters: amplitude values of voltage of 30 - 60 kV, pulse repetition rate of 250 - 400 kHz. Ultrastructure changes in cells and biofilms of E. coli M17, affected by PPCD, generated in air, were studied by typical methods of transmission electron microscopy. Disturbances of integrity of surface and abyssal structures of biofilms, as well as changes of morphological properties of E. coli M17 cells, characteristic for sub-lethal heat impact, were detected. Destructive changes of bacterial cells were developed by formation of focal disturbance of cytoplasmic membrane, extension of periplasmic space, formation of globular structures, characteristic for heat effect, and destruction of cytoplasm. Bactericidal effect of PPCD on E. coli M17 cells as part of biofilms was shown. Destructive morphological changes in cells and biofilms of E. coli M17 after the effect of PPCD were detected for the first time on electron-microscopic level.
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[BIOLOGICAL ACTIVITY OF ANTIMICROBIAL PEPTIDES FROM CHICKENS THROMBOCYTES].
Sycheva, M V; Vasilchenko, A S; Rogozhin, E A; Pashkova, T M; Popova, L P; Kartashova, O L
2016-01-01
Isolation and study of biological activity of antimicrobial peptides from chickens thrombocytes. Peptides from chickens thrombocytes, obtained by reverse-phase high-performance liquid chromatography method with stepped and linear gradients of concentration increase of the organic solvent were used in the study. Their antimicrobial activity was determined by microtitration method in broth; mechanism of biological effect--by using fluorescent spectroscopy method with DNA-tropic dyes. Individual fractions of peptides were isolated from chickens thrombocytes, that possess antimicrobial activity against Staphylococcus aureus P209 and Escherichia coli K12. A disruption of integrity of barrier structures of microorganisms under the effect of thrombocyte antimicrobial peptides and predominance of cells with damaged membrane in the population of E. coli was established. The data obtained on antimicrobial activity and mechanism of bactericidal effect of the peptide fractions from chickens thrombocytes isolated for the first time expand the understanding of functional properties of chickens thrombocytes and open a perspective for their further study with the aim of use as antimicrobial means.
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Kim, Younghoon; Arruda, Jennifer M.; Davenport, Andrew; Wood, Thomas K.; Peti, Wolfgang; Page, Rebecca
2009-01-01
One mechanism by which bacteria survive environmental stress is through the formation of bacterial persisters, a sub-population of genetically identical quiescent cells that exhibit multidrug tolerance and are highly enriched in bacterial toxins. Recently, the Escherichia coli gene mqsR (b3022) was identified as the gene most highly upregulated in persisters. Here, we report multiple individual and complex three-dimensional structures of MqsR and its antitoxin MqsA (B3021), which reveal that MqsR:MqsA form a novel toxin:antitoxin (TA) pair. MqsR adopts an α/β fold that is homologous with the RelE/YoeB family of bacterial ribonuclease toxins. MqsA is an elongated dimer that neutralizes MqsR toxicity. As expected for a TA pair, MqsA binds its own promoter. Unexpectedly, it also binds the promoters of genes important for E. coli physiology (e.g., mcbR, spy). Unlike canonical antitoxins, MqsA is also structured throughout its entire sequence, binds zinc and coordinates DNA via its C- and not N-terminal domain. These studies reveal that TA systems, especially the antitoxins, are significantly more diverse than previously recognized and provide new insights into the role of toxins in maintaining the persister state. PMID:20041169
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E. coli release from streambed to water column during base flow periods: a modeling study
USDA-ARS?s Scientific Manuscript database
Microbial quality of stream water is important for recreation, irrigation, and other uses. It is usually evaluated by concentrations of fecal indicator bacteria (FIB) such as E. coli. Streambed sediments have been shown to harbor large FIB populations that could be released into the water column dur...
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USDA-ARS?s Scientific Manuscript database
Like common bacteriophages, Shiga toxin-producing Escherichia coli (STEC) bacteriophages are viruses that recognize and bind to specific bacterial host (STEC) for propagation. They co-exist with STEC hosts, which cause epidemic food and waterborne illnesses, but may act as host populations limiting ...
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Zhao, Tong; Zhao, Ping; Doyle, Michael P
2010-11-01
Studies were conducted to determine the best concentration and exposure time for treatment of alfalfa seeds with levulinic acid plus sodium dodecyl sulfate (SDS) to inactivate Escherichia coli O157:H7 and Salmonella without adversely affecting seed germination. Alfalfa seeds inoculated with a five-strain mixture of E. coli O157:H7 or Salmonella Typhimurium were dried in a laminar flow hood at 21°C for up to 72 h. Inoculated alfalfa seeds dried for 4 h then treated for 5 min at 21°C with 0.5% levulinic acid and 0.05% SDS reduced the population of E. coli O157:H7 and Salmonella Typhimurium by 5.6 and 6.4 log CFU/g, respectively. On seeds dried for 72 h, treatment with 0.5% levulinic acid and 0.05% SDS for 20 min at 21°C reduced E. coli O157:H7 and Salmonella Typhimurium populations by 4 log CFU/g. Germination rates of alfalfa seeds treated with 0.5% levulinic acid plus 0.05% SDS for up to 1 h at 21°C were compared with a treatment of 20,000 ppm of calcium hypochlorite or tap water only. Treatment of alfalfa seeds with 0.5% levulinic acid plus 0.05% SDS for 5 min at 21°C resulted in a >3.0-log inactivation of E. coli O157:H7 and Salmonella.
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Peirano, Gisele; Gregson, Daniel B.; Kuhn, Susan; Vanderkooi, Otto G.; Nobrega, Diego B.; Pitout, Johann D.D.
2017-01-01
Background: A previous study in Calgary showed that travel to India was associated with high risk of community-onset infections with extended-spectrum β-lactamase (ESBL)-producing Escherichia coli. We performed a follow-up study to determine the rate of rectal acquisition of ESBL-producing E. coli among travellers to South Asia and to identify the behaviours putting such travellers at high risk for acquiring ESBL-producing E. coli. Methods: The study was performed at a travel clinic in Calgary. Travellers 18 years or older who were planning to visit South Asia for a period of at least 5 days were included. Three rectal swabs were obtained, and 2 questionaires were administered (before and after travel). Results: A total of 149 travellers participated between January 2012 and July 2014; of these, 116 (78%) provided rectal swabs upon return to Calgary and completed both pre- and post-travel questionaires. Of the 109 travellers without colonization with ESBL-producing E. coli upon enrollment, 70 (64%) acquired ESBL-producing E. coli during travel. Of the 90 participants who visited India, 66 (73%) were positive for ESBL-producing E. coli upon their return to Calgary. Most ESBL-producing E. coli specimens were identified as producing the enzyme CTX-M-15. Behaviours associated with a statistically significant risk of acquiring ESBL-producing E. coli included visiting India (odds ratio [OR] 19.9, 95% confidence interval [CI] 4.5-88.8), consuming meals with the local population (OR 6.9, 95% CI 1.2-39.6), taking any type of antibiotic during travel (OR 4.3, 95% CI 1.3-14.3) and travelling for any purpose other than business (OR 12.4, 95% CI 2.8-55.2). Interpretation: In this study, travel to India was associated with the highest risk of acquiring ESBL-producing E. coli relative to travel to other countries in South Asia. Nonbusiness travel, consuming foods with the local population and the use of antibiotics while travelling were associated with an increased risk of acquiring these antibiotic-resistant organisms while in India. Trial registration: ClinicalTrials.gov, no. NCT01296165. PMID:29246886
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Søgaard, M; Heide-Jørgensen, U; Vandenbroucke, J P; Schønheyder, H C; Vandenbroucke-Grauls, C M J E
2017-12-01
To verify the role of proton pump inhibitors (PPI) and nitrofurantoin, which have appeared as novel risk factors for carriage of extended-spectrum β-lactamase (ESBL) -producing Escherichia coli, as risk factors for ESBL E. coli urinary tract infection (UTI). We included known risk factors to ascertain whether our findings are comparable with those of previous studies. Population-based case-control study including 339 cases with community-onset ESBL E. coli UTI in 2007-2012, 3390 non-ESBL E. coli UTI controls and 3390 population controls. We investigated potential risk factors by estimating ORs and 95% CIs adjusting for sex, age and co-morbidity. Comparing cases with non-ESBL E. coli UTI, PPI use yielded an OR of 1.6 (95% CI 1.2-2.0) and antibiotic exposure gave an OR of 1.4 (95% CI 1.1-1.8); these were driven by nitrofurantoin (OR 1.8; 95% CI 1.3-2.6) and macrolides (OR 1.7; 95% CI 1.2-2.3). Other risk factors included previous hospitalization with one or two and more than two hospitalizations versus none yielding ORs of 1.9 (95% CI 1.4-2.5) and 4.6 (95% CI 3.2-6.8), recent surgery (OR 2.0; 95% CI 1.5-2.8), renal disease (OR 2.2; 95% CI 1.4-3.4), chronic pulmonary disease (OR 1.4; 95% CI 1.0-2.0) and cancer (OR 1.5; 95% CI 1.1-2.1). Comparing cases with population controls, we found that most risk factors were also risk factors for non-ESBL UTI. ESBL E. coli UTI were associated with previous hospitalization and surgery. Nitrofurantoin and macrolides augmented the risk. PPIs had a moderate effect but may be important facilitators of ESBL carriage due to their widespread use. Copyright © 2017 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
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Ro, Eun Young; Ko, Young Mi; Yoon, Ki Sun
2015-08-01
This study investigated both the level of microbial contamination and the presence of enterohemorrhagic Escherichia coli (EHEC) in frozen meat products, followed by the evaluation of its survival over 180 days under frozen temperature. We also examined the effect of calcium oxide on the populations of EHEC, E. coli O157:H7 and EPEC under both 10 °C and -18 °C storage conditions. Afterward, the morphological changes occurring in EHEC cells in response to freezer storage temperature and calcium oxide (CaO) treatments were examined using transmission electron microscopy. Among the frozen meat products tested, the highest contamination levels of total aerobic counts, coliforms and E. coli were observed in pork cutlets. Examination showed that 20% of the frozen meat products contained virulence genes, including verotoxin (VT) 1 and 2. Over 180 days of frozen storage and after 3 freeze-thaw cycles, the population of EHEC did not change regardless of the type of products or initial inoculated concentration, indicating the strong survival ability of EHEC. Subsequent testing revealed that the growth of three pathogenic E. coli strains was completely inhibited in meat patties prepared with 1% CaO, stored at 10 °C. However, the addition of 2% CaO was necessary to control the survival of EHEC, E. coli O157:H7 and EPEC in meat patties stored at -18 °C. CaO reduced the population of E. coli O157:H7 more effectively than the other EHEC and EPEC strains at both 10 °C and -18 °C. Transmission electron microscopy analysis revealed that exposed EHEC cells were resistant to the freezer storage temperature, although some cells incurred injury and death after several freeze-thaw cycles. Most of the cells exposed to CaO were found to have died or lost their cellular integrity and membranes, indicating that CaO has the potential to be used as a powerful antimicrobial agent for manufacturing frozen meat products. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Simpkin, Adam J; Rigden, Daniel J
2016-07-13
Proteins produced by bacteriophages can have potent antimicrobial activity. The study of phage-host interactions can therefore inform small molecule drug discovery by revealing and characterising new drug targets. Here we characterise in silico the predicted interaction of gene protein 0.4 (GP0.4) from the Escherichia coli (E. coli) phage T7 with E. coli filamenting temperature-sensitive mutant Z division protein (FtsZ). FtsZ is a tubulin homolog which plays a key role in bacterial cell division and that has been proposed as a drug target. Using ab initio, fragment assembly structure modelling, we predicted the structure of GP0.4 with two programs. A structure similarity-based network was used to identify a U-shaped helix-turn-helix candidate fold as being favoured. ClusPro was used to dock this structure prediction to a homology model of E. coli FtsZ resulting in a favourable predicted interaction mode. Alternative docking methods supported the proposed mode which offered an immediate explanation for the anti-filamenting activity of GP0.4. Importantly, further strong support derived from a previously characterised insertion mutation, known to abolish GP0.4 activity, that is positioned in close proximity to the proposed GP0.4/FtsZ interface. The mode of interaction predicted by bioinformatics techniques strongly suggests a mechanism through which GP0.4 inhibits FtsZ and further establishes the latter's druggable intrafilament interface as a potential drug target.
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Corsaro, M Michela; Parrilli, Ermenegilda; Lanzetta, Rosa; Naldi, Teresa; Pieretti, Giuseppina; Lindner, Buko; Carpentieri, Andrea; Parrilli, Michelangelo; Tutino, M Luisa
2009-08-01
The role of lipopolysaccharides (LPSs) in the biogenesis of outer membrane proteins have been investigated in several studies. Some of these analyses showed that LPS is required for correct and efficient folding of outer membrane proteins; other studies support the idea of independence of outer membrane proteins biogenesis from LPS structure. In this article, we investigated the involvement of LPS structure in the anomalous aggregation of outer membrane proteins in a E. coli mutant strain (S17-1(lambdapir)). To achieve this aim, the LPS structure of the mutant strain was carefully determined and compared with the E. coli K-12 one. It turned out that LPS of these two strains differs in the inner core for the absence of a heptose residue (HepIII). We demonstrated that this difference is due to a mutation in waaQ, a gene encoding the transferase for the branch heptose HepIII residue. The mutation was complemented to find out if the restoration of LPS structure influenced the observed outer membrane proteins aggregation. Data reported in this work demonstrated that, in E. coli S17-1(lambdapir) there is no influence of LPS structure on the outer membrane proteins inclusion bodies formation.
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Janjaroen, Dao; Ling, Fangqiong; Monroy, Guillermo; Derlon, Nicolas; Mogenroth, Eberhard; Boppart, Stephen A.; Liu, Wen-Tso; Nguyen, Thanh H.
2013-01-01
Mechanisms of Escherichia coli attachment on biofilms grown on PVC coupons were investigated. Biofilms were grown in CDC reactors using groundwater as feed solution over a period up to 27 weeks. Biofilm physical structure was characterized at the micro- and meso-scales using Scanning Electron Microscopy (SEM) and Optical Coherence Tomography (OCT), respectively. Microbial community diversity was analyzed with Terminal Restricted Fragment Length Polymorphism (T-RFLP). Both physical structure and microbial community diversity of the biofilms were shown to be changing from 2 weeks to 14 weeks, and became relatively stable after 16 weeks. A parallel plate flow chamber coupled with an inverted fluorescent microscope was also used to monitor the attachment of fluorescent microspheres and E. coli on clean PVC surfaces and biofilms grown on PVC surfaces for different ages. Two mechanisms of E. coli attachment were identified. The adhesion rate coefficients (kd) of E. coli on nascent PVC surfaces and 2-week biofilms increased with ionic strength. However, after biofilms grew for 8 weeks, the adhesion was found to be independent of solution chemistry. Instead, a positive correlation between kd and biofilm roughness as determined by OCT was obtained, indicating that the physical structure of biofilms could play an important role in facilitating the adhesion of E. coli cells. PMID:23497979
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Reed-Jones, Neiunna L; Marine, Sasha Cahn; Everts, Kathryne L; Micallef, Shirley A
2016-01-04
Cover crops provide several ecosystem services, but their impact on enteric bacterial survival remains unexplored. The influence of cover cropping on foodborne pathogen indicator bacteria was assessed in five cover crop/green manure systems: cereal rye, hairy vetch, crimson clover, hairy vetch-rye and crimson clover-rye mixtures, and bare ground. Cover crop plots were inoculated with Escherichia coli and Listeria innocua in the fall of 2013 and 2014 and tilled into the soil in the spring to form green manure. Soil samples were collected and the bacteria enumerated. Time was a factor for all bacterial populations studied in all fields (P < 0.001). E. coli levels declined when soil temperatures dipped to <5°C and were detected only sporadically the following spring. L. innocua diminished somewhat but persisted, independently of season. In an organic field, the cover crop was a factor for E. coli in year 1 (P = 0.004) and for L. innocua in year 2 (P = 0.011). In year 1, E. coli levels were highest in the rye and hairy vetch-rye plots. In year 2, L. innocua levels were higher in hairy vetch-rye (P = 0.01) and hairy vetch (P = 0.03) plots than in the rye plot. Bacterial populations grew (P < 0.05) or remained the same 4 weeks after green manure incorporation, although initial reductions in L. innocua numbers were observed after tilling (P < 0.05). Green manure type was a factor only for L. innocua abundance in a transitional field (P < 0.05). Overall, the impacts of cover crops/green manures on bacterial population dynamics in soil varied, being influenced by bacterial species, time from inoculation, soil temperature, rainfall, and tillage; this reveals the need for long-term studies. Copyright © 2016, American Society for Microbiology. All Rights Reserved.
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Abdul-Raouf, U M; Beuchat, L R; Ammar, M S
1993-01-01
A study was undertaken to determine the fate of Escherichia coli O157:H7 in ground, roasted beef as influenced by the combined effects of pH, acidulants, temperature, and time. There was essentially no change in the viable population of E. coli O157:H7 when beef salads (pH 5.40 to 6.07) containing up to 40% mayonnaise were incubated at 5 degrees C for up to 72 h. At 21 and 30 degrees C, significant (P < or = 0.05) increases in populations of the organism occurred in salads containing 16 to 32% mayonnaise (pH 5.94 to 5.55) between 10 and 24 h of incubation. Death was more rapid as the pH of acidified beef slurries incubated at 5 degrees C was decreased from 5.98 to 4.70. E. coli O157:H7 grew in control slurries (pH 5.98) and in slurries containing citric and lactic acids (pHs 5.00 and 5.40) incubated at 21 degrees C for 24 h; decreases occurred in slurries acidified to pHs 4.70, 5.00, and 5.40 with acetic acid or pH 4.70 with citric or lactic acid. At 30 degrees C, populations decreased in slurries acidified to pHs 4.70 and 5.00 with acetic acid. Citric and lactic acids failed to prevent significant increases in populations in slurries at pH 4.70 to 5.40 between 10 and 24 h of incubation. The order of effectiveness of acidulants in inhibiting growth was acetic acid > lactic acid > or = citric acid. The same order was observed for inactivation of E. coli O157:H7 in acidified (pH 5.00) beef slurry heated at 54 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8368828
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Bacterial predator–prey dynamics in microscale patchy landscapes
Rotem, Or; Jurkevitch, Edouard; Dekker, Cees
2016-01-01
Soil is a microenvironment with a fragmented (patchy) spatial structure in which many bacterial species interact. Here, we explore the interaction between the predatory bacterium Bdellovibrio bacteriovorus and its prey Escherichia coli in microfabricated landscapes. We ask how fragmentation influences the prey dynamics at the microscale and compare two landscape geometries: a patchy landscape and a continuous landscape. By following the dynamics of prey populations with high spatial and temporal resolution for many generations, we found that the variation in predation rates was twice as large in the patchy landscape and the dynamics was correlated over shorter length scales. We also found that while the prey population in the continuous landscape was almost entirely driven to extinction, a significant part of the prey population in the fragmented landscape persisted over time. We observed significant surface-associated growth, especially in the fragmented landscape and we surmise that this sub-population is more resistant to predation. Our results thus show that microscale fragmentation can significantly influence bacterial interactions. PMID:26865299
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Xiao, Zhenlei; Nou, Xiangwu; Luo, Yanguang; Wang, Qin
2014-12-01
Both sprouts and microgreens are popular tender produce items, typically grown and harvested in indoor facilities which allow a higher degree of control compared to open field production. While sprouts, which have frequently been implicated in foodborne illness outbreaks, are the subject of numerous national and international standards for their production and distribution, there is a lack of data pertaining to the microbiological safety of microgreens. In this study, sprouts and microgreens were produced from radish seeds inoculated with Escherichia coli O157: H7 or O104: H4 and E. coli populations on the harvested products compared to assess the potentials of product contamination from contaminated seeds during sprouting and microgreen production. Both E. coli O157:H7 and O104:H4 grew rapidly during sprouting, reaching levels of 5.8-8.1 log cfu/g and 5.2-7.3 log cfu/g, respectively, depending on the initial inoculation levels of the seeds (1.5-4.6 log cfu/g and 0.8-4.3 log cfu/g on radish seeds, respectively). In comparison, E. coli O157:H7 and O104:H4 populations on harvested microgreens ranged from 0.8 to 4.5 log cfu/g and from 0.6 to 4.0 log cfu/g, respectively. Although harvested microgreens carried significantly less (P < 0.001) E. coli than sprouts germinated from seeds inoculated at the same levels, proliferation of E. coli O157:H7 and O104:H4 occurred during both sprouting and microgreen growth. Published by Elsevier Ltd.
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Macarisin, Dumitru; Patel, Jitendra; Bauchan, Gary; Giron, Jorge A; Ravishankar, Sadhana
2013-11-01
Similar to phytopathogens, human bacterial pathogens have been shown to colonize the plant phylloplane. In addition to environmental factors, such as temperature, UV, relative humidity, etc., the plant cultivar and, specifically, the leaf blade morphological characteristics may affect the persistence of enteropathogens on leafy greens. This study was conducted to evaluate the effect of cultivar-dependent leaf topography and the role of strain phenotypic characteristics on Escherichia coli O157:H7 persistence on organic spinach. Spinach cultivars Emilia, Lazio, Space, and Waitiki were experimentally inoculated with the foodborne E. coli O157:H7 isolate EDL933 and its isogenic mutants deficient in cellulose, curli, or both curli and cellulose production. Leaves of 6-week-old plants were inoculated with 6.5 log CFU per leaf in a biosafety level 2 growth chamber. At 0, 1, 7, and 14 days, E. coli O157:H7 populations were determined by plating on selective medium and verified by laser scanning confocal microscopy. Leaf morphology (blade roughness and stoma density) was evaluated by low-temperature and variable-pressure scanning electron microscopy. E. coli O157:H7 persistence on spinach was significantly affected by cultivar and strain phenotypic characteristics, specifically, the expression of curli. Leaf blade roughness and stoma density influenced the persistence of E. coli O157:H7 on spinach. Cultivar Waitiki, which had the greatest leaf roughness, supported significantly higher E. coli O157:H7 populations than the other cultivars. These two morphological characteristics of spinach cultivars should be taken into consideration in developing intervention strategies to enhance the microbial safety of leafy greens.
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Worley, Jay N; Flores, Kristopher A; Yang, Xun; Chase, Jennifer A; Cao, Guojie; Tang, Shuai; Meng, Jianghong; Atwill, Edward R
2017-08-15
Escherichia coli serotype O157:H7 is a zoonotic food- and waterborne bacterial pathogen that causes a high hospitalization rate and can cause life-threatening complications. Increasingly, E. coli O157:H7 infections appear to originate from fresh produce. Ruminants, such as cattle, are a prominent reservoir of E. coli O157:H7 in the United States. California is one of the most agriculturally productive regions in the world for fresh produce, beef, and milk. The close proximity of fresh produce and cattle presents food safety challenges on a uniquely large scale. We performed a survey of E. coli O157:H7 on 20 farms in California to observe the regional diversity and prevalence of E. coli O157:H7. Isolates were obtained from enrichment cultures of cow feces. Some farms were sampled on two dates. Genomes from isolates were sequenced to determine their relatedness and pathogenic potential. E. coli O157:H7 was isolated from approximately half of the farms. The point prevalence of E. coli O157:H7 on farms was highly variable, ranging from zero to nearly 90%. Within farms, generally one or a few lineages were found, even when the rate of isolation was high. On farms with high isolation rates, a single clonal lineage accounted for most of the isolates. Farms that were visited months after the first visit might have had the same lineages of E. coli O157:H7. Strains of E. coli O157:H7 may be persistent for months on farms. IMPORTANCE This survey of 20 cow-calf operations from different regions of California provides an in depth look at resident Escherichia coli O157:H7 populations at the molecular level. E. coli O157:H7 is found to have a highly variable prevalence, and with whole-genome sequencing, high prevalences in herds were found to be due to a single lineage shed from multiple cows. Few repeat lineages were found between farms in this area; therefore, we predict that E. coli O157:H7 has significant diversity in this area beyond what is detected in this survey. All isolates from this study were found to have pathogenic potential based on the presence of key virulence gene sequences. This represents a novel insight into pathogen diversity within a single subtype and will inform future attempts to survey regional pathogen populations. Copyright © 2017 American Society for Microbiology.
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Worley, Jay N.; Flores, Kristopher A.; Yang, Xun; Chase, Jennifer A.; Cao, Guojie; Tang, Shuai; Meng, Jianghong
2017-01-01
ABSTRACT Escherichia coli serotype O157:H7 is a zoonotic food- and waterborne bacterial pathogen that causes a high hospitalization rate and can cause life-threatening complications. Increasingly, E. coli O157:H7 infections appear to originate from fresh produce. Ruminants, such as cattle, are a prominent reservoir of E. coli O157:H7 in the United States. California is one of the most agriculturally productive regions in the world for fresh produce, beef, and milk. The close proximity of fresh produce and cattle presents food safety challenges on a uniquely large scale. We performed a survey of E. coli O157:H7 on 20 farms in California to observe the regional diversity and prevalence of E. coli O157:H7. Isolates were obtained from enrichment cultures of cow feces. Some farms were sampled on two dates. Genomes from isolates were sequenced to determine their relatedness and pathogenic potential. E. coli O157:H7 was isolated from approximately half of the farms. The point prevalence of E. coli O157:H7 on farms was highly variable, ranging from zero to nearly 90%. Within farms, generally one or a few lineages were found, even when the rate of isolation was high. On farms with high isolation rates, a single clonal lineage accounted for most of the isolates. Farms that were visited months after the first visit might have had the same lineages of E. coli O157:H7. Strains of E. coli O157:H7 may be persistent for months on farms. IMPORTANCE This survey of 20 cow-calf operations from different regions of California provides an in depth look at resident Escherichia coli O157:H7 populations at the molecular level. E. coli O157:H7 is found to have a highly variable prevalence, and with whole-genome sequencing, high prevalences in herds were found to be due to a single lineage shed from multiple cows. Few repeat lineages were found between farms in this area; therefore, we predict that E. coli O157:H7 has significant diversity in this area beyond what is detected in this survey. All isolates from this study were found to have pathogenic potential based on the presence of key virulence gene sequences. This represents a novel insight into pathogen diversity within a single subtype and will inform future attempts to survey regional pathogen populations. PMID:28550057
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Thurman, Jill; Parry, Jacqueline D; Hill, Philip J; Laybourn-Parry, Johanna
2010-10-01
This study examined whether two ciliates could discriminate between equally-sized bacterial prey in mixture and if so, how selectivity might benefit the ciliate population. Live Klebsiella aerogenes, K. ozaenae and Escherichia coli, expressing different coloured fluorescent proteins, were cultured in such a way as to provide populations containing equally-sized cells (to prevent size-selective grazing taking place) and these prey were fed to each ciliate in 50:50 mixtures. Colpidium striatum selected K. aerogenes over K. ozaenae which itself was selected over E. coli. Tetrahymena pyriformis showed no selectivity between K. aerogenes and E. coli but K. aerogenes was selected over K. ozaenae while E. coli was not. This apparent selection of K. aerogenes over K. ozaenae was sustained in ciliate populations with different feeding histories and when K. aerogenes comprised only 20% of the prey mixture, suggesting possible optimal foraging behaviour. The metabolic benefits for selecting K. aerogenes were identified as possibly being an increase in cell biovolume and yield for C. striatum and T. pyriformis, respectively. The mechanism by which these ciliates selected specific bacterial cells in mixture is currently unknown but the use of live fluorescent bacteria, in prey mixtures, offers an exciting avenue for further investigation of selective feeding by protozoa. Copyright 2010 Elsevier Ltd. All rights reserved.
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Fosfomycin Resistance in Escherichia coli, Pennsylvania, USA.
Alrowais, Hind; McElheny, Christi L; Spychala, Caressa N; Sastry, Sangeeta; Guo, Qinglan; Butt, Adeel A; Doi, Yohei
2015-11-01
Fosfomycin resistance in Escherichia coli is rare in the United States. An extended-spectrum β-lactamase-producing E. coli clinical strain identified in Pennsylvania, USA, showed high-level fosfomycin resistance caused by the fosA3 gene. The IncFII plasmid carrying this gene had a structure similar to those found in China, where fosfomycin resistance is commonly described.
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Xue, Yuan; Chen, Jianfei; Wang, Yulong; Zhang, Yanlong; Liu, Dan; Hua, Yuping
2013-12-01
The present study was undertaken to identify and characterize integrons and integrated resistance gene cassettes among multidrug resistant Escherichia coli isolates from a captive population of Amur tigers (Panthera tigris altaica) in China. In addition, the prevalence of antimicrobial resistance and class I integrons was assessed in E. coli strains (n = 61) isolated from a captive population of Amur tigers in Heilongjiang Amur Tiger Park, China. Among the isolates, 52.46% (32 of 61) were positive for intI1, but no isolates carried intI2 or intI3. Most isolates were susceptible to amoxicillin/clavulanic acid, aztreonam, and polymyxin B, while they also exhibited high incidence rates of resistance to ampicillin, doxycycline, chloramphenicol, tetracycline, and dihydrofolate reductase. Sequencing analysis revealed three gene cassettes, which encoded resistance to dihydrofolate reductase (dfrA15), dihydrofolate reductase (dfrA12), and adenyltransferase (aadA2). The gene cassette arrays dfrA15 (31%) and dfrA12-aadA2 (19%) were most prevalent among these isolates.
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Modeling a synthetic multicellular clock: repressilators coupled by quorum sensing.
Garcia-Ojalvo, Jordi; Elowitz, Michael B; Strogatz, Steven H
2004-07-27
Diverse biochemical rhythms are generated by thousands of cellular oscillators that somehow manage to operate synchronously. In fields ranging from circadian biology to endocrinology, it remains an exciting challenge to understand how collective rhythms emerge in multicellular structures. Using mathematical and computational modeling, we study the effect of coupling through intercell signaling in a population of Escherichia coli cells expressing a synthetic biological clock. Our results predict that a diverse and noisy community of such genetic oscillators interacting through a quorum-sensing mechanism should self-synchronize in a robust way, leading to a substantially improved global rhythmicity in the system. As such, the particular system of coupled genetic oscillators considered here might be a good candidate to provide the first quantitative example of a synchronization transition in a population of biological oscillators.
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Modeling a synthetic multicellular clock: Repressilators coupled by quorum sensing
NASA Astrophysics Data System (ADS)
Garcia-Ojalvo, Jordi; Elowitz, Michael B.; Strogatz, Steven H.
2004-07-01
Diverse biochemical rhythms are generated by thousands of cellular oscillators that somehow manage to operate synchronously. In fields ranging from circadian biology to endocrinology, it remains an exciting challenge to understand how collective rhythms emerge in multicellular structures. Using mathematical and computational modeling, we study the effect of coupling through intercell signaling in a population of Escherichia coli cells expressing a synthetic biological clock. Our results predict that a diverse and noisy community of such genetic oscillators interacting through a quorum-sensing mechanism should self-synchronize in a robust way, leading to a substantially improved global rhythmicity in the system. As such, the particular system of coupled genetic oscillators considered here might be a good candidate to provide the first quantitative example of a synchronization transition in a population of biological oscillators.
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Structure and genetics of the O-specific polysaccharide of Escherichia coli O27.
Perepelov, Andrei V; Chen, Tingting; Senchenkova, Sofya N; Filatov, Andrei V; Song, Jingjie; Shashkov, Alexander S; Liu, Bin; Knirel, Yuriy A
2018-02-01
The O-specific polysaccharide (O-antigen) is a part of the lipopolysaccharide on the cell surface of Gram-negative bacteria. The O-polysaccharide was obtained by mild acid hydrolysis of the lipopolysaccharide of Escherichia coli O27 and studied by sugar analysis and Smith degradation along with 1 H and 13 C NMR spectroscopy. The following structure of the branched hexasaccharide repeating unit was established, which is unique among known structures of bacterial polysaccharides:where GlcA is non-stoichiometrically O-acetylated at position 3 (∼22%) or 4 (∼37%). Functions of genes in the O-antigen gene cluster of E. coli O27 were tentatively assigned by comparison with sequences in the available databases and found to be consistent with the O-polysaccharide structure. Copyright © 2017 Elsevier Ltd. All rights reserved.
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The effectiveness of triclosan-incorporated plastic against bacteria on beef surfaces.
Cutter, C N
1999-05-01
Triclosan is a nonionic, broad-spectrum, antimicrobial agent that has been incorporated into a variety of personal hygiene products, including hand soaps, deodorants, shower gels, mouthwashes, and toothpastes. In this study, plastic containing 1,500 ppm of triclosan was evaluated in plate overlay assays and meat experiments as a means of reducing populations of bacteria. Plate overlay assays indicated that the triclosan-incorporated plastic (TIP) inhibited the following organisms: Brochothrix thermosphacta ATCC 11509, Salmonella Typhimurium ATCC 14028, Staphylococcus aureus ATCC 12598, Bacillus subtilis ATCC 6051, Shigella flexneri ATCC 12022, Escherichia coli ATCC 25922, and several strains of E. coli O157:H7. In meat experiment 1, irradiated, lean beef surfaces inoculated with B. thermosphacta, Salmonella Typhimurium, E. coli O157:H7, or B. subtilis were covered with TIP, vacuum packaged, and stored for 24 h at 4 degrees C. Of the organisms tested, only populations of B. thermosphacta were slightly reduced. In meat experiment 2, prerigor beef surfaces were inoculated with E. coli O157: H7, Salmonella Typhimurium, or B. thermosphacta incubated at 4 degrees C for 24 h, wrapped in TIP or control plastic, vacuum packaged, and stored at 4 degrees C for up to 14 days. There was a slight reduction in the population of the organisms after initial application with TIP. However, bacterial populations following long-term, refrigerated (4 degrees C), vacuum-packaged storage up to 14 days were not statistically (P< or =0.05) or numerically different than controls. In meat experiment 3, even TIP-wrapped, vacuum-packaged beef samples that were temperature abused at 12 degrees C did not exhibit significant (P< or =0.05) or sustainable reductions after 14 days of 4 degrees C storage. Another study indicated that populations of E. coli O157:H7 or B. thermosphacta added directly to TIP were not affected after 2 h of refrigerated storage or that the antimicrobial activity could be extracted from the plastic. Additional experiments suggest that presence of fatty acids or adipose may diminish the antimicrobial activity of TIP on meat surfaces. This study demonstrates that while antimicrobial activity is detected against bacterial cultures in antimicrobial plate assays, plastic containing 1,500 ppm of triclosan does not effectively reduce bacterial populations on refrigerated, vacuum-packaged meat surfaces.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Timofeev, V. I., E-mail: inna@ns.crys.ras.ru, E-mail: tostars@mail.ru, E-mail: ugama@yandex.ru; Abramchik, Yu. A.; Zhukhlistova, N. E.
2016-01-15
Phosphoribosyl pyrophosphate synthetase from Escherichia coli was cloned, purified, and crystallized. Single crystals of the enzyme were grown under microgravity. The X-ray diffraction data set was collected at the Spring-8 synchrotron facility and used to determine the three-dimensional structure of the enzyme by the molecular-replacement method at 2.71 Å resolution. The active and regulatory sites in the molecule of E. coli phosphoribosyl pyrophosphate synthetase were revealed by comparison with the homologous protein from Bacillus subtilis, the structure of which was determined in a complex with functional ligands. The conformations of polypeptide-chain fragments surrounding and composing the active and regulatory sitesmore » were shown to be identical in both proteins.« less
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Association of Escherichia coli O157:H7 with Houseflies on a Cattle Farm†
Alam, Muhammad J.; Zurek, Ludek
2004-01-01
The ecology of Escherichia coli O157:H7 is not well understood. The aims of this study were to determine the prevalence of and characterize E. coli O157:H7 associated with houseflies (HF). Musca domestica L. HF (n = 3,440) were collected from two sites on a cattle farm over a 4-month period and processed individually for E. coli O157:H7 isolation and quantification. The prevalence of E. coli O157:H7 was 2.9 and 1.4% in HF collected from feed bunks and a cattle feed storage shed, respectively. E. coli O157:H7 counts ranged from 3.0 × 101 to 1.5 × 105 CFU among the positive HF. PCR analysis of the E. coli O157:H7 isolates revealed that 90.4, 99.2, 99.2, and 100% of them (n = 125) possessed the stx1, stx2, eaeA, and fliC genes, respectively. Large populations of HF on cattle farms may play a role in the dissemination of E. coli O157:H7 among animals and to the surrounding environment. PMID:15574966
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Association of Escherichia coli O157:H7 with houseflies on a cattle farm.
Alam, Muhammad J; Zurek, Ludek
2004-12-01
The ecology of Escherichia coli O157:H7 is not well understood. The aims of this study were to determine the prevalence of and characterize E. coli O157:H7 associated with houseflies (HF). Musca domestica L. HF (n = 3,440) were collected from two sites on a cattle farm over a 4-month period and processed individually for E. coli O157:H7 isolation and quantification. The prevalence of E. coli O157:H7 was 2.9 and 1.4% in HF collected from feed bunks and a cattle feed storage shed, respectively. E. coli O157:H7 counts ranged from 3.0 x 10(1) to 1.5 x 10(5) CFU among the positive HF. PCR analysis of the E. coli O157:H7 isolates revealed that 90.4, 99.2, 99.2, and 100% of them (n = 125) possessed the stx1, stx2, eaeA, and fliC genes, respectively. Large populations of HF on cattle farms may play a role in the dissemination of E. coli O157:H7 among animals and to the surrounding environment.
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Maherchandani, Sunil; Shringi, B. N.; Kashyap, Sudhir Kumar
2018-01-01
ABSTRACT Aims: Multiple antimicrobial resistance in Escherichia coli of wild vertebrates is a global concern with scarce assessments on the subject from developing countries that have high human-wild species interactions. We studied the ecology of E. coli in a wintering population of Egyptian Vultures in India to understand temporal changes in both E. coli strains and patterns of antimicrobial resistance. Methods and Results: We ribotyped E. coli strains and assessed antimicrobial resistance from wintering vultures at a highly synanthropic carcass dump in north-west India. Both E. coli occurence (90.32%) and resistance to multiple antimicrobials (71.43%) were very high. Clear temporal patterns were apparent. Diversity of strains changed and homogenized at the end of the Vultures’ wintering period, while the resistance pattern showed significantly difference inter-annually, as well as between arrival and departing individuals within a wintering cycle. Significance of study: The carcass dump environment altered both E. coli strains and multiple antimicrobial resistance in migratory Egyptian Vultures within a season. Long-distance migratory species could therefore disseminate resistant E. coli strains across broad geographical scales rendering regional mitigation strategies to control multiple antimicrobial resistance in bacteria ineffective. PMID:29755700
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Marcus, Nir; Ashkenazi, Shai; Yaari, Arnon; Samra, Zmira; Livni, Gilat
2005-07-01
Currently hospitalization for children with urinary tract infections (UTIs) is reserved for severe or complicated cases. Changes may have taken place in the characteristics and causative uropathogens of hospital-treated community-acquired UTI. To study children hospitalized in a tertiary center with community-acquired UTI, compare Escherichia coli and non-E. coli UTI, define predictors for non-E. coli UTI and elucidate the appropriate therapeutic approach. A prospective clinical and laboratory study from 2001 through 2002 in a tertiary pediatric medical center. Patients were divided by results of the urine culture into E. coli and non-E. coli UTI groups, which were compared. Of 175 episodes of culture-proved UTI, 70 (40%) were caused by non-E. coli pathogens. Non-E. coli UTI was more commonly found in children who were male (P = 0.005), who had underlying renal abnormalities (P = 0.0085) and who had received antibiotic therapy in the prior month (P = 0.0009). Non-E. coli uropathogens were often resistant to antibiotics usually recommended for initial therapy for UTI, including cephalosporins and aminoglycosides; 19% were initially treated with inappropriate empiric intravenous antibiotics (compared with 2% for E. coli UTI, P = 0.0001), with a longer hospitalization. Current treatment routines are often inappropriate for hospitalized children with non-E. coli UTI, which is relatively common in this population. The defined risk factors associated with non-E. coli UTIs and its antimicrobial resistance patterns should be considered to improve empiric antibiotic therapy for these infections.
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Genotypic Diversity of Escherichia coli in the Water and Soil of Tropical Watersheds in Hawaii ▿
Goto, Dustin K.; Yan, Tao
2011-01-01
High levels of Escherichia coli were frequently detected in tropical soils in Hawaii, which present important environmental sources of E. coli to water bodies. This study systematically examined E. coli isolates from water and soil of several watersheds in Hawaii and observed high overall genotypic diversity (35.5% unique genotypes). In the Manoa watershed, fewer than 9.3% of the observed E. coli genotypes in water and 6.6% in soil were shared between different sampling sites, suggesting the lack of dominant fecal sources in the watershed. High temporal variability of E. coli genotypes in soil was also observed, which suggests a dynamic E. coli population corresponding with the frequently observed high concentrations in tropical soils. When E. coli genotypes detected from the same sampling events were compared, limited sharing between the soil and water samples was observed in the majority of comparisons (73.5%). However, several comparisons reported up to 33.3% overlap of E. coli genotypes between soil and water, illustrating the potential for soil-water interactions under favorable environmental conditions. In addition, genotype accumulation curves for E. coli from water and soil indicated that the sampling efforts in the Manoa watershed could not exhaust the overall genotypic diversity. Comparisons of E. coli genotypes from other watersheds on Oahu, Hawaii, identified no apparent grouping according to sampling locations. The results of the present study demonstrate the complexity of using E. coli as a fecal indicator bacterium in tropical watersheds and highlight the need to differentiate environmental sources of E. coli from fecal sources in water quality monitoring. PMID:21515724
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Byappanahalli, Muruleedhara N; Shively, Dawn A; Nevers, Meredith B; Sadowsky, Michael J; Whitman, Richard L
2003-11-01
The macro-alga Cladophora glomerata is found in streams and lakes worldwide. High concentrations of Escherichia coli and enterococci have been reported in Cladophora along the Lake Michigan shore. The objective of this study was to determine if Cladophora supported growth of these indicator bacteria. Algal leachate readily supported in vitro multiplication of E. coli and enterococci, suggesting that leachates contain necessary growth-promoting substances. Growth was directly related to the concentration of algal leachate. E. coli survived for over 6 months in dried Cladophora stored at 4 degrees C; residual E. coli grew after mat rehydration, reaching a carrying capacity of 8 log CFU g(-1) in 48 h. Results of this study also show that the E. coli strains associated with Cladophora are highly related; in most instances they are genetically different from each other, suggesting that the relationship between E. coli and Cladophora may be casual. These findings indicate that Cladophora provides a suitable environment for indicator bacteria to persist for extended periods and to grow under natural conditions.
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Byappanahalli, M.N.; Shively, D.A.; Nevers, M.B.; Sadowsky, M.J.; Whitman, R.L.
2003-01-01
The macro-alga Cladophora glomerata is found in streams and lakes worldwide. High concentrations of Escherichia coli and enterococci have been reported in Cladophora along the Lake Michigan shore. The objective of this study was to determine if Cladophora supported growth of these indicator bacteria. Algal leachate readily supported in vitro multiplication of E. coli and enterococci, suggesting that leachates contain necessary growth-promoting substances. Growth was directly related to the concentration of algal leachate. E. coli survived for over 6 months in dried Cladophora stored at 4°C; residual E. coli grew after mat rehydration, reaching a carrying capacity of 8 log CFU g-1 in 48 h. Results of this study also show that the E. coli strains associated with Cladophora are highly related; in most instances they are genetically different from each other, suggesting that the relationship between E. coli and Cladophora may be casual. These findings indicate that Cladophora provides a suitable environment for indicator bacteria to persist for extended periods and to grow under natural conditions.
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Three-dimensional structure of E. Coli purine nucleoside phosphorylase at 0.99 Å resolution
DOE Office of Scientific and Technical Information (OSTI.GOV)
Timofeev, V. I., E-mail: tostars@mail.ru; Abramchik, Yu. A., E-mail: ugama@yandex.ru; Zhukhlistova, N. E., E-mail: inna@ns.crys.ras.ru
2016-03-15
Purine nucleoside phosphorylases (PNPs) catalyze the reversible phosphorolysis of nucleosides and are key enzymes involved in nucleotide metabolism. They are essential for normal cell function and can catalyze the transglycosylation. Crystals of E. coli PNP were grown in microgravity by the capillary counterdiffusion method through a gel layer. The three-dimensional structure of the enzyme was determined by the molecular-replacement method at 0.99 Å resolution. The structural features are considered, and the structure of E. coli PNP is compared with the structures of the free enzyme and its complexes with purine base derivatives established earlier. A comparison of the environment ofmore » the purine base in the complex of PNP with formycin A and of the pyrimidine base in the complex of uridine phosphorylase with thymidine revealed the main structural features of the base-binding sites. Coordinates of the atomic model determined with high accuracy were deposited in the Protein Data Bank (PDB-ID: 4RJ2).« less
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NASA Astrophysics Data System (ADS)
Ling, Shenglong; Wang, Wei; Yu, Lu; Peng, Junhui; Cai, Xiaoying; Xiong, Ying; Hayati, Zahra; Zhang, Longhua; Zhang, Zhiyong; Song, Likai; Tian, Changlin
2016-01-01
Electron paramagnetic resonance (EPR)-based hybrid experimental and computational approaches were applied to determine the structure of a full-length E. coli integral membrane sulfurtransferase, dimeric YgaP, and its structural and dynamic changes upon ligand binding. The solution NMR structures of the YgaP transmembrane domain (TMD) and cytosolic catalytic rhodanese domain were reported recently, but the tertiary fold of full-length YgaP was not yet available. Here, systematic site-specific EPR analysis defined a helix-loop-helix secondary structure of the YagP-TMD monomers using mobility, accessibility and membrane immersion measurements. The tertiary folds of dimeric YgaP-TMD and full-length YgaP in detergent micelles were determined through inter- and intra-monomer distance mapping and rigid-body computation. Further EPR analysis demonstrated the tight packing of the two YgaP second transmembrane helices upon binding of the catalytic product SCN-, which provides insight into the thiocyanate exportation mechanism of YgaP in the E. coli membrane.
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1998-08-01
communication). Various hER fragments were expressed in Esherichia coli (E. coli ) as glutathione-S-transferace (GST) fusion proteins, separated by...Using an E. coli expression vector, we successfully overexpressed hER[253-341] as a fusion protein with an N-terminal poly-histidine tag (Figure 1A...of hER fused to GST were expressed in E. coli , and they were then separated on SDS PAGE, and then transferred to a blotting membrane. The membrane was
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Vanden Heuvel, Amy; McDermott, Colleen; Pillsbury, Robert; Sandrin, Todd; Kinzelman, Julie; Ferguson, John; Sadowsky, Michael; Byappanahalli, Muruleedhara; Whitman, Richard; Kleinheinz, Gregory T
2010-01-01
A linkage between Cladophora mats and exceedances of recreational water quality criteria has been suggested, but not directly studied. This study investigates the spatial and temporal association between Escherichia coli concentrations within and near Cladophora mats at two northwestern Lake Michigan beaches in Door County, Wisconsin. Escherichia coli concentrations in water underlying mats were significantly greater than surrounding water (p < 0.001). Below mat E. coli increased as the stranded mats persisted at the beach swash zone. Water adjacent to Cladophora mats had lower E. coli concentrations, but surpassed EPA swimming criteria the majority of sampling days. A significant positive association was found between E. coli concentrations attached to Cladophora and in underlying water (p < 0.001). The attached E. coli likely acted as a reservoir for populating water underlying the mat. Fecal bacterial pathogens, however, could not be detected by microbiological culture methods either attached to mat biomass or in underlying water. Removal of Cladophora mats from beach areas may improve aesthetic and microbial water quality at affected beaches. These associations and potential natural growth of E. coli in bathing waters call into question the efficacy of using E. coli as a recreational water quality indicator of fecal contaminations.
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USDA-ARS?s Scientific Manuscript database
We previously reported the distinct acid resistance between the curli-producing (C+) and curli-deficient (C-) variants of E. coli O157:H7, although the curli fimbriae were not associated with this intra-strain phenotypic divergence. Here we investigated the underlying molecular mechanism by examinin...
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USDA-ARS?s Scientific Manuscript database
Shiga Toxin-Producing Escherichia coli (STEC) are frequently implicated in foodborne illness outbreaks and recalls of ground beef. In this study we determined the High Pressure Processing (HPP) D-10 value (the processing conditions needed to reduce the microbial population by 1 log) of 39 individua...
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USDA-ARS?s Scientific Manuscript database
Shiga toxin-producing E. coli (STEC) strains, commensal to gastrointestinal tracts of ruminants or other animals, have been associated with serious human illnesses and high mortality among immunocompromised populations. Along with the detection of STEC strains from fecal-contaminated environments su...
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USDA-ARS?s Scientific Manuscript database
This study was conducted to evaluate the effect of biosurfactants on the populations of Escherichia coli O157:H7 in suspension and on spinach leaves. Eight surfactants including four soybean oil-based biosurfactants, sodium dodecyl sulfate (SDS), polyoxyethylene sorbitan monooleate (Tween 80), sopho...
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Age and diet effects on fecal populations of a multi-drug-resistant Escherichia coli in dairy calves
USDA-ARS?s Scientific Manuscript database
The use of antimicrobial drugs is reported to increase the prevalence of resistant bacteria, including commensals. Dairy calves are colonized at a very young age by a multi-drug-resistant E. coli (MDR EC), and research indicates that the prevalence is not related to recent use of antimicrobials but...
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Birgy, André; Mariani-Kurkdjian, Patricia; Bidet, Philippe; Doit, Catherine; Genel, Nathalie; Courroux, Céline; Arlet, Guillaume; Bingen, Edouard
2013-06-01
Maternal-fetal Escherichia coli infections, such as neonatal bacteremia and meningitis, are important causes of morbidity and mortality. From 2006 to 2010, we studied newborns and their mothers who were colonized with E. coli in a French hospital in order to document (i) the epidemiology and genetic characteristics of extended-spectrum-beta-lactamase (ESBL)-producing E. coli strains, (ii) the prevalence of associated virulence genes, (iii) the prevalence of clone sequence type 131 (ST131), and (iv) the genetic relationship among ESBL-producing strains. Among the 2,755 E. coli cultures recovered from vaginal or neonatal samples, 68 were ESBL producers (2.46%). We found a wide diversity of ESBL genes, with the majority being bla(CTX-M-14), bla(CTX-M-1), and bla(CTX-M-15), distributed among the 4 main phylogenetic groups. Genes encoding virulence factors were found in 90.7% of the isolates, with ≥ 2 virulence genes present in 76% of cases. The prevalence of ST131 among ESBL-producing E. coli isolates was 9.4% (6/64). Five of these 6 ST131 isolates possessed bla(CTX-M-15) enzymes (and also were resistant to quinolones), and one possessed bla(CTX-M-2) enzymes. Two possessed virulence genes, suggesting the presence of pathogenicity island IIJ96 (PAI IIJ96)-like domains. Pulsed-field gel electrophoresis (PFGE) revealed a high level of genomic diversity overall, except for 3 closely related isolates belonging to clonal group ST131. Repetitive PCR showed that the six ST131 isolates were closely related to ST131 control strains (>95% similarity). This study shows a high prevalence of ESBL-producing E. coli strains and clonal group ST131 in the French maternal-fetal population. These results suggest a widespread distribution of ESBL enzymes in the community and highlight the early transmission between mothers and neonates. These findings are worrisome, especially for this particularly vulnerable population.
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Medhanie, Genet A; Pearl, David L; McEwen, Scott A; Guerin, Michele T; Jardine, Claire M; Schrock, Jennifer; LeJeune, Jeffrey T
2016-11-01
Wild birds that forage around livestock facilities have been implicated as vectors of antimicrobial resistant organisms. Although antimicrobial resistant bacteria have been isolated from European starlings (Sturnus vulgaris), their role in the dissemination of antimicrobial resistant elements in livestock facilities needs further investigation. To determine whether on-farm starling density and other factors were associated with the presence of cefotaxime and ciprofloxacin resistant E. coli among dairy cows in Ohio, bovine fecal pats from 150 farms were tested for the presence of cefotaxime and ciprofloxacin resistant E. coli. Each farm was visited twice (during the summer and fall of 2007-2009). Multi-level logistic regression models with a random intercept to account for fecal pats collected within a specific visit to a farm were used to assess the associations. The percentage of samples with cefotaxime and ciprofloxacin resistant E. coli was 13.4% and 13.6%, respectively. The percentage of farms having at least one sample testing positive for cefotaxime and ciprofloxacin resistant E. coli was 56.7% and 48.7%, respectively. The odds of detecting cefotaxime and ciprofloxacin resistant E. coli in the samples was significantly higher in 2007 compared to 2008 and 2009, in fall compared to summer, and from farms closer than 60km to starling night roost sites compared to the farms further than 60km. The presence of starlings during the day had a negative association with the likelihood of detecting cefotaxime resistant E. coli. Presence of calves also had a negative association with the likelihood of detecting both cefotaxime and ciprofloxacin resistant E. coli. European starlings might play a role in the dissemination of antimicrobial resistant agents in livestock facilities related to their daily population movements rather than the specific density of birds on farm during the day. Copyright © 2016 Elsevier B.V. All rights reserved.
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Syal, Karan; Shen, Simon; Yang, Yunze; Wang, Shaopeng; Haydel, Shelley E; Tao, Nongjian
2017-08-25
To combat antibiotic resistance, a rapid antibiotic susceptibility testing (AST) technology that can identify resistant infections at disease onset is required. Current clinical AST technologies take 1-3 days, which is often too slow for accurate treatment. Here we demonstrate a rapid AST method by tracking sub-μm scale bacterial motion with an optical imaging and tracking technique. We apply the method to clinically relevant bacterial pathogens, Escherichia coli O157: H7 and uropathogenic E. coli (UPEC) loosely tethered to a glass surface. By analyzing dose-dependent sub-μm motion changes in a population of bacterial cells, we obtain the minimum bactericidal concentration within 2 h using human urine samples spiked with UPEC. We validate the AST method using the standard culture-based AST methods. In addition to population studies, the method allows single cell analysis, which can identify subpopulations of resistance strains within a sample.
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Effect of disinfection upon dissolved organic carbon (DOC) in wastewater: bacterial bioassays.
Arana, I; Santorum, P; Muela, A; Barcina, I
2000-08-01
Quantitative and qualitative changes in organic matter content of wastewater effluents attributable to chlorination and ozonation have been analysed using bioassays as well as organic carbon direct measures. Bioassays were carried out using the bacterial populations of wastewater and two Escherichia coli strains as test micro-organisms. Our results indicate that pure strains present some advantages over indigenous bacteria. Although wastewater bacterial populations are better adapted to growth in wastewater, E. coli strains are more sensitive to changes in dissolved organic carbon (DOC) content. Moreover, the use of pure cultures allows estimation of the portion of DOC which can be converted in cell biomass, the assimilable organic carbon (AOC). Finally, the results obtained using prototrophic and the auxotrophic strains of E. coli suggested that ozonation alters the amino acid composition of wastewater while chlorination does not change the quantity nor the quality of the DOC present in effluents.
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Phenotypic bistability in Escherichia coli's central carbon metabolism
Kotte, Oliver; Volkmer, Benjamin; Radzikowski, Jakub L; Heinemann, Matthias
2014-01-01
Fluctuations in intracellular molecule abundance can lead to distinct, coexisting phenotypes in isogenic populations. Although metabolism continuously adapts to unpredictable environmental changes, and although bistability was found in certain substrate-uptake pathways, central carbon metabolism is thought to operate deterministically. Here, we combine experiment and theory to demonstrate that a clonal Escherichia coli population splits into two stochastically generated phenotypic subpopulations after glucose-gluconeogenic substrate shifts. Most cells refrain from growth, entering a dormant persister state that manifests as a lag phase in the population growth curve. The subpopulation-generating mechanism resides at the metabolic core, overarches the metabolic and transcriptional networks, and only allows the growth of cells initially achieving sufficiently high gluconeogenic flux. Thus, central metabolism does not ensure the gluconeogenic growth of individual cells, but uses a population-level adaptation resulting in responsive diversification upon nutrient changes. PMID:24987115
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Xu, Dong; Zhang, Yang
2013-01-01
Genome-wide protein structure prediction and structure-based function annotation have been a long-term goal in molecular biology but not yet become possible due to difficulties in modeling distant-homology targets. We developed a hybrid pipeline combining ab initio folding and template-based modeling for genome-wide structure prediction applied to the Escherichia coli genome. The pipeline was tested on 43 known sequences, where QUARK-based ab initio folding simulation generated models with TM-score 17% higher than that by traditional comparative modeling methods. For 495 unknown hard sequences, 72 are predicted to have a correct fold (TM-score > 0.5) and 321 have a substantial portion of structure correctly modeled (TM-score > 0.35). 317 sequences can be reliably assigned to a SCOP fold family based on structural analogy to existing proteins in PDB. The presented results, as a case study of E. coli, represent promising progress towards genome-wide structure modeling and fold family assignment using state-of-the-art ab initio folding algorithms. PMID:23719418
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Johnson, James R; McCabe, James S; White, David G; Johnston, Brian; Kuskowski, Michael A; McDermott, Patrick
2009-07-15
The origins and virulence potential of meat product-associated Escherichia coli are undefined. Two hundred eighty-seven E. coli isolates (145 resistant and 142 susceptible to trimethoprim-sulfamethoxazole, nalidixic acid, and/or ceftiofur), recovered by the United States National Antimicrobial Monitoring System from retail beef, pork, chicken, and turkey products (from Oregon, Tennessee, Georgia, and Maryland, 2002-2004) underwent polymerase chain reaction testing for phylogenetic groupings and 59 virulence-associated genes. However analyzed, resistant and susceptible isolates differed minimally according to the assessed characteristics. In contrast, the 4 meat types differed greatly for multiple individual traits and aggregate virulence scores. Poultry isolates exhibited virulence genes associated with avian pathogenic E. coli; beef isolates exhibited traits associated with E. coli from diseased cattle. Overall, 20% of isolates qualified as extraintestinal pathogenic E. coli, with poultry isolates exhibiting significantly higher virulence scores than beef and pork isolates (P < .001). Within this systematically collected, geographically distributed sample of recent retail meat isolates, the carriage of extraintestinal pathogenic E. coli virulence genes in antimicrobial-resistant and antimicrobial-susceptible E. coli appeared similar, whereas isolates from different types of meat differed, consistent with on-farm acquisition of resistance within host species-specific E. coli populations. A substantial minority of meat-source E. coli (whether susceptible or resistant) may represent potential human pathogens.
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Navab-Daneshmand, Tala; Friedrich, Max N D; Gächter, Marja; Montealegre, Maria Camila; Mlambo, Linn S; Nhiwatiwa, Tamuka; Mosler, Hans-Joachim; Julian, Timothy R
2018-03-01
Escherichia coli pathotypes (i.e., enteropathogenic and enterotoxigenic) have been identified among the pathogens most responsible for moderate-to-severe diarrhea in low- and middle-income countries (LMICs). Pathogenic E. coli are transmitted from infected human or animal feces to new susceptible hosts via environmental reservoirs such as hands, water, and soil. Commensal E. coli , which includes nonpathogenic E. coli strains, are widely used as fecal bacteria indicator, with their presence associated with increased likelihood of enteric pathogens and/or diarrheal disease. In this study, we investigated E. coli contamination in environmental reservoirs within households ( N = 142) in high-population density communities of Harare, Zimbabwe. We further assessed the interconnectedness of the environmental compartments by investigating associations between, and household-level risk factors for, E. coli contamination. From the data we collected, the source and risk factors for E. coli contamination are not readily apparent. One notable exception is the presence of running tap water on the household plot, which is associated with significantly less E. coli contamination of drinking water, handwashing water, and hands after handwashing. In addition, E. coli levels on hands after washing are significantly associated with handwashing water contamination, hand contamination before washing, and diarrhea incidence. Finally, we observed that animal ownership increases E. coli contamination in soil, and E. coli in soil are correlated with contamination on hands before washing. This study highlights the complexity of E. coli contamination in household environments within LMICs. More, larger, studies are needed to better identify sources and exposure pathways of E. coli -and enteric pathogens generally-to identify effective interventions.
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Growth of bacteria in 3-d colonies
Mugler, Andrew; Kim, Justin
2017-01-01
The dynamics of growth of bacterial populations has been extensively studied for planktonic cells in well-agitated liquid culture, in which all cells have equal access to nutrients. In the real world, bacteria are more likely to live in physically structured habitats as colonies, within which individual cells vary in their access to nutrients. The dynamics of bacterial growth in such conditions is poorly understood, and, unlike that for liquid culture, there is not a standard broadly used mathematical model for bacterial populations growing in colonies in three dimensions (3-d). By extending the classic Monod model of resource-limited population growth to allow for spatial heterogeneity in the bacterial access to nutrients, we develop a 3-d model of colonies, in which bacteria consume diffusing nutrients in their vicinity. By following the changes in density of E. coli in liquid and embedded in glucose-limited soft agar, we evaluate the fit of this model to experimental data. The model accounts for the experimentally observed presence of a sub-exponential, diffusion-limited growth regime in colonies, which is absent in liquid cultures. The model predicts and our experiments confirm that, as a consequence of inter-colony competition for the diffusing nutrients and of cell death, there is a non-monotonic relationship between total number of colonies within the habitat and the total number of individual cells in all of these colonies. This combined theoretical-experimental study reveals that, within 3-d colonies, E. coli cells are loosely packed, and colonies produce about 2.5 times as many cells as the liquid culture from the same amount of nutrients. We verify that this is because cells in liquid culture are larger than in colonies. Our model provides a baseline description of bacterial growth in 3-d, deviations from which can be used to identify phenotypic heterogeneities and inter-cellular interactions that further contribute to the structure of bacterial communities. PMID:28749935
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[Effect of nutritional stress on autophagy in free-living amoeba].
Wang, Nan-Ning; Tan, Yu-Zhen; Wang, Hai-Jie
2010-12-30
To investigate the change of autophagy and morphological characteristics of the autophagic structures in free-living amoeba under nutritional stress. Free-living amoebae were incubated on the agaric solid medium which had been covered with Escherichia cdi in control group. In the experiment group, amoebae incubated on the agaric solid medium with E. coli were collected and moved to another solid medium without E. coli and incubated for 12 h. The morphological changes of free-living amoeba in the medium without E. coli were viewed with scanning electron microscope. The changes of autophagy and the structural features of the autophagosome precursors, autophagosomes and autophagolysosomes in amoeba were examined with transmission electron microscope, and the cross-section areas of the autophagic structures and cytoplasm were measured with an image analyzer. The autophagosomes in the organism were labeled with monodansylcadaverine (MDC) staining and quantitated using laser scanning confocal microscope. In the control group, free-living amoebae were all in the form of trophozoite. In the experiment group, trophozoites were induced to transform to cysts gradually. In control group, amoeba was full of fragment of E. coli. There was merely little autophagy with fewer autophagic structures in amoeba. When compared with the control group, the autophagic abilities of amoeba were enhanced significantly, number of autophagic structures increased in the experiment group. In addition, the ratio of the cross-sectional areas of the autophagic structures to that of the cytoplasm of amoeba was greater (P < 0.05 or 0.01). There was fragment of E. coli that was not digested in some of the amoebae. In the circumstance of nutritional stress, amoebic trophozoites were induced to transform to cysts gradually. The autophagic ability of free-living amoeba significantly enhanced.
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Perepelov, Andrei V; Liu, Bin; Shevelev, Sergei D; Senchenkova, Sof'ya N; Shashkov, Alexander S; Feng, Lu; Knirel, Yuriy A; Wang, Lei
2010-04-19
O-Polysaccharides were isolated by mild acid degradation of the lipopolysaccharides of Escherichia coli O123 and Salmonella enterica O58 and studied by chemical methods and 2D (1)H and (13)C NMR spectroscopy, including experiments in a H(2)O/D(2)O mixture, which enabled observation of correlations for nitrogen-linked protons. The following structure of the O-polysaccharide of E. coli O123 was established: -->3)-beta-D-Quip4NAlaHb-(1-->6)-alpha-D-GlcpNAc-(1-->3)-alpha-L-QuipNAc-(1-->3)-alpha-D-Glcp (6)(approx. 30% OAc)NAc-(1--> where L-QuipNAc stands for 2-acetamido-2,6-dideoxy-L-glucose and D-Qui4NAlaHb for 4-{N-[(S)-3-hydroxybutanoyl]-D-alanyl}amino-4,6-dideoxy-D-glucose. The latter was isolated as an ethylene glycol glycoside by three sequential Smith degradations of the O-deacetylated O-polysaccharide. The structure established in this work is at variance with the E. coli O123-polysaccharide structure reported earlier [Clark, C. G.; Kropinski, A. M.; Parolis, H.; Grant, C. C.; Trout-Yakel, K. M.; Franklin, K.; Ng, L. K.; Paramonov, N. A.; Parolis, L. A.; Rahn, K.; Tabor, H. J. Med. Microbiol.2009, 58, 884-894]. In accordance with the genetic data, the O-polysaccharide of S. enterica O58 has the same structure, except for it lacks the O-acetylation. Copyright (c) 2010 Elsevier Ltd. All rights reserved.
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Ferreira, Joseane Cristina; Penha Filho, Rafael Antonio Casarin; Kuaye, Ana Paula Yorika; Andrade, Leonardo Neves; Berchieri Junior, Angelo; Darini, Ana Lúcia da Costa
2018-06-01
The expression of plasmid-mediated quinolone resistance (PMQR) genes confers low-level quinolone and fluoroquinolones resistance alone. However, the association to chromosomal resistance mechanisms determines an expressively higher resistance in Enterobacteriaceae. These mechanisms are horizontally disseminated within plasmids and have contributed to the emergence of bacteria with reduced susceptibility or resistant to therapies worldwide. The epidemiological characterization of PMQR dissemination is highly relevant in the scientific and medical context, to investigate the dissemination within enterobacteria, from different populations, including humans and food-producing animals. In the present study, 200 Enterobacteriaceae isolates were harvested from poultry with cloacal swabs and identified as Escherichia coli (90.5%), Escherichia fergusonii (5.5%), Klebsiella oxytoca (2.5%) and Klebsiella pneumoniae (1.5%). Among isolates evaluated, 46 (23%) harboured PMQR genes including qnrB (43/200), qnrS (2/200) and aac(6')-Ib-cr (1/200). All isolates carrying PMQR genes showed multidrug-resistance phenotype. The 36 E. coli isolates showed 18 different PFGE types. All E. fergusonii isolates showed the same PFGE type. The two Klebsiella oxytoca belonged to two different PFGE types. The phylogenetic groups A, B1, and D were found among the E. coli harboring PMQR genes. Based on the phylogenetic analysis and PFGE, the population structure of E. coli isolates was diverse, even within the same farm. All isolates carrying qnrB and qnrS genes also harboured ColE-like plasmids. The Southern blot hybridization using the S1-PFGE revealed that the qnrB genes were located on low molecular weight plasmids, smaller than 10Kb. Resistance plasmids were sequenced and showed 100% identity with plasmid pPAB19-3. The association of PMQR genes with mobile genetic elements, such as transferable plasmids, favours the selection and dissemination of (fluoro) quinolones resistant bacteria among food-producing animals, and may play an important role in the current increased prevalence of resistant bacteria in different environments reported worldwide. Copyright © 2018. Published by Elsevier B.V.
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Despite extensive genetic, biochemical and structural studies on Escherichia coli RNA polymerase (RNAP), little is known about its location and distribution in response to environmental changes. To visualize the RNAP by fluorescence microscopy in E. coli under different physiological conditions, we constructed a functional rpoC-gfp gene fusion on the chromosome.
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Seasonal and spatial community dynamics in the meromictic Lake Cadagno.
Bosshard, P P; Stettler, R; Bachofen, R
2000-09-01
The seasonal and spatial variations in the community structure of bacterioplankton in the meromictic alpine Lake Cadagno were examined by temporal temperature gradient gel electrophoresis (TTGE) of PCR-amplified 16S rDNA fragments. Two different amplifications were performed, one specific for the domain Bacteria (Escherichia coli positions 8-536) and another specific for the family Chromatiaceae (E. coli positions 8-1005). The latter was followed by semi-nested reamplification with the bacterial primer set, allowing comparison of the two PCR approaches by TTGE. The TTGE patterns of samples from the chemocline and the anoxic monimolimnion were essentially identical, whereas the oxic mixolimnion displayed distinctively different banding patterns. For samples from the chemocline and the monimolimnion, dominant bands in the Bacteria-specific TTGE profiles comigrated with bands obtained by the semi-nested PCR approach specific for Chromatiaceae. This observation suggested that Chromatiaceae are in high abundance in the anoxic water layer. All dominant bands were excised and sequenced. Changes in the community structure, as indicated by changes in the TTGE profiles, were observed in samples taken at different times of the year. In the chemocline, Chomatium okenii was dominant in the summer months, whereas Amoebobacter purpureus populations dominated in autumn and winter. This change was confirmed by fluorescent in situ hybridization.
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Detection of Escherichia Coli Bacteria in Wastewater by using Graphene as a Sensing Material
NASA Astrophysics Data System (ADS)
Wibowo, K. M.; Sahdan, M. Z.; Ramli, N. I.; Muslihati, A.; Rosni, N.; Tsen, V. H.; Saim, H.; Ahmad, S. A.; Sari, Y.; Mansor, Z.
2018-04-01
Graphene is a family of carbon bonded in hexagonal honeycomb crystalline structure that has many superior properties. It was very suitable to be applied on sensor application due to the superior properties on electrical, physical, and optical. Furthermore, graphene also provide a large detection area since it has 2D structure. In this research, we develop graphene as a nanosensor for detection of Escherichia coli (E. coli) bacteria. The sample E. coli bacteria were cultured from domestic wastewater by using plate culture method and then isolated to get pure single colony. The serial dilution was performed to create different concentration of bacteria. Field emission scanning electron microscope and biochemical test were performed to ensure the sample genuinely target E. coli that defined by the physical size and optical properties. Raman spectroscopy measurements were also performed on the grapheme films, and it was found that the ratio of G peak and D peak intensity changing do to the presence of E. coli. The electrical properties of graphene shows the increasing number of the bacteria 4 to 273 cfu result in decreasing the resistance from 4.371 to 3.903 ohm gradually.
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Ram, Siya; Vajpayee, Poornima; Shanker, Rishi
2007-11-01
The consumption of polluted surface water for domestic and recreational purposes by large populations in developing nations is a major cause of diarrheal disease related mortality. The river Ganga and its tributaries meet 40% of the water requirement for drinking and irrigation in India. In this study, Escherichia coli isolates (n=75) of the river Ganga water were investigated for resistance to antimicrobial agents (n=15) and virulence genes specific to shiga toxin (STEC) and enterotoxin producing E. coli (ETEC). E. coli isolates from the river Ganga water exhibit resistance to multiple antimicrobial agents. The distribution of antimicrobial agent resistance in E. colivaries significantly (chi2: 81.28 at df = 24, p < 0.001) between the sites. Both stx1 and stx2 genes were present in 82.3% of STEC (n=17) while remaining isolates possess either stxl (11.8%) or stx2 (5.9%). The presence of eaeA, hlyA, and chuA genes was observed in 70.6, 88.2, and 58.8% of STEC, respectively. Both LT1 and ST1 genes were positive in 66.7% of ETEC (n=15) while 33.3% of isolates harbor only LT1 gene. The prevalence of multi-antimicrobial-agent resistant E. coli in the river Ganga water poses increased risk of infections in the human population.
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Gohar, Maha Kamal; Atta, Amal Hassan
2016-01-01
Fecal contamination of drinking water is a major health problem which accounts for many cases of diarrhea mainly in infants and foreigners. This contamination is a complex interaction of many parameters. Antibiotic resistance among bacterial isolates complicates the problem. The study was done to identify fecal contamination of drinking water by Diarrheagenic Antibiotic-Resistant Escherichia coli in Zagazig city and to trace reasons for such contamination, three hundred potable water samples were investigated for E. coli existence. Locations of E. coli positive samples were investigated in relation to population density, water source, and type of water pipe. Sixteen E. coli strains were isolated. Antibiotic sensitivity was done and enterotoxigenic, enteropathogenic, and enterohaemorrhagic virulence genes were investigated by PCR. Probability of fecal contamination correlated with higher population density, with increased distance from Zagazig water plant, and with asbestos cement water pipes. Resistance to at least one antimicrobial drug was found in all isolates. Virulence genes were detected in a rate of 26.27%, 13.13%, 20%, 6.67%, and 33.33% for LT, ST, stx1, stx2, and eae genes, respectively. This relatively high frequency of fecal contamination points towards the high risk of developing diarrhea by antibiotic resistant DEC in low socioeconomic communities particularly with old fashion distribution systems. PMID:27725834
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Kim, Myounggon; Jung, Taekeon; Kim, Youngjin; Lee, Changgeun; Woo, Kyungchul; Seol, Jae Hun; Yang, Sung
2015-12-15
While sensors that allow for high-throughput enumeration of microorganisms within drinking water are useful for water quality monitoring, it is particularly challenging to accurately quantify microorganisms that are present in low numbers (<100 CFU/mL) in a high-throughput manner. Negative dielectrophoresis (nDEP) is typically utilized in DEP-based cell focusing methods; however, due to its low conductivity, drinking water cannot be analyzed by this approach. Here, we report a positive DEP (pDEP)-based Escherichia coli detection system that is integrated with a focusing and sensing electrode. By incorporating a passivation layer, we avoided issues with adhesion of E. coli to the electrode, and achieved efficient cell focusing under high flow rate conditions (1500 μL/h). The resulting focused E. coli cells were then trapped on the sensor electrode, resulting in changes in impedance. The proposed system was evaluated using four different E. coli populations (150-1500 CFU/mL). We successfully enumerated populations as low as 300 CFU/mL within 1 min, and the signal variation was 1.13±0.37%. The device introduced in this study provides the basis for the development of portable, highly sensitive microorganism sensors that enable rapid detection of bacteria in drinking water. Copyright © 2015 Elsevier B.V. All rights reserved.
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Bergholz, Peter W; Strawn, Laura K; Ryan, Gina T; Warchocki, Steven; Wiedmann, Martin
2016-03-01
Although flooding introduces microbiological, chemical, and physical hazards onto croplands, few data are available on the spatial extent, patterns, and development of contamination over time postflooding. To address this paucity of information, we conducted a spatially explicit study of Escherichia coli and Salmonella contamination prevalence and genetic diversity in produce fields after the catastrophic flooding that occurred in New England during 2011. Although no significant differences were detected between the two participating farms, both random forest and logistic regression revealed changes in the spatial pattern of E. coli contamination in drag swab samples over time. Analyses also indicated that E. coli detection was associated with changes in farm management to remediate the land after flooding. In particular, E. coli was widespread in drag swab samples at 21 days postflooding, but the spatial pattern changed by 238 days postflooding such that E. coli was then most prevalent in close proximity to surface water features. The combined results of several population genetics analyses indicated that over time postflooding E. coli populations on the farms (i) changed in composition and (ii) declined overall. Salmonella was primarily detected in surface water features, but some Salmonella strains were isolated from soil and drag swab samples at 21 and 44 days postflooding. Although postflood contamination and land management responses should always be evaluated in the context of each unique farm landscape, our results provide quantitative data on the general patterns of contamination after flooding and support the practice of establishing buffer zones between flood-contaminated cropland and harvestable crops in produce fields.
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Manges, Amee R; Mende, Katrin; Murray, Clinton K; Johnston, Brian D; Sokurenko, Evgeni V; Tchesnokova, Veronika; Johnson, James R
2017-04-01
Antimicrobial-resistant Escherichia coli are a concern for military health services. We studied 100 extended-spectrum beta-lactamase (ESBL)-producing and non-producing E. coli clinical and surveillance isolates from military personnel and civilians at Brooke Army Medical Center (2007-2011). Major E. coli lineages, most prominently ST10 (24%), ST131 (16%), and ST648 (8%), were distributed much as reported for other North American populations. ST131, represented mainly by its resistance-associated ST131-H30 clonal subset, was uniquely associated with a clinical origin, regardless of ESBL status. Thus, clonal background predicted resistance phenotype and clinical versus surveillance origin, and these findings could assist military clinicians and epidemiologists. Published by Elsevier Inc.
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USDA-ARS?s Scientific Manuscript database
Shiga toxin (Stx)-producing, food-contaminating Escherichia coli (STEC) is a major health concern. Plant-derived pectin and pectic-oligosaccharides (POS) that are abundant in biomass have been considered as prebiotics and for the protection of humans from Stx intoxication. Five structurally differ...
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Fyfe, Cameron D.; Grinter, Rhys; Josts, Inokentijs
The X-ray structure of protease-cleaved E. coli α-2-macroglobulin is described, which reveals a putative mechanism of activation and conformational change essential for protease inhibition. Bacterial α-2-macroglobulins have been suggested to function in defence as broad-spectrum inhibitors of host proteases that breach the outer membrane. Here, the X-ray structure of protease-cleaved Escherichia coli α-2-macroglobulin is described, which reveals a putative mechanism of activation and conformational change essential for protease inhibition. In this competitive mechanism, protease cleavage of the bait-region domain results in the untethering of an intrinsically disordered region of this domain which disrupts native interdomain interactions that maintain E. colimore » α-2-macroglobulin in the inactivated form. The resulting global conformational change results in entrapment of the protease and activation of the thioester bond that covalently links to the attacking protease. Owing to the similarity in structure and domain architecture of Escherichia coli α-2-macroglobulin and human α-2-macroglobulin, this protease-activation mechanism is likely to operate across the diverse members of this group.« less
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Steil, Daniel; Pohlentz, Gottfried; Legros, Nadine; Mormann, Michael; Mellmann, Alexander; Karch, Helge; Müthing, Johannes
2018-06-25
Shiga toxin (Stx)-producing Escherichia coli (STEC) and enterohemorrhagic E. coli (EHEC) as a human-pathogenic subgroup of STEC are characterized by releasing Stx AB5-toxin as the major virulence factor. Worldwide disseminated EHEC strains cause sporadic infections and outbreaks in the human population and swine-pathogenic STEC strains represent greatly feared pathogens in pig breeding and fattening plants. Among the various Stx subtypes Stx1a and Stx2a are of eminent clinical importance in human infections being associated with life-threatening hemorrhagic colitis and hemolytic uremic syndrome, whereas Stx2e subtype is associated with porcine edema disease with generalized fatal outcome for the animals. Binding towards the glycosphingolipid globotriaosylceramide (Gb3Cer) is a common feature of all Stx subtypes analyzed so far. Here we report on the development of a matched strategy combining (i) miniaturized one-step affinity purification of native Stx subtypes from culture supernatant of bacterial wild-type strains using Gb3-functionalized magnetic beads, (ii) structural analysis and identification of Stx holotoxins by electrospray ionization ion mobility mass spectrometry (ESI MS) (iii), functional Stx-receptor real-time interaction analysis employing the surface acoustic wave technology (SAW), and (iv) Vero cell culture assays for determining Stx-caused cytotoxic effects. Structural investigations revealed diagnostic tryptic peptide ions for purified Stx1a, Stx2a and Stx2e, respectively, and functional analysis resulted in characteristic binding kinetics of each Stx subtype. Cytotoxicity studies revealed differing toxin-mediated cell damage ranked with Stx1a > Stx2a > Stx2e. Collectively, this matched procedure represents a promising clinical application for the characterization of life-endangering Stx subtypes at the protein level.
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Lane, Jonathan A; Mariño, Karina; Rudd, Pauline M; Carrington, Stephen D; Slattery, Helen; Hickey, Rita M
2012-07-01
Many studies have demonstrated the capacity of glycan-based compounds to disrupt microbial binding to mucosal epithelia. Therefore, oligosaccharides have potential application in the prevention of certain bacterial diseases. However, current screening methods for the identification of anti-adhesive oligosaccharides have limitations: they are time-consuming and require large amounts of oligosaccharides. There is a need to develop analytical techniques which can quickly screen for, and structurally define, anti-adhesive oligosaccharides prior to using human cell line models of infection. Considering this, we have developed a rapid method for screening complex oligosaccharide mixtures for potential anti-adhesive activity against bacteria. Our approach involves the use of whole bacterial cells to "deplete" free oligosaccharides from solution. As a case study, the free oligosaccharides from the colostrum of Holstein Friesian cows were screened for interactions with whole Escherichia coli cells. Reductions in oligosaccharide concentrations were determined by High pH Anion Exchange Chromatography and Hydrophilic Interaction Liquid Chromatography (HILIC-HPLC). Oligosaccharide structures were confirmed by a combination of HILIC-HPLC, exoglycosidase digestion and off-line negative ion mode MS/MS. The depletion assay confirmed selective bacterial interaction with certain bovine oligosaccharides which in previous studies, by other methodologies, had been shown to interact with E. coli. In particular, the bacterial cells depleted the following oligosaccharides in a population dependent manner: 3'-sialyllactose, disialyllactose, and 6'-sialyllactosamine. The assay methodology was further validated by studies in which we demonstrated the inhibitory activity of 3'-sialyllactose, and a mixture of bovine colostrum oligosaccharides, on E. coli adhesion to differentiated HT-29 cells. Copyright © 2012 Elsevier B.V. All rights reserved.
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Espina, Laura; Gelaw, Tilahun K.; de Lamo-Castellví, Sílvia; Pagán, Rafael; García-Gonzalo, Diego
2013-01-01
This work explores the bactericidal effect of (+)-limonene, the major constituent of citrus fruits' essential oils, against E. coli. The degree of E. coli BJ4 inactivation achieved by (+)-limonene was influenced by the pH of the treatment medium, being more bactericidal at pH 4.0 than at pH 7.0. Deletion of rpoS and exposure to a sub-lethal heat or an acid shock did not modify E. coli BJ4 resistance to (+)-limonene. However, exposure to a sub-lethal cold shock decreased its resistance to (+)-limonene. Although no sub-lethal injury was detected in the cell envelopes after exposure to (+)-limonene by the selective-plating technique, the uptake of propidium iodide by inactivated E. coli BJ4 cells pointed out these structures as important targets in the mechanism of action. Attenuated Total Reflectance Infrared Microspectroscopy (ATR-IRMS) allowed identification of altered E. coli BJ4 structures after (+)-limonene treatments as a function of the treatment pH: β-sheet proteins at pH 4.0 and phosphodiester bonds at pH 7.0. The increased sensitivity to (+)-limonene observed at pH 4.0 in an E. coli MC4100 lptD4213 mutant with an increased outer membrane permeability along with the identification of altered β-sheet proteins by ATR-IRMS indicated the importance of this structure in the mechanism of action of (+)-limonene. The study of mechanism of inactivation by (+)-limonene led to the design of a synergistic combined process with heat for the inactivation of the pathogen E. coli O157:H7 in fruit juices. These results show the potential of (+)-limonene in food preservation, either acting alone or in combination with lethal heat treatments. PMID:23424676
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Espina, Laura; Gelaw, Tilahun K; de Lamo-Castellví, Sílvia; Pagán, Rafael; García-Gonzalo, Diego
2013-01-01
This work explores the bactericidal effect of (+)-limonene, the major constituent of citrus fruits' essential oils, against E. coli. The degree of E. coli BJ4 inactivation achieved by (+)-limonene was influenced by the pH of the treatment medium, being more bactericidal at pH 4.0 than at pH 7.0. Deletion of rpoS and exposure to a sub-lethal heat or an acid shock did not modify E. coli BJ4 resistance to (+)-limonene. However, exposure to a sub-lethal cold shock decreased its resistance to (+)-limonene. Although no sub-lethal injury was detected in the cell envelopes after exposure to (+)-limonene by the selective-plating technique, the uptake of propidium iodide by inactivated E. coli BJ4 cells pointed out these structures as important targets in the mechanism of action. Attenuated Total Reflectance Infrared Microspectroscopy (ATR-IRMS) allowed identification of altered E. coli BJ4 structures after (+)-limonene treatments as a function of the treatment pH: β-sheet proteins at pH 4.0 and phosphodiester bonds at pH 7.0. The increased sensitivity to (+)-limonene observed at pH 4.0 in an E. coli MC4100 lptD4213 mutant with an increased outer membrane permeability along with the identification of altered β-sheet proteins by ATR-IRMS indicated the importance of this structure in the mechanism of action of (+)-limonene. The study of mechanism of inactivation by (+)-limonene led to the design of a synergistic combined process with heat for the inactivation of the pathogen E. coli O157:H7 in fruit juices. These results show the potential of (+)-limonene in food preservation, either acting alone or in combination with lethal heat treatments.
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Electron crystallography of PhoE porin, an outer membrane, channel- forming protein from E. coli
DOE Office of Scientific and Technical Information (OSTI.GOV)
Walian, P.J.
1989-11-01
One approach to studying the structure of membrane proteins is the use of electron crystallography. Dr. Bing Jap has crystallized PhoE pore-forming protein (porin) from the outer membrane of escherichia coli (E. coli) into monolayer crystals. The findings of this research and those of Jap (1988, 1989) have determined these crystals to be highly ordered, yielding structural information to a resolution of better than 2.8 angstroms. The task of this thesis has been to collect and process the electron diffraction patterns necessary to generate a complete three-dimensional set of high resolution structure factor amplitudes of PhoE porin. Fourier processing ofmore » these amplitudes when combined with the corresponding phase data is expected to yield the three-dimensional structure of PhoE porin at better than 3.5 angstroms resolution. 92 refs., 33 figs., 3 tabs. (CBS)« less
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Brownell, M J; Harwood, V J; Kurz, R C; McQuaig, S M; Lukasik, J; Scott, T M
2007-08-01
The effect of a stormwater conveyance system on indicator bacteria levels at a Florida beach was assessed using microbial source tracking methods, and by investigating indicator bacteria population structure in water and sediments. During a rain event, regulatory standards for both fecal coliforms and Enterococcus spp. were exceeded, contrasting with significantly lower levels under dry conditions. Indicator bacteria levels were high in sediments under all conditions. The involvement of human sewage in the contamination was investigated using polymerase chain reaction (PCR) assays for the esp gene of Enterococcus faecium and for the conserved T antigen of human polyomaviruses, all of which were negative. BOX-PCR subtyping of Escherichia coli and Enterococcus showed higher population diversity during the rain event; and higher population similarity during dry conditions, suggesting that without fresh inputs, only a subset of the population survives the selective pressure of the secondary habitat. These data indicate that high indicator bacteria levels were attributable to a stormwater system that acted as a reservoir and conduit, flushing high levels of indicator bacteria to the beach during a rain event. Such environmental reservoirs of indicator bacteria further complicate the already questionable relationship between indicator organisms and human pathogens, and call for a better understanding of the ecology, fate and persistence of indicator bacteria.
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Rosen, Laura E.; Connell, Katelyn B.; Marqusee, Susan
2014-01-01
The molten globule, a conformational ensemble with significant secondary structure but only loosely packed tertiary structure, has been suggested to be a ubiquitous intermediate in protein folding. However, it is difficult to assess the tertiary packing of transiently populated species to evaluate this hypothesis. Escherichia coli RNase H is known to populate an intermediate before the rate-limiting barrier to folding that has long been thought to be a molten globule. We investigated this hypothesis by making mimics of the intermediate that are the ground-state conformation at equilibrium, using two approaches: a truncation to generate a fragment mimic of the intermediate, and selective destabilization of the native state using point mutations. Spectroscopic characterization and the response of the mimics to further mutation are consistent with studies on the transient kinetic intermediate, indicating that they model the early intermediate. Both mimics fold cooperatively and exhibit NMR spectra indicative of a closely packed conformation, in contrast to the hypothesis of molten tertiary packing. This result is important for understanding the nature of the subsequent rate-limiting barrier to folding and has implications for the assumption that many other proteins populate molten globule folding intermediates. PMID:25258414
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Rosen, Laura E; Connell, Katelyn B; Marqusee, Susan
2014-10-14
The molten globule, a conformational ensemble with significant secondary structure but only loosely packed tertiary structure, has been suggested to be a ubiquitous intermediate in protein folding. However, it is difficult to assess the tertiary packing of transiently populated species to evaluate this hypothesis. Escherichia coli RNase H is known to populate an intermediate before the rate-limiting barrier to folding that has long been thought to be a molten globule. We investigated this hypothesis by making mimics of the intermediate that are the ground-state conformation at equilibrium, using two approaches: a truncation to generate a fragment mimic of the intermediate, and selective destabilization of the native state using point mutations. Spectroscopic characterization and the response of the mimics to further mutation are consistent with studies on the transient kinetic intermediate, indicating that they model the early intermediate. Both mimics fold cooperatively and exhibit NMR spectra indicative of a closely packed conformation, in contrast to the hypothesis of molten tertiary packing. This result is important for understanding the nature of the subsequent rate-limiting barrier to folding and has implications for the assumption that many other proteins populate molten globule folding intermediates.
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USDA-ARS?s Scientific Manuscript database
In response to U.S. foodborne illnesses caused by contaminated spinach, growers have adopted regulations stated in the California Leafy Greens Marketing Agreement (LGMA). The LGMA permits a maximum population mean of 126 Most Probable Number (MPN) generic E. coli per 100 ml irrigation water. These...
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USDA-ARS?s Scientific Manuscript database
Shiga toxin-producing E. coli (STEC), one of the most prevalent foodborne pathogens, are notorious for hemolytic uremic syndrome (HUS) and causing high mortality among children and the elder population after infection. Besides O157 STEC, non-O157 STEC—particularly serogroup O145—is commonly associat...
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USDA-ARS?s Scientific Manuscript database
Sprouts have frequently been implicated in outbreaks of foodborne illnesses, mostly due to contaminated seeds. Intervention technologies to decontaminate seeds without affecting sprout yield are needed. In the present study, we compared gamma rays with electron beam in inactivating E. coli artifici...
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USDA-ARS?s Scientific Manuscript database
The use of antimicrobial drugs is reported to increase the prevalence of resistant bacteria, including commensals. Dairy calves are colonized at a very young age by a multi-drug-resistant E. coli (MDR EC), and research indicates that the prevalence is not related to recent use of antimicrobials but...
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Navab-Daneshmand, Tala; Friedrich, Max N. D.; Gächter, Marja; Montealegre, Maria Camila; Mlambo, Linn S.; Nhiwatiwa, Tamuka; Mosler, Hans-Joachim; Julian, Timothy R.
2018-01-01
Abstract. Escherichia coli pathotypes (i.e., enteropathogenic and enterotoxigenic) have been identified among the pathogens most responsible for moderate-to-severe diarrhea in low- and middle-income countries (LMICs). Pathogenic E. coli are transmitted from infected human or animal feces to new susceptible hosts via environmental reservoirs such as hands, water, and soil. Commensal E. coli, which includes nonpathogenic E. coli strains, are widely used as fecal bacteria indicator, with their presence associated with increased likelihood of enteric pathogens and/or diarrheal disease. In this study, we investigated E. coli contamination in environmental reservoirs within households (N = 142) in high-population density communities of Harare, Zimbabwe. We further assessed the interconnectedness of the environmental compartments by investigating associations between, and household-level risk factors for, E. coli contamination. From the data we collected, the source and risk factors for E. coli contamination are not readily apparent. One notable exception is the presence of running tap water on the household plot, which is associated with significantly less E. coli contamination of drinking water, handwashing water, and hands after handwashing. In addition, E. coli levels on hands after washing are significantly associated with handwashing water contamination, hand contamination before washing, and diarrhea incidence. Finally, we observed that animal ownership increases E. coli contamination in soil, and E. coli in soil are correlated with contamination on hands before washing. This study highlights the complexity of E. coli contamination in household environments within LMICs. More, larger, studies are needed to better identify sources and exposure pathways of E. coli—and enteric pathogens generally—to identify effective interventions. PMID:29363444
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Lu, Shan; Jin, Dong; Wu, Shusheng; Yang, Jing; Lan, Ruiting; Bai, Xiangning; Liu, Sha; Meng, Qiong; Yuan, Xuejiao; Zhou, Juan; Pu, Ji; Chen, Qiang; Dai, Hang; Hu, Yuanyuan; Xiong, Yanwen; Ye, Changyun; Xu, Jianguo
2016-01-01
Escherichia coli is both of a widespread harmless gut commensal and a versatile pathogen of humans. Domestic animals are a well-known reservoir for pathogenic E. coli. However, studies of E. coli populations from wild animals that have been separated from human activities had been very limited. Here we obtained 580 isolates from intestinal contents of 116 wild Marmot Marmota himalayana from Qinghai–Tibet plateau, China, with five isolates per animal. We selected 125 (hereinafter referred to as strains) from the 580 isolates for genome sequencing, based on unique pulse field gel electrophoresis patterns and at least one isolate per animal. Whole genome sequence analysis revealed that all 125 strains carried at least one and the majority (79.2%) carried multiple virulence genes based on the analysis of 22 selected virulence genes. In particular, the majority of the strains carried virulence genes from different pathovars as potential 'hybrid pathogens'. The alleles of eight virulence genes from the Marmot E. coli were found to have diverged earlier than all known alleles from human and other animal E. coli. Phylogenetic analysis of the 125 Marmot E. coli genomes and 355 genomes selected from 1622 human and other E. coli strains identified two new phylogroups, G and H, both of which diverged earlier than the other phylogroups. Eight of the 12 well-known pathogenic E. coli lineages were found to share a most recent common ancestor with one or more Marmot E. coli strains. Our results suggested that the intestinal E. coli of the Marmots contained a diverse virulence gene pool and is potentially pathogenic to humans. These findings provided a new understanding of the evolutionary origin of pathogenic E. coli. PMID:27924811
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Lu, Shan; Jin, Dong; Wu, Shusheng; Yang, Jing; Lan, Ruiting; Bai, Xiangning; Liu, Sha; Meng, Qiong; Yuan, Xuejiao; Zhou, Juan; Pu, Ji; Chen, Qiang; Dai, Hang; Hu, Yuanyuan; Xiong, Yanwen; Ye, Changyun; Xu, Jianguo
2016-12-07
Escherichia coli is both of a widespread harmless gut commensal and a versatile pathogen of humans. Domestic animals are a well-known reservoir for pathogenic E. coli. However, studies of E. coli populations from wild animals that have been separated from human activities had been very limited. Here we obtained 580 isolates from intestinal contents of 116 wild Marmot Marmota himalayana from Qinghai-Tibet plateau, China, with five isolates per animal. We selected 125 (hereinafter referred to as strains) from the 580 isolates for genome sequencing, based on unique pulse field gel electrophoresis patterns and at least one isolate per animal. Whole genome sequence analysis revealed that all 125 strains carried at least one and the majority (79.2%) carried multiple virulence genes based on the analysis of 22 selected virulence genes. In particular, the majority of the strains carried virulence genes from different pathovars as potential 'hybrid pathogens'. The alleles of eight virulence genes from the Marmot E. coli were found to have diverged earlier than all known alleles from human and other animal E. coli. Phylogenetic analysis of the 125 Marmot E. coli genomes and 355 genomes selected from 1622 human and other E. coli strains identified two new phylogroups, G and H, both of which diverged earlier than the other phylogroups. Eight of the 12 well-known pathogenic E. coli lineages were found to share a most recent common ancestor with one or more Marmot E. coli strains. Our results suggested that the intestinal E. coli of the Marmots contained a diverse virulence gene pool and is potentially pathogenic to humans. These findings provided a new understanding of the evolutionary origin of pathogenic E. coli.
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Lin, Jingxia; Wang, Xiuna; Deng, Xianbo; Feng, Youjun
2016-01-01
The emergence of the mobilized colistin resistance gene, representing a novel mechanism for bacterial drug resistance, challenges the last resort against the severe infections by Gram-negative bacteria with multi-drug resistances. Very recently, we showed the diversity in the mcr-1-carrying plasmid reservoirs from the gut microbiota. Here, we reported that a similar but more complex scenario is present in the healthy swine populations, Southern China, 2016. Amongst the 1026 pieces of Escherichia coli isolates from 3 different pig farms, 302 E. coli isolates were determined to be positive for the mcr-1 gene (30%, 302/1026). Multi-locus sequence typing assigned no less than 11 kinds of sequence types including one novel Sequence Type to these mcr-1-positive strains. PCR analyses combined with the direct DNA sequencing revealed unexpected complexity of the mcr-1-harbouring plasmids whose backbones are at least grouped into 6 types four of which are new. Transcriptional analyses showed that the mcr-1 promoter of different origins exhibits similar activity. It seems likely that complex dissemination of the diversified mcr-1-bearing plasmids occurs amongst the various ST E. coli inhabiting the healthy swine populations, in Southern China. PMID:27741523
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Guillemet, Mélanie L; Moreau, Patrice L
2012-01-01
Escherichia coli K-12 suffers acetic acid stress during prolonged incubation in glucose minimal medium containing a limiting concentration of inorganic phosphate (0.1 mM P(i)), which decreases the number of viable cells from 6 × 10(8) to ≤10 CFU/ml between days 6 and 14 of incubation. Here we show that following two serial transfers into P(i)-limiting medium, evolved mutants survived prolonged incubation (≈10(7) CFU/ml on day 14 of incubation). The evolved strains that overtook the populations were generally PhnE(+), whereas the ancestral K-12 strain carries an inactive phnE allele, which prevents the transport of phosphonates. The switching in phnE occurred with a high frequency as a result of the deletion of an 8-bp repeated sequence. In a mixed culture starved for P(i) that contained the K-12 ancestral strain in majority, evolved strains grew through PhnE-dependent scavenging of probably organic phosphate esters (not phosphonates or P(i)) released by E. coli K-12 between days 1 and 3, before acetic acid excreted by E. coli K-12 reached toxic levels. The growth yield of phnE(+) strains in mixed culture was dramatically enhanced by mutations that affect glucose metabolism, such as an rpoS mutation inactivating the alternative sigma factor RpoS. The long-term viability of evolved populations was generally higher when the ancestral strain carried an inactive rather than an active phnE allele, which indicates that cross-feeding of phosphorylated products as a result of the phnE polymorphism may be essential for the spread of mutants which eventually help populations to survive under P(i) starvation conditions.
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Blanch, A R; Galofré, B; Lucena, F; Terradillos, A; Vilanova, X; Ribas, F
2007-03-01
To compare the bacterial coliforms detected from occurrences in three zones of a water distribution system supplied by two separate water sources. Conventional and standardized protocols for identifying enterobacterial populations were applied. Additional tests to confirm isolates were included. Analyses of diversity and population similarity were performed using the Phene Plate System, a miniaturized biochemical phenotyping method. Isolates were identified by the API 20E system in tandem with biochemical phenotyping. A total of 16 576 samples were taken from the water distribution system, with 1416 isolates analysed. A low number of coliform occurrences were observed (2%). Escherichia coli was not detected in either water origin or in Zone 2 samples; however, in Zones 1 and 3 a low number of cases of E. coli were recorded. The percentages of E. coli depended on the identification criteria. Eight biochemical profiles for coliform populations were defined according to the results of the confirmative tests. There was a high diversity among these populations in the three zones studied, although no significant variations in their composition (associated with occurrences in the different zones) were observed. Klebsiella oxytoca was the most commonly detected species irrespective of zone, although seven other enterobacterial genera were also found. Analysis of the enzymatic activity of beta-glucuronidase or application of the criteria established in the norm ISO 9308-1, in tandem with thermotolerance was needed to evaluate the occurrence of E. coli in the distribution systems. Detected occurrences of bacterial coliforms could be associated with re-growth patterns for specific sampling points in the distribution system. Seasonal differences, independent of the studied zones, were observed. Biochemical phenotyping of bacterial coliforms was shown to be a useful method on the characterization of occurrences in water distribution systems.
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Hiramatsu, Reiji; Matsumoto, Masakado; Sakae, Kenji; Miyazaki, Yutaka
2005-01-01
In order to determine desiccation tolerances of bacterial strains, the survival of 58 diarrheagenic strains (18 salmonellae, 35 Shiga toxin-producing Escherichia coli [STEC], and 5 shigellae) and of 15 nonpathogenic E. coli strains was determined after drying at 35°C for 24 h in paper disks. At an inoculum level of 107 CFU/disk, most of the salmonellae (14/18) and the STEC strains (31/35) survived with a population of 103 to 104 CFU/disk, whereas all of the shigellae (5/5) and the majority of the nonpathogenic E. coli strains (9/15) did not survive (the population was decreased to less than the detection limit of 102 CFU/disk). After 22 to 24 months of subsequent storage at 4°C, all of the selected salmonellae (4/4) and most of the selected STEC strains (12/15) survived, keeping the original populations (103 to 104 CFU/disk). In contrast to the case for storage at 4°C, all of 15 selected strains (5 strains each of Salmonella spp., STEC O157, and STEC O26) died after 35 to 70 days of storage at 25°C and 35°C. The survival rates of all of these 15 strains in paper disks after the 24 h of drying were substantially increased (10 to 79 times) by the presence of sucrose (12% to 36%). All of these 15 desiccated strains in paper disks survived after exposure to 70°C for 5 h. The populations of these 15 strains inoculated in dried foods containing sucrose and/or fat (e.g., chocolate) were 100 times higher than those in the dried paper disks after drying for 24 h at 25°C. PMID:16269694
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Modelling the impacts of global change on concentrations of Escherichia coli in an urban river
NASA Astrophysics Data System (ADS)
Jalliffier-Verne, Isabelle; Leconte, Robert; Huaringa-Alvarez, Uriel; Heniche, Mourad; Madoux-Humery, Anne-Sophie; Autixier, Laurène; Galarneau, Martine; Servais, Pierre; Prévost, Michèle; Dorner, Sarah
2017-10-01
Discharges of combined sewer system overflows (CSOs) affect water quality in drinking water sources despite increasing regulation and discharge restrictions. A hydrodynamic model was applied to simulate the transport and dispersion of fecal contaminants from CSO discharges and to quantify the impacts of climate and population changes on the water quality of the river used as a drinking water source in Québec, Canada. The dispersion model was used to quantify Escherichia coli (E. coli) concentrations at drinking water intakes. Extreme flows during high and low water events were based on a frequency analysis in current and future climate scenarios. The increase of the number of discharges was quantified in current and future climate scenarios with regards to the frequency of overflows observed between 2009 and 2012. For future climate scenarios, effects of an increase of population were estimated according to current population growth statistics, independently of local changes in precipitation that are more difficult to predict than changes to regional scale hydrology. Under ;business-as-usual; scenarios restricting increases in CSO discharge frequency, mean E. coli concentrations at downstream drinking water intakes are expected to increase by up to 87% depending on the future climate scenario and could lead to changes in drinking water treatment requirements for the worst case scenarios. The greatest uncertainties are related to future local discharge loads. Climate change adaptation with regards to drinking water quality must focus on characterizing the impacts of global change at a local scale. Source water protection planning must consider the impacts of climate and population change to avoid further degradation of water quality.
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NASA Astrophysics Data System (ADS)
Sagitova, A.; Yaminsky, I.; Meshkov, G.
2016-08-01
Visualization of the structure of biological objects plays a key role in medicine, biotechnology, nanotechnology and IT-technology. Atomic force microscopy (AFM) is a promising method of studying of objects’ morphology and structure. In this work, AFM was used to determine the size and shape of the bacterial strains of Escherichia coli M-17 and visualization its interaction with the nanoparticles of zinc oxide. The suspension of E.coli bacteria was applied to natural mica and studied by contact mode using the FemtoScan multifunctional scanning probe microscope.
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The Escherichia coli supX locus is topA, the structural gene for DNA topoisomerase I.
Margolin, P; Zumstein, L; Sternglanz, R; Wang, J C
1985-01-01
Mutations in the supX locus, which result in the absence of DNA topoisomerase I enzyme activity in both Salmonella typhimurium and Escherichia coli, are all selected as suppressors of the leu-500 promoter mutation in S. typhimurium. To determine whether the supX locus is the structural gene topA for the DNA topoisomerase I enzyme or is a positive-acting regulator/activator gene for a nearby topA structural gene, nonsense mutations were selected in the E. coli supX gene carried on an F' episome in S. typhimurium cells. The cysB-topA region of the episomes with nonsense-mutant supX alleles were then cloned onto plasmid pBR322 and transformed into E. coli cells lacking a chromosomal supX gene. Three such E. coli strains, each carrying cloned DNA from episomes with different nonsense-mutant supX alleles, all lacked DNA topoisomerase I activity but expressed antigenic determinants specific to the enzyme; control cells lacked both enzyme activity and antigenic determinants. Maxicell studies of plasmid-coded proteins demonstrated the absence of the DNA topoisomerase I protein (100 kDa) in the three strains but the appearance of a new smaller peptide in each (36, 47, and 64 kDa). These new peptides must represent fragments of the enzyme resulting from translation termination at the supX nonsense codons and confirm the interpretation that the supX gene is topA, the structural gene for DNA topoisomerase I. Images PMID:2991925
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Alicea, Ismael; Marvin, Jonathan S; Miklos, Aleksandr E; Ellington, Andrew D; Looger, Loren L; Schreiter, Eric R
2011-12-02
The phnD gene of Escherichia coli encodes the periplasmic binding protein of the phosphonate (Pn) uptake and utilization pathway. We have crystallized and determined structures of E. coli PhnD (EcPhnD) in the absence of ligand and in complex with the environmentally abundant 2-aminoethylphosphonate (2AEP). Similar to other bacterial periplasmic binding proteins, 2AEP binds near the center of mass of EcPhnD in a cleft formed between two lobes. Comparison of the open, unliganded structure with the closed 2AEP-bound structure shows that the two lobes pivot around a hinge by ~70° between the two states. Extensive hydrogen bonding and electrostatic interactions stabilize 2AEP, which binds to EcPhnD with low nanomolar affinity. These structures provide insight into Pn uptake by bacteria and facilitated the rational design of high signal-to-noise Pn biosensors based on both coupled small-molecule dyes and autocatalytic fluorescent proteins. Copyright © 2011 Elsevier Ltd. All rights reserved.
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Alicea, Ismael; Marvin, Jonathan S.; Miklos, Aleksandr E.; Ellington, Andrew D.; Looger, Loren L.; Schreiter, Eric R.
2012-01-01
The phnD gene of Escherichia coli encodes the periplasmic binding protein of the phosphonate uptake and utilization pathway. We have crystallized and determined structures of E. coli PhnD (EcPhnD) in the absence of ligand and in complex with the environmentally abundant 2-aminoethylphosphonate (2AEP). Similar to other bacterial periplasmic binding proteins, 2AEP binds near the center of mass of EcPhnD in a cleft formed between two lobes. Comparison of the open, unliganded structure with the closed 2AEP-bound structure shows that the two lobes pivot around a hinge by ~70° between the two states. Extensive hydrogen bonding and electrostatic interactions stabilize 2AEP, which binds to EcPhnD with low nanomolar affinity. These structures provide insight into phosphonate uptake by bacteria and facilitated the rational design of high signal-to-noise phosphonate biosensors based both on coupled small molecule dyes and autocatalytic fluorescent proteins. PMID:22019591
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Qiu, Xiayang; Choudhry, Anthony E.; Janson, Cheryl A.
{beta}-Ketoacyl-ACP synthase III (FabH), an essential enzyme for bacterial viability, catalyzes the initiation of fatty acid elongation by condensing malonyl-ACP with acetyl-CoA. We have determined the crystal structure of FabH from Staphylococcus aureus, a Gram-positive human pathogen, to 2 {angstrom} resolution. Although the overall structure of S. aureus FabH is similar to that of Escherichia coli FabH, the primer binding pocket in S. aureus FabH is significantly larger than that present in E. coli FabH. The structural differences, which agree with kinetic parameters, provide explanation for the observed varying substrate specificity for E. coli and S. aureus FabH. The rankmore » order of activity of S. aureus FabH with various acyl-CoA primers was as follows: isobutyryl- > hexanoyl- > butyryl- > isovaleryl- >> acetyl-CoA. The availability of crystal structure may aid in designing potent, selective inhibitors of S. aureus FabH.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Alicea, Ismael; Marvin, Jonathan S.; Miklos, Aleksandr E.
2012-09-17
The phnD gene of Escherichia coli encodes the periplasmic binding protein of the phosphonate (Pn) uptake and utilization pathway. We have crystallized and determined structures of E. coli PhnD (EcPhnD) in the absence of ligand and in complex with the environmentally abundant 2-aminoethylphosphonate (2AEP). Similar to other bacterial periplasmic binding proteins, 2AEP binds near the center of mass of EcPhnD in a cleft formed between two lobes. Comparison of the open, unliganded structure with the closed 2AEP-bound structure shows that the two lobes pivot around a hinge by {approx}70{sup o} between the two states. Extensive hydrogen bonding and electrostatic interactionsmore » stabilize 2AEP, which binds to EcPhnD with low nanomolar affinity. These structures provide insight into Pn uptake by bacteria and facilitated the rational design of high signal-to-noise Pn biosensors based on both coupled small-molecule dyes and autocatalytic fluorescent proteins.« less
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Wickramasinghe, Nimal H; Xu, Li; Eustace, Andrew; Shabir, Sahida; Saluja, Tranprit; Hawkey, Peter M
2012-05-01
To determine the proportion of E. coli carrying specific CTX-M extended-spectrum β-lactamase (ESBL) genotypes in a community population of East and North Birmingham. General practice and outpatient stool samples from 732 individuals submitted for examination for faecal pathogens in 2010 were screened for ESBL-producing E. coli using chromogenic agar. Multiplex PCR, denaturing HPLC, DNA sequencing and PFGE were used to determine the CTX-M genotype and clonal subtype. Isolates from people were assigned to 'Europe', 'Middle East/South Asia' (MESA) or 'uncategorized' groups using software to determine probable global origin based on the subject's full name. Prevalence of CTX-M carriage in the sample population was 11.3%. There was a statistically significant difference (P < 0.001) between carriage in the Europe group (8.1%) and the MESA group (22.8%). There was also a higher rate of carriage of CTX-M-15-producing E. coli (P < 0.001) in MESA subjects. The high community carriage rate and the significant difference in carriage between the Europe and MESA subjects may have important consequences for therapy. If the rising trend in carriage of bacteria producing ESBLs continues, guidelines for empirical therapy for patients presenting from the community may need to be modified. The findings also raise the concern that the pattern and routes of spread of CTX-M-15 may be replicated in the future by broader-spectrum β-lactamases, such as New Delhi metallo-β-lactamase ('NDM-1').
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The isolation of Escherichia coli from a poultry packing station and an abattoir
Shooter, R. A.; Cooke, E. Mary; O'Farrell, Sheila; Bettelheim, K. A.; Chandler, Mary E.; Bushrod, Frances M.
1974-01-01
The distribution and serotype of strains of Escherichia coli from a poultry packing station and an abattoir are described. The results indicated that animal faecal strains contaminated the environment and the animal carcasses. Using 150 O antisera, a high proportion of the E. coli strains were non-typable. This suggests that the serotype distribution of E. coli in animals is different from that in man. Strains with single antigenic differences were isolated, and the possibility of genetic transfer of these antigenic structures is suggested. PMID:4608415
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2008-05-01
4 ). The three-dimensional spatial orientation of the atoms for these resolved solution structures (Protein Data Bank accession codes: 2gt3...Crystal structure of the Escherichia coli peptide methionine sulphoxide reductase at 1.9 Å resolution . Struct. Fold. Des. 8: 1167 – 1178. 2 . Brot...sources (8). There is a 67% sequence identity between the E.coli and human MsrA ( 2 ). N-terminus C-terminus Figure 2 . Three-dimensional structure
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In Escherichia coli the genome must be compacted ∼1,000-fold to be contained in a cellular structure termed the nucleoid. It is proposed that the structure of the nucleoid is determined by a balance of multiple compaction forces and one major expansion force. The latter is mediated by transertion, a coupling of transcription, translation, and translocation of nascent membrane
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Heuvel, A.V.; McDermott, C.; Pillsbury, R.; Sandrin, T.; Kinzelman, J.; Ferguson, J.; Sadowsky, M.; Byappanahalli, M.; Whitman, R.; Kleinheinz, G.T.
2010-01-01
A linkage between Cladophora mats and exceedances of recreational water quality criteria has been suggested, but not directly studied. Th is study investigates the spatial and temporal association between Escherichia coli concentrations within and near Cladophora mats at two northwestern Lake Michigan beaches in Door County, Wisconsin. Escherichia coli concentrations in water underlying mats were significantly greater than surrounding water (p < 0.001). Below mat E. coli increased as the stranded mats persisted at the beach swash zone. Water adjacent to Cladophora mats had lower E. coli concentrations, but surpassed EPA swimming criteria the majority of sampling days. A signifi cant positive association was found between E. coli concentrations attached to Cladophora and in underlying water (p < 0.001). The attached E. coli likely acted as a reservoir for populating water underlying the mat. Fecal bacterial pathogens, however, could not be detected by microbiological culture methods either attached to mat biomass or in underlying water. Removal of Cladophora mats from beach areas may improve aesthetic and microbial water quality at affected beaches. These associations and potential natural growth of E. coli in bathing waters call into question the efficacy of using E. coli as a recreational water quality indicator of fecal contaminations. Copyright ?? 2010 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.
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Effect of chelators and nisin produced in situ on inhibition and inactivation of gram negatives.
Boziaris, I S; Adams, M R
1999-12-15
The ability of chelators and nisin generated in situ to inhibit and inactivate E. coli and other gram negatives in a model substrate was investigated. The effect of various chelators and different concentrations of exogenous nisin on inhibition of E. coli in broth medium showed that only EDTA and pyrophosphates were able to cause appreciable inhibition of E. coli by nisin. In a broth where L. lactis NCFB 497 produced nisin in a concentration of 250-300 IU/ml, pyrophosphates were unable to inactivate E. coli. Under the same conditions, addition of EDTA led to inactivation of E. coli at neutral and slightly acidic pH only. A cocktail of strains of E. coli was less sensitive than E. coli ATCC 25922 alone. Pseudomonas aeruginosa was more sensitive and salmonellae more resistant. EDTA also caused a slight reduction in the L. lactis population and its biochemical activity as regards pH drop and acid production. Some of the inhibition of E. coli could be ascribed to the physical presence of Lactococcus cells rather than their metabolites excreted into the medium. Failure to observe any inhibition in fermented broths at their natural pH (4.0) was ascribed to the poor chelating power of EDTA under acid conditions.
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Three-dimensional structure of Escherichia coli initiator tRNA/f//Met/
NASA Technical Reports Server (NTRS)
Woo, N. H.; Rich, A.; Roe, B. A.
1980-01-01
The crystal structure of Escherichia coli tRNA(f)(Met), an initiator transfer RNA, has been determined. While grossly similar to that of the chain-elongating yeast tRNA(Phe), there are three major differences. One involves the folding of the anticodon loop; in particular, the position of the constant uridine, U33. This difference was unexpected and may be of functional significance.
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Kwan, Grace; Charkowski, Amy O.; Barak, Jeri D.
2013-01-01
ABSTRACT Although enteric human pathogens are usually studied in the context of their animal hosts, a significant portion of their life cycle occurs on plants. Plant disease alters the phyllosphere, leading to enhanced growth of human pathogens; however, the impact of human pathogens on phytopathogen biology and plant health is largely unknown. To characterize the interaction between human pathogens and phytobacterial pathogens in the phyllosphere, we examined the interactions between Pectobacterium carotovorum subsp. carotovorum and Salmonella enterica or Escherichia coli O157:H7 with regard to bacterial populations, soft rot progression, and changes in local pH. The presence of P. carotovorum subsp. carotovorum enhanced the growth of both S. enterica and E. coli O157:H7 on leaves. However, in a microaerophilic environment, S. enterica reduced P. carotovorum subsp. carotovorum populations and soft rot progression by moderating local environmental pH. Reduced soft rot was not due to S. enterica proteolytic activity. Limitations on P. carotovorum subsp. carotovorum growth, disease progression, and pH elevation were not observed on leaves coinoculated with E. coli O157:H7 or when leaves were coinoculated with S. enterica in an aerobic environment. S. enterica also severely undermined the relationship between the phytobacterial population and disease progression of a P. carotovorum subsp. carotovorum budB mutant defective in the 2,3-butanediol pathway for acid neutralization. Our results show that S. enterica and E. coli O157:H7 interact differently with the enteric phytobacterial pathogen P. carotovorum subsp. carotovorum. S. enterica inhibition of soft rot progression may conceal a rapidly growing human pathogen population. Whereas soft rotted produce can alert consumers to the possibility of food-borne pathogens, healthy-looking produce may entice consumption of contaminated vegetables. PMID:23404399
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Horowitz, Scott; Salmon, Loïc; Koldewey, Philipp
We present that challenges in determining the structures of heterogeneous and dynamic protein complexes have greatly hampered past efforts to obtain a mechanistic understanding of many important biological processes. One such process is chaperone-assisted protein folding. Obtaining structural ensembles of chaperone–substrate complexes would ultimately reveal how chaperones help proteins fold into their native state. To address this problem, we devised a new structural biology approach based on X-ray crystallography, termed residual electron and anomalous density (READ). READ enabled us to visualize even sparsely populated conformations of the substrate protein immunity protein 7 (Im7) in complex with the Escherichia coli chaperonemore » Spy, and to capture a series of snapshots depicting the various folding states of Im7 bound to Spy. The ensemble shows that Spy-associated Im7 samples conformations ranging from unfolded to partially folded to native-like states and reveals how a substrate can explore its folding landscape while being bound to a chaperone.« less
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Decontamination of green onions and baby spinach by vaporized ethyl pyruvate.
Durak, M Zeki; Churey, John J; Gates, Matthew; Sacks, Gavin L; Worobo, Randy W
2012-06-01
Foodborne illnesses associated with fresh produce continue to be a major concern as consumer demand for healthier and nonthermally processed food increases. The objective of this study was to evaluate vaporized ethyl pyruvate (EP; CAS 617-35-6) as a safe alternative antimicrobial agent for the decontamination of Escherichia coli O157:H7 on green onions and spinach. Baby spinach leaves and green onions were inoculated with a five-strain cocktail of E. coli O157:H7 (pGFP) by the dipping method. Samples were treated with concentrations of 0, 42, 105, and 420 mg/liter vaporized EP in a 2.6-liter enclosed container. The efficacy of EP vapors for reducing E. coli O157:H7((GFP)) populations on green onions and baby spinach at 4 and 10°C was monitored for 7 and 5 days, respectively. The lowest EP concentration (42 mg/liter) resulted in a 1.7-log reduction of E. coli O157:H7((GFP)) on green onions after 7 days at 4°C and a 1.9-log reduction after 5 days at 10°C (P < 0.05). In baby spinach, the same concentration resulted in 0.9-log and 1.4-log reductions (P < 0.05) of E. coli O157:H7((GFP)) after 7 days at 4°C and 5 days at 10°C, respectively. On green onions, the highest concentration of EP (420 mg/liter) reduced the population of E. coli O157:H7((GFP)) by >4.7 log CFU/g after 7 days at 4°C and 5 days at 10°C. The same concentration was also effective for reducing E. coli O157:H7((GFP)) populations in baby spinach by 4.3 log CFU/g after 7 days at 4°C and by >6.5 log CFU/g after 3 days at 10°C. Although the successful EP treatments minimally affected the sensory attributes of green onions, the treatments resulted in significant changes in the sensory attributes of baby spinach samples stored at 4 and 10°C. These results indicate that EP is an effective antimicrobial that could be used to enhance the safety of fresh produce depending on the sensory characteristics of the product.
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1.8 Å structure of murine GITR ligand dimer expressed in Drosophila melanogaster S2 cells
DOE Office of Scientific and Technical Information (OSTI.GOV)
Chattopadhyay, Kausik; Ramagopal, Udupi A.; Nathenson, Stanley G., E-mail: nathenso@aecom.yu.edu
2009-05-01
1.8 Å X-ray crystal structure of mouse GITRL expressed in D. melanogaster S2 cells shows an identical ‘strand-exchanged’ dimeric assembly similar to that observed previously for the E. coli-expressed protein. Glucocorticoid-induced TNF receptor ligand (GITRL), a prominent member of the TNF superfamily, activates its receptor on both effector and regulatory T cells to generate critical costimulatory signals that have been implicated in a wide range of T-cell immune functions. The crystal structures of murine and human orthologs of GITRL recombinantly expressed in Escherichia coli have previously been determined. In contrast to all classical TNF structures, including the human GITRL structure,more » murine GITRL demonstrated a unique ‘strand-exchanged’ dimeric organization. Such a novel assembly behavior indicated a dramatic impact on receptor activation as well as on the signaling mechanism associated with the murine GITRL costimulatory system. In this present work, the 1.8 Å resolution crystal structure of murine GITRL expressed in Drosophila melanogaster S2 cells is reported. The eukaryotic protein-expression system allows transport of the recombinant protein into the extracellular culture medium, thus maximizing the possibility of obtaining correctly folded material devoid of any folding/assembly artifacts that are often suspected with E. coli-expressed proteins. The S2 cell-expressed murine GITRL adopts an identical ‘strand-exchanged’ dimeric structure to that observed for the E. coli-expressed protein, thus conclusively demonstrating the novel quaternary structure assembly behavior of murine GITRL.« less
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Douglas, C M; Guidi-Rontani, C; Collier, R J
1987-11-01
We subcloned the structural gene for exotoxin A (ETA) of Pseudomonas aeruginosa in front of the tac promoter in an Escherichia coli expression vector and studied the intracellular location and properties of the protein product. The E. coli K-12 strain that carried this recombinant plasmid produced an immunoreactive protein that was identical to authentic ETA in size and in cytotoxic and ADP-ribosyl transferase activities per unit of immunoreactive material. The protein was predominantly in the periplasmic fraction; and a mutation in the secA gene blocked secretion, processing, and conversion of the protein to a fully toxic conformation. The results indicate that expression of the ETA gene in E. coli yields native ETA, which is localized within the periplasmic space. This organism may therefore serve as a useful host for studying structure and function in ETA.
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Persistence of culturable Escherichia coli fecal contaminants in dairy alpine grassland soils.
Texier, Stéphanie; Prigent-Combaret, Claire; Gourdon, Marie Hélène; Poirier, Marie Andrée; Faivre, Pierre; Dorioz, Jean Marcel; Poulenard, Jérome; Jocteur-Monrozier, Lucile; Moënne-Loccoz, Yvan; Trevisan, Dominique
2008-01-01
Our knowledge of Escherichia coli (E. coli) ecology in the field is very limited in the case of dairy alpine grassland soils. Here, our objective was to monitor field survival of E. coli in cow pats and underlying soils in four different alpine pasture units, and to determine whether the soil could constitute an environmental reservoir. E. coli was enumerated by MPN using a selective medium. E. coli survived well in cow pats (10(7) to 10(8) cells g(-1) dry pat), but cow pats disappeared within about 2 mo. In each pasture unit, constant levels of E. coli (10(3) to 10(4) cells g(-1) dry soil) were recovered from all topsoil (0-5 cm) samples regardless of the sampling date, that is, under the snow cover, immediately after snow melting, or during the pasture season (during and after the decomposition of pats). In deeper soil layers below the root zone (5-25 cm), E. coli persistence varied according to soil type, with higher numbers recovered in poorly-drained soils (10(3) to 10(4) cells g(-1) dry soil) than in well-drained soils (< 10(2) cells g(-1) dry soil). A preliminary analysis of 38 partial uidA sequences of E. coli from pat and soils highlighted a cluster containing sequences only found in this work. Overall, this study raises the possibility that fecal E. coli could have formed a naturalized (sub)population, which is now part of the indigenous soil community of alpine pasture grasslands, the soil thus representing an environmental reservoir of E. coli.
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Colibactin: More Than a New Bacterial Toxin.
Faïs, Tiphanie; Delmas, Julien; Barnich, Nicolas; Bonnet, Richard; Dalmasso, Guillaume
2018-04-10
Cyclomodulins are bacterial toxins that interfere with the eukaryotic cell cycle. A new cyclomodulin called colibactin, which is synthetized by the pks genomic island, was discovered in 2006. Despite many efforts, colibactin has not yet been purified, and its structure remains elusive. Interestingly, the pks island is found in members of the family Enterobacteriaceae (mainly Escherichia coli and Klebsiella pneumoniae ) isolated from different origins, including from intestinal microbiota, septicaemia, newborn meningitis, and urinary tract infections. Colibactin-producing bacteria induce chromosomal instability and DNA damage in eukaryotic cells, which leads to senescence of epithelial cells and apoptosis of immune cells. The pks island is mainly observed in B2 phylogroup E. coli strains, which include extra-intestinal pathogenic E. coli strains, and pks E. coli are over-represented in biopsies isolated from colorectal cancer. In addition, pks E. coli bacteria increase the number of tumours in diverse colorectal cancer mouse models. Thus, colibactin could have a major impact on human health. In the present review, we will focus on the biological effects of colibactin, the distribution of the pks island, and summarize what is currently known about its synthesis and its structure.
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Modeling a synthetic multicellular clock: Repressilators coupled by quorum sensing
Garcia-Ojalvo, Jordi; Elowitz, Michael B.; Strogatz, Steven H.
2004-01-01
Diverse biochemical rhythms are generated by thousands of cellular oscillators that somehow manage to operate synchronously. In fields ranging from circadian biology to endocrinology, it remains an exciting challenge to understand how collective rhythms emerge in multicellular structures. Using mathematical and computational modeling, we study the effect of coupling through intercell signaling in a population of Escherichia coli cells expressing a synthetic biological clock. Our results predict that a diverse and noisy community of such genetic oscillators interacting through a quorum-sensing mechanism should self-synchronize in a robust way, leading to a substantially improved global rhythmicity in the system. As such, the particular system of coupled genetic oscillators considered here might be a good candidate to provide the first quantitative example of a synchronization transition in a population of biological oscillators. PMID:15256602
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Meza-Aguilar, J. Domingo; Fromme, Petra; Torres-Larios, Alfredo; Mendoza-Hernández, Guillermo; Hernandez-Chiñas, Ulises; Monteros, Roberto A. Arreguin-Espinosa de los; Campos, Carlos A. Eslava; Fromme, Raimund
2014-01-01
Autotransporters (ATs) represent a superfamily of proteins produced by a variety of pathogenic bacteria, which include the pathogenic groups of Escherichia coli (E. coli) associated with gastrointestinal and urinary tract infections. We present the first X-ray structure of the passenger domain from the Plasmid-encoded toxin (Pet) a 100 kDa protein at 2.3 Å resolution which is a cause of acute diarrhea in both developing and industrialized countries. Pet is a cytoskeleton-altering toxin that induces loss of actin stress fibers. While Pet (pdb code: 4OM9) shows only a sequence identity of 50 % compared to the closest related protein sequence, extracellular serine protease plasmid (EspP) the structural features of both proteins are conserved. A closer structural look reveals that Pet contains a β-pleaded sheet at the sequence region of residues 181-190, the corresponding structural domain in EspP consists of a coiled loop. Secondary, the Pet passenger domain features a more pronounced beta sheet between residues 135-143 compared to the structure of EspP. PMID:24530907
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Ling, Shenglong; Wang, Wei; Yu, Lu; Peng, Junhui; Cai, Xiaoying; Xiong, Ying; Hayati, Zahra; Zhang, Longhua; Zhang, Zhiyong; Song, Likai; Tian, Changlin
2016-01-01
Electron paramagnetic resonance (EPR)-based hybrid experimental and computational approaches were applied to determine the structure of a full-length E. coli integral membrane sulfurtransferase, dimeric YgaP, and its structural and dynamic changes upon ligand binding. The solution NMR structures of the YgaP transmembrane domain (TMD) and cytosolic catalytic rhodanese domain were reported recently, but the tertiary fold of full-length YgaP was not yet available. Here, systematic site-specific EPR analysis defined a helix-loop-helix secondary structure of the YagP-TMD monomers using mobility, accessibility and membrane immersion measurements. The tertiary folds of dimeric YgaP-TMD and full-length YgaP in detergent micelles were determined through inter- and intra-monomer distance mapping and rigid-body computation. Further EPR analysis demonstrated the tight packing of the two YgaP second transmembrane helices upon binding of the catalytic product SCN−, which provides insight into the thiocyanate exportation mechanism of YgaP in the E. coli membrane. PMID:26817826
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A case study in evolutionary contingency.
Blount, Zachary D
2016-08-01
Biological evolution is a fundamentally historical phenomenon in which intertwined stochastic and deterministic processes shape lineages with long, continuous histories that exist in a changing world that has a history of its own. The degree to which these characteristics render evolution historically contingent, and evolutionary outcomes thereby unpredictably sensitive to history has been the subject of considerable debate in recent decades. Microbial evolution experiments have proven among the most fruitful means of empirically investigating the issue of historical contingency in evolution. One such experiment is the Escherichia coli Long-Term Evolution Experiment (LTEE), in which twelve populations founded from the same clone of E. coli have evolved in parallel under identical conditions. Aerobic growth on citrate (Cit(+)), a novel trait for E. coli, evolved in one of these populations after more than 30,000 generations. Experimental replays of this population's evolution from various points in its history showed that the Cit(+) trait was historically contingent upon earlier mutations that potentiated the trait by rendering it mutationally accessible. Here I review this case of evolutionary contingency and discuss what it implies about the importance of historical contingency arising from the core processes of evolution. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Kinetics of uropathogenic Escherichia coli metapopulation movement during urinary tract infection.
Walters, Matthew S; Lane, M Chelsea; Vigil, Patrick D; Smith, Sara N; Walk, Seth T; Mobley, Harry L T
2012-01-01
The urinary tract is one of the most frequent sites of bacterial infection in humans. Uropathogenic Escherichia coli (UPEC) strains are the leading cause of urinary tract infections (UTIs) and are responsible for greater than 80% of uncomplicated cases in adults. Infection of the urinary tract occurs in an ascending manner, with colonization of the bladder leading to possible kidney infection and bacteremia. The goal of this study was to examine the population dynamics of UPEC in vivo using a murine model of ascending UTI. To track individual UPEC lineages within a host, we constructed 10 isogenic clones of UPEC strain CFT073 by inserting unique signature tag sequences between the pstS and glmS genes at the attTn7 chromosomal site. Mice were transurethrally inoculated with a mixture containing equal numbers of unique clones. After 4 and 48 h, the tags present in the bladders, kidneys, and spleens of infected mice were enumerated using tag-specific primers and quantitative real-time PCR. The results indicated that kidney infection and bacteremia associated with UTI are most likely the result of multiple rounds of ascension and dissemination from motile UPEC subpopulations, with a distinct bottleneck existing between the kidney and bloodstream. The abundance of tagged lineages became more variable as infection progressed, especially after bacterial ascension to the upper urinary tract. Analysis of the population kinetics of UPEC during UTI revealed metapopulation dynamics, with lineages that constantly increased and decreased in abundance as they migrated from one organ to another. Urinary tract infections are some of the most common infections affecting humans, and Escherichia coli is the primary cause in most uncomplicated cases. These infections occur in an ascending manner, with bacteria traveling from the bladder to the kidneys and potentially the bloodstream. Little is known about the spatiotemporal population dynamics of uropathogenic E. coli within a host. Here we describe a novel approach for tracking lineages of isogenic tagged E. coli strains within a murine host by the use of quantitative real-time PCR. Understanding the in vivo population dynamics and the factors that shape the bacterial population may prove to be of significant value in the development of novel vaccines and drug therapies.
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Detection and characterization of fecal verotoxin-producing Escherichia coli from healthy cattle.
Montenegro, M A; Bülte, M; Trumpf, T; Aleksić, S; Reuter, G; Bulling, E; Helmuth, R
1990-01-01
Verotoxin-producing Escherichia coli isolates from feces of healthy cattle were identified by DNA hybridization with verotoxin 1- and verotoxin 2-specific gene probes. Among 259 animals investigated, 28 (10.8%) were found to carry verotoxin-producing E. coli strains. Characterization of the verotoxin-producing isolates revealed a heterogeneous population in terms of serotype and toxin type. Nearly 40% of the strains belonged to serogroups known to be pathogenic for humans, i.e., O22, O39, O82, O91, O113, O116, O126, and O136. Two isolates from different bulls were identified as serotype O157:H7. Results obtained in this study indicate that cattle may be an important source of verotoxigenic E. coli involved in human disease. Images PMID:2199502
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Tong, Yan Qing; Xin, Bing; Zhu, Li
2014-01-01
Background: Plasmid transfer among bacteria provides a means for dissemination of resistance. Plasmid Analysis has made it possible to track plasmids that induce resistance in bacterial population. Objectives: To screen the presence of herb-resistance plasmid in Escherichia coli strains and determine the transferability of this resistance plasmid directly from E. coli to the Gram-positive, Staphylococcus aureus. Materials and Methods: The donor strain E. coli CP9 and recipient strain S. aureus RN450RF were isolated from UTI patients. E. coli CP9 was highly resistant to herbal concoction. Isolates of S. aureus RN450RF were fully susceptible. Total plasmid DNA was prepared and transferred into E. coli DH5α. Transconjugants were selected on agar plates containing serial dilutions of herbal concoction. Resistance plasmid was transferred to susceptible S. aureus RN450RFin triple replicas. The mating experiments were repeated twice. Results: The identified 45 kb herb-resistance plasmid could be transferred from E. coli CP9 isolates to E. coli DH5α. As a consequence E. coli DH5α transconjugant MIC increased from 0.0125 g/mL to 0.25 g/mL. The plasmid was easily transferred from E. coli CP9 strain to S. aureus RN450RF with a mean transfer rate of 1×10-2 transconjugants/recipient. The E. coli donor and the S. aureus RN450RF transconjugant contained a plasmid of the same size, which was absent in the recipient before mating. Susceptibility testing showed that the S. aureus RN450RF transconjugant was resistant to herbal concoction. Conclusions: E. coli herb-resistance plasmid can replicate and be expressed in S. aureus. PMID:25147679
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Schmidt, Carrie E; Shringi, Smriti; Besser, Thomas E
2016-01-01
Escherichia coli O157:H7 is a food-borne bacterium that causes hemorrhagic diarrhea and hemolytic uremic syndrome in humans. While cattle are a known source of E. coli O157:H7 exposure resulting in human infection, environmental reservoirs may also be important sources of infection for both cattle and humans. Bacteriophage-encoded Shiga toxins (Stx) carried by E. coli O157:H7 may provide a selective advantage for survival of these bacteria in the environment, possibly through their toxic effects on grazing protozoa. To determine Stx effects on protozoan grazing, we co-cultured Paramecium caudatum, a common ciliate protozoon in cattle water sources, with multiple strains of Shiga-toxigenic E. coli O157:H7 and non-Shiga toxigenic cattle commensal E. coli. Over three days at ambient laboratory temperature, P. caudatum consistently reduced both E. coli O157:H7 and non-Shiga toxigenic E. coli populations by 1-3 log cfu. Furthermore, a wild-type strain of Shiga-toxigenic E. coli O157:H7 (EDL933) and isogenic mutants lacking the A subunit of Stx 2a, the entire Stx 2a-encoding bacteriophage, and/or the entire Stx 1-encoding bacteriophage were grazed with similar efficacy by both P. caudatum and Tetrahymena pyriformis (another ciliate protozoon). Therefore, our data provided no evidence of a protective effect of either Stx or the products of other bacteriophage genes on protozoan predation of E. coli. Further research is necessary to determine if the grazing activity of naturally-occurring protozoa in cattle water troughs can serve to decrease cattle exposure to E. coli O157:H7 and other Shiga-toxigenic E. coli.
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NASA Astrophysics Data System (ADS)
Salvucci, A. E.; Elton, M.; Siler, J. D.; Zhang, W.; Richards, B. K.; Geohring, L. D.; Warnick, L. D.; Hay, A. G.; Steenhuis, T.
2010-12-01
The introduction of microbial pathogens into the environment from untreated manure represents a threat to water quality and human health. Thus, understanding the effect of manure management strategies is imperative to effectively mitigate the inadvertent release of pathogens, particularly in subsurface environments where they can be transported through macropores to the groundwater or through agricultural tile line to open water bodies. The production of cell-surface biomolecules is also suspected to play an important role in the environmental survival and transport of enterobacterial pathogens. This study collected Escherichia coli samples from three dairy farms with artificial tile drainage systems and active manure spreading in the Central New York region over a three-month period. Sampling targeted four potential source locations on each farm: (i) cow housing, (ii) manure storage facilities, (iii) field soil, and (iv) subsurface drainage effluent. Over 2800 E. coli isolates were recovered and consequently analyzed for the cell surface components, cellulose and curli, traits associated with increased environmental survival, altered transport and pathogenicity. The E. coli isolates from locations i-iii displayed highly variable curli and cellulose-producing communities, while isolates collected from subsurface runoff on each farm had stable curli and cellulose production communities over all sampling dates. Furthermore, the method of manure application to the fields influenced the population characteristics found in drainage effluent isolates. Incorporation of manure into the soil was correlated to isolate populations largely deficient of curli and cellulose; whereas farms that only surface-applied manure were correlated to isolate populations of high curli and cellulose production. The production of curli and cellulose has previously been shown to be a response to environmental stress on the cell. Therefore, incorporation of manure directly into the soil appears to minimize environmental stresses, like UV radiation, desiccation and temperature fluctuation, typically found on the soil surface. Our findings indicate that E. coli strains above the surface are largely diverse, until they enter subsurface environments where specific extracellular characteristics are likely advantageous for survival and/or transport.
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Krzeska, I; Ostojska, J; Dzierzanowska, D
An infection with E. coli is the most frequent cause of the urinary infections in childhood. Virulence depends on several factors out of which a principal role is played by the adhesion of bacteria to the urinary tract epithelium. Such a property have E. coli strains with adherence mannose-positive fimbriae of type P with antigens recognizing and binding glycolipid receptors on epithelial cells in the urinary tract. Children with such infections owe their "sensitivity+" (10% of the population) to genetically determined large number o receptors binding E. coli strains. Incidence and clinical course of the urinary tract infections have been analysed in the group of 184 children. Moreover, sequelae of the urinary tract infections with E. coli have been analysed in dependence on E. coli strain characteristics, i.e. presence or absence of adherent fimbriae from cases of cystitis and significant asymptomatic bacteriuria. Considering pathogenesis of the urinary tract infections as the result of interactions between bacteria and host, antigenic properties of adherent fimbriae might be used for preparation of a vaccine preventing such infections.
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Massot, Méril; Daubié, Anne-Sophie; Clermont, Olivier; Jauréguy, Françoise; Couffignal, Camille; Dahbi, Ghizlane; Mora, Azucena; Blanco, Jorge; Branger, Catherine; Mentré, France; Eddi, Alain; Picard, Bertrand; Denamur, Erick; The Coliville Group
2016-04-01
It is important to study commensal populations of Escherichia coli because they appear to be the reservoir of both extra-intestinal pathogenic E. coli and antibiotic resistant strains of E. coli. We studied 279 dominant faecal strains of E. coli from 243 adults living in the community in the Paris area in 2010. The phylogenetic group and subgroup [sequence type complex (STc)] of the isolates and the presence of 20 virulence genes were determined by PCR assays. The O-types and resistance to 18 antibiotics were assessed phenotypically. The B2 group was the most frequently recovered (34.0 %), followed by the A group (28.7 %), and other groups were more rare. The most prevalent B2 subgroups were II (STc73), IV (STc141), IX (STc95) and I (STc131), with 22.1, 21.1, 16.8 and 13.7 %, respectively, of the B2 group strains. Virulence factors (VFs) were more common in B2 group than other strains. One or more resistances were found in 125 strains (44.8 % of the collection) but only six (2.2 % of the collection) were multiresistant; no extended-spectrum beta-lactamase-producing strain was isolated. The C phylogroup and clonal group A strains were the most resistant. No trade-off between virulence and resistance was evidenced. We compared these strains with collections of strains gathered under the same conditions 30 and 10 years ago. There has been a parallel and linked increase in the frequency of B2 group strains (from 9.4 % in 1980, to 22.7 % in 2000 and 34.0 % in 2010) and of VFs. Antibiotic resistance also increased, from 22.6 % of strains resistant to at least one antibiotic in 1980, to 31.8 % in 2000 and 44.8 % in 2010; resistance to streptomycin, however, remained stable. Commensal human E. coli populations have clearly evolved substantially over time, presumably reflecting changes in human practices, and particularly increasing antibiotic use.
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Jin, Tony; Zhang, Howard; Boyd, Glenn
2010-05-01
Antimicrobial films of polylactic acid polymer incorporated with nisin, EDTA, sodium benzoate (SB), potassium sorbate (PS), and their combinations were developed, and their antimicrobial effects on the inactivation of Escherichia coli O157:H7 and natural background microflora (total aerobic bacteria, molds, and yeasts) in strawberry puree at 10 and 22 degrees C were determined. Direct addition of SB+PS to strawberry puree was also used as a comparison with SB+PS film treatment. The combination treatment reduced the cell populations of E. coli O157:H7 from 3.5 log CFU/ml to undetectable levels (<1 CFU/ml) after 14 days and 1 day at 10 and 22 degrees C, respectively, while the cells of E. coli O157:H7 in control samples survived up to 48 days at 10 degrees C and more than 14 days at 22 degrees C. The SB+PS film treatment produced a greater reduction of population of E. coli O157:H7 cells than did the SB+PS direct addition treatment. Similar results were observed for inactivation of natural microflora. In general, the antimicrobial effect was in the following order: film combination > SB+PS film > SB+PS direct addition > EDTA film > nisin film. The data obtained in this study suggest two approaches toward the development of control interventions against E. coli O157:H7 and extension of the microbiological shelf life of strawberry puree: (i) using antimicrobial packaging and (ii) using combinations of preservatives. The film formulas developed here can be used to make bottles or as coatings on the surface of bottles for use in liquid food packaging.
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Domain structure of the ribozyme from eubacterial ribonuclease P.
Loria, A; Pan, T
1996-01-01
Large RNAs can be composed of discrete domains that fold independently. One such "folding domain" has been identified previously in the ribozyme from Bacillus subtilis ribonuclease P (denoted P RNA). This domain contains roughly one-third of all residues. Folding of an RNA construct consisting of the remaining two-thirds of B. subtilis P RNA was examined by Fe(II)-EDTA hydroxyl radical protection. This molecule folds into the proper higher-order structure under identical conditions as the full-length P RNA, suggesting the presence of a second folding domain in B. subtilis P RNA. Folding analysis of the Escherichia coli P RNA by hydroxyl radical protection shows that this P RNA is completely folded at 5-6 mM Mg2+. In order to analyze the structural organization of folding domains in E. coli P RNA, constructs were designed based on the domain structure of B. subtilis P RNA. Fe(II)-EDTA protection indicates that E. coli P RNA also contains two folding domains. Despite the significant differences at the secondary structure level, both P RNAs appear to converge structurally at the folding domain level. The pre-tRNA substrate, localized in previous studies, may bind across the folding domains with the acceptor stem/3'CCA contacting the domain including the active site and the T stem-loop contacting the other. Because all eubacterial P RNAs share considerable homology in secondary structure to either B. subtilis or E. coli P RNA, these results suggest that this domain structure may be applicable for most, if not all, eubacterial P RNAs. Identification of folding domains should be valuable in dissecting structure-function relationship of large RNAs. PMID:8718684
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Solà-Ginés, Marc; Cameron-Veas, Karla; Badiola, Ignacio; Dolz, Roser; Majó, Natalia; Dahbi, Ghizlane; Viso, Susana; Mora, Azucena; Blanco, Jorge; Piedra-Carrasco, Nuria; González-López, Juan José; Migura-Garcia, Lourdes
2015-01-01
Avian pathogenic Escherichia coli (APEC) are the major cause of colibacillosis in poultry production. In this study, a total of 22 E. coli isolated from colibacillosis field cases and 10 avian faecal E. coli (AFEC) were analysed. All strains were characterised phenotypically by susceptibility testing and molecular typing methods such as pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The presence of 29 virulence genes associated to APEC and human extraintestinal pathogenic E. coli (ExPEC) was also evaluated. For cephalosporin resistant isolates, cephalosporin resistance genes, plasmid location and replicon typing was assessed. Avian isolates belonged to 26 O:H serotypes and 24 sequence types. Out of 22 APEC isolates, 91% contained the virulence genes predictors of APEC; iutA, hlyF, iss, iroN and ompT. Of all strains, 34% were considered ExPEC. PFGE analysis demonstrated a high degree of genetic polymorphism. All strains were multi-resistant, including those isolated from healthy animals. Eleven strains were resistant to cephalosporins; six contained blaCTX-M-14, two blaSHV-12, two blaCMY-2 and one blaSHV-2. Two strains harboured qnrA, and two qnrA together with aac(6')-Ib-cr. Additionally, the emergent clone O25b:H4-B2-ST131 was isolated from a healthy animal which harboured blaCMY-2 and qnrS genes. Cephalosporin resistant genes were mainly associated to the presence of IncK replicons. This study demonstrates a very diverse population of multi-drug resistant E. coli containing a high number of virulent genes. The E. coli population among broilers is a reservoir of resistance and virulence-associated genes that could be transmitted into the community through the food chain. More epidemiological studies are necessary to identify clonal groups and resistance mechanisms with potential relevance to public health.
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Solà-Ginés, Marc; Cameron-Veas, Karla; Badiola, Ignacio; Dolz, Roser; Majó, Natalia; Dahbi, Ghizlane; Viso, Susana; Mora, Azucena; Blanco, Jorge; Piedra-Carrasco, Nuria; González-López, Juan José; Migura-Garcia, Lourdes
2015-01-01
Avian pathogenic Escherichia coli (APEC) are the major cause of colibacillosis in poultry production. In this study, a total of 22 E. coli isolated from colibacillosis field cases and 10 avian faecal E. coli (AFEC) were analysed. All strains were characterised phenotypically by susceptibility testing and molecular typing methods such as pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The presence of 29 virulence genes associated to APEC and human extraintestinal pathogenic E. coli (ExPEC) was also evaluated. For cephalosporin resistant isolates, cephalosporin resistance genes, plasmid location and replicon typing was assessed. Avian isolates belonged to 26 O:H serotypes and 24 sequence types. Out of 22 APEC isolates, 91% contained the virulence genes predictors of APEC; iutA, hlyF, iss, iroN and ompT. Of all strains, 34% were considered ExPEC. PFGE analysis demonstrated a high degree of genetic polymorphism. All strains were multi-resistant, including those isolated from healthy animals. Eleven strains were resistant to cephalosporins; six contained bla CTX-M-14, two bla SHV-12, two bla CMY-2 and one bla SHV-2. Two strains harboured qnrA, and two qnrA together with aac(6’)-Ib-cr. Additionally, the emergent clone O25b:H4-B2-ST131 was isolated from a healthy animal which harboured bla CMY-2 and qnrS genes. Cephalosporin resistant genes were mainly associated to the presence of IncK replicons. This study demonstrates a very diverse population of multi-drug resistant E. coli containing a high number of virulent genes. The E. coli population among broilers is a reservoir of resistance and virulence-associated genes that could be transmitted into the community through the food chain. More epidemiological studies are necessary to identify clonal groups and resistance mechanisms with potential relevance to public health. PMID:26600205
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Song, Won-Jae; Sung, Hye-Jung; Kim, Sung-Youn; Kim, Kwang-Pyo; Ryu, Sangryeol; Kang, Dong-Hyun
2014-02-17
This study evaluated the efficacy of gamma irradiation to inactivate foodborne pathogens in black pepper (Piper nigrum) and red pepper (dried Capsicum annuum). Black pepper and red pepper inoculated with Escherichia coli O157:H7 and Salmonella Typhimurium were subjected to gamma irradiation in the range of 0, 1, 2, 3 and 5 kGy, and color change was evaluated after treatment. Pathogen populations decreased with increasing treatment doses. A gamma irradiation dose of 5 kGy decreased E. coli O157:H7 and S. Typhimurium populations >4.4 to >5.2 log CFU/g in black pepper without causing color change. Similarly, 5 kGy of gamma irradiation yielded reduction of 3.8 to >5.2 log CFU/g for E. coli O157:H7 and S. Typhimurium in red pepper. During gamma irradiation treatment, L*, a* and b* values of red pepper were not significantly changed except for 297 μm to 420 μm size red pepper treated with 5 kGy of gamma irradiation. Based on the D-value of pathogens in black pepper and red pepper, S. Typhimurium showed more resistant to gamma irradiation than did E. coli O157:H7. These results show that gamma irradiation has potential as a non-thermal process for inactivating foodborne pathogens in spices with minimal color changes. Copyright © 2013 Elsevier B.V. All rights reserved.
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Vivant, Anne-Laure; Boutin, Catherine; Prost-Boucle, Stéphanie; Papias, Sandrine; Hartmann, Alain; Depret, Géraldine; Ziebal, Christine; Le Roux, Sophie; Pourcher, Anne-Marie
2016-11-01
The fates of Escherichia coli and extended-spectrum beta-lactamase-producing E. coli (ESBL E. coli) were studied over a period of one year in a free water surface constructed wetland (FWS CW) with a succession of open water zones and vegetation ponds (Typha or Phragmites), that received the effluent from a wastewater treatment plant. ESBL E. coli were detected and isolated from all sampling areas of the FWS CW throughout the study period. They represented 1‰ of the total E. coli population regardless of the origin of samples. Two main factors affected the log removal of E. coli and of ESBL E. coli: the season and the presence of vegetation. Between the inlet and the outlet of the FWS CW, the log removal of E. coli ranged from 1.5 in the warmer season (summer and fall) to 3.0 in the colder season (winter and spring). The concentrations of E. coli decreased significantly in the vegetated areas during the colder season, but increased in the warmer season, suggesting an effect of the plant growth stage on the survival of E. coli. Among the 369 ESBL E. coli isolates collected during our study, 84% harbored the CTX-M-ESBL type and 55.3% carried bla genes on plasmid DNA. Furthermore, 93% of the ESBL E. coli isolates were multidrug resistant but the proportion of resistant strains did not change significantly along the FWS CW. ESBL E. coli were characterized by MLST analysis using the 7 genes based Achtman Scheme. ESBL E. coli isolated from water, sediments, roots and feces of myocastors collected in the FWS CW and in the recipient river were genotypically related, suggesting persistence and circulation of the ESBL producing E. coli throughout the FWS CW and in the receiving river. Overall, these observations show that FWS CW could be an efficient treatment for ESBL E. coli disinfection of wastewater and could limit their dissemination in the aquatic environment. Copyright © 2016 Elsevier Ltd. All rights reserved.
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The functional landscape bound to the transcription factors of Escherichia coli K-12.
Pérez-Rueda, Ernesto; Tenorio-Salgado, Silvia; Huerta-Saquero, Alejandro; Balderas-Martínez, Yalbi I; Moreno-Hagelsieb, Gabriel
2015-10-01
Motivated by the experimental evidences accumulated in the last ten years and based on information deposited in RegulonDB, literature look up, and sequence analysis, we analyze the repertoire of 304 DNA-binding Transcription factors (TFs) in Escherichia coli K-12. These regulators were grouped in 78 evolutionary families and are regulating almost half of the total genes in this bacterium. In structural terms, 60% of TFs are composed by two-domains, 30% are monodomain, and 10% three- and four-structural domains. As previously noticed, the most abundant DNA-binding domain corresponds to the winged helix-turn-helix, with few alternative DNA-binding structures, resembling the hypothesis of successful protein structures with the emergence of new ones at low scales. In summary, we identified and described the characteristics associated to the DNA-binding TF in E. coli K-12. We also identified twelve functional modules based on a co-regulated gene matrix. Finally, diverse regulons were predicted based on direct associations between the TFs and potential regulated genes. This analysis should increase our knowledge about the gene regulation in the bacterium E. coli K-12, and provide more additional clues for comprehensive modelling of transcriptional regulatory networks in other bacteria. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Large behavioral variability of motile E. coli revealed in 3D spatial exploration
NASA Astrophysics Data System (ADS)
Figueroa-Morales, N.; Darnige, T.; Martinez, V.; Douarche, C.; Soto, R.; Lindner, A.; Clement, E.
2017-11-01
Bacterial motility determines the spatio-temporal structure of microbial communities, controls infection spreading and the microbiota organization in guts or in soils. Quantitative modeling of chemotaxis and statistical descriptions of active bacterial suspensions currently rely on the classical vision of a run-and-tumble strategy exploited by bacteria to explore their environment. Here we report a large behavioral variability of wild-type E. coli, revealed in their three-dimensional trajectories. We found a broad distribution of run times for individual cells, in stark contrast with the accepted vision of a single characteristic time. We relate our results to the slow fluctuations of a signaling protein which triggers the switching of the flagellar motor reversal responsible for tumbles. We demonstrate that such a large distribution of run times introduces measurement biases in most practical situations. These results reconcile a notorious conundrum between observations of run times and motor switching statistics. Our study implies that the statistical modeling of transport properties and of the chemotactic response of bacterial populations need to be profoundly revised to correctly account for the large variability of motility features.
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Microbiological examination of vegetable seed sprouts in Korea.
Kim, Hoikyung; Lee, Youngjun; Beuchat, Larry R; Yoon, Bong-June; Ryu, Jee-Hoon
2009-04-01
Sprouted vegetable seeds used as food have been implicated as sources of outbreaks of Salmonella and Escherichia coli O157:H7 infections. We profiled the microbiological quality of sprouts and seeds sold at retail shops in Seoul, Korea. Ninety samples of radish sprouts and mixed sprouts purchased at department stores, supermarkets, and traditional markets and 96 samples of radish, alfalfa, and turnip seeds purchased from online stores were analyzed to determine the number of total aerobic bacteria (TAB) and molds or yeasts (MY) and the incidence of Salmonella, E. coli O157:H7, and Enterobacter sakazakii. Significantly higher numbers of TAB (7.52 log CFU/g) and MY (7.36 log CFU/g) were present on mixed sprouts than on radish sprouts (6.97 and 6.50 CFU/g, respectively). Populations of TAB and MY on the sprouts were not significantly affected by location of purchase. Radish seeds contained TAB and MY populations of 4.08 and 2.42 log CFU/g, respectively, whereas populations of TAB were only 2.54 to 2.84 log CFU/g and populations of MY were 0.82 to 1.69 log CFU/g on alfalfa and turnip seeds, respectively. Salmonella and E. coli O157:H7 were not detected on any of the sprout and seed samples tested. E. sakazakii was not found on seeds, but 13.3% of the mixed sprout samples contained this potentially pathogenic bacterium.
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Ku, K-J; Hong, Y-H; Song, K B
2008-04-01
We prepared an edible Gelidium corneum (GC) film containing catechin and examined the microbial growth and quality change during storage of sausages packaged with the film. Incorporation of catechin in the film improved film tensile strength and water vapor permeability. The film's antimicrobial activity against Eschericha coli O157:H7 increased with increasing catechin concentrations and resulted in a decrease in the populations of the bacteria by 1.93 log CFU/g at 150 mg of catechin. For the sausage samples inoculated with E. coli O157:H7 and Listeria monocytogenes, the samples packed with the GC film showed a decrease in populations of E. coli O157:H7 and L. monocytogenes by 1.81 and 1.44 log CFU/g, respectively, compared to the control after 5 d of storage. In addition, the sausage samples packed with the GC film had lower degrees of lipid oxidation. The results suggest that sausages can be packed with GC film to extend shelf life.
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Jepson, Alys K; Schwarz-Linek, Jana; Ryan, Lloyd; Ryadnov, Maxim G; Poon, Wilson C K
2016-01-01
We measured the minimum inhibitory concentration (MIC) of the antimicrobial peptide pexiganan acting on Escherichia coli , and found an intrinsic variability in such measurements. These results led to a detailed study of the effect of pexiganan on the growth curve of E. coli, using a plate reader and manual plating (i.e. time-kill curves). The measured growth curves, together with single-cell observations and peptide depletion assays, suggested that addition of a sub-MIC concentration of pexiganan to a population of this bacterium killed a fraction of the cells, reducing peptide activity during the process, while leaving the remaining cells unaffected. This pharmacodynamic hypothesis suggests a considerable inoculum effect, which we quantified. Our results cast doubt on the use of the MIC as 'a measure of the concentration needed for peptide action' and show how 'coarse-grained' studies at the population level give vital information for the correct planning and interpretation of MIC measurements.
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Pek, Han Bin; Klement, Maximilian; Ang, Kok Siong; Chung, Bevan Kai-Sheng; Ow, Dave Siak-Wei; Lee, Dong-Yup
2015-01-01
Various isoforms of invertases from prokaryotes, fungi, and higher plants has been expressed in Escherichia coli, and codon optimisation is a widely-adopted strategy for improvement of heterologous enzyme expression. Successful synthetic gene design for recombinant protein expression can be done by matching its translational elongation rate against heterologous host organisms via codon optimization. Amongst the various design parameters considered for the gene synthesis, codon context bias has been relatively overlooked compared to individual codon usage which is commonly adopted in most of codon optimization tools. In addition, matching the rates of transcription and translation based on secondary structure may lead to enhanced protein folding. In this study, we evaluated codon context fitness as design criterion for improving the expression of thermostable invertase from Thermotoga maritima in Escherichia coli and explored the relevance of secondary structure regions for folding and expression. We designed three coding sequences by using (1) a commercial vendor optimized gene algorithm, (2) codon context for the whole gene, and (3) codon context based on the secondary structure regions. Then, the codon optimized sequences were transformed and expressed in E. coli. From the resultant enzyme activities and protein yield data, codon context fitness proved to have the highest activity as compared to the wild-type control and other criteria while secondary structure-based strategy is comparable to the control. Codon context bias was shown to be a relevant parameter for enhancing enzyme production in Escherichia coli by codon optimization. Thus, we can effectively design synthetic genes within heterologous host organisms using this criterion. Copyright © 2015 Elsevier Inc. All rights reserved.
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Engineering strategy of yeast metabolism for higher alcohol production.
Matsuda, Fumio; Furusawa, Chikara; Kondo, Takashi; Ishii, Jun; Shimizu, Hiroshi; Kondo, Akihiko
2011-09-08
While Saccharomyces cerevisiae is a promising host for cost-effective biorefinary processes due to its tolerance to various stresses during fermentation, the metabolically engineered S. cerevisiae strains exhibited rather limited production of higher alcohols than that of Escherichia coli. Since the structure of the central metabolism of S. cerevisiae is distinct from that of E. coli, there might be a problem in the structure of the central metabolism of S. cerevisiae. In this study, the potential production of higher alcohols by S. cerevisiae is compared to that of E. coli by employing metabolic simulation techniques. Based on the simulation results, novel metabolic engineering strategies for improving higher alcohol production by S. cerevisiae were investigated by in silico modifications of the metabolic models of S. cerevisiae. The metabolic simulations confirmed that the high production of butanols and propanols by the metabolically engineered E. coli strains is derived from the flexible behavior of their central metabolism. Reducing this flexibility by gene deletion is an effective strategy to restrict the metabolic states for producing target alcohols. In contrast, the lower yield using S. cerevisiae originates from the structurally limited flexibility of its central metabolism in which gene deletions severely reduced cell growth. The metabolic simulation demonstrated that the poor productivity of S. cerevisiae was improved by the introduction of E. coli genes to compensate the structural difference. This suggested that gene supplementation is a promising strategy for the metabolic engineering of S. cerevisiae to produce higher alcohols which should be the next challenge for the synthetic bioengineering of S. cerevisiae for the efficient production of higher alcohols.
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THE EVOLUTION OF RESTRAINT IN BACTERIAL BIOFILMS UNDER NONTRANSITIVE COMPETITION
Prado, Federico; Kerr, Benjamin
2009-01-01
Theoretical and empirical evidence indicates that competing species can coexist if dispersal, migration, and competitive interactions occur over relatively small spatial scales. In particular, spatial structure appears to be critical to certain communities with nontransitive competition. A typical nontransitive system involves three competing species that satisfy a relationship similar to the children’s game of rock–paper–scissors. Although the ecological dynamics of nontransitive systems in spatially structured communities have received some attention, fewer studies have incorporated evolutionary change. Here we investigate evolution within toxic bacterial biofilms using an agent-based simulation that represents a nontransitive community containing three populations of Escherichia coli. In structured, nontransitive communities, strains evolve that do not maximize their competitive ability: They do not reduce their probability of death to a minimum or increase their toxicity to a maximum. That is, types evolve that exercise restraint. We show that nontransitivity and spatial structure (in the form of localized interactions) are both necessary for the evolution of restraint in these biofilms. PMID:18039324
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The evolution of restraint in bacterial biofilms under nontransitive competition.
Prado, Federico; Kerr, Benjamin
2008-03-01
Theoretical and empirical evidence indicates that competing species can coexist if dispersal, migration, and competitive interactions occur over relatively small spatial scales. In particular, spatial structure appears to be critical to certain communities with nontransitive competition. A typical nontransitive system involves three competing species that satisfy a relationship similar to the children's game of rock-paper-scissors. Although the ecological dynamics of nontransitive systems in spatially structured communities have received some attention, fewer studies have incorporated evolutionary change. Here we investigate evolution within toxic bacterial biofilms using an agent-based simulation that represents a nontransitive community containing three populations of Escherichia coli. In structured, nontransitive communities, strains evolve that do not maximize their competitive ability: They do not reduce their probability of death to a minimum or increase their toxicity to a maximum. That is, types evolve that exercise restraint. We show that nontransitivity and spatial structure (in the form of localized interactions) are both necessary for the evolution of restraint in these biofilms.
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Romero-Mangado, Jaione; Nordlund, Dennis; Soberon, Felipe; ...
2016-02-12
This paper presents the morphological and chemical modification of the cell structure of aerosolized Escherichia coli treated with a dielectric barrier discharge (DBD). Exposure to DBD results in severe oxidation of the bacteria, leading to the formation of hydroxyl groups and carbonyl groups and a significant reduction in amine functionalities and phosphate groups. Near edge x-ray absorption fine structure(NEXAFS) measurements confirm the presence of additional oxide bonds upon DBD treatment, suggesting oxidation of the outer layer of the cell wall. Electron microscopy images show that the bacteria undergo physical distortion to varying degrees, resulting in deformation of the bacterial structure.more » The electromagnetic field around the DBD coil causes severe damage to the cell structure, possibly resulting in leakage of vital cellular materials. The oxidation and chemical modification of the bacterial components are evident from the Fourier transform infrared spectroscopy and NEXAFS results. The bacterial reculture experiments confirm inactivation of airborne E. coli upon treating with DBD.« less
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Autolysis of Escherichia coli and Bacillus subtilis cells in low gravity
NASA Technical Reports Server (NTRS)
Kacena, M. A.; Smith, E. E.; Todd, P.
1999-01-01
The role of gravity in the autolysis of Bacillus subtilis and Escherichia coli was studied by growing cells on Earth and in microgravity on Space Station Mir. Autolysis analysis was completed by examining the death phase or exponential decay of cells for approximately 4 months following the stationary phase. Consistent with published findings, the stationary-phase cell population was 170% and 90% higher in flight B. subtilis and E. coli cultures, respectively, than in ground cultures. Although both flight autolysis curves began at higher cell densities than control curves, the rate of autolysis in flight cultures was identical to that of their respective ground control rates.
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Stanford, K; Stephens, T P; McAllister, T A
2011-01-01
Super-shedders, cattle shedding at least 10(4) cfu of Escherichia coli O157:H7 per gram of feces, increase the risks of contaminating the food chain and disseminating the organism through cattle populations. Because detecting super-shedders in cattle populations is laborious and time-consuming, a study was conducted to evaluate the role of hide and pen-floor contamination by model super shedders (MSS) in transmission of E. coli O157:H7. Steers (n = 48) negative for E. coli O157:H7 were allocated to 6 pens, with 2 replicate pens per treatment. Treatment A consisted of 3,000 g of feces inoculated with 10(6) cfu/g of a 5-strain mixture of nalidixic acid-resistant E. coli O157:H7 and spread in simulated fecal pats on the pen floor for d 0 through 4 and d 14 through 18. For treatment B, 100 g of the feces per day was spread on the perineum of 1 MSS per pen, and the remaining feces was placed on the pen floor as fecal pats similar to treatment A. Treatment C differed from B in that 50 g of feces was spread on the perineum and 50 g on the brisket of the MSS steer. Fecal samples, perineal swabs (500-cm(2) area around the anus), freshly voided fecal pats and manila rope samples were collected during a 56-d experimental period. More positive rope samples were found in treatments B and C compared with A (P = 0.05), and steers within treatments B and C were 1.3 times more likely (P = 0.05) to shed E. coli O157:H7 in their feces than steers in treatment A. Even though the number of E. coli O157:H7 introduced into pens was similar, results indicate an increased importance of hide compared with pen-floor contamination for transmission of this organism to cattle. Because cattle within treatment B were persistently colonized with E. coli O157:H7, this design should prove suitable for future studies investigating the role of super-shedders in the transmission of E. coli O157:H7.
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Fransisca, Lilia; Park, Hee Kyung; Feng, Hao
2012-02-01
It has been reported that washing seeds with a 20000 ppm Ca(OCl)(2) solution as recommended by the U.S. Food and Drug Administration is unable to eliminate E. coli cells attached to seed surfaces, and the bacterial cells that have survived a sanitation wash can proliferate during sprouting to a high population. The objectives of this research were to examine the efficacy of malic acid (MA) and thiamine dilauryl sulfate (TDS) combined treatments on the inactivation of E. coli O157:H7 on alfalfa seeds, to study the growth of the remaining E. coli cells during sprouting, and to evaluate the sprout quality. When 10 g of inoculated alfalfa seeds were washed in a 10% MA-1% TDS solution, a complete elimination of E. coli was achieved. The same result was observed by washing the seeds in a 20000 ppm Ca(OCl)(2) solution. However, when the seed size was increased to 50 g while maintaining the same seed-to-sanitizer ratio, both the MA + TDS and the 20000 ppm chlorine washes failed to completely inactivate the E. coli cells on the seeds. Nevertheless, the 10% MA-1% TDS solution was significantly more effective in E. coli count reduction compared to the 20000 ppm chlorine wash. The E. coli O157:H7 cells remaining on the seeds after treatments with both sanitizers grew up to 7 to 8 log CFU/g sprout after 96 h of sprouting. Under the treatment conditions used in this study, none of the treatments resulted in significant differences in germination rate, yield, or quality of the sprouts. The malic acid (MA) and thiamine dilauryl sulfate (TDS) combined treatment may provide a new solution to secure the microbial safety of seeds and sprouts. An important finding of this study is that seed sample size has a significant impact on the inactivation of E. coli O157:H7 on alfalfa seeds. The microbial inactivation results obtained in a laboratory set-up cannot be directly applied to a large scale operation. A validation test on the large scale has to be performed to evaluate the efficacy of the sanitizer. © 2012 Institute of Food Technologists®
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Characterization of Escherichia coli and other Enterobacteriaceae in producer-distributor bulk milk.
Ntuli, V; Njage, P M K; Buys, E M
2016-12-01
The current study was undertaken to characterize Escherichia coli and other Enterobacteriaceae in raw and pasteurized producer-distributor bulk milk (PDBM). A total of 258 samples were collected from purchase points in 8 provinces in South Africa. The samples were tested for antibiotic residues, phosphatase, total aerobic bacteria, coliforms, and E. coli counts. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used for identification of isolates. Escherichia coli isolates were characterized for virulence factors, antimicrobial resistance, serotypes, and presumptive E. coli O157:H7. Antibiotic residues and alkaline phosphatase were detected in 2% of both raw and pasteurized PDBM (n=258) and 21% pasteurized PDBM (n=104) samples, respectively. A total of 729 isolates belonging to 21 genera and 59 species were identified. Escherichia coli, Enterobacter cloacae, Klebsiella oxytoca, and Raoultella ornithinolytica were the most abundant species. Spoilage Enterobacteriaceae species exceeded 50% of the total isolates. Escherichia coli was detected and isolated from 36% of the milk samples. Thirty-one E. coli isolates harbored virulence genes stx1/stx2 and 38% (n=121) were presumptive O157:H7. The prevalence of samples with presumptive shigatoxin producing E. coli was 10%. Antimicrobial-resistant E. coli isolates were detected in 70% of the milk samples with 36% of stx1/stx2 positive E. coli showing multi-drug resistance. Information obtained from the study will be used for modeling the public health risk posed by milkborne pathogens in PDBM, which in many cases is consumed by poor and vulnerable members of the population. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
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Effect of oxygen on survival of faecal pollution indicators in drinking water.
Roslev, P; Bjergbaek, L A; Hesselsoe, M
2004-01-01
The aim of this study was to determine the effect of oxygen on the survival of faecal pollution indicators including Escherichia coli in nondisinfected drinking water. Aerobic and anaerobic drinking water microcosms were inoculated with E. coli ATCC 25922 or raw sewage. Survival of E. coli was monitored by membrane filtration combined with cultivation on standard media, and by in situ hybridization with 16S rRNA-targeted fluorescent oligonucleotide probes. Anaerobic conditions significantly increased the survival of E. coli in drinking water compared with aerobic conditions. Escherichia coli ATCC 25922 showed a biphasic decrease in survival under aerobic conditions with an initial first-order decay rate of -0.11 day(-1) followed by a more rapid rate of -0.35 day(-1). In contrast, the first-order decay rate under anaerobic conditions was only -0.02 day(-1). After 35 days, <0.01% of the initial E. coli ATCC 25922 population remained detectable in aerobic microcosms compared with 48% in anaerobic microcosms. A poor survival was observed under aerobic conditions regardless of whether E. coli ATCC 25922 or sewage-derived E. coli was examined, and regardless of the detection method used (CFU or fluorescent in situ hybridization). Aerobic conditions in drinking water also appeared to decrease the survival of faecal enterococci, somatic coliphages and coliforms other than E. coli. The results indicate that oxygen is a major regulator of the survival of E. coli in nondisinfected drinking water. The results also suggest that faecal pollution indicators other than E. coli may persist longer in drinking water under anaerobic conditions. The effect of oxygen should be considered when evaluating the survival potential of enteric pathogens in oligotrophic environments.
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Visvalingam, Jeyachchandran; Liu, Yang; Yang, Xianqin
2017-03-06
The objective of this study was to examine the effect of dry chilling on the genetic diversity of naturally occurring Escherichia coli on beef carcasses, and to examine whether two populations of E. coli recovered from carcasses during chilling and E. coli O157 differed in their response to desiccation. Isolates of E. coli were obtained from beef carcasses during a 67h dry chilling process and were genotyped using multiple-locus variable-number tandem-repeat analysis (MLVA). Ten E. coli genotypes found only at 0h (group A) and found more than once (group B), as well as five strains of E. coli O157 (group C) were inoculated on stainless steel coupons and their survival was examined after exposure to 75 and 100% relative humidity (RH) at 0 or 35°C for 67h. A total of 450 E. coli isolates were obtained, with 254, 49, 49, 51, 23, 20, and 4 from 0, 1, 2, 4, 6, 8 and 24h of chilling, respectively. No E. coli were recovered at 67h. MLVA of the isolates revealed 173 distinct genotypes. Genetic diversity of E. coli isolates, defined as ratio of the number of isolates to the number of genotypes, remained between 2.3 and 1.3 during the 24h of chilling. All strains inoculated on stainless steel coupons and exposed to 75% RH at 35°C were completely inactivated, irrespective of their groups. Inactivation of E. coli of the three groups was not significantly (P>0.05) different by exposure to 75% RH at 0°C. The findings indicate that the genetic diversity of E. coli on beef carcasses was not affected by dry chilling. In addition, inactivation of E. coli genotypes and E. coli O157 by desiccation on stainless steel simulating dry chilling conditions did not differ significantly (P>0.05). Thus, dry chilling may be used as an effective antimicrobial intervention for beef carcasses. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.
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Rodríguez-Garcia, O; González-Romero, V M; Fernández-Escartín, E
2011-09-01
This study was intended to evaluate the bactericidal effect of electrolyzed oxidizing water (EOW) and chlorinated water on populations of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes inoculated on avocados (Persea americana var. Hass). In the first experiment, inoculated avocados were treated with a water wash applied by spraying tap water containing 1 mg/liter free chlorine for 15 s (WW); WW treatment and then spraying sodium hypochlorite in water containing 75 mg/liter free chlorine for 15 s (Cl75); WW treatment and then spraying alkaline EOW for 30 s (AkEW) and then spraying acid EOW (AcEW) for 15 s; and spraying AkEW and then AcEW. In another experiment, the inoculated avocados were treated by spraying AkEW and then AcEW for 15, 30, 60, or 90 s. All three pathogen populations were lowered between 3.6 and 3.8 log cycles after WW treatment. The application of Cl75 did not produce any further reduction in counts, whereas AkEW and then AcEW treatment resulted in significantly lower bacterial counts for L. monocytogenes and E. coli O157:H7 but not for Salmonella. Treatments with AkEW and then AcEW produced a significant decrease in L. monocytogenes, Salmonella, and E. coli O157:H7 populations, with estimated log reductions of 3.9 to 5.2, 5.1 to 5.9, and 4.2 to 4.9 log CFU/cm², respectively. Spraying AcEW for more than 15 s did not produce any further decrease in counts of Salmonella or E. coli O157:H7, whereas L. monocytogenes counts were significantly lower after spraying AcEW for 60 s. Applying AkEW and then AcEW for 15 or 30 s seems to be an effective alternative to reduce bacterial pathogens on avocado surfaces.
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Gautam, Raju; Bani-Yaghoub, Majid; Neill, William H; Döpfer, Dörte; Kaspar, Charles; Ivanek, Renata
2011-10-01
To explore the potential role of ambient temperature on infection transmission dynamics for pathogens, we used Escherichia coli O157:H7 in a dairy herd and the surrounding farm environment as a model system. For this system, we developed a mathematical model in which a Susceptible-Infectious-Susceptible (SIS) model of infection spread through the host population is coupled with a metapopulation model of E. coli O157:H7 free-living stage in the environment allowing bacterial growth to be influenced by ambient temperature. Model results indicate that seasonal variation in ambient temperature could have a considerable impact on pathogen populations in the environment, specifically on barn surfaces and in water troughs, and consequently on the prevalence of infection in the host population. Based on model assumptions, contaminated drinking water was the most important pathway of E. coli O157:H7 transmission to cattle. Sensitivity analysis indicated that water-borne transmission is amplified during the warmer months if the amount of standing drinking water available to the cattle herd is high. This is because warmer ambient temperature favors faster pathogen replication which when combined with slower water replacement-rate due to high amount of available standing water leads to a greater pathogen load in drinking water. These results offer a possible explanation of the seasonal variation in E. coli O157:H7 prevalence in cattle and suggest that improved drinking-water management could be used for control of this infection in cattle. Our study demonstrates how consideration of ambient temperature in transmission cycles of pathogens able to survive and grow in the environment outside the host could offer novel perspectives on the spread and control of infections caused by such pathogens. Copyright © 2011 Elsevier B.V. All rights reserved.
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Merino-Bohórquez, V; Docobo-Pérez, F; Sojo, J; Morales, I; Lupión, C; Martín, D; Cameán, M; Hope, W; Pascual, Á; Rodríguez-Baño, J
2018-04-10
To describe the population pharmacokinetics of fosfomycin for patients with bacteraemic urinary tract infection (BUTI). The analysis identified optimal regimens on the basis of pharmacodynamic targets and assessed the adequacy of Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) susceptibility breakpoints for Escherichia coli. Data of 16 patients with BUTI caused by multidrug-resistant E. coli (FOREST clinical trial) received intravenous fosfomycin (4 g every 6 hours) were analysed. A population pharmacokinetic analysis was performed, and Monte Carlo simulations were undertaken using 4 g every 6 hours and 8 g every 8 hours. The probability of pharmacodynamic target attainment was assessed using pharmacodynamic targets for E. coli for static effect, 1-log drop in bacterial burden and resistance suppression. Sixty-four plasma samples were collected over a single dosing interval (day 2 or 3 after starting fosfomycin treatment). Fosfomycin concentrations were highly variable. Pharmacodynamic target attainment analysis showed mild improvement by increasing fosfomycin dosing (4 g every 6 hours vs. every 8 hours). These dosages showed success for decreasing 1-log bacterial burden in 89% to 96% (EUCAST breakpoints) and 33% to 54% (CLSI breakpoints) of patients, but they were unable to reach bacterial resistance suppression targets. Fosfomycin concentrations are highly variable-a fact partially explained by renal impairment. The present work supports the use of 4 g every 6 hours as an effective regimen for the treatment of non-critically ill patients with BUTI caused by multidrug-resistant E. coli, as higher dosages might increase toxicity but may not significantly increase efficacy. The current information may suggest that fosfomycin susceptibility breakpoints need to be reappraised. Copyright © 2018 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
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Heterogeneity of spontaneous DNA replication errors in single isogenic Escherichia coli cells
2018-01-01
Despite extensive knowledge of the molecular mechanisms that control mutagenesis, it is not known how spontaneous mutations are produced in cells with fully operative mutation-prevention systems. By using a mutation assay that allows visualization of DNA replication errors and stress response transcriptional reporters, we examined populations of isogenic Escherichia coli cells growing under optimal conditions without exogenous stress. We found that spontaneous DNA replication errors in proliferating cells arose more frequently in subpopulations experiencing endogenous stresses, such as problems with proteostasis, genome maintenance, and reactive oxidative species production. The presence of these subpopulations of phenotypic mutators is not expected to affect the average mutation frequency or to reduce the mean population fitness in a stable environment. However, these subpopulations can contribute to overall population adaptability in fluctuating environments by serving as a reservoir of increased genetic variability.
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Recorbet, G; Robert, C; Givaudan, A; Kudla, B; Normand, P; Faurie, G
1993-01-01
The sacB gene from Bacillus subtilis confers sucrose sensitivity upon gram-negative bacteria. The gene was investigated for use as a potential conditional suicide system for Escherichia coli released into soil. To ensure against the loss of the cell death function encoded under nonselective conditions, the nptI-sacR-B suicide cassette was inserted into the E. coli chromosome by using a circular nonreplicative integration vector. Stability studies yielded no loss of the suicide cassette in the integrated E. coli EL1026 strain. sacB induction in the absence of a selective pressure resulted in a lysis efficiency of up to 99.9%. The microcosm experiments confirmed the ability of the suicide cassette to limit the growth and reduce the survival of E. coli strains released into soil. Sucrose addition to sterile soil resulted in a 10(-3)-fold reduction of the final E. coli population density. sacB induction prevented the proliferation and triggered the rapid disappearance of E. coli from natural soil. Mutation to sucrose tolerance occurred at a frequency of 10(-5), making E. coli EL1026 a potential counterselectable donor strain for gene transfer studies. Specificity and potential adaptability to a wide range of gram-negative bacteria are additional conveniences of this conditional suicide system for the containment and counterselection of engineered microorganisms. PMID:8517732
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Recorbet, G; Robert, C; Givaudan, A; Kudla, B; Normand, P; Faurie, G
1993-05-01
The sacB gene from Bacillus subtilis confers sucrose sensitivity upon gram-negative bacteria. The gene was investigated for use as a potential conditional suicide system for Escherichia coli released into soil. To ensure against the loss of the cell death function encoded under nonselective conditions, the nptI-sacR-B suicide cassette was inserted into the E. coli chromosome by using a circular nonreplicative integration vector. Stability studies yielded no loss of the suicide cassette in the integrated E. coli EL1026 strain. sacB induction in the absence of a selective pressure resulted in a lysis efficiency of up to 99.9%. The microcosm experiments confirmed the ability of the suicide cassette to limit the growth and reduce the survival of E. coli strains released into soil. Sucrose addition to sterile soil resulted in a 10(-3)-fold reduction of the final E. coli population density. sacB induction prevented the proliferation and triggered the rapid disappearance of E. coli from natural soil. Mutation to sucrose tolerance occurred at a frequency of 10(-5), making E. coli EL1026 a potential counterselectable donor strain for gene transfer studies. Specificity and potential adaptability to a wide range of gram-negative bacteria are additional conveniences of this conditional suicide system for the containment and counterselection of engineered microorganisms.
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Rangel-Vargas, Esmeralda; Gómez-Aldapa, Carlos A; Torres-Vitela, M Del Refugio; Villarruel-López, Angélica; Gordillo-Martínez, Alberto J; Castro-Rosas, Javier
2015-03-01
Data on the presence of diarrheagenic Escherichia coli pathotypes (DEPs) in alfalfa sprouts and correlations between the presence of coliform bacteria (CB), fecal coliforms (FC), E. coli, DEPs, and Salmonella in alfalfa sprouts are not available. The presence of and correlations between CB, FC, E. coli, DEPs, and Salmonella in alfalfa sprouts were determined. One hundred sprout samples were collected from retail markets in Pachuca, Hidalgo State, Mexico. The presence of indicator bacteria and Salmonella was determined using conventional culture procedures. DEPs were identified using two multiplex PCR procedures. One hundred percent of samples were positive for CB, 90% for FC, 84% for E. coli, 10% for DEPs, and 4% for Salmonella. The populations of CB ranged from 6.2 up to 8.6 log CFU/g. The FC and E. coli concentrations were between , 3 and 1,100 most probable number (MPN)/g. The DEPs identified included enterotoxigenic E. coli (ETEC; 2%), enteropathogenic E. coli (EPEC; 3%), and Shiga toxin-producing E. coli (STEC; 5%). No E. coli O157:H7 strains were detected in any STEC-positive samples. In samples positive for DEPs, the concentrations ranged from 210 to 240 MPN/g for ETEC, 28 to 1,100 MPN/g for EPEC, and 3.6 to 460 MPN/g for STEC. The Salmonella isolates identified included Salmonella enterica serotype Typhimurium in three samples and Salmonella enterica serotype Enteritidis in one. STEC and Salmonella Typhimurium were identified together in one sample. Positive correlations were observed between FC and E. coli, between FC and DEPs, and between E. coli and DEPs. Negative correlations occurred between CB and DEPs and between CB and Salmonella. Neither FC nor E. coli correlated with Salmonella in the sprout samples. To our knowledge, this is the first report of ETEC, EPEC, and STEC isolated from alfalfa sprouts and the first report of correlations between different indicator groups versus DEPs and Salmonella.
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A Novel Physical Technique for E. Coli Removal from Stormwater
In addition to heavy metals and polymeric aromatic hydrocarbons(PAHs), pathogens such as E.Coli contribute to the overall pollutant load in urban stormwater runoff. A number of constructed landscape features, collectively known as structural best management practices (BMPs) are e...
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Adamus-Bialek, Wioletta; Zajac, Elzbieta; Parniewski, Pawel; Kaca, Wieslaw
2013-04-01
Escherichia coli and Proteus mirabilis are important urinary tract pathogens. The constant increase in the antibiotic resistance of clinical bacterial strains has become an important clinical problem. The aim of this study was to compare the antibiotic resistance of 141 clinical (Sweden and Poland) and 42 laboratory (Czech Republic) P. mirabilis strains and 129 clinical (Poland) uropathogenic E. coli strains. The proportion of unique versus diverse patterns in Swedish clinical and laboratory P. mirabilis strain collections was comparable. Notably, a similar proportion of unique versus diverse patterns was observed in Polish clinical P. mirabilis and E. coli strain collections. Mathematical models of the antibiotic resistance of E. coli and P. mirabilis strains based on Kohonen networks and association analysis are presented. In contrast to the three clinical strain collections, which revealed complex associations with the antibiotics tested, laboratory P. mirabilis strains provided simple antibiotic association diagrams. The monitoring of antibiotic resistance patterns of clinical E. coli and P. mirabilis strains plays an important role in the treatment procedures for urinary tract infections and is important in the context of the spreading drug resistance in uropathogenic strain populations. The adaptability and flexibility of the genomes of E. coli and P. mirabilis strains are discussed.
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Quantitative risk assessment of E. coli in street-vended cassava-based delicacies in the Philippines
NASA Astrophysics Data System (ADS)
Mesias, I. C. P.
2018-01-01
In the Philippines, rootcrop-based food products are gaining popularity in street food trade. However, a number of street-vended food products in the country are reported to be contaminated with E. coli posing possible risk among consumers. In this study, information on quantitative risk assessment of E. coli in street-vended cassava-based delicacies was generated. The assessment started with the prevalence and concentration of E. coli at post production in packages of the cassava-based delicacies. Combase growth predictor was used to trace the microbial population of E. coli in each step of the food chain. The @Risk software package, version 6 (Palisade USA) was used to run the simulations. Scenarios in the post-production to consumption pathway were simulated. The effect was then assessed in relation to exposure to the defined infective dose. In the worst case scenario, a minimum and most likely concentration of 6.3 and 7.8 log CFU of E. coli per serving respectively were observed. The simulation revealed that lowering the temperature in the chain considerably decreased the E. coli concentration prior to consumption and subsequently decreased the percentage of exposure to the infective dose. Exposure to infective dose however was increased with longer lag time from postproduction to consumption.
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A Survey for Escherichia coli Virulence Factors in Asymptomatic Free-Ranging Parrots
Becker Saidenberg, André; Robaldo Guedes, Neiva Maria; Fernandes Seixas, Gláucia Helena; da Costa Allgayer, Mariangela; Pacífico de Assis, Erica; Fabio Silveira, Luis; Anne Melville, Priscilla; Benites, Nilson Roberti
2012-01-01
Parrots in captivity are frequently affected by Escherichia coli (E. coli) infections. The objective of this study was to collect information on the carrier state for E. coli pathotypes in asymptomatic free-ranging parrots. Cloacal swabs were collected from nestlings of Hyacinth, Lear's macaws and Blue-fronted Amazon parrots and tested by polymerase chain reaction (PCR) for virulence factors commonly found in enteropathogenic, avian pathogenic, and uropathogenic E. coli strains. In total, 44 samples were cultured and E. coli isolates were yielded, from which DNA was extracted and processed by PCR. Genes commonly found in APEC isolates from Blue-fronted Amazon parrots and Hyacinth macaws were expressed in 14 of these 44 samples. One atypical EPEC isolate was obtained from a sample from Lear's macaw. The most commonly found gene was the increased serum survival (iss) gene. This is the first report, that describes such pathotypes in asymptomatic free-living parrots. The findings of this study suggest the presence of a stable host/parasite relationship at the time of the sampling brings a new understanding to the role that E. coli plays in captive and wild parrots. Such information can be used to improve husbandry protocols as well as help conservation efforts of free-living populations. PMID:23738135
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Harnessing recombination to speed adaptive evolution in Escherichia coli.
Winkler, James; Kao, Katy C
2012-09-01
Evolutionary engineering typically involves asexual propagation of a strain to improve a desired phenotype. However, asexual populations suffer from extensive clonal interference, a phenomenon where distinct lineages of beneficial clones compete and are often lost from the population given sufficient time. Improved adaptive mutants can likely be generated by genetic exchange between lineages, thereby reducing clonal interference. We present a system that allows continuous in situ recombination by using an Esherichia coli F-based conjugation system lacking surface exclusion. Evolution experiments revealed that Hfr-mediated recombination significantly speeds adaptation in certain circumstances. These results show that our system is stable, effective, and suitable for use in evolutionary engineering applications. Copyright © 2012 Elsevier Inc. All rights reserved.
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MreB Orientation Correlates with Cell Diameter in Escherichia coli.
Ouzounov, Nikolay; Nguyen, Jeffrey P; Bratton, Benjamin P; Jacobowitz, David; Gitai, Zemer; Shaevitz, Joshua W
2016-09-06
Bacteria have remarkably robust cell shape control mechanisms. For example, cell diameter only varies by a few percent across a given population. The bacterial actin homolog, MreB, is necessary for establishment and maintenance of rod shape although the detailed properties of MreB that are important for shape control remained unknown. In this study, we perturb MreB in two ways: by treating cells with the polymerization-inhibiting drug A22 and by creating point mutants in mreB. These perturbations modify the steady-state diameter of cells over a wide range, from 790 ± 30 nm to 1700 ± 20 nm. To determine which properties of MreB are important for diameter control, we correlated structural characteristics of fluorescently tagged MreB polymers with cell diameter by simultaneously analyzing three-dimensional images of MreB and cell shape. Our results indicate that the helical pitch angle of MreB inversely correlates with the cell diameter of Escherichia coli. Other correlations between MreB and cell diameter are not found to be significant. These results demonstrate that the physical properties of MreB filaments are important for shape control and support a model in which MreB organizes the cell wall growth machinery to produce a chiral cell wall structure and dictate cell diameter. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.
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HU content and dynamics in Escherichia coli during the cell cycle and at different growth rates.
Abebe, Anteneh Hailu; Aranovich, Alexander; Fishov, Itzhak
2017-10-16
DNA-binding proteins play an important role in maintaining bacterial chromosome structure and functions. Heat-unstable (HU) histone-like protein is one of the most abundant of these proteins and participates in all major chromosome-related activities. Owing to its low sequence specificity, HU fusions with fluorescent proteins were used for general staining of the nucleoid, aiming to reveal its morphology and dynamics. We have exploited a single chromosomal copy of hupA-egfp fusion under the native promoter and used quantitative microscopy imaging to investigate the amount and dynamics of HUα in Escherichia coli cells. We found that in steady-state growing populations the cellular HUα content is proportional to the cell size, whereas its concentration is size independent. Single-cell live microscopy imaging confirmed that the amount of HUα exponentially increases during the cell cycle, but its concentration is maintained constant. This supports the existence of an auto-regulatory mechanism underlying the HUα cellular level, in addition to reflecting the gene copy number. Both the HUα amount and concentration strongly increase with the cell growth rate in different culture media. Unexpectedly, the HU/DNA stoichiometry also remarkably increases with the growth rate. This last finding may be attributed to a higher requirement for maintaining the chromosome structure in nucleoids with higher complexity. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Yang, Youjun; Severin, Anatoly; Chopra, Rajiv; Krishnamurthy, Girija; Singh, Guy; Hu, William; Keeney, David; Svenson, Kristine; Petersen, Peter J.; Labthavikul, Pornpen; Shlaes, David M.; Rasmussen, Beth A.; Failli, Amedeo A.; Shumsky, Jay S.; Kutterer, Kristina M. K.; Gilbert, Adam; Mansour, Tarek S.
2006-01-01
A series of 3,5-dioxopyrazolidines was identified as novel inhibitors of UDP-N-acetylenolpyruvylglucosamine reductase (MurB). Compounds 1 to 3, which are 1,2-bis(4-chlorophenyl)-3,5-dioxopyrazolidine-4-carboxamides, inhibited Escherichia coli MurB, Staphyloccocus aureus MurB, and E. coli MurA with 50% inhibitory concentrations (IC50s) in the range of 4.1 to 6.8 μM, 4.3 to 10.3 μM, and 6.8 to 29.4 μM, respectively. Compound 4, a C-4-unsubstituted 1,2-bis(3,4-dichlorophenyl)-3,5-dioxopyrazolidine, showed moderate inhibitory activity against E. coli MurB, S. aureus MurB, and E. coli MurC (IC50s, 24.5 to 35 μM). A fluorescence-binding assay indicated tight binding of compound 3 with E. coli MurB, giving a dissociation constant of 260 nM. Structural characterization of E. coli MurB was undertaken, and the crystal structure of a complex with compound 4 was obtained at 2.4 Å resolution. The crystal structure indicated the binding of a compound at the active site of MurB and specific interactions with active-site residues and the bound flavin adenine dinucleotide cofactor. Peptidoglycan biosynthesis studies using a strain of Staphylococcus epidermidis revealed reduced peptidoglycan biosynthesis upon incubation with 3,5-dioxopyrazolidines, with IC50s of 0.39 to 11.1 μM. Antibacterial activity was observed for compounds 1 to 3 (MICs, 0.25 to 16 μg/ml) and 4 (MICs, 4 to 8 μg/ml) against gram-positive bacteria including methicillin-resistant S. aureus, vancomycin-resistant Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae. PMID:16436710
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Colibactin: More Than a New Bacterial Toxin
Faïs, Tiphanie; Delmas, Julien; Barnich, Nicolas; Bonnet, Richard
2018-01-01
Cyclomodulins are bacterial toxins that interfere with the eukaryotic cell cycle. A new cyclomodulin called colibactin, which is synthetized by the pks genomic island, was discovered in 2006. Despite many efforts, colibactin has not yet been purified, and its structure remains elusive. Interestingly, the pks island is found in members of the family Enterobacteriaceae (mainly Escherichia coli and Klebsiella pneumoniae) isolated from different origins, including from intestinal microbiota, septicaemia, newborn meningitis, and urinary tract infections. Colibactin-producing bacteria induce chromosomal instability and DNA damage in eukaryotic cells, which leads to senescence of epithelial cells and apoptosis of immune cells. The pks island is mainly observed in B2 phylogroup E. coli strains, which include extra-intestinal pathogenic E. coli strains, and pks E. coli are over-represented in biopsies isolated from colorectal cancer. In addition, pks E. coli bacteria increase the number of tumours in diverse colorectal cancer mouse models. Thus, colibactin could have a major impact on human health. In the present review, we will focus on the biological effects of colibactin, the distribution of the pks island, and summarize what is currently known about its synthesis and its structure. PMID:29642622
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Barbosa, Alynne da Silva; Barbosa, Helene Santos; Souza, Sandra Maria de Oliveira; Dib, Laís Verdan; Uchôa, Claudia Maria Antunes; Bastos, Otilio Machado Pereira; Amendoeira, Maria Regina Reis
2018-06-26
Balantioides coli is a ciliated protozoon that inhabits the intestine of pigs, non-human primates and humans. Light microscopy studies have described over 50 species of the genus Balantioides but their validity is in doubt. Due to the limited information about this genus, this study is aimed to identify morphological characteristics of Balantioides coli isolated using fluorescence microscopy and both scanning (SEM) and transmission electron microscopy (TEM). Trophozoites isolated from the feces of pig and macaque were washed and subjected to centrifugation. These cells were fixed with paraformaldehyde for immunofluorescence. Other aliquots of these trophozoites were fixed with glutaraldehyde, post fixed with osmium tetroxide and processed for SEM and TEM. Immunofluorescence studies revealed microtubules with a longitudinal distribution to the main axis of the parasite and in the constitution of cilia. SEM demonstrated a high concentration of cilia covering the oral apparatus and a poor presence of such structures in cytopyge. TEM revealed in the plasma membrane, several associated structures were observed to delineate the cellular cortex and mucocysts. The cytoskeleton of the oral region was observed in detail and had an organization pattern consisting of microtubules, which formed files and nematodesmal networks. Organelles such as hydrogenosomes like and peroxisomes were observed close to the cortex. Macronuclei were observed, but structures that were consistent with micronuclei were not identified. Ultrastructural morphological analysis of isolates confirms its similarity to Balantioides coli. In this study were identified structures that had not yet been described, such as hydrogenosomes like and cytoskeletal structures.
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Manjasetty, Babu A; Chance, Mark R
2006-07-07
Escherichia coli L-arabinose isomerase (ECAI; EC 5.3.1.4) catalyzes the isomerization of L-arabinose to L-ribulose in vivo. This enzyme is also of commercial interest as it catalyzes the conversion of D-galactose to D-tagatose in vitro. The crystal structure of ECAI was solved and refined at 2.6 A resolution. The subunit structure of ECAI is organised into three domains: an N-terminal, a central and a C-terminal domain. It forms a crystallographic trimeric architecture in the asymmetric unit. Packing within the crystal suggests the idea that ECAI can form a hexameric assembly. Previous electron microscopic and biochemical studies supports that ECAI is hexameric in solution. A comparison with other known structures reveals that ECAI adopts a protein fold most similar to E. coli fucose isomerase (ECFI) despite very low sequence identity 9.7%. The structural similarity between ECAI and ECFI with regard to number of domains, overall fold, biological assembly, and active site architecture strongly suggests that the enzymes have functional similarities. Further, the crystal structure of ECAI forms a basis for identifying molecular determinants responsible for isomerization of arabinose to ribulose in vivo and galactose to tagatose in vitro.
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The crystal structure of human GDP-L-fucose synthase.
Zhou, Huan; Sun, Lihua; Li, Jian; Xu, Chunyan; Yu, Feng; Liu, Yahui; Ji, Chaoneng; He, Jianhua
2013-09-01
Human GDP-l-fucose synthase, also known as FX protein, synthesizes GDP-l-fucose from its substrate GDP-4-keto-6-deoxy-d-mannose. The reaction involves epimerization at both C-3 and C-5 followed by an NADPH-dependent reduction of the carbonyl at C-4. In this paper, the first crystal structure of human FX protein was determined at 2.37 Å resolution. The asymmetric unit of the crystal structure contains four molecules which form two homodimers. Each molecule consists of two domains, a Rossmann-fold NADPH-binding motif and a carboxyl terminal domain. Compared with the Escherichia coli GDP-l-fucose synthase, the overall structures of these two enzymes have four major differences. There are four loops in the structure of human FX protein corresponding to two α-helices and two β-sheets in that of the E. coli enzyme. Besides, there are seven different amino acid residues binding with NAPDH comparing human FX protein with that from E. coli. The structure of human FX reveals the key catalytic residues and could be useful for the design of drugs for the treatment of inflammation, auto-immune diseases, and possibly certain types of cancer.
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Chlortetracycline - resistant intestinal bacteria in organically-raised and feral swine
USDA-ARS?s Scientific Manuscript database
Organically-raised swine had high fecal populations of chlortetracycline (CTC)-resistant (growing at 64 micro g CTC/ml) Escherichia coli, Megasphaera elsdenii and anaerobe populations. By comparison, predominant CTC-resistant bacteria in feral swine feces were over 1000-fold fewer and exhibited lo...
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Molecular epidemiology of Escherichia coli mediated urinary tract infections.
Zhang, Lixin; Foxman, Betsy
2003-01-01
Urinary tract infection (UTI) is one of the most frequently acquired bacterial infections and Escherichia coli accounts for as many as 90% of all UTIs seen among ambulatory populations. Risk factors for UTIs include host behaviors, host characteristics and bacterial characteristics. Sexual activity and contraceptive method are the strongest determinant of a symptomatic UTI episode. The characteristics of cell receptors, anatomical differences and genetic predisposition in the host may be important determinants of increased risk for recurrent infections. Uropathogenic E. coli have special characteristics causing urovirulence. They most likely belong to phylogenic lineage B2. They usually possess specific adhesins such as P, S or Dr to facilitate their colonization in the urinary tract, and toxins such as hemolysin and cytotoxic necrotizing factor 1 to provoke inflammatory response that possibly are responsible for the development of UTI symptoms. Interestingly, virulence genes in uropathogenic E. coli are often co-located on pathogenicity islands. Currently, however, none of the known virulence genes or set of genes can clearly define the prototypic uropathogenic E. coli. Additional studies are needed to identify factors that promote uropathogen transmission and persistent colonization, and to investigate potential different modes of pathogenesis by E. coli strains with different compositions of virulence genes.
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Nicolas-Chanoine, Marie-Hélène; Petitjean, Marie; Mora, Azucena; Mayer, Noémie; Lavigne, Jean-Philippe; Boulet, Olivier; Leflon-Guibout, Véronique; Blanco, Jorge; Hocquet, Didier
2017-03-27
In 2006, we found healthy subjects carrying ST131 Escherichia coli in their intestinal microbiota consisting of two populations: a subdominant population of fluoroquinolone-resistant E. coli belonging to subclone H30 (H30-R or subclade C1), the current worldwide dominant ST131 subclone, and a dominant E. coli population composed of antibiotic-susceptible E. coli belonging to subclone H22 (clade B), the precursor of subclone H30. We sequenced the whole genome of fecal H22 strain S250, compared it to the genomes of ExPEC ST131 H30-Rx strain JJ1886 and commensal ST131 H41 strain SE15, sought the H22-H30 genomic differences in our fecal strains and assessed their phenotypic consequences. We detected 173 genes found in the Virulence Factor Database, of which 148 were shared by the three ST131 genomes, whereas some were genome-specific, notably those allowing determination of virotype (D for S250 and C for JJ1886). We found three sequences of the FimH site involved in adhesion: two in S250 and SE15 close and identical, respectively, to that previously reported to confer strong intestinal adhesion, and one in JJ1886, corresponding to that commonly present in uropathogenic E. coli. Among the genes involved in sugar metabolism, one encoding a gluconate kinase lacked in S250 and JJ1886. Although this gene was also absent in both our fecal H22 and H30-R strains, H22 strains showed a higher capacity to grow in minimal medium with gluconate. Among the genes involved in gluconate metabolism, only the ghrB gene differed between S250/H22 and JJ1886/H30-R strains, resulting in different gluconate reductases. Of the genes involved in biofilm formation, two were absent in the three genomes and one, fimB, in the JJ1886 genome. Our fecal H30-R strains lacking intact fimB displayed delayed biofilm formation relative to our fecal H22 strains. The H22 strains differed by subclade B type and plasmid content, whereas the H30-R strains were identical. Phenotypic analysis of our fecal strains based on observed genomic differences between S250 and JJ1886 strains suggests the presence of traits related to bacterial commensalism in our H22 strains and traits commonly found in uropathogenic E. coli in our H30-R strains.
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Biswal, Basanta Kumar; Khairallah, Ramzi; Bibi, Kareem; Mazza, Alberto; Gehr, Ronald; Masson, Luke; Frigon, Dominic
2014-06-01
Wastewater discharges may increase the populations of pathogens, including Escherichia coli, and of antimicrobial-resistant strains in receiving waters. This study investigated the impact of UV and peracetic acid (PAA) disinfection on the prevalence of virulence and antimicrobial resistance genes in uropathogenic Escherichia coli (UPEC), the most abundant E. coli pathotype in municipal wastewaters. Laboratory disinfection experiments were conducted on wastewater treated by physicochemical, activated sludge, or biofiltration processes; 1,766 E. coli isolates were obtained for the evaluation. The target disinfection level was 200 CFU/100 ml, resulting in UV and PAA doses of 7 to 30 mJ/cm(2) and 0.9 to 2.0 mg/liter, respectively. The proportions of UPECs were reduced in all samples after disinfection, with an average reduction by UV of 55% (range, 22% to 80%) and by PAA of 52% (range, 11% to 100%). Analysis of urovirulence genes revealed that the decline in the UPEC populations was not associated with any particular virulence factor. A positive association was found between the occurrence of urovirulence and antimicrobial resistance genes (ARGs). However, the changes in the prevalence of ARGs in potential UPECs were different following disinfection, i.e., UV appears to have had no effect, while PAA significantly reduced the ARG levels. Thus, this study showed that both UV and PAA disinfections reduced the proportion of UPECs and that PAA disinfection also reduced the proportion of antimicrobial resistance gene-carrying UPEC pathotypes in municipal wastewaters.
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Biswal, Basanta Kumar; Khairallah, Ramzi; Bibi, Kareem; Mazza, Alberto; Gehr, Ronald; Masson, Luke
2014-01-01
Wastewater discharges may increase the populations of pathogens, including Escherichia coli, and of antimicrobial-resistant strains in receiving waters. This study investigated the impact of UV and peracetic acid (PAA) disinfection on the prevalence of virulence and antimicrobial resistance genes in uropathogenic Escherichia coli (UPEC), the most abundant E. coli pathotype in municipal wastewaters. Laboratory disinfection experiments were conducted on wastewater treated by physicochemical, activated sludge, or biofiltration processes; 1,766 E. coli isolates were obtained for the evaluation. The target disinfection level was 200 CFU/100 ml, resulting in UV and PAA doses of 7 to 30 mJ/cm2 and 0.9 to 2.0 mg/liter, respectively. The proportions of UPECs were reduced in all samples after disinfection, with an average reduction by UV of 55% (range, 22% to 80%) and by PAA of 52% (range, 11% to 100%). Analysis of urovirulence genes revealed that the decline in the UPEC populations was not associated with any particular virulence factor. A positive association was found between the occurrence of urovirulence and antimicrobial resistance genes (ARGs). However, the changes in the prevalence of ARGs in potential UPECs were different following disinfection, i.e., UV appears to have had no effect, while PAA significantly reduced the ARG levels. Thus, this study showed that both UV and PAA disinfections reduced the proportion of UPECs and that PAA disinfection also reduced the proportion of antimicrobial resistance gene-carrying UPEC pathotypes in municipal wastewaters. PMID:24727265
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Lin, Chia-Min; Wu, Fone-Mao; Kim, Hoi-Kyung; Doyle, Michael P; Michael, Barry S; Williams, L Keoki
2003-12-01
Compared with other parts of the hand, the area beneath fingernails harbors the most microorganisms and is most difficult to clean. Artificial fingernails, which are usually long and polished, reportedly harbor higher microbial populations than natural nails. Hence, the efficacy of different hand washing methods for removing microbes from natural and artificial fingernails was evaluated. Strains of nonpathogenic Escherichia coli JM109 and feline calicivirus (FCV) strain F9 were used as bacterial and viral indicators, respectively. Volunteers with artificial or natural nails were artificially contaminated with ground beef containing E. coli JM109 or artificial feces containing FCV. Volunteers washed their hands with tap water, regular liquid soap, antibacterial liquid soap, alcohol-based hand sanitizer gel, regular liquid soap followed by alcohol gel, or regular liquid soap plus a nailbrush. The greatest reduction of inoculated microbial populations was obtained by washing with liquid soap plus a nailbrush, and the least reduction was obtained by rubbing hands with alcohol gel. Lower but not significantly different (P > 0.05) reductions of E. coli and FCV counts were obtained from beneath artificial than from natural fingernails. However, significantly (P < or = 0.05) higher E. coli and FCV counts were recovered from hands with artificial nails than from natural nails before and after hand washing. In addition, microbial cell numbers were correlated with fingernail length, with greater numbers beneath fingernails with longer nails. These results indicate that best practices for fingernail sanitation of food handlers are to maintain short fingernails and scrub fingernails with soap and a nailbrush when washing hands.
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Lowrance, T Courtney; Loneragan, Guy H; Kunze, David J; Platt, Tammy M; Ives, Samuel E; Scott, H Morgan; Norby, Bo; Echeverry, Alejandro; Brashears, Mindy M
2007-05-01
To determine effects of administration of ceftiofur crystalline-free acid (CCFA) on antimicrobial susceptibility of Escherichia coli in feedlot cattle. 61 feedlot steers. A cohort study was conducted. Steers were housed in pens (5 pens with 10 steers and 1 pen with 11 steers). Five steers in each pen were administered CCFA, and 5 served as control steers (1 pen had 6 control steers). The CCFA administration included a single-dose regimen (6.6 mg/kg, SC, on day 0), two-thirds-dose regimen (4.4 mg/kg, SC, on day 0), and 3-dose regimen (6.6 mg/kg, SC, on days 0, 6, and 13). Fecal samples were collected on days 0, 2, 6, 9, 13, 16, 20, and 28. Fecal samples were collected immediately before CCFA administration. Minimum inhibitory concentrations of 15 antimicrobials were determined for 3 E coli isolates/fecal sample. Escherichia coli were enumerated by use of direct-plating techniques. Resistance to 1 or more antimicrobials was detected in 986 of 1,441 (68.4%) isolates recovered. Administration of CCFA was associated with a transient increase in the population of ceftiofur-resistant isolates. Susceptibility returned to day 0 values (ie, samples collected immediately before CCFA administration) approximately 2 weeks after completion of CCFA administration. Agreement between ceftiofur resistance and co-resistance to ampicillin, chloramphenicol, streptomycin, sulfisoxazole, and tetracycline was almost perfect (kappa 0.97). We did not detect variation in susceptibility of E coli recovered from commingled control steers. Administration of CCFA provided selection pressure that favored transient expansion of multiple-resistant variants.
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Reisner, Andreas; Maierl, Mario; Jörger, Michael; Krause, Robert; Berger, Daniela; Haid, Andrea; Tesic, Dijana; Zechner, Ellen L
2014-03-01
Biofilm formation on catheters is thought to contribute to persistence of catheter-associated urinary tract infections (CAUTI), which represent the most frequent nosocomial infections. Knowledge of genetic factors for catheter colonization is limited, since their role has not been assessed using physicochemical conditions prevailing in a catheterized human bladder. The current study aimed to combine data from a dynamic catheterized bladder model in vitro with in vivo expression analysis for understanding molecular factors relevant for CAUTI caused by Escherichia coli. By application of the in vitro model that mirrors the physicochemical environment during human infection, we found that an E. coli K-12 mutant defective in type 1 fimbriae, but not isogenic mutants lacking flagella or antigen 43, was outcompeted by the wild-type strain during prolonged catheter colonization. The importance of type 1 fimbriae for catheter colonization was verified using a fimA mutant of uropathogenic E. coli strain CFT073 with human and artificial urine. Orientation of the invertible element (IE) controlling type 1 fimbrial expression in bacterial populations harvested from the colonized catheterized bladder in vitro suggested that the vast majority of catheter-colonizing cells (up to 88%) express type 1 fimbriae. Analysis of IE orientation in E. coli populations harvested from patient catheters revealed that a median level of ∼73% of cells from nine samples have switched on type 1 fimbrial expression. This study supports the utility of the dynamic catheterized bladder model for analyzing catheter colonization factors and highlights a role for type 1 fimbriae during CAUTI.
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Studer, Patrick; Heller, Werner E; Hummerjohann, Jörg; Drissner, David
2013-08-01
Sprouts contaminated with human pathogens are able to cause food-borne diseases due to the favorable growth conditions for bacteria during germination and because of minimal processing steps prior to consumption. We have investigated the potential of hot humid air, i.e., aerated steam, to treat alfalfa and mung bean seeds which have been artificially contaminated with Escherichia coli O157:H7, Salmonella enterica subsp. enterica serovar Weltevreden, and Listeria monocytogenes Scott A. In addition, a recently collected E. coli O178:H12 isolate, characterized by a reduced heat sensitivity, was exposed to the treatment described. Populations of E. coli O157:H7 and S. enterica on alfalfa and mung bean seeds could be completely eliminated by a 300-s treatment with steam at 70 ± 1°C as revealed by enrichment studies. L. monocytogenes and E. coli O178:H12 could not be completely eliminated from artificially inoculated seeds. However, bacterial populations were reduced by more than 5 log CFU/g on alfalfa and by more than 4 log CFU/g on mung bean seeds. The germination rate of mung beans was not affected by the 300-s treatment compared to the germination rate of untreated seeds whereas that of alfalfa seeds was significantly lower by 11.9%. This chemical-free method is an effective alternative to the 20,000-ppm hypochlorite treatment presently recommended by the U.S. Food and Drug Administration (FDA).
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Studer, Patrick; Heller, Werner E.; Hummerjohann, Jörg
2013-01-01
Sprouts contaminated with human pathogens are able to cause food-borne diseases due to the favorable growth conditions for bacteria during germination and because of minimal processing steps prior to consumption. We have investigated the potential of hot humid air, i.e., aerated steam, to treat alfalfa and mung bean seeds which have been artificially contaminated with Escherichia coli O157:H7, Salmonella enterica subsp. enterica serovar Weltevreden, and Listeria monocytogenes Scott A. In addition, a recently collected E. coli O178:H12 isolate, characterized by a reduced heat sensitivity, was exposed to the treatment described. Populations of E. coli O157:H7 and S. enterica on alfalfa and mung bean seeds could be completely eliminated by a 300-s treatment with steam at 70 ± 1°C as revealed by enrichment studies. L. monocytogenes and E. coli O178:H12 could not be completely eliminated from artificially inoculated seeds. However, bacterial populations were reduced by more than 5 log CFU/g on alfalfa and by more than 4 log CFU/g on mung bean seeds. The germination rate of mung beans was not affected by the 300-s treatment compared to the germination rate of untreated seeds whereas that of alfalfa seeds was significantly lower by 11.9%. This chemical-free method is an effective alternative to the 20,000-ppm hypochlorite treatment presently recommended by the U.S. Food and Drug Administration (FDA). PMID:23709507
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Cryo-EM structure of the large subunit of the spinach chloroplast ribosome
Ahmed, Tofayel; Yin, Zhan; Bhushan, Shashi
2016-01-01
Protein synthesis in the chloroplast is mediated by the chloroplast ribosome (chloro-ribosome). Overall architecture of the chloro-ribosome is considerably similar to the Escherichia coli (E. coli) ribosome but certain differences are evident. The chloro-ribosome proteins are generally larger because of the presence of chloroplast-specific extensions in their N- and C-termini. The chloro-ribosome harbours six plastid-specific ribosomal proteins (PSRPs); four in the small subunit and two in the large subunit. Deletions and insertions occur throughout the rRNA sequence of the chloro-ribosome (except for the conserved peptidyl transferase center region) but the overall length of the rRNAs do not change significantly, compared to the E. coli. Although, recent advancements in cryo-electron microscopy (cryo-EM) have provided detailed high-resolution structures of ribosomes from many different sources, a high-resolution structure of the chloro-ribosome is still lacking. Here, we present a cryo-EM structure of the large subunit of the chloro-ribosome from spinach (Spinacia oleracea) at an average resolution of 3.5 Å. High-resolution map enabled us to localize and model chloro-ribosome proteins, chloroplast-specific protein extensions, two PSRPs (PSRP5 and 6) and three rRNA molecules present in the chloro-ribosome. Although comparable to E. coli, the polypeptide tunnel and the tunnel exit site show chloroplast-specific features. PMID:27762343
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The social structure of microbial community involved in colonization resistance.
He, Xuesong; McLean, Jeffrey S; Guo, Lihong; Lux, Renate; Shi, Wenyuan
2014-03-01
It is well established that host-associated microbial communities can interfere with the colonization and establishment of microbes of foreign origins, a phenomenon often referred to as bacterial interference or colonization resistance. However, due to the complexity of the indigenous microbiota, it has been extremely difficult to elucidate the community colonization resistance mechanisms and identify the bacterial species involved. In a recent study, we have established an in vitro mice oral microbial community (O-mix) and demonstrated its colonization resistance against an Escherichia coli strain of mice gut origin. In this study, we further analyzed the community structure of the O-mix by using a dilution/regrowth approach and identified the bacterial species involved in colonization resistance against E. coli. Our results revealed that, within the O-mix there were three different types of bacterial species forming unique social structure. They act as 'Sensor', 'Mediator' and 'Killer', respectively, and have coordinated roles in initiating the antagonistic action and preventing the integration of E. coli. The functional role of each identified bacterial species was further confirmed by E. coli-specific responsiveness of the synthetic communities composed of different combination of the identified players. The study reveals for the first time the sophisticated structural and functional organization of a colonization resistance pathway within a microbial community. Furthermore, our results emphasize the importance of 'Facilitation' or positive interactions in the development of community-level functions, such as colonization resistance.
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Guy, Lionel; Jernberg, Cecilia; Arvén Norling, Jenny; Ivarsson, Sofie; Hedenström, Ingela; Melefors, Öjar; Liljedahl, Ulrika; Engstrand, Lars; Andersson, Siv G E
2013-01-01
The sequencing of highly virulent Escherichia coli O104:H4 strains isolated during the outbreak of bloody diarrhea and hemolytic uremic syndrome in Europe in 2011 revealed a genome that contained a Shiga toxin encoding prophage and a plasmid encoding enteroaggregative fimbriae. Here, we present the draft genome sequence of a strain isolated in Sweden from a patient who had travelled to Tunisia in 2010 (E112/10) and was found to differ from the outbreak strains by only 38 SNPs in non-repetitive regions, 16 of which were mapped to the branch to the outbreak strain. We identified putatively adaptive mutations in genes for transporters, outer surface proteins and enzymes involved in the metabolism of carbohydrates. A comparative analysis with other historical strains showed that E112/10 contained Shiga toxin prophage genes of the same genotype as the outbreak strain, while these genes have been replaced by a different genotype in two otherwise very closely related strains isolated in the Republic of Georgia in 2009. We also present the genome sequences of two enteroaggregative E. coli strains affiliated with phylogroup A (C43/90 and C48/93) that contain the agg genes for the AAF/I-type fimbriae characteristic of the outbreak population. Interestingly, C43/90 also contained a tet/mer antibiotic resistance island that was nearly identical in sequence to that of the outbreak strain, while the corresponding island in the Georgian strains was most similar to E. coli strains of other serotypes. We conclude that the pan-genome of the outbreak population is shared with strains of the A phylogroup and that its evolutionary history is littered with gene replacement events, including most recently independent acquisitions of antibiotic resistance genes in the outbreak strains and its nearest neighbors. The results are summarized in a refined evolutionary model for the emergence of the O104:H4 outbreak population.
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Guy, Lionel; Jernberg, Cecilia; Arvén Norling, Jenny; Ivarsson, Sofie; Hedenström, Ingela; Melefors, Öjar; Liljedahl, Ulrika; Engstrand, Lars; Andersson, Siv G. E.
2013-01-01
The sequencing of highly virulent Escherichia coli O104:H4 strains isolated during the outbreak of bloody diarrhea and hemolytic uremic syndrome in Europe in 2011 revealed a genome that contained a Shiga toxin encoding prophage and a plasmid encoding enteroaggregative fimbriae. Here, we present the draft genome sequence of a strain isolated in Sweden from a patient who had travelled to Tunisia in 2010 (E112/10) and was found to differ from the outbreak strains by only 38 SNPs in non-repetitive regions, 16 of which were mapped to the branch to the outbreak strain. We identified putatively adaptive mutations in genes for transporters, outer surface proteins and enzymes involved in the metabolism of carbohydrates. A comparative analysis with other historical strains showed that E112/10 contained Shiga toxin prophage genes of the same genotype as the outbreak strain, while these genes have been replaced by a different genotype in two otherwise very closely related strains isolated in the Republic of Georgia in 2009. We also present the genome sequences of two enteroaggregative E. coli strains affiliated with phylogroup A (C43/90 and C48/93) that contain the agg genes for the AAF/I-type fimbriae characteristic of the outbreak population. Interestingly, C43/90 also contained a tet/mer antibiotic resistance island that was nearly identical in sequence to that of the outbreak strain, while the corresponding island in the Georgian strains was most similar to E. coli strains of other serotypes. We conclude that the pan-genome of the outbreak population is shared with strains of the A phylogroup and that its evolutionary history is littered with gene replacement events, including most recently independent acquisitions of antibiotic resistance genes in the outbreak strains and its nearest neighbors. The results are summarized in a refined evolutionary model for the emergence of the O104:H4 outbreak population. PMID:23675451
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Baurhoo, B; Phillip, L; Ruiz-Feria, C A
2007-06-01
A study was conducted to evaluate lignin and mannan oligosaccharides as potential alternatives to antibiotic growth promoters in broilers. Dietary treatments included an antibiotic-free diet (CTL-), a positive control (CTL+, 11 mg/kg of virginiamycin), and an antibiotic-free diet containing BioMos (MOS, 0.2% to 21 d and 0.1% thereafter) or Alcell lignin at 1.25% (LL) or 2.5% (HL) of the diet. Each treatment was randomly assigned to 4 floor pen replicates (40 birds each). Body weight and feed conversion were recorded weekly throughout 42 d. Jejunum histology was analyzed at d 14, 28, and 42. At d 28 and 42, cecal contents were assayed for Escherichia coli, Salmonella, lactobacilli, and bifidobacteria, and the litter was analyzed for E. coli and Salmonella. Birds fed the CTL- diet were heavier (P<0.05) than those fed the other dietary treatments, but feed conversion was not affected by dietary treatments. Birds fed MOS and LL had increased jejunum villi height and a higher number of goblet cells per villus (P<0.05) when compared with those fed the CTL+ diet. At d 42, birds fed MOS, LL, or HL had greater lactobacilli numbers than those fed the CTL+ diet. Compared with the CTL+ diet, the MOS diet increased the populations of bifidobacteria (P<0.05) in the ceca. Litter E. coli load was lower in birds fed MOS (P<0.05) than in birds fed the CTL+ diet but comparable to that of birds fed the LL or HL diet. Broiler performance was similar in birds fed antibiotics or antibiotic-free diets containing either MOS or lignin. However, birds fed MOS and LL had a comparative advantage over birds fed antibiotics as evidenced by an increased population of beneficial bacteria in the ceca, increased villi height and number of goblet cells in the jejunum, and lower population of E. coli in the litter.
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Cranberry xyloglucan structure and inhibition of Escherichia coli adhesion to epithelial cells
USDA-ARS?s Scientific Manuscript database
Cranberry juice has been used to treat urinary tract infections based on scientific reports of proanthocyanidin anti-adhesion activity for Escherichia coli as well as folklore. Xyloglucan oligosaccharides were also detected in cranberry juice and the pulp remaining following commercial juice extract...
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Ikram, Rosemary; Psutka, Rebecca; Carter, Alison; Priest, Patricia
2015-06-09
Prevention of infection due to multi-drug resistant organisms is particularly challenging because of the spread of resistant bacteria beyond hospitals into the community, including nursing homes. This study aimed to identify risk factors for the acquisition of a multidrug resistant (MDR) Escherichia coli in a local outbreak. Study participants were all aged over 65 years. Cases had the MDR E. coli isolated from a routine urine sample, and controls had a urine sample submitted to the laboratory in the same time period but the MDR E. coli was not isolated. Information from clinical records was used to identify risk factors both in the hospital and the community setting for acquisition of the MDR E. coli. 76 cases and 156 controls were identified and included in the study. In a multivariate analysis, risk factors statistically significantly associated with acquisition of the MDR E. coli were female gender (adjusted OR 3.2; 95 % confidence interval 1.5-6.9), level of care (high dependency OR 7.5; 2.2-25.7) compared with living independently), and in hospital prescription of antimicrobials to which the MDR E. coli was resistant (OR 5.6; 2.5-12.9). The major risk factors for the acquisition of a MDR E. coli were found to be residence in a nursing home and in-hospital prescription of antimicrobials to which the MDR E. coli was resistant. This emphasises that prevention of transmission of MDROs within a community needs to involve both hospitals and also other healthcare organizations, in this case nursing homes.
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Yori, Pablo Peñataro; Rouhani, Saba; Siguas Salas, Mery; Paredes Olortegui, Maribel; Rengifo Trigoso, Dixner; Pisanic, Nora; Burga, Rosa; Meza, Rina; Meza Sanchez, Graciela; Gregory, Michael J.; Houpt, Eric R.; Platts-Mills, James A.; Kosek, Margaret N.
2018-01-01
Background Campylobacter is one of the main causes of gastroenteritis worldwide. Most of the current knowledge about the epidemiology of this food-borne infection concerns two species, C. coli and C. jejuni. Recent studies conducted in developing countries and using novel diagnostic techniques have generated evidence of the increasing burden and importance of other Campylobacter species, i.e. non-C. coli/jejuni. We performed a nested case-control study to compare the prevalence of C. coli/jejuni and other Campylobacter in children with clinical dysentery and severe diarrhea as well as without diarrhea to better understand the clinical importance of infections with Campylobacter species other than C. coli/jejuni. Methodology/Principal findings Our nested case-control study of 439 stool samples included dysenteric stools, stools collected during severe diarrhea episodes, and asymptomatic stools which were systematically selected to be representative of clinical phenotypes from 9,160 stools collected during a birth cohort study of 201 children followed until two years of age. Other Campylobacter accounted for 76.4% of the 216 Campylobacter detections by qPCR and were more prevalent than C. coli/jejuni across all clinical groups. Other Campylobacter were also more prevalent than C. coli/jejuni across all age groups, with older children bearing a higher burden of other Campylobacter. Biomarkers of intestinal inflammation and injury (methylene blue, fecal occult test, myeloperoxidase or MPO) showed a strong association with dysentery, but mixed results with infection. MPO levels were generally higher among children infected with C. coli/jejuni, but Shigella-infected children suffering from dysentery recorded the highest levels (26,224 ng/mL); the lowest levels (10,625 ng/mL) were among asymptomatic children infected with other Campylobacter. Adjusting for age, sex, and Shigella infection, dysentery was significantly associated with C. coli/jejuni but not with other Campylobacter, whereas severe diarrhea was significantly associated with both C. coli/jejuni and other Campylobacter. Compared to asymptomatic children, children suffering from dysentery had a 14.6 odds of C. coli/jejuni infection (p-value < 0.001, 95% CI 5.5–38.7) but were equally likely to have other Campylobacter infections–odds ratio of 1.3 (0.434, 0.7–2.4). Children suffering from severe diarrhea were more likely than asymptomatic children to test positive for both C. coli/jejuni and other Campylobacter–OR of 2.8 (0.034, 1.1–7.1) and 1.9 (0.018, 1.1–3.1), respectively. Compared to the Campylobacter-free group, the odds of all diarrhea given C. coli/jejuni infection and other Campylobacter infection were 8.8 (<0.001, 3.0–25.7) and 2.4 (0.002, 1.4–4.2), respectively. Eliminating other Campylobacter in this population would eliminate 24.9% of the diarrhea cases, which is almost twice the population attributable fraction of 15.1% due to C. coli/jejuni. Conclusions/Significance Eighty-seven percent of the dysentery and 59.5% of the severe diarrhea samples were positive for Campylobacter, Shigella, or both, emphasizing the importance of targeting these pathogens to limit the impact of dysentery and severe diarrhea in children. Notably, the higher prevalence of other Campylobacter compared to C. coli/jejuni, their increasing burden during early childhood, and their association with severe diarrhea highlight the importance of these non-C. coli/jejuni Campylobacter species and suggest a need to clarify their importance in the etiology of clinical disease across different epidemiological contexts. PMID:29415075
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François, Ruthly; Yori, Pablo Peñataro; Rouhani, Saba; Siguas Salas, Mery; Paredes Olortegui, Maribel; Rengifo Trigoso, Dixner; Pisanic, Nora; Burga, Rosa; Meza, Rina; Meza Sanchez, Graciela; Gregory, Michael J; Houpt, Eric R; Platts-Mills, James A; Kosek, Margaret N
2018-02-01
Campylobacter is one of the main causes of gastroenteritis worldwide. Most of the current knowledge about the epidemiology of this food-borne infection concerns two species, C. coli and C. jejuni. Recent studies conducted in developing countries and using novel diagnostic techniques have generated evidence of the increasing burden and importance of other Campylobacter species, i.e. non-C. coli/jejuni. We performed a nested case-control study to compare the prevalence of C. coli/jejuni and other Campylobacter in children with clinical dysentery and severe diarrhea as well as without diarrhea to better understand the clinical importance of infections with Campylobacter species other than C. coli/jejuni. Our nested case-control study of 439 stool samples included dysenteric stools, stools collected during severe diarrhea episodes, and asymptomatic stools which were systematically selected to be representative of clinical phenotypes from 9,160 stools collected during a birth cohort study of 201 children followed until two years of age. Other Campylobacter accounted for 76.4% of the 216 Campylobacter detections by qPCR and were more prevalent than C. coli/jejuni across all clinical groups. Other Campylobacter were also more prevalent than C. coli/jejuni across all age groups, with older children bearing a higher burden of other Campylobacter. Biomarkers of intestinal inflammation and injury (methylene blue, fecal occult test, myeloperoxidase or MPO) showed a strong association with dysentery, but mixed results with infection. MPO levels were generally higher among children infected with C. coli/jejuni, but Shigella-infected children suffering from dysentery recorded the highest levels (26,224 ng/mL); the lowest levels (10,625 ng/mL) were among asymptomatic children infected with other Campylobacter. Adjusting for age, sex, and Shigella infection, dysentery was significantly associated with C. coli/jejuni but not with other Campylobacter, whereas severe diarrhea was significantly associated with both C. coli/jejuni and other Campylobacter. Compared to asymptomatic children, children suffering from dysentery had a 14.6 odds of C. coli/jejuni infection (p-value < 0.001, 95% CI 5.5-38.7) but were equally likely to have other Campylobacter infections-odds ratio of 1.3 (0.434, 0.7-2.4). Children suffering from severe diarrhea were more likely than asymptomatic children to test positive for both C. coli/jejuni and other Campylobacter-OR of 2.8 (0.034, 1.1-7.1) and 1.9 (0.018, 1.1-3.1), respectively. Compared to the Campylobacter-free group, the odds of all diarrhea given C. coli/jejuni infection and other Campylobacter infection were 8.8 (<0.001, 3.0-25.7) and 2.4 (0.002, 1.4-4.2), respectively. Eliminating other Campylobacter in this population would eliminate 24.9% of the diarrhea cases, which is almost twice the population attributable fraction of 15.1% due to C. coli/jejuni. Eighty-seven percent of the dysentery and 59.5% of the severe diarrhea samples were positive for Campylobacter, Shigella, or both, emphasizing the importance of targeting these pathogens to limit the impact of dysentery and severe diarrhea in children. Notably, the higher prevalence of other Campylobacter compared to C. coli/jejuni, their increasing burden during early childhood, and their association with severe diarrhea highlight the importance of these non-C. coli/jejuni Campylobacter species and suggest a need to clarify their importance in the etiology of clinical disease across different epidemiological contexts.
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Dynamics of Reactive Microbial Hotspots in Concentration Gradient.
NASA Astrophysics Data System (ADS)
Hubert, A.; Farasin, J.; Tabuteau, H.; Dufresne, A.; Meheust, Y.; Le Borgne, T.
2017-12-01
In subsurface environments, bacteria play a major role in controlling the kinetics of a broad range of biogeochemical reactions. In such environments, nutrients fluxes and solute concentrations needed for bacteria metabolism may be highly variable in space and intermittent in time. This can lead to the formation of reactive hotspots where and when conditions are favorable to particular microorganisms, hence inducing biogeochemical reaction kinetics that differ significantly from those measured in homogeneous model environments. To investigate the impact of chemical gradients on the spatial structure and temporal dynamics of subsurface microorganism populations, we develop microfluidic cells allowing for a precise control of flow and chemical gradient conditions, as well as quantitative monitoring of the bacteria's spatial distribution and biofilm development. Using the non-motile Escherichia coli JW1908-1 strain and Gallionella capsiferriformans ES-2 as model organisms, we investigate the behavior and development of bacteria over a range of single and double concentration gradients in the concentrations of nutrients, electron donors and electron acceptors. We measure bacterial activity and population growth locally in precisely known hydrodynamic and chemical environments. This approach allows time-resolved monitoring of the location and intensity of reactive hotspots in micromodels as a function of the flow and chemical gradient conditions. We compare reactive microbial hotspot dynamics in our micromodels to classic growth laws and well-known growth parameters for the laboratory model bacteria Escherichia coli.We also discuss consequences for the formation and temporal dynamics of biofilms in the subsurface.
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Energetic Coupling between Ligand Binding and Dimerization in E. coli Phosphoglycerate Mutase
Gardner, Nathan W.; Monroe, Lyman K.; Kihara, Daisuke; Park, Chiwook
2016-01-01
Energetic coupling of two molecular events in a protein molecule is ubiquitous in biochemical reactions mediated by proteins, such as catalysis and signal transduction. Here, we investigate energetic coupling between ligand binding and folding of a dimer using a model system that shows three-state equilibrium unfolding in an exceptional quality. The homodimeric E. coli cofactor-dependent phosphoglycerate mutase (dPGM) was found to be stabilized by ATP in a proteome-wide screen, although dPGM does not require or utilize ATP for enzymatic function. We investigated the effect of ATP on the thermodynamic stability of dPGM using equilibrium unfolding. In the absence of ATP, dPGM populates a partially unfolded, monomeric intermediate during equilibrium unfolding. However, addition of 1.0 mM ATP drastically reduces the population of the intermediate by selectively stabilizing the native dimer. Using a computational ligand docking method, we predicted ATP binds to the active site of the enzyme using the triphosphate group. By performing equilibrium unfolding and isothermal titration calorimetry with active-site variants of dPGM, we confirmed that active-site residues are involved in ATP binding. Our findings show that ATP promotes dimerization of the protein by binding to the active site, which is distal from the dimer interface. This cooperativity suggests an energetic coupling between the active-site and the dimer interface. We also propose a structural link to explain how ligand binding to the active site is energetically coupled with dimerization. PMID:26919584
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Fuma, Shoichi; Kawaguchi, Isao; Kubota, Yoshihisa; Yoshida, Satoshi; Kawabata, Zen'ichiro; Polikarpov, Gennady G
2012-02-01
Effects of chronic γ-irradiation were investigated in the aquatic microcosm consisting of flagellate algae Euglena gracilis as producers, ciliate protozoa Tetrahymena thermophila as consumers and bacteria Escherichia coli as decomposers. At 1.1 Gy day(-1), no effects were observed. At 5.1 Gy day(-1), cell densities of E. coli showed a tendency to be lower than those of controls. At 9.7 and 24.7 Gy day(-1), population decrease was observed in E. coli. E. gracilis and T. thermophila died out after temporal population decrease and subsequent population increase in T. thermophila. It is likely that this temporal population increase was an indirect effect due to interspecies interactions. Effect dose rates of γ-rays were compared with effect concentrations of some metals using the radiochemoecological conceptual model and the effect index for microcosm. Comparison of these community-level effects data with environmental exposure data suggests that ionising radiation, gadolinium and dysprosium have low risks to affect aquatic microbial communities while manganese, nickel and copper have considerable risks. Effects of chronic irradiation were smaller than those of acute irradiation, and an acute to chronic ratio was calculated to be 28 by dividing an acute dose by chronic daily dose rate at which the effect index was 10%. This ratio would be useful for community-level extrapolation from acute to chronic radiation effects. Copyright © 2011 Elsevier Ltd. All rights reserved.
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Santos, M V; Zaritzky, N; Califano, A
2008-07-01
The presence of Escherichia coli is linked with sanitary deficiencies and undercooking of meat products. Recent studies have detected E. coli O157:H7 in black blood sausages. Minimum time-temperature specifications to kill the bacteria were obtained by numerical simulations of the microscopic heat conduction equation using the finite element method, and calculating the temperature profile of the sausage and the population of E. coli at the coldest point during heating. The model was validated by heating sausages in a water-bath. The effects of heat transfer coefficients and water temperatures on the required time to achieve an inactivation value (IV) of 12(log) are reported. Macroscopic heat balances were simultaneously solved to consider the temperature drop in the water batch as a function of the ratio between the mass of thermally treated sausage and the heat capacity of the system.
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NASA Astrophysics Data System (ADS)
Suhartono, S.; Ismail, Y. S.; Yulvizar, C.; Nursanty, R.; Mahyuddin, M.; Jannah, M.
2018-03-01
Of aquatic environment, antibiotic resistant bacteria, including total coliforms and E. coli disseminate and emerge at an alarming rate. The study aims to determine enumerate, isolate,E. coliand determine their antibiotic resistance and compare between those which were recovered from residentials and home industries in Banda Aceh and its surrounding area. The bacterial density and antibiotic susceptibility of total coliforms and E. coli were determined using Standard Total Coliform Multiple-Tube (MPN) Fermentation method and the disk diffusion method, respectively. Despite there was no significant difference of total coliforms and E. coli population between residentials and home industries (P > 0.05) in this study, their density as well as prevalence remained high in the water sample. This might expose serious health risks since the resistance might be easily spread acquired through horizontal gene transfer within the aquatic environment.
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Bamford, Vicki A; Armour, Maria; Mitchell, Sue A; Cartron, Michaël; Andrews, Simon C; Watson, Kimberly A
2008-09-01
YqjH is a cytoplasmic FAD-containing protein from Escherichia coli; based on homology to ViuB of Vibrio cholerae, it potentially acts as a ferri-siderophore reductase. This work describes its overexpression, purification, crystallization and structure solution at 3.0 A resolution. YqjH shares high sequence similarity with a number of known siderophore-interacting proteins and its structure was solved by molecular replacement using the siderophore-interacting protein from Shewanella putrefaciens as the search model. The YqjH structure resembles those of other members of the NAD(P)H:flavin oxidoreductase superfamily.
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1.8 Astroms Structure of Murine GITR Ligand Dimer Expressed in Drosophila Melanogaster S2 Cells
DOE Office of Scientific and Technical Information (OSTI.GOV)
Chattopadhyay, K.; Ramagopal, U; Nathenson, S
2009-01-01
Glucocorticoid-induced TNF receptor ligand (GITRL), a prominent member of the TNF superfamily, activates its receptor on both effector and regulatory T cells to generate critical costimulatory signals that have been implicated in a wide range of T-cell immune functions. The crystal structures of murine and human orthologs of GITRL recombinantly expressed in Escherichia coli have previously been determined. In contrast to all classical TNF structures, including the human GITRL structure, murine GITRL demonstrated a unique 'strand-exchanged' dimeric organization. Such a novel assembly behavior indicated a dramatic impact on receptor activation as well as on the signaling mechanism associated with themore » murine GITRL costimulatory system. In this present work, the 1.8 {angstrom} resolution crystal structure of murine GITRL expressed in Drosophila melanogaster S2 cells is reported. The eukaryotic protein-expression system allows transport of the recombinant protein into the extracellular culture medium, thus maximizing the possibility of obtaining correctly folded material devoid of any folding/assembly artifacts that are often suspected with E. coli-expressed proteins. The S2 cell-expressed murine GITRL adopts an identical 'strand-exchanged' dimeric structure to that observed for the E. coli-expressed protein, thus conclusively demonstrating the novel quaternary structure assembly behavior of murine GITRL.« less
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Byappanahalli, Muruleedhara N.; Roll, Bruce M.; Fujioka, Roger S.
2012-01-01
High densities of Escherichia coli and enterococci are common in freshwaters on Oahu and other Hawaiian Islands. Soil along stream banks has long been suspected as the likely source of these bacteria; however, the extent of their occurrence and distribution in a wide range of soils remained unknown until the current investigation. Soil samples representing the seven major soil associations were collected on the island of Oahu and analyzed for fecal coliforms, E. coli, and enterococci by the most probable number method. Fecal coliforms, E. coli, and enterococci were found in most of the samples analyzed; log mean densities (MPN ± SE g soil−1) were 1.96±0.18, n=61; 1.21±0.17, n=57; and 2.99±0.12, n=62, respectively. Representative, presumptive cultures of E. coli and enterococci collected from the various soils were identified and further speciated using the API scheme; at least six species of Enterococcus, including Enterococcus faecalis and Enterococcus faecium, were identified. In mesocosm studies, E. coli and enterococci increased by 100-fold in 4 days, after mixing sewage-spiked soil (one part) with autoclaved soil (nine parts). E. coli remained metabolically active in the soil and readily responded to nutrients, as evidenced by increased dehydrogenase activity. Collectively, these findings indicate that populations of E. coli and enterococci are part of the natural soil microflora, potentially influencing the quality of nearby water bodies.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Domingo Meza-Aguilar, J.; Laboratorio de Patogenicidad Bacteriana, Unidad de Hemato Oncología e Investigación, Hospital Infantil de México Federico Gómez 06720, D.F.; Fromme, Petra
Highlights: • X-ray crystal structure of the passenger domain of Plasmid encoded toxin at 2.3 Å. • Structural differences between Pet passenger domain and EspP protein are described. • High flexibility of the C-terminal beta helix is structurally assigned. - Abstract: Autotransporters (ATs) represent a superfamily of proteins produced by a variety of pathogenic bacteria, which include the pathogenic groups of Escherichia coli (E. coli) associated with gastrointestinal and urinary tract infections. We present the first X-ray structure of the passenger domain from the Plasmid-encoded toxin (Pet) a 100 kDa protein at 2.3 Å resolution which is a cause ofmore » acute diarrhea in both developing and industrialized countries. Pet is a cytoskeleton-altering toxin that induces loss of actin stress fibers. While Pet (pdb code: 4OM9) shows only a sequence identity of 50% compared to the closest related protein sequence, extracellular serine protease plasmid (EspP) the structural features of both proteins are conserved. A closer structural look reveals that Pet contains a β-pleaded sheet at the sequence region of residues 181–190, the corresponding structural domain in EspP consists of a coiled loop. Secondary, the Pet passenger domain features a more pronounced beta sheet between residues 135 and 143 compared to the structure of EspP.« less
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Quantitative high-throughput population dynamics in continuous-culture by automated microscopy.
Merritt, Jason; Kuehn, Seppe
2016-09-12
We present a high-throughput method to measure abundance dynamics in microbial communities sustained in continuous-culture. Our method uses custom epi-fluorescence microscopes to automatically image single cells drawn from a continuously-cultured population while precisely controlling culture conditions. For clonal populations of Escherichia coli our instrument reveals history-dependent resilience and growth rate dependent aggregation.
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Microbiological quality of raw and processed wild and cultured edible snails.
Parlapani, Foteini F; Neofitou, Christos; Boziaris, Ioannis S
2014-03-15
An increasing interest in snail farming in Greece and other European countries has been observed. Despite the fact that edible snails have been involved with problems of Salmonella spp. contamination, there are to our knowledge only limited studies regarding microbiological safety and hygiene of such products. Enumeration of microbial populations and presence/absence of Salmonella spp. in snail meat and intestines of wild Cornu aspersum, Helix lucorum and cultured Cornu aspersum snails from indoor/outdoor type farms was conducted. Furthermore, snail-processing steps were simulated in the laboratory and the population reduction in snail meat was determined. Microbial populations were higher in intestines than snail meat in almost all cases. Escherichia coli/coliforms and Enterococcus spp. populations were lower in the intestines and snail meat of cultured C. aspersum. Salmonella spp. were detected in the intestines and snail meat of wild snails only. The high levels of bacterial populations were considerably reduced after the appropriate processing. The lower populations of E. coli/coliforms, Enterococcus spp. and especially the absence of Salmonella spp. in cultured snails show that the controlled conditions decrease the possibility of pathogen presence and contribute to food safety and public health. © 2013 Society of Chemical Industry.
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Merino, Irene; Shaw, Evelyn; Horcajada, Juan Pablo; Cercenado, Emilia; Mirelis, Beatriz; Pallarés, M Angeles; Gómez, Juliá; Xercavins, M; Martínez-Martínez, Luis; De Cueto, Marina; Cantón, Rafael; Ruiz-Garbajosa, Patricia
2016-08-01
The objective of this study was to assess the prevalence and molecular epidemiology of ESBL-producing Escherichia coli causing healthcare-associated (HCA) and community-associated (CA) bacteraemia of urinary origin (BUO) in Spain. An observational cohort study was conducted at eight hospitals from different Spanish geographical areas (2010-11). BUO episodes (n = 425) were classified as HCA (n = 215) and CA (n = 210), and one blood isolate per episode was collected. Susceptibility testing was performed, ESBLs were screened by double-disc diffusion test and ESBL and OXA-1 genes were characterized (PCR and sequencing). Population structure (phylogenetic groups, XbaI-PFGE and MLST) and ST131 subtyping (PCR) were determined. Virulence genes were detected by PCR and virulence score, profiles and extraintestinal pathogenic E. coli (ExPEC) status calculated. ESBL-producing E. coli prevalence was 9.2% (39/425). ESBL-producing E. coli episodes were significantly associated with HCA-BUO episodes [14% (30/215) versus 4.3% (9/210); P = 0.001]. The highest non-susceptibility proportions corresponded to ciprofloxacin (97.4%), amoxicillin/clavulanate (74.4%), co-trimoxazole (69.2%) and tobramycin (61.5%). Of the 39 ESBL-producing E. coli isolates, 34 produced CTX-M enzymes (21 CTX-M-15, 11 CTX-M-14 and 2 CTX-M-1). Fifteen STs were identified, the B2-ST131 clone being the most prevalent (54%; 21/39). All ST131 isolates were ExPEC and had the highest virulence scores, but they showed less diversity in virulence profiles than other STs. The H30Rx subclone accounted for most ST131 isolates (20/21), co-produced CTX-M-15 (20/20) and OXA-1 (19/20) enzymes and was associated with HCA episodes (16/20). The CTX-M-15-ST131-H30Rx subclone is a relevant MDR pathogen causing BUO, mainly HCA episodes. The dominance of this subclone with comparatively less diversity of virulence profiles reflects the spread of a successful and MDR ESBL ST131 lineage in Spain. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
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Ekmekciu, Ira; von Klitzing, Eliane; Neumann, Christian; Bacher, Petra; Scheffold, Alexander; Bereswill, Stefan; Heimesaat, Markus M
2017-01-01
The essential role of the intestinal microbiota in the well-functioning of host immunity necessitates the investigation of species-specific impacts on this interplay. Aim of this study was to examine the ability of defined Gram-positive and Gram-negative intestinal commensal bacterial species, namely Escherichia coli and Lactobacillus johnsonii , respectively, to restore immune functions in mice that were immunosuppressed by antibiotics-induced microbiota depletion. Conventional mice were subjected to broad-spectrum antibiotic treatment for 8 weeks and perorally reassociated with E. coli , L. johnsonii or with a complex murine microbiota by fecal microbiota transplantation (FMT). Analyses at days (d) 7 and 28 revealed that immune cell populations in the small and large intestines, mesenteric lymph nodes and spleens of mice were decreased after antibiotic treatment but were completely or at least partially restored upon FMT or by recolonization with the respective bacterial species. Remarkably, L. johnsonii recolonization resulted in the highest CD4+ and CD8+ cell numbers in the small intestine and spleen, whereas neither of the commensal species could stably restore those cell populations in the colon until d28. Meanwhile less efficient than FMT, both species increased the frequencies of regulatory T cells and activated dendritic cells and completely restored intestinal memory/effector T cell populations at d28. Furthermore, recolonization with either single species maintained pro- and anti-inflammatory immune functions in parallel. However, FMT could most effectively recover the decreased frequencies of cytokine producing CD4+ lymphocytes in mucosal and systemic compartments. E. coli recolonization increased the production of cytokines such as TNF, IFN-γ, IL-17, and IL-22, particularly in the small intestine. Conversely, only L. johnsonii recolonization maintained colonic IL-10 production. In summary, FMT appears to be most efficient in the restoration of antibiotics-induced collateral damages to the immune system. However, defined intestinal commensals such as E. coli and L. johnsonii have the potential to restore individual functions of intestinal and systemic immunity. In conclusion, our data provide novel insights into the distinct role of individual commensal bacteria in maintaining immune functions during/following dysbiosis induced by antibiotic therapy thereby shaping host immunity and might thus open novel therapeutical avenues in conditions of perturbed microbiota composition.
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Ekmekciu, Ira; von Klitzing, Eliane; Neumann, Christian; Bacher, Petra; Scheffold, Alexander; Bereswill, Stefan; Heimesaat, Markus M.
2017-01-01
The essential role of the intestinal microbiota in the well-functioning of host immunity necessitates the investigation of species-specific impacts on this interplay. Aim of this study was to examine the ability of defined Gram-positive and Gram-negative intestinal commensal bacterial species, namely Escherichia coli and Lactobacillus johnsonii, respectively, to restore immune functions in mice that were immunosuppressed by antibiotics-induced microbiota depletion. Conventional mice were subjected to broad-spectrum antibiotic treatment for 8 weeks and perorally reassociated with E. coli, L. johnsonii or with a complex murine microbiota by fecal microbiota transplantation (FMT). Analyses at days (d) 7 and 28 revealed that immune cell populations in the small and large intestines, mesenteric lymph nodes and spleens of mice were decreased after antibiotic treatment but were completely or at least partially restored upon FMT or by recolonization with the respective bacterial species. Remarkably, L. johnsonii recolonization resulted in the highest CD4+ and CD8+ cell numbers in the small intestine and spleen, whereas neither of the commensal species could stably restore those cell populations in the colon until d28. Meanwhile less efficient than FMT, both species increased the frequencies of regulatory T cells and activated dendritic cells and completely restored intestinal memory/effector T cell populations at d28. Furthermore, recolonization with either single species maintained pro- and anti-inflammatory immune functions in parallel. However, FMT could most effectively recover the decreased frequencies of cytokine producing CD4+ lymphocytes in mucosal and systemic compartments. E. coli recolonization increased the production of cytokines such as TNF, IFN-γ, IL-17, and IL-22, particularly in the small intestine. Conversely, only L. johnsonii recolonization maintained colonic IL-10 production. In summary, FMT appears to be most efficient in the restoration of antibiotics-induced collateral damages to the immune system. However, defined intestinal commensals such as E. coli and L. johnsonii have the potential to restore individual functions of intestinal and systemic immunity. In conclusion, our data provide novel insights into the distinct role of individual commensal bacteria in maintaining immune functions during/following dysbiosis induced by antibiotic therapy thereby shaping host immunity and might thus open novel therapeutical avenues in conditions of perturbed microbiota composition. PMID:29321764
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2016-06-01
Effective antimicrobial intervention strategies to reduce Shiga toxin-producing Escherichia coli (STEC) risks associated with veal are needed. This study evaluated the efficacy of lactic acid (4.5%, pH 2.0), Citrilow (pH 1.2), and Beefxide (2.25%, pH 2.3) for reducing STEC surrogates on prerigor and chilled bob veal carcasses and monitored the effects of these interventions on chilled carcass color. Dehided bob veal carcasses were inoculated with a five-strain cocktail of rifampin-resistant, surrogate E. coli bacteria.E. coli surrogates were enumerated after inoculation, after water wash, after prechill carcass antimicrobial spray application, after chilling for 24 h, and after postchill carcass antimicrobial spray application; carcass color was measured throughout the process. A standard carcass water wash (∼50°C) reduced the STEC surrogate population by 0.9 log CFU/cm(2) (P ≤ 0.05). All three antimicrobial sprays applied to prerigor carcasses delivered an additional ∼0.5-log reduction (P ≤ 0.05) of the surrogates. Chilling of carcasses for 24 h reduced (P ≤ 0.05) the surrogate population by an additional ∼0.4 log cycles. The postchill application of the antimicrobial sprays provided no further reductions. Carcass L*, a*, and b* color values were not different (P > 0.05) among carcass treatments. Generally, the types and concentrations of the antimicrobial sprays evaluated herein did not negatively impact visual or instrumental color of chilled veal carcasses. This study demonstrates that warm water washing, followed by a prechill spray treatment with a low-pH chemical intervention, can effectively reduce STEC risks associated with veal carcasses; this provides processors a validated control point in slaughter operations.
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Cell division in Escherichia coli cultures monitored at single cell resolution
Roostalu, Johanna; Jõers, Arvi; Luidalepp, Hannes; Kaldalu, Niilo; Tenson, Tanel
2008-01-01
Background A fundamental characteristic of cells is the ability to divide. To date, most parameters of bacterial cultures, including cell division, have been measured as cell population averages, assuming that all bacteria divide at a uniform rate. Results We monitored the division of individual cells in Escherichia coli cultures during different growth phases. Our experiments are based on the dilution of green fluorescent protein (GFP) upon cell division, monitored by flow cytometry. The results show that the vast majority of E. coli cells in exponentially growing cultures divided uniformly. In cultures that had been in stationary phase up to four days, no cell division was observed. However, upon dilution of stationary phase culture into fresh medium, two subpopulations of cells emerged: one that started dividing and another that did not. These populations were detectable by GFP dilution and displayed different side scatter parameters in flow cytometry. Further analysis showed that bacteria in the non-growing subpopulation were not dead, neither was the difference in growth capacity reducible to differences in stationary phase-specific gene expression since we observed uniform expression of several stress-related promoters. The presence of non-growing persisters, temporarily dormant bacteria that are tolerant to antibiotics, has previously been described within growing bacterial populations. Using the GFP dilution method combined with cell sorting, we showed that ampicillin lyses growing bacteria while non-growing bacteria retain viability and that some of them restart growth after the ampicillin is removed. Thus, our method enables persisters to be monitored even in liquid cultures of wild type strains in which persister formation has low frequency. Conclusion In principle, the approaches developed here could be used to detect differences in cell division in response to different environmental conditions and in cultures of unicellular organisms other than E. coli. PMID:18430255
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Venkitanarayanan, K S; Ezeike, G O; Hung, Y C; Doyle, M P
1999-08-01
One milliliter of culture containing a five-strain mixture of Escherichia coli O157:H7 (approximately 10(10) CFU) was inoculated on a 100-cm2 area marked on unscarred cutting boards. Following inoculation, the boards were air-dried under a laminar flow hood for 1 h, immersed in 2 liters of electrolyzed oxidizing water or sterile deionized water at 23 degrees C or 35 degrees C for 10 or 20 min; 45 degrees C for 5 or 10 min; or 55 degrees C for 5 min. After each temperature-time combination, the surviving population of the pathogen on cutting boards and in soaking water was determined. Soaking of inoculated cutting boards in electrolyzed oxidizing water reduced E. coli O157:H7 populations by > or = 5.0 log CFU/100 cm2 on cutting boards. However, immersion of cutting boards in deionized water decreased the pathogen count only by 1.0 to 1.5 log CFU/100 cm2. Treatment of cutting boards inoculated with Listeria monocytogenes in electrolyzed oxidizing water at selected temperature-time combinations (23 degrees C for 20 min, 35 degrees C for 10 min, and 45 degrees C for 10 min) substantially reduced the populations of L. monocytogenes in comparison to the counts recovered from the boards immersed in deionized water. E. coli O157:H7 and L. monocytogenes were not detected in electrolyzed oxidizing water after soaking treatment, whereas the pathogens survived in the deionized water used for soaking the cutting boards. This study revealed that immersion of kitchen cutting boards in electrolyzed oxidizing water could be used as an effective method for inactivating foodborne pathogens on smooth, plastic cutting boards.
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Song, M K; Kim, H W; Rhee, M S
2016-06-01
We previously reported that a combination of heat and relative humidity (RH) had a marked bactericidal effect on Escherichia coli O157:H7 on radish seeds. Here, response surface methodology with a Box-Behnken design was used to build a model to predict reductions in E. coli O157:H7 populations based on three independent variables: heating temperature (55 °C, 60 °C, or 65 °C), RH (40%, 60%, and 80%), and holding time (8, 15, or 22 h). Optimum treatment conditions were selected using a desirability function. The predictive model for microbial reduction had a high regression coefficient (R(2) = 0.97), and the accuracy of the model was verified using validation data (R(2) = 0.95). Among the three variables examined, heating temperature (P < 0.0001) and RH (P = 0.004) were the most significant in terms of bacterial reduction and seed germination, respectively. The optimum conditions for microbial reduction (6.6 log reduction) determined by ridge analysis were as follows: 64.5 °C and 63.2% RH for 17.7 h. However, when both microbial reduction and germination rate were taken into consideration, the desirability function yielded optimal conditions of 65 °C and 40% RH for 8 h (6.6 log reduction in the bacterial population; 94.4% of seeds germinated). This study provides comprehensive data that improve our understanding of the effects of heating temperature, RH, and holding time on the E. coli O157:H7 population on radish seeds. Radish seeds can be exposed to these conditions before sprouting, which greatly increases the microbiological safety of the products. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Wang, Xueying; Gautam, Raju; Pinedo, Pablo J; Allen, Linda J S; Ivanek, Renata
2014-08-01
Many infectious agents transmitting through a contaminated environment are able to persist in the environment depending on the temperature and sanitation determined rates of their replication and clearance, respectively. There is a need to elucidate the effect of these factors on the infection transmission dynamics in terms of infection outbreaks and extinction while accounting for the random nature of the process. Also, it is important to distinguish between the true and apparent extinction, where the former means pathogen extinction in both the host and the environment while the latter means extinction only in the host population. This study proposes a stochastic-differential equation model as an approximation to a Markov jump process model, using Escherichia coli O157:H7 in cattle as a model system. In the model, the host population infection dynamics are described using the standard susceptible-infected-susceptible framework, and the E. coli O157:H7 population in the environment is represented by an additional variable. The backward Kolmogorov equations that determine the probability distribution and the expectation of the first passage time are provided in a general setting. The outbreak and apparent extinction of infection are investigated by numerically solving the Kolmogorov equations for the probability density function of the associated process and the expectation of the associated stopping time. The results provide insight into E. coli O157:H7 transmission and apparent extinction, and suggest ways for controlling the spread of infection in a cattle herd. Specifically, this study highlights the importance of ambient temperature and sanitation, especially during summer.
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Holliday, S L; Scouten, A J; Beuchat, L R
2001-10-01
Alfalfa seeds are sometimes subjected to a scarification treatment to enhance water uptake, which results in more rapid and uniform germination during sprout production. It has been hypothesized that this mechanical abrasion treatment diminishes the efficacy of chemical treatments used to kill or remove pathogenic bacteria from seeds. A study was done to compare the effectiveness of chlorine (20,000 ppm), H2O, (8%), Ca(OH)2 (1%), Ca(OH)2 (1%) plus Tween 80 (1%), and Ca(OH)2 (1%) plus Span 20 (1%) treatments in killing Salmonella and Escherichia coli O157:H7 inoculated onto control, scarified, and polished alfalfa seeds obtained from two suppliers. The influence of the presence of organic material in the inoculum carrier on the efficacy of sanitizers was investigated. Overall, treatment with 1% Ca(OH)2 was the most effective in reducing populations of the pathogens. Reduction in populations of pathogens on seeds obtained from supplier I indicate that chemical treatments are less efficacious in eliminating the pathogens on scarified seeds compared to control seeds. However, the effectiveness of chemical treatment in removing Salmonella and E. coli O157:H7 from seeds obtained from supplier 2 was not markedly affected by scarification or polishing. The presence of organic material in the inoculum carrier did not have a marked influence on the efficacy of chemicals in reducing populations of test pathogens. Additional lots of control, scarified, and polished alfalfa seeds of additional varieties need to be tested before conclusions can be drawn concerning the impact of mechanical abrasion on the efficacy of chemical treatment in removing or killing Salmonella and E. coli O157:H7.
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Stochastic Switching Induced Adaptation in a Starved Escherichia coli Population
Ito, Yoichiro; Ying, Bei-Wen; Yomo, Tetsuya
2011-01-01
Population adaptation can be determined by stochastic switching in living cells. To examine how stochastic switching contributes to the fate decision for a population under severe stress, we constructed an Escherichia coli strain crucially dependent on the expression of a rewired gene. The gene essential for tryptophan biosynthesis, trpC, was removed from the native regulatory unit, the Trp operon, and placed under the extraneous control of the lactose utilisation network. Bistability of the network provided the cells two discrete phenotypes: the induced and suppressed level of trpC. The two phenotypes permitted the cells to grow or not, respectively, under conditions of tryptophan depletion. We found that stochastic switching between the two states allowed the initially suppressed cells to form a new population with induced trpC in response to tryptophan starvation. However, the frequency of the transition from suppressed to induced state dropped off dramatically in the starved population, in comparison to that in the nourished population. This reduced switching rate was compensated by increasing the initial population size, which probably provided the cell population more chances to wait for the rarely appearing fit cells from the unfit cells. Taken together, adaptation of a starved bacterial population because of stochasticity in the gene rewired from the ancient regulon was experimentally confirmed, and the nutritional status and the population size played a great role in stochastic adaptation. PMID:21931628
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USDA-ARS?s Scientific Manuscript database
Functional amyloid, in the form of adhesive fimbrial proteins termed curli, was first described in Salmonella and Escherichia coli. Curli fibers adhere to various host cells and structural proteins, interact with components of the host immune system, and participate in biofilm formation. Shiga toxin...
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Boughton, Berin A; Dobson, Renwick C J; Hutton, Craig A
2012-08-01
The crystal structure of Escherichia coli dihydrodipicolinate synthase with pyruvate and substrate analogue succinic acid semialdehyde condensed with the active site lysine-161 was solved to a resolution of 2.3 Å. Comparative analysis to a previously reported structure both resolves the configuration at the aldol addition center, where the final addition product clearly displays the (S)-configuration, and the final conformation of the adduct within the active site. Direct comparison to two other crystal structures found in the Protein Data Bank, 1YXC, and 3DU0, demonstrates significant similarity between the active site residues of these structures. Copyright © 2012 Wiley Periodicals, Inc.
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Perepelov, A V; Lu, B; Sebchenkova, S N; Shevelev, S D; Wang, V; Shashkov, A S; Feng, L; Wang, L; Knirel', Iu A
2007-01-01
A phosphorylated O-specific polysaccharide was obtained by mild acidic degradation of the lipopolysaccharide from the intestinal bacterium Escherichia coli 0130 and characterized by the methods of chemical analysis, including dephosphorylation, and 1H and 13C NMR spectroscopy. The polysaccharide was shown to be composed of branched tetrasaccharide repeating units containing two N-acetyl-D-galactosamine residues, D-galactose, D-glucose, and glycerophosphate residues (one of each). The polysaccharide has the following structure, which is unique among the known bacterial polysaccharides.
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Chain length effect on the structure and stability of antimicrobial peptides of the (RW)n series.
Phambu, Nsoki; Almarwani, Bashiyar; Garcia, Arlette M; Hamza, Nafisa S; Muhsen, Amira; Baidoo, Jacqueline E; Sunda-Meya, Anderson
2017-08-01
Three peptides containing (RW) n -NH 2 units (where n=4, 6, and 8) have been chosen to study the effect of the chain length on the structure and stability of the peptide using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. Their interactions with Escherichia coli (E. coli) membrane mimetic vesicles are discussed. Infrared results indicate that addition of (RW) n -NH 2 units increases intermolecular H bonds with antiparallel orientation. TGA and DSC results reveal that (RW) 6 -NH 2 shows the optimal chain length in terms of stability and all three peptides show a preferential interaction with one of the anionic lipids in E. coli membranes. SEM images of (RW) 4 -NH 2 present large aggregates while those of (RW) 6 -NH 2 and (RW) 8 -NH 2 present layers of sheet-like structure. In the presence of model membranes, (RW) n -NH 2 show fibrillar peptide superstructures. This study suggests that repeating structures of (RW) n -NH 2 promotes lateral assembly. Copyright © 2017 Elsevier B.V. All rights reserved.
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Junier, Ivan; Boccard, Frédéric; Espéli, Olivier
2014-01-01
The mechanisms that control chromosome conformation and segregation in bacteria have not yet been elucidated. In Escherichia coli, the mere presence of an active process remains an open question. Here, we investigate the conformation and segregation pattern of the E. coli genome by performing numerical simulations on a polymer model of the chromosome. We analyze the roles of the intrinsic structuring of chromosomes and the forced localization of specific loci, which are observed in vivo. Specifically, we examine the segregation pattern of a chromosome that is divided into four structured macrodomains (MDs) and two non-structured regions. We find that strong osmotic-like organizational forces, which stem from the differential condensation levels of the chromosome regions, dictate the cellular disposition of the chromosome. Strikingly, the comparison of our in silico results with fluorescent imaging of the chromosome choreography in vivo reveals that in the presence of MDs the targeting of the origin and terminus regions to specific positions are sufficient to generate a segregation pattern that is indistinguishable from experimentally observed patterns. PMID:24194594
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Meineke, Birthe; Shuman, Stewart, E-mail: s-shuman@ski.mskcc.org
2012-06-05
Breakage of tRNA by Escherichia coli anticodon nuclease PrrC (EcoPrrC) underlies a host antiviral response to phage T4 infection. Expression of EcoPrrC is cytocidal in yeast, signifying that PrrC ribotoxicity crosses phylogenetic domain boundaries. EcoPrrC consists of an N-terminal NTPase module that resembles ABC transporters and a C-terminal nuclease module that is sui generis. PrrC homologs are prevalent in many other bacteria. Here we report that Haemophilus influenzae PrrC is toxic in E. coli and yeast. To illuminate structure-activity relations, we conducted a new round of mutational analysis of EcoPrrC guided by primary structure conservation among toxic PrrC homologs. Wemore » indentify 17 candidate active site residues in the NTPase module that are essential for toxicity in yeast when EcoPrrC is expressed at high gene dosage. Their functions could be educed by integrating mutational data with the atomic structure of the transition-state complex of a homologous ABC protein.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Tan, Kemin; Zhou, Qingxuan; Cheng, Bokun
Escherichia coli topoisomerase I has an essential function in preventing hypernegative supercoiling of DNA. A full length structure of E. coli topoisomerase I reported here shows how the C-terminal domains bind single-stranded DNA (ssDNA) to recognize the accumulation of negative supercoils in duplex DNA. These C-terminal domains of E. coli topoisomerase I are known to interact with RNA polymerase, and two flexible linkers within the C-terminal domains may assist in the movement of the ssDNA for the rapid removal of transcription driven negative supercoils. The structure has also unveiled for the first time how the 4-Cys zinc ribbon domain andmore » zinc ribbon-like domain bind ssDNA with primarily π -stacking interactions. Finally, this novel structure, in combination with new biochemical data, provides important insights into the mechanism of genome regulation by type IA topoisomerases that is essential for life, as well as the structures of homologous type IA TOP3α and TOP3β from higher eukaryotes that also have multiple 4-Cys zinc ribbon domains required for their physiological functions.« less
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Kim, Seong Keun; Lee, Dae-Hee; Kim, Oh Cheol; Kim, Jihyun F; Yoon, Sung Ho
2017-09-15
Most inducible expression systems suffer from growth defects, leaky basal induction, and inhomogeneous expression levels within a host cell population. These difficulties are most prominent with the overproduction of membrane proteins that are toxic to host cells. Here, we developed an Escherichia coli inducible expression system for membrane protein production based on titrated expression of a mutant lac repressor (mLacI). Performance of the mLacI inducible system was evaluated in conjunction with commonly used lac operator-based expression vectors using a T7 or tac promoter. Remarkably, expression of a target gene can be titrated by the dose-dependent addition of l-rhamnose, and the expression levels were homogeneous in the cell population. The developed system was successfully applied to overexpress three membrane proteins that were otherwise difficult to produce in E. coli. This gene expression control system can be easily applied to a broad range of existing protein expression systems and should be useful in constructing genetic circuits that require precise output signals.
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Inactivation of fecal bacteria in drinking water by solar heating.
Joyce, T M; McGuigan, K G; Elmore-Meegan, M; Conroy, R M
1996-02-01
We report simulations of the thermal effect of strong equatorial sunshine on water samples contaminated with high populations of fecal coliforms. Water samples, heavily contaminated with a wild-type strain of Escherichia coli (starting population = 20 x 10(5) CFU/ml), are heated to those temperatures recorded for 2-liter samples stored in transparent plastic bottles and exposed to full Kenyan sunshine (maximum water temperature, 55 degrees C). The samples are completely disinfected within 7 h, and no viable E. coli organisms are detected at either the end of the experiment or a further 12 h later, showing that no bacterial recovery has occurred. The feasibility of employing solar disinfection for highly turbid, fecally contaminated water is discussed.
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Maslennikova, Irina L; Kuznetsova, Marina V; Nekrasova, Irina V; Shirshev, Sergei V
2017-11-30
Pseudomonas aeruginosa (PA) responsible for acute and chronic infections often forms a well-organized bacterial population with different microbial species including commensal strains of Escherichia coli. Bacterial extracellular components of mixed culture can modulate the influence of bacteria on the neutrophil functions. The objective of this study was to compare the effect of pyocyanin, pyoverdine, LPS, exopolysaccharide of single species and mixed culture supernatants of PA strains and E. coli K12 on microbicidal, secretory activity of human neutrophils in vitro. Bacterial components of E. coli K12 in mixed supernatants with 'biofilm' PA strains (PA ATCC, PA BALG) enhanced short-term microbicidal mechanisms and inhibited neutrophil secretion delayed in time. The influence of 'planktonic' PA (PA 9-3) exometabolites in mixed culture is almost mimicked by E. coli K12 effect on functional neutrophil changes. This investigation may help to understand some of the mechanisms of neutrophil response to mixed infections of different PA with other bacteria species. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Alonso, Jose L.; Soriano, Adela; Carbajo, Oscar; Amoros, Inmaculada; Garelick, Hemda
1999-01-01
This study compared the performance of a commercial chromogenic medium, CHROMagarECC (CECC), and CECC supplemented with sodium pyruvate (CECCP) with the membrane filtration lauryl sulfate-based medium (mLSA) for enumeration of Escherichia coli and non-E. coli thermotolerant coliforms (KEC). To establish that we could recover the maximum KEC and E. coli population, we compared two incubation temperature regimens, 41 and 44.5°C. Statistical analysis by the Fisher test of data did not demonstrate any statistically significant differences (P = 0.05) in the enumeration of E. coli for the different media (CECC and CECCP) and incubation temperatures. Variance analysis of data performed on KEC counts showed significant differences (P = 0.01) between KEC counts at 41 and 44.5°C on both CECC and CECCP. Analysis of variance demonstrated statistically significant differences (P = 0.05) in the enumeration of total thermotolerant coliforms (TTCs) on CECC and CECCP compared with mLSA. Target colonies were confirmed to be E. coli at a rate of 91.5% and KEC of likely fecal origin at a rate of 77.4% when using CECCP incubated at 41°C. The results of this study showed that CECCP agar incubated at 41°C is efficient for the simultaneous enumeration of E. coli and KEC from river and marine waters. PMID:10427079
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Natural inactivation of Escherichia coli in anaerobic and reduced groundwater.
Lisle, J T
2016-06-01
Inactivation rates of Escherichia coli in groundwater have most often been determined in aerobic and oxidized systems. This study examined E. coli inactivation rates in anaerobic and extremely reduced groundwater systems that have been identified as recharge zones. Groundwater from six artesian wells was diverted to above-ground, flow-through mesocosms that contained laboratory grown E. coli in diffusion chambers. All groundwater was anaerobic and extremely reduced (ORP < -300 mV). Cells were plated onto mTEC agar during 21-day incubation periods. All data fit a bi-phasic inactivation model, with >95% of the E. coli population being inactivated <11·0 h (mean k = 0·488 ±0·188 h(-1) ). The groundwater geochemical conditions enhanced the inactivation of E. coli to rates approx. 21-fold greater than previously published inactivation rate in groundwater (mean k = 0·023 ± 0·030 h(-1) ). Also, mTEC agar inhibits E. coli growth following exposure to anaerobic and reduced groundwater. Aquifer recharge zones with geochemical characteristics observed in this study complement above-ground engineered processes (e.g. filtration, disinfection), while increasing the overall indicator micro-organism log-reduction rate of a facility. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Sunita,S.; Zhenxing, H.; Swaathi, J.
2006-01-01
Pseudouridine synthases catalyze the isomerization of uridine to pseudouridine ({psi}) in rRNA and tRNA. The pseudouridine synthase RluF from Escherichia coli (E.C. 4.2.1.70) modifies U2604 in 23S rRNA, and belongs to a large family of pseudouridine synthases present in all kingdoms of life. Here we report the domain architecture and crystal structure of the catalytic domain of E. coli RluF at 2.6 Angstroms resolution. Limited proteolysis, mass spectrometry and N-terminal sequencing indicate that RluF has a distinct domain architecture, with the catalytic domain flanked at the N and C termini by additional domains connected to it by flexible linkers. Themore » structure of the catalytic domain of RluF is similar to those of RsuA and TruB. RluF is a member of the RsuA sequence family of {psi}-synthases, along with RluB and RluE. Structural comparison of RluF with its closest structural homologues, RsuA and TruB, suggests possible functional roles for the N-terminal and C-terminal domains of RluF.« less
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NASA Astrophysics Data System (ADS)
Goularte, L.; Martins, C. G.; Morales-Aizpurúa, I. C.; Destro, M. T.; Franco, B. D. G. M.; Vizeu, D. M.; Hutzler, B. W.; Landgraf, M.
2004-09-01
The feasibility of gamma radiation in combination with minimal processing (MP) to reduce the number of Salmonella spp. and Escherichia coli O157:H7 in iceberg lettuce ( Lactuca sativa, L.) (shredded) was studied in order to increase the safety of the product. The reduction of the microbial population during the processing, the D10-values for Salmonella spp. and E. coli O157:H7 inoculated on shredded iceberg lettuce as well as the sensory evaluation of the irradiated product were evaluated. The immersion in chlorine (200 ppm) reduced coliform and aerobic mesophilic microorganisms by 0.9 and 2.7 log, respectively. D-values varied from 0.16 to 0.23 kGy for Salmonella spp. and from 0.11 to 0.12 kGy for E. coli O157:H7. Minimally processed iceberg lettuce exposed to 0.9 kGy does not show any change in sensory attributes. However, the texture of the vegetable was affected during the exposition to 1.1 kGy. The exposition of MP iceberg lettuce to 0.7 kGy reduced the population of Salmonella spp. by 4.0 log and E. coli by 6.8 log without impairing the sensory attributes. The combination of minimal process and gamma radiation to improve the safety of iceberg lettuce is feasible if good hygiene practices begins at farm stage.
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Mehinagic, Kemal; Rosengarten, Renate; Hoelzl, Franz; Knauer, Felix; Walzer, Chris
2013-01-01
In order to test whether rooks (Corvus frugilegus) represent good indicators for the potential circulation of antibiotics in their native habitat, two populations with different migratory behavior were tested for the presence of beta-lactamase producing Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA). In all, 54 and 102 samples of fresh feces of a migratory and a resident population were investigated. A total of 24 and 3 cefotaxime-resistant enterobacterial isolates were obtained from the migratory and resident population, respectively. In these isolates CTX-M-1 (n = 15), CTX-M-3 (n = 3), and CTX-M-15 (n = 3) genes were detected. TEM-1 and OXA-1 were associated with CTX-M in 3 and 2 isolates, respectively. In two E. coli isolates CMY-2 could be detected, where from one isolate displayed an overexpression of chromosomal AmpC as well. Among E. coli isolates the most common phylogenetic group was A (n = 11) and ST1683 (n = 5). In one E. coli of B2-ST131 the rfbO25b locus was detected. Three Enterobacter isolates were stably derepressed AmpC-producers. In five samples of the migratory population, PVL positive MRSA could be isolated. Two isolates were typed SCCmec IVa, spa type t127, and ST1. Three isolates carried a SCCmec type IVc, with spa type t852 and ST22. The highly significant difference of the occurrence of antibiotic resistance between the migratory population from eastern Europe compared to resident population in our study indicates that rooks may be good indicator species for the evaluation of environmental contamination with antibiotic resistant bacteria, especially due to their ecology, foraging behavior and differing migratory behavior. PMID:24391878
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Howells, Michaela E; Pruetz, Jill; Gillespie, Thomas R
2011-02-01
The exponential decline of great apes over the past 50 years has resulted in an urgent need for data to inform population viability assessment and conservation strategies. Health monitoring of remaining ape populations is an important component of this process. In support of this effort, we examined endoparasitic and commensal prevalence and richness as proxies of population health for western chimpanzees (Pan troglodytes verus) and sympatric guinea baboons (Papio hamadryas papio) at Fongoli, Senegal, a site dominated by woodland-savanna at the northwestern extent of chimpanzees' geographic range. The small population size and extreme environmental pressures experienced by Fongoli chimpanzees make them particularly sensitive to the potential impact of pathogens. One hundred thirty-two chimpanzee and seventeen baboon fecal samples were processed using sodium nitrate floatation and fecal sedimentation to isolate helminth eggs, larvae, and protozoal cysts. Six nematodes (Physaloptera sp., Ascaris sp., Stronglyloides fuelleborni, Trichuris sp., an unidentified hookworm, and an unidentified larvated nematode), one cestode (Bertiella sp.), and five protozoans (Iodamoeba buetschlii, Entamoeba coli, Troglodytella abrassarti, Troglocorys cava, and an unidentified ciliate) were detected in chimpanzee fecal samples. Four nematodes (Necator sp., S. fuelleborni, Trichuris sp., and an unidentified hookworm sp.), two trematodes (Shistosoma mansoni and an unidentified fluke), and six protozoans (Entamoeba histolytica/dispar, E. coli, Chilomastix mesnili, Balantidium coli, T. abrassarti, and T. cava) were detected in baboon fecal samples. The low prevalence of pathogenic parasite species and high prevalence of symbiotic protozoa in Fongoli chimpanzees are indicative of good overall population health. However, the high prevalence of pathogenic parasites in baboons, who may serve as transport hosts, highlight the need for ongoing pathogen surveillance of the Fongoli chimpanzee population and point to the need for further research into the epidemiology and cross-species transmission ecology of zoonotic pathogens at this site. © 2010 Wiley-Liss, Inc.
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Spread of avian pathogenic Escherichia coli ST117 O78:H4 in Nordic broiler production.
Ronco, Troels; Stegger, Marc; Olsen, Rikke Heidemann; Sekse, Camilla; Nordstoga, Anne Bang; Pohjanvirta, Tarja; Lilje, Berit; Lyhs, Ulrike; Andersen, Paal Skytt; Pedersen, Karl
2017-01-03
Escherichia coli infections known as colibacillosis constitute a considerable challenge to poultry farmers worldwide, in terms of decreased animal welfare and production economy. Colibacillosis is caused by avian pathogenic E. coli (APEC). APEC strains are extraintestinal pathogenic E. coli and have in general been characterized as being a genetically diverse population. In the Nordic countries, poultry farmers depend on import of Swedish broiler breeders which are part of a breeding pyramid. During 2014 to 2016, an increased occurrence of colibacillosis on Nordic broiler chicken farms was reported. The aim of this study was to investigate the genetic diversity among E. coli isolates collected on poultry farms with colibacillosis issues, using whole genome sequencing. Hundred and fourteen bacterial isolates from both broilers and broiler breeders were whole genome sequenced. The majority of isolates were collected from poultry with colibacillosis on Nordic farms. Subsequently, comparative genomic analyses were carried out. This included in silico typing (sero- and multi-locus sequence typing), identification of virulence and resistance genes and phylogenetic analyses based on single nucleotide polymorphisms. In general, the characterized poultry isolates constituted a genetically diverse population. However, the phylogenetic analyses revealed a major clade of 47 closely related ST117 O78:H4 isolates. The isolates in this clade were collected from broiler chickens and breeders with colibacillosis in multiple Nordic countries. They clustered together with a human ST117 isolate and all carried virulence genes that previously have been associated with human uropathogenic E. coli. The investigation revealed a lineage of ST117 O78:H4 isolates collected in different Nordic countries from diseased broilers and breeders. The data indicate that the closely related ST117 O78:H4 strains have been transferred vertically through the broiler breeding pyramid into distantly located farms across the Nordic countries.
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La, Ju A; Lim, Sora; Park, Hyo Jeong; Heo, Min-Ji; Sang, Byoung-In; Oh, Min-Kyu; Cho, Eun Chul
2016-08-24
We present a plasmonic-based strategy for the colourimetric and spectroscopic differentiation of various organic acids produced by bacteria. The strategy is based on our discovery that particular concentrations of dl-lactic, acetic, and butyric acids induce different assembly structures, colours, and optical spectra of gold nanoparticles. We selected wild-type (K-12 W3110) and genetically-engineered (JHL61) Escherichia coli (E. coli) that are known to primarily produce acetic and butyric acid, respectively. Different assembly structures and optical properties of gold nanoparticles were observed when different organic acids, obtained after the removal of acid-producing bacteria, were mixed with gold nanoparticles. Moreover, at moderate cell concentrations of K-12 W3110 E. coli, which produce sufficient amounts of acetic acid to induce the assembly of gold nanoparticles, a direct estimate of the number of bacteria was possible based on time-course colour change observations of gold nanoparticle aqueous suspensions. The plasmonic-based colourimetric and spectroscopic methods described here may enable onsite testing for the identification of organic acids produced by bacteria and the estimation of bacterial numbers, which have applications in health and environmental sciences. Copyright © 2016 Elsevier B.V. All rights reserved.
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Visualizing chaperone-assisted protein folding
Horowitz, Scott; Salmon, Loïc; Koldewey, Philipp; ...
2016-05-30
We present that challenges in determining the structures of heterogeneous and dynamic protein complexes have greatly hampered past efforts to obtain a mechanistic understanding of many important biological processes. One such process is chaperone-assisted protein folding. Obtaining structural ensembles of chaperone–substrate complexes would ultimately reveal how chaperones help proteins fold into their native state. To address this problem, we devised a new structural biology approach based on X-ray crystallography, termed residual electron and anomalous density (READ). READ enabled us to visualize even sparsely populated conformations of the substrate protein immunity protein 7 (Im7) in complex with the Escherichia coli chaperonemore » Spy, and to capture a series of snapshots depicting the various folding states of Im7 bound to Spy. The ensemble shows that Spy-associated Im7 samples conformations ranging from unfolded to partially folded to native-like states and reveals how a substrate can explore its folding landscape while being bound to a chaperone.« less
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Structure of Escherichia coli AdhP (ethanol-inducible dehydrogenase) with bound NAD.
Thomas, Leonard M; Harper, Angelica R; Miner, Whitney A; Ajufo, Helen O; Branscum, Katie M; Kao, Lydia; Sims, Paul A
2013-07-01
The crystal structure of AdhP, a recombinantly expressed alcohol dehydrogenase from Escherichia coli K-12 (substrain MG1655), was determined to 2.01 Å resolution. The structure, which was solved using molecular replacement, also included the structural and catalytic zinc ions and the cofactor nicotinamide adenine dinucleotide (NAD). The crystals belonged to space group P21, with unit-cell parameters a = 68.18, b = 118.92, c = 97.87 Å, β = 106.41°. The final R factor and Rfree were 0.138 and 0.184, respectively. The structure of the active site of AdhP suggested a number of residues that may participate in a proton relay, and the overall structure of AdhP, including the coordination to structural and active-site zinc ions, is similar to those of other tetrameric alcohol dehydrogenase enzymes.
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Impact of Vacuum Cooling on Escherichia coli O157:H7 Infiltration into Lettuce Tissue▿
Li, Haiping; Tajkarimi, Mehrdad; Osburn, Bennie I.
2008-01-01
Vacuum cooling is a common practice in the California leafy green industry. This study addressed the impact of vacuum cooling on the infiltration of Escherichia coli O157:H7 into lettuce as part of the risk assessment responding to the E. coli O157:H7 outbreaks associated with leafy green produce from California. Vacuum cooling significantly increased the infiltration of E. coli O157:H7 into the lettuce tissue (2.65E+06 CFU/g) compared to the nonvacuumed condition (1.98E+05 CFU/g). A stringent surface sterilization and quadruple washing could not eliminate the internalized bacteria from lettuce. It appeared that vacuuming forcibly changed the structure of lettuce tissue such as the stomata, suggesting a possible mechanism of E. coli O157:H7 internalization. Vacuuming also caused a lower reduction rate of E. coli O157:H7 in stored lettuce leaves than that for the nonvacuumed condition. PMID:18344328
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Doza, Solaiman; Jabeen Rahman, Musarrat; Islam, Mohammad Aminul; Kwong, Laura H.; Unicomb, Leanne; Ercumen, Ayse; Pickering, Amy J.; Parvez, Sarker Masud; Naser, Abu Mohd; Ashraf, Sania; Das, Kishor Kumar; Luby, Stephen P.
2018-01-01
Abstract. Consumption of contaminated stored food can cause childhood diarrhea. Flies carry enteropathogens, although their contribution to food contamination remains unclear. We investigated the role of flies in contaminating stored food by collecting food and flies from the same households in rural Bangladesh. We selected 182 households with children ≤ 24 months old that had stored foods for later feeding at room temperature for ≥ 3 hours. We collected food samples and captured flies with fly tapes hung by the kitchen. We used the IDEXX Quanti-Tray System (Colilert-18 media; IDEXX Laboratories, Inc., Westbrook, ME) to enumerate Escherichia coli with the most probable number (MPN) method. Escherichia coli–positive IDEXX wells were analyzed by polymerase chain reaction for pathogenic E. coli genes (eae, ial, bfp, ipaH, st, lt, aat, aaiC, stx1, and stx2). Escherichia coli was detected in 61% (111/182) of food samples, with a mean of 1.1 log10 MPN/dry g. Fifteen samples (8%) contained pathogenic E. coli; seven (4%) had enteropathogenic E. coli (EPEC) genes (eae and/or bfp); and 10 (5%) had enteroaggregative E. coli genes (aat and/or aaiC). Of flies captured in 68 (37%) households, E. coli was detected in 41 (60%, mean 2.9 log10 MPN/fly), and one fly (1%) had an EPEC gene (eae). For paired fly-food samples, each log10 MPN E. coli increase in flies was associated with a 0.31 log10 MPN E. coli increase in stored food (95% confidence interval: 0.07, 0.55). In rural Bangladesh, flies possibly a likely route for fecal contamination of stored food. Controlling fly populations may reduce contamination of food stored for young children. PMID:29436348
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Copper oxide assisted cysteine hierarchical structures for immunosensor application
NASA Astrophysics Data System (ADS)
Pandey, Chandra Mouli; Sumana, Gajjala; Tiwari, Ida
2014-09-01
The present work describes the promising electrochemical immunosensing strategy based on copper (II) assisted hierarchical cysteine structures (CuCys) varying from star to flower like morphology. The CuCys having average size of 10 μm have been synthesised using L-Cysteine as initial precursor in presence of copper oxide under environmentally friendly conditions in aqueous medium. To delineate the synthesis mechanism, detailed structural investigations have been carried out using characterization techniques such as X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The electrochemical behaviour of self-assembled CuCys on gold electrode shows surface controlled electrode reaction with an apparent electron transfer rate constant of 3.38 × 10-4 cm s-1. This innovative platform has been utilized to fabricate an immunosensor by covalently immobilizing monoclonal antibodies specific for Escherichia coli O157:H7 (E. coli). Under the optimal conditions, the fabricated immunosensor is found to be sensitive and specific for the detection of E. coli with a detection limit of 10 cfu/ml.
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2010-01-01
Background We have previously identified two mineral mixtures, CB07 and BY07, and their respective aqueous leachates that exhibit in vitro antibacterial activity against a broad spectrum of pathogens. The present study assesses cellular ultrastructure and membrane integrity of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli after exposure to CB07 and BY07 aqueous leachates. Methods We used scanning and transmission electron microscopy to evaluate E. coli and MRSA ultrastructure and morphology following exposure to antibacterial leachates. Additionally, we employed Baclight LIVE/DEAD staining and flow cytometry to investigate the cellular membrane as a possible target for antibacterial activity. Results Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging of E. coli and MRSA revealed intact cells following exposure to antibacterial mineral leachates. TEM images of MRSA showed disruption of the cytoplasmic contents, distorted cell shape, irregular membranes, and distorted septa of dividing cells. TEM images of E. coli exposed to leachates exhibited different patterns of cytoplasmic condensation with respect to the controls and no apparent change in cell envelope structure. Although bactericidal activity of the leachates occurs more rapidly in E. coli than in MRSA, LIVE/DEAD staining demonstrated that the membrane of E. coli remains intact, while the MRSA membrane is permeabilized following exposure to the leachates. Conclusions These data suggest that the leachate antibacterial mechanism of action differs for Gram-positive and Gram-negative organisms. Upon antibacterial mineral leachate exposure, structural integrity is retained, however, compromised membrane integrity accounts for bactericidal activity in Gram-positive, but not in Gram-negative cells. PMID:20846374
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Crystal structure of E. coli ZinT with one zinc-binding mode and complexed with citrate.
Chen, Jinli; Wang, Lulu; Shang, Fei; Dong, Yuesheng; Ha, Nam-Chul; Nam, Ki Hyun; Quan, Chunshan; Xu, Yongbin
2018-06-02
The ZnuABC ATP-binding cassette transporter found in gram-negative bacteria has been implicated in ensuring adequate zinc import into Zn(II)-poor environments. ZinT is an essential component of ZnuABC and contributes to metal transport by transferring metals to ZnuA, which delivers them to ZnuB in periplasmic zinc recruitment. Although several structures of E. coli ZinT have been reported, its zinc-binding sites and oligomeric state have not been clearly identified. Here, we report the crystal structure of E. coli ZinT at 1.76 Å resolution. This structure contains one zinc ion in its calycin-like domain, and this ion is coordinated by three highly conserved histidine residues (His167, His176 and His178). Moreover, three oxygen atoms (O 1 , O 6 and O 7 ) from the citrate molecule interact with zinc, giving the zinc ion stable octahedral coordination. Our EcZinT structure shows the fewest zinc ions bound of all reported EcZinT structures. Crystallographic packing and size exclusion chromatography suggest that EcZinT prefers to form monomers in solution. Our results provide insights into the molecular function of ZinT. Copyright © 2018. Published by Elsevier Inc.
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Development of an Integrated Metabolomic Profiling Approach for Infectious Diseases Research
Lv, Haitao; Hung, Chia S.; Chaturvedi, Kaveri S.; Hooton, Thomas M.; Henderson, Jeffrey P.
2013-01-01
Metabolomic profiling offers direct insights into the chemical environment and metabolic pathway activities at sites of human disease. During infection, this environment may receive important contributions from both host and pathogen. Here we apply untargeted metabolomics approach to identify compounds associated with an E. coli urinary tract infection population. Correlative and structural data from minimally processed samples were obtained using an optimized LC-MS platform capable of resolving ∼2300 molecular features. Principal components analysis readily distinguished patient groups and multiple supervised chemometric analyses resolved robust metabolomic shifts between groups. These analyses revealed nine compounds whose provisional structures suggest candidate infection-associated endocrine, catabolic, and lipid pathways. Several of these metabolite signatures may derive from microbial processing of host metabolites. Overall, this study highlights the ability of metabolomic approaches to directly identify compounds encountered by, and produced from, bacterial pathogens within human hosts. PMID:21922104
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Disassa, Nigatu; Sibhat, Berhanu; Mengistu, Shimelis; Muktar, Yimer; Belina, Dinaol
2017-01-01
A cross-sectional study was conducted from October 2014 to July 2015 to determine the prevalence and populations of E. coli as well as the prevalence and antimicrobial susceptibility of E. coli O157:H7 isolated from raw milk. Biochemical and serological tests methods were used to confirm E. coli and E. coli O157:H7 and isolates were subjected to antimicrobial susceptibility test using the agar disc diffusion method. Out of 380 raw milk samples examined, 129 (33.9%) and 11 (2.9%) were contaminated with E. coli and E. coli O157:H7, respectively. The highest prevalence was recorded in samples obtained from vendors (39.1%, 4.978 ± 0.180 log 10 /ml) compared with samples from farmers (28.1%, 3.93 ± 0.01 log 10 /ml) with significant differences ( P = 0.02). The frequency of contamination was higher in the samples collected from milk that was stored and transported in plastic containers (39.4%) than in the containers made of stainless steel (23.0%) ( P = 0.002). The antimicrobial susceptibility profile showed that E. coli O157:H7 were resistant to tetracycline (81.8%), streptomycin (81.8%), and kanamycin (63.6%). Milk samples were produced and handled under poor hygienic conditions, stored, and transported in inappropriate containers and under temperature abuse conditions leading to high health risk to the consumers. Additional studies would be needed to establish association between the occurrences of E. coli O157:H7 in raw milk and all the risk factors involved in and around Asosa town.
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Keskinen, Lindsey A; Annous, Bassam A
2011-06-30
Numerous Escherichia coli O157:H7 outbreaks have been linked to consumption of fresh lettuce. The development of effective and easily implemented wash treatment could reduce such incidents. The purpose of this study was to evaluate the addition of food-grade detergents to sanitizer solutions for inactivation of E. coli O157:H7 on Romaine lettuce. Freshly-cut leaves of Romaine lettuce were dip-inoculated to achieve a final cell concentration of 7.8±0.2 log CFU/g, air-dried for 2h, and stored overnight at 4 °C. Leaves were then washed for 2 min in an experimental short chain fatty acid formulation (SCFA) or in one of the following solutions with or without 0.2% dodecylbenzenesulfonic acid or 0.2% sodium 2-ethyl hexyl sulfate: 1) deionized water; 2) 100 ppm chlorine dioxide; 3) 100 ppm chlorine; and 4) 200 ppm chlorine. Following wash treatment, samples were blended in neutralizing buffer (1:3) and surface plated on the selective media CT-SMAC. The efficacy of wash treatments, with or without the detergents, in inactivating E. coli O157:H7 cells on lettuce leaves were not significantly different. The most effective wash solution was SCFA, which was capable of reducing E. coli O157:H7 populations by more than 5 log CFU/g. The rest of the wash treatments resulted in a population reduction of less than 1 log CFU/g. The effectiveness of SCFA surpasses that of other sanitizer treatments tested in this study and requires further research to optimize treatments to preserve lettuce quality. Conventional detergents did not enhance the efficacy of any of the wash treatments tested during this study. Published by Elsevier B.V.
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Vélez Echeverri, Catalina; Serna-Higuita, Lina María; Serrano, Ana Katherina; Ochoa-García, Carolina; Rojas Rosas, Luisa; María Bedoya, Ana; Suárez, Margarita; Hincapié, Catalina; Henao, Adriana; Ortiz, Diana; Vanegas, Juan José; Zuleta, John Jairo; Espinal, David
2014-01-01
Urinary tract infection (UTI) is one of the most common bacterial infections in childhood and causes acute and chronic morbidity and long-term hypertension and chronic kidney disease. To describe the demographic characteristics, infectious agents, patterns of antibiotic resistance, etiologic agent and profile of susceptibility and response to empirical treatment of UTI in a pediatric population. This is a descriptive, retrospective study. Included in the study were 144 patients, 1:2.06 male to female ratio. The most common symptom was fever (79.9%) and 31.3% had a history of previous UTI. 72.0% of the patients had positive urine leukocyte count (>5 per field), urine gram was positive in 85.0% of samples and gram negative bacilli accounted for 77.8% for the total pathogens isolated. The most frequent uropathogens isolated were Escherichia coli and Klebsiella pneumoniae. Our E.coli isolates had a susceptibility rate higher than 90% to most of the antibiotics used, but a resistance rate of 42.6% to TMP SMX and 45.5% to ampicillin sulbactam. 6.3% of E. coli was extended-spectrum beta-lactamases producer strains. The most frequent empirical antibiotic used was amikacin, which was used in 66.0% of the patients. 17 of 90 patients who underwent voiding cistouretrography (VCUG) had vesicoureteral reflux. This study revealed that E. coli was the most frequent pathogen of community acquired UTI. We found that E. coli and other uropathogens had a high resistance rate against TMP SMX and ampicillin sulbactam. In order to ensure a successful empirical treatment, protocols should be based on local epidemiology and susceptibility rates.
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Vélez Echeverri, Catalina; Serrano, Ana Katherina; Ochoa-García, Carolina; Rojas Rosas, Luisa; María Bedoya, Ana; Suárez, Margarita; Hincapié, Catalina; Henao, Adriana; Ortiz, Diana; Vanegas, Juan José; Zuleta, John Jairo; Espinal, David
2014-01-01
Introduction: Urinary tract infection (UTI) is one of the most common bacterial infections in childhood and causes acute and chronic morbidity and long-term hypertension and chronic kidney disease. Objectives: To describe the demographic characteristics, infectious agents, patterns of antibiotic resistance, etiologic agent and profile of susceptibility and response to empirical treatment of UTI in a pediatric population. Methods: This is a descriptive, retrospective study. Results: Included in the study were 144 patients, 1:2.06 male to female ratio. The most common symptom was fever (79.9%) and 31.3% had a history of previous UTI. 72.0% of the patients had positive urine leukocyte count (>5 per field), urine gram was positive in 85.0% of samples and gram negative bacilli accounted for 77.8% for the total pathogens isolated. The most frequent uropathogens isolated were Escherichia coli and Klebsiella pneumoniae. Our E.coli isolates had a susceptibility rate higher than 90% to most of the antibiotics used, but a resistance rate of 42.6% to TMP SMX and 45.5% to ampicillin sulbactam. 6.3% of E. coli was extended-spectrum beta-lactamases producer strains. The most frequent empirical antibiotic used was amikacin, which was used in 66.0% of the patients. 17 of 90 patients who underwent voiding cistouretrography (VCUG) had vesicoureteral reflux. Conclusion: This study revealed that E. coli was the most frequent pathogen of community acquired UTI. We found that E. coli and other uropathogens had a high resistance rate against TMP SMX and ampicillin sulbactam. In order to ensure a successful empirical treatment, protocols should be based on local epidemiology and susceptibility rates. PMID:24970958
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Khalil, Uzma; Younus, Mahwish; Asghar, Naeem; Siddiqui, Fariha; Gómez-Duarte, Oscar G; Wren, Brendan W; Bokhari, Habib
2016-10-01
Enteroaggregative Escherichia coli (EAEC) are a leading cause of diarrhea among children. The objective of this study was to define the frequency of EAEC among diarrheal children from flood-affected areas as well as sporadic cases, determine multidrug resistance, and evaluation of virulence using an in vivo model of pathogenesis. Stool samples were collected from 225 diarrheal children from 2010 to 2011 from flood-affected areas as well as from sporadic cases in Pakistan. Identified EAEC isolates were characterized by phylogrouping, antibiotic resistance patterns including the extended-spectrum beta lactamase spectrum, single nucleotide polymorphism detection in gyrA and parC, and virulence potential using wax worm, G. mellonella. A total of 35 (12.5%) confirmed EAEC isolates were identified among 225 E. coli isolates. EAEC isolates displayed high resistance to tetracycline, ampicillin, and cefaclor. A total of 34.28% were ESBL positive. Single nucleotide polymorphism detection revealed 37.14% and 68.57% isolates were positive for SNPs in gyrA (A660 -T660 ) and parC (C330 -T330 ), respectively. Phylogrouping revealed that B2 phylogroup was more prevalent among all EAEC isolates tested followed by D, A, B1, and non-typeable (NT). Infection of G. mellonella with EAEC showed that killing infective dose was 100% higher than E. coli DH5 alpha control. EAEC are prevalent among Pakistani children with diarrhea, they are highly resistant to antibiotics, and predominantly fall into B2 phylogroup. Epidemiologic surveillance of EAEC and other E. coli pathotypes is critical to assess not only the role of these pathogens in diarrheal disease but also to determine the extent of multidrug resistance among the population. © 2016 APMIS. Published by John Wiley & Sons Ltd.
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Synthesis and evaluation of optical and antimicrobial properties of Ag-SnO2 nanocomposites
NASA Astrophysics Data System (ADS)
Kumar Nair, Kishore; Kumar, Promod; Kumar, Vinod; Harris, R. A.; Kroon, R. E.; Viljoen, Bennie; Shumbula, P. M.; Mlambo, M.; Swart, H. C.
2018-04-01
We report on the sol-gel based room temperature synthesis of undoped SnO2 and Ag-SnO2 nanostructures. The synthesized nanostructures were characterized by Fourier transform infrared spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, High-resolution transmission electron microscopy (HR-TEM) and UV-visible spectroscopy. The XRD pattern confirmed that the obtained nanostructures have a tetragonally rutile structure. No extra phase changes were observed after Ag doping. UV-visible spectroscopy measurements indicated that the band gap of 3.59 eV for pure SnO2 nanostructures, decreased to 3.39 eV after doping. TEM analysis showed that no regular shape morphology existed and some rod-shaped particles were also detected in the nanostructures. The antibacterial activity of the nanostructures against E. coli was evaluated and a continuous decrease of microbial count was observed. The microbial population decreased from 6 × 105 cfu/ml to 7 × 104 cfu/ml and 5 × 104 cfu/ml on SnO2 and Ag-SnO2 treatments, respectively. Thus, the nanostructures can be used for the biorational management of E. coli for waste water treatment before discharge.
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Matsumura, Hiroyoshi; Xie, Yong; Shirakata, Shunsuke; Inoue, Tsuyoshi; Yoshinaga, Takeo; Ueno, Yoshihisa; Izui, Katsura; Kai, Yasushi
2002-12-01
Phosphoenolpyruvate carboxylase (PEPC) catalyzes the first step in the fixation of atmospheric CO(2) during C(4) photosynthesis. The crystal structure of C(4) form maize PEPC (ZmPEPC), the first structure of the plant PEPCs, has been determined at 3.0 A resolution. The structure includes a sulfate ion at the plausible binding site of an allosteric activator, glucose 6-phosphate. The crystal structure of E. coli PEPC (EcPEPC) complexed with Mn(2+), phosphoenolpyruvate analog (3,3-dichloro-2-dihydroxyphosphinoylmethyl-2-propenoate), and an allosteric inhibitor, aspartate, has also been determined at 2.35 A resolution. Dynamic movements were found in the ZmPEPC structure, compared with the EcPEPC structure, around two loops near the active site. On the basis of these molecular structures, the mechanisms for the carboxylation reaction and for the allosteric regulation of PEPC are proposed.
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Confirming the Revised C-Terminal Domain of the MscL Crystal Structure
Maurer, Joshua A.; Elmore, Donald E.; Clayton, Daniel; Xiong, Li; Lester, Henry A.; Dougherty, Dennis A.
2008-01-01
The structure of the C-terminal domain of the mechanosensitive channel of large conductance (MscL) has generated significant controversy. As a result, several structures have been proposed for this region: the original crystal structure (1MSL) of the Mycobacterium tuberculosis homolog (Tb), a model of the Escherichia coli homolog, and, most recently, a revised crystal structure of Tb-MscL (2OAR). To understand which of these structures represents a physiological conformation, we measured the impact of mutations to the C-terminal domain on the thermal stability of Tb-MscL using circular dichroism and performed molecular dynamics simulations of the original and the revised crystal structures of Tb-MscL. Our results imply that this region is helical and adopts an α-helical bundle conformation similar to that observed in the E. coli MscL model and the revised Tb-MscL crystal structure. PMID:18326638
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Patra, Sova; Das, T K; Avila, C; Cabello, V; Castillo, F; Sarkar, D; Lahiri, Susmita; Jana, B B
2012-04-01
The incidence pattern of cadmium tolerance and antibiotics resistance by Escherichia coli was examined periodically from the samples of water, sludge and intestine of fish raised in waste stabilization ponds in a sewage treatment plant. Samples of water and sludge were collected from all the selected ponds and were monitored for total counts of fecal coliform (FC), total coliform (TC) and the population of Escherichia coli, which was also obtained from the intestine of fishes. Total counts of both FC and TC as well as counts of E. coli were markedly reduced from the facultative pond to the last maturation pond. Tolerance limit to cadmium by E. coli tended to decline as the distance of the sewage effluent from the source increased; the effective lethal concentration of cadmium ranged from 0.1 mM in split chamber to 0.05 mM in first maturation pond. E. coli isolated from water, sludge and fish gut were sensitive to seven out of ten antibiotics tested. It appears that holistic functions mediated through the mutualistic growth of micro algae and heterotrophic bacteria in the waste stabilization ponds were responsible for the promotion of water quality and significant reduction of coliform along the sewage effluent gradient.
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Understanding the association of Escherichia coli with diverse macroalgae in the lagoon of Venice
NASA Astrophysics Data System (ADS)
Quero, Grazia M.; Fasolato, Luca; Vignaroli, Carla; Luna, Gian Marco
2015-06-01
Recent studies provided evidence that the macroalga Cladopohora in lakes hosts associated Escherichia coli, with consequences on the environmental and human health. We expanded these investigations to other macroalgae (Ulva spp., Sargassum muticum and Undaria pinnatifida) widespread in the lagoon of Venice (Italy). Attached E. coli were abundant, accounting up to 3,250 CFU gram-1 of alga. Macroalgal-associated isolates belonged to all E. coli phylogroups, including pathogenic ones, and to Escherichia cryptic clades. Attached E. coli showed potential to grow even at in situ temperature on macroalgal extracts as only source of carbon and nutrients, and ability to produce biofilm in vitro. The genotypic diversity of the attached isolates was high, with significant differences between algae and the overlying water. Our evidences suggest that attached populations consist of both resident and transient strains, likely resulting from the heterogeneous input of fecal bacteria from the city. We report that cosmopolitan and invasive macroalgae may serve as source of E. coli, including pathogenic genotypes, and that this habitat can potentially support their growth. Considering the global diffusion of the macroalgae here studied, this phenomenon is likely occurring in other coastal cities worldwide and deserves further investigations from either the sanitary and ecological perspectives.
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Understanding the association of Escherichia coli with diverse macroalgae in the lagoon of Venice
Quero, Grazia M.; Fasolato, Luca; Vignaroli, Carla; Luna, Gian Marco
2015-01-01
Recent studies provided evidence that the macroalga Cladopohora in lakes hosts associated Escherichia coli, with consequences on the environmental and human health. We expanded these investigations to other macroalgae (Ulva spp., Sargassum muticum and Undaria pinnatifida) widespread in the lagoon of Venice (Italy). Attached E. coli were abundant, accounting up to 3,250 CFU gram−1 of alga. Macroalgal-associated isolates belonged to all E. coli phylogroups, including pathogenic ones, and to Escherichia cryptic clades. Attached E. coli showed potential to grow even at in situ temperature on macroalgal extracts as only source of carbon and nutrients, and ability to produce biofilm in vitro. The genotypic diversity of the attached isolates was high, with significant differences between algae and the overlying water. Our evidences suggest that attached populations consist of both resident and transient strains, likely resulting from the heterogeneous input of fecal bacteria from the city. We report that cosmopolitan and invasive macroalgae may serve as source of E. coli, including pathogenic genotypes, and that this habitat can potentially support their growth. Considering the global diffusion of the macroalgae here studied, this phenomenon is likely occurring in other coastal cities worldwide and deserves further investigations from either the sanitary and ecological perspectives. PMID:26043415
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Understanding the association of Escherichia coli with diverse macroalgae in the lagoon of Venice.
Quero, Grazia M; Fasolato, Luca; Vignaroli, Carla; Luna, Gian Marco
2015-06-04
Recent studies provided evidence that the macroalga Cladopohora in lakes hosts associated Escherichia coli, with consequences on the environmental and human health. We expanded these investigations to other macroalgae (Ulva spp., Sargassum muticum and Undaria pinnatifida) widespread in the lagoon of Venice (Italy). Attached E. coli were abundant, accounting up to 3,250 CFU gram(-1) of alga. Macroalgal-associated isolates belonged to all E. coli phylogroups, including pathogenic ones, and to Escherichia cryptic clades. Attached E. coli showed potential to grow even at in situ temperature on macroalgal extracts as only source of carbon and nutrients, and ability to produce biofilm in vitro. The genotypic diversity of the attached isolates was high, with significant differences between algae and the overlying water. Our evidences suggest that attached populations consist of both resident and transient strains, likely resulting from the heterogeneous input of fecal bacteria from the city. We report that cosmopolitan and invasive macroalgae may serve as source of E. coli, including pathogenic genotypes, and that this habitat can potentially support their growth. Considering the global diffusion of the macroalgae here studied, this phenomenon is likely occurring in other coastal cities worldwide and deserves further investigations from either the sanitary and ecological perspectives.
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Development of functionalised polyelectrolyte capsules using filamentous Escherichia coli cells.
Lederer, Franziska L; Günther, Tobias J; Weinert, Ulrike; Raff, Johannes; Pollmann, Katrin
2012-12-23
Escherichia coli is one of the best studied microorganisms and finds multiple applications especially as tool in the heterologous production of interesting proteins of other organisms. The heterologous expression of special surface (S-) layer proteins caused the formation of extremely long E. coli cells which leave transparent tubes when they divide into single E. coli cells. Such natural structures are of high value as bio-templates for the development of bio-inorganic composites for many applications. In this study we used genetically modified filamentous Escherichia coli cells as template for the design of polyelectrolyte tubes that can be used as carrier for functional molecules or particles. Diversity of structures of biogenic materials has the potential to be used to construct inorganic or polymeric superior hybrid materials that reflect the form of the bio-template. Such bio-inspired materials are of great interest in diverse scientific fields like Biology, Chemistry and Material Science and can find application for the construction of functional materials or the bio-inspired synthesis of inorganic nanoparticles. Genetically modified filamentous E. coli cells were fixed in 2% glutaraldehyde and coated with alternating six layers of the polyanion polyelectrolyte poly(sodium-4styrenesulfonate) (PSS) and polycation polyelectrolyte poly(allylamine-hydrochloride) (PAH). Afterwards we dissolved the E. coli cells with 1.2% sodium hypochlorite, thus obtaining hollow polyelectrolyte tubes of 0.7 μm in diameter and 5-50 μm in length. For functionalisation the polyelectrolyte tubes were coated with S-layer protein polymers followed by metallisation with Pd(0) particles. These assemblies were analysed with light microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The thus constructed new material offers possibilities for diverse applications like novel catalysts or metal nanowires for electrical devices. The novelty of this work is the use of filamentous E. coli templates and the use of S-layer proteins in a new material construct.
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USDA-ARS?s Scientific Manuscript database
Introduction: Escherichia coli O157:H7 outbreaks of infections associated with the consumption of fresh produce have increased in recent years. Bacterial cell surface appendages such as curli and the spinach leaf structure topography influence pathogen attachment and subsequent survival on spinach ...
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Babiker, E E; Azakami, H; Ogawa, T; Kato, A
2000-02-01
To elucidate the molecular mechanism of the allergenicity of soybean P34 protein recognized as the most allergenic protein in soybean, the protein was expressed in Escherichia coli transformed with a plasmid carrying P34 cDNA. SDS-PAGE pattern showed that the molecular weight of the recombinant P34 was approximately 2 kDa less than that of the native soybean P34. The difference in the molecular mass between these two proteins could be due to the native P34 in soybean being glycosylated at position Asn(170), whereas the recombinant protein generated in E. coli lacks this post-translational modification. Immunoblot analysis showed that both soybean and recombinant P34 proteins cross-reacted not only with polyclonal and monoclonal antibodies produced against P34 and crude soybean protein but also with patients' sera. The results suggest that the recombinant P34 is immunologically reactive, indicating that both proteins have similar epitope structures. Thus, the recombinant P34 produced by the E. coli expression system can be used as a standard allergen for molecular design to reduce the allergenic structure.
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Krishna Raja, M; Ghosh, Asit Ranjan; Vino, S; Sajitha Lulu, S
2015-01-01
Features of heat-labile enterotoxins of Escherichia coli which make them fit to use as novel receptors for antidiarrheals are not completely explored. Data-set of 14 different serovars of enterotoxigenic Escherichia coli producing heat-labile toxins were taken from NCBI Genbank database and used in the study. Sequence analysis showed mutations in different subunits and also at their interface residues. As these toxins lack crystallography structures, homology modeling using Modeller 9.11 led to the structural approximation for the E. coli producing heat-labile toxins. Interaction of modeled toxin subunits with proanthocyanidin, an antidiarrheal showed several strong hydrogen bonding interactions at the cost of minimized energy. The hits were subsequently characterized by molecular dynamics simulation studies to monitor their binding stabilities. This study looks into novel space where the ligand can choose the receptor preference not as a whole but as an individual subunit. Mutation at interface residues and interaction among subunits along with the binding of ligand to individual subunits would help to design a non-toxic labile toxin and also to improve the therapeutics.
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Bamford, Vicki A.; Armour, Maria; Mitchell, Sue A.; Cartron, Michaël; Andrews, Simon C.; Watson, Kimberly A.
2008-01-01
YqjH is a cytoplasmic FAD-containing protein from Escherichia coli; based on homology to ViuB of Vibrio cholerae, it potentially acts as a ferri-siderophore reductase. This work describes its overexpression, purification, crystallization and structure solution at 3.0 Å resolution. YqjH shares high sequence similarity with a number of known siderophore-interacting proteins and its structure was solved by molecular replacement using the siderophore-interacting protein from Shewanella putrefaciens as the search model. The YqjH structure resembles those of other members of the NAD(P)H:flavin oxidoreductase superfamily. PMID:18765906
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Solving a four-destination traveling salesman problem using Escherichia coli cells as biocomputers.
Esau, Michael; Rozema, Mark; Zhang, Tuo Huang; Zeng, Dawson; Chiu, Stephanie; Kwan, Rachel; Moorhouse, Cadence; Murray, Cameron; Tseng, Nien-Tsu; Ridgway, Doug; Sauvageau, Dominic; Ellison, Michael
2014-12-19
The Traveling Salesman Problem involves finding the shortest possible route visiting all destinations on a map only once before returning to the point of origin. The present study demonstrates a strategy for solving Traveling Salesman Problems using modified E. coli cells as processors for massively parallel computing. Sequential, combinatorial DNA assembly was used to generate routes, in the form of plasmids made up of marker genes, each representing a path between destinations, and short connecting linkers, each representing a given destination. Upon growth of the population of modified E. coli, phenotypic selection was used to eliminate invalid routes, and statistical analysis was performed to successfully identify the optimal solution. The strategy was successfully employed to solve a four-destination test problem.
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Nicholson, April M; Gurtler, Joshua B; Bailey, Rebecca B; Niemira, Brendan A; Douds, David D
2015-01-02
The objectives of this study were to determine the influence of a symbiotic arbuscular mycorrhizal (AM) fungus on persistence of Salmonella and enterohemorrhagic Escherichia coli O157:H7 (EHEC) within soil, and survival within Romaine lettuce. Romaine seedlings were grown with or without AM fungi. Soil surrounding plants was inoculated with ca. 8 log CFU/plant of either Salmonella enterica or E. coli EHEC composites. Samples (soil, root, and shoot) were analyzed on days 1, 8, 15 and 22 for Salmonella and EHEC by direct plating and selective enrichment. Twenty-four hours after inoculation, populations of Salmonella and EHEC, respectively, were 4.20 and 3.24 log CFU/root, 2.52 and 1.17 log CFU/shoot, and 5.46 and 5.17 log CFU/g soil. By selective enrichment, samples tested positive for Salmonella or EHEC at day 22 at rates of 94 and 68% (shoot), 97 and 56% (root), and 100 and 75% (soil), respectively, suggesting that Salmonella has a greater propensity for survival than EHEC. Salmonella populations in soil remained as high as 4.35 log CFU/g by day 22, while EHEC populations dropped to 1.12 log CFU/g in the same amount of time. Ninety-two percent of all Romaine leaves in our study were positive for internalized Salmonella from days 8 to 22 and remained as high as 1.26 log CFU/shoot on day 22 in AM fungi+Romaine plants. There were no differences (P>0.05) between the survival of either pathogen based on the presence or absence of mycorrhizal fungi. Results of this study suggest that AM fungi do not affect the internalization and/or survival of either S. enterica or E. coli O157:H7 in Romaine lettuce seedlings. Our results should provide Romaine lettuce farmers confidence that the presence and/or application of AM fungi to crop soil is not a contributing factor to the internalization and survival of Salmonella or E. coli O157:H7 within Romaine lettuce plants. Published by Elsevier B.V.
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A Structure-Function Analysis of Shiga-Like Toxin Type 2 of Enterohemorrhagic Escherichia Coli
1990-05-07
like toxins are summarized in Table 2. The genes coding for both SLT-I and SLT-II are borne on coliphage , and toxin expression by E. coli occurs as...A stock | | ’ • * suspension of toxin-converting W coliphage was prepared by inducing the phage from | "fif the E. coli C600(933W) lysogen with...mitomycin C as described previously (Marques et al., 1987). An appropriate amount of the W coliphage stock was added to an l| exponential culture of
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Solar to Liquid Fuels Production: Light-Driven Reduction of Carbon Dioxide to Formic Acid
2014-03-29
molecular wire. The X-ray crystal structure for the E . coli FDH enzyme shows that a [4Fe-4S] cluster is located near the surface of the protein. The...CO2 to formic acid. E . coli FDH, encoded by fdhF, was chosen for this work because it is a single-subunit enzyme that has been studied in detail, and...mutagenesis was employed to change surface-located Cys11 to Gly to open a coordination site. The proteins were overproduced in E . coli and purified
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Akhter, Asma; Imran, Mohd; Akhter, Firoz
2014-01-01
The distribution of resistance to ampicillin, chloramphenicol, sulfonamides, tetracycline, and streptomycin among coliform in the Gomti river water samples was investigated. The coliform populations were isolated on Mac Conky and eosin methylene blue (EMB) agar plates supplemented with antibiotics. The incidence of resistance among the coliform population varied considerably in different drug and water sampling sites. Coliform bacteria showed lower drug resistant viable count in sampling site-III (receiving treated wastewater) as compared to more polluted site-I and site-II. Viable count of coliform population obtained on both medium was recorded higher against erythromycin from sampling site-III. Lower viable count of coliforms was recorded against tetracycline in site-II and III. Similar resistance pattern was obtained in the frequency of E. coli and Enterobacter species from all the three sampling sites. Percentage of antibiotic resistant E. coli was observed higher than Enterobacter spp among the total coliforms against all antibiotics tested without Erythromycin and penicillin in site-I and II respectively. Isolates of E. coli and Enterobacter spp. showed their tolerance level (MIC) in the range of 2-100 against the antibiotics tested. Maximum number of isolates of both genus exhibited their MICs at lower concentration range 2-5µg/ml against ciprofloxacin, tetracyclin and amoxycillin. EMB - Eosin methylene blue, IMViC tests - Indole, Methyl Red, Voges Proskauer and Citrate Utilization Tests, MIC - Minimum inhibitory concentration.
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Akhter, Asma; Imran, Mohd; Akhter, Firoz
2014-01-01
The distribution of resistance to ampicillin, chloramphenicol, sulfonamides, tetracycline, and streptomycin among coliform in the Gomti river water samples was investigated. The coliform populations were isolated on Mac Conky and eosin methylene blue (EMB) agar plates supplemented with antibiotics. The incidence of resistance among the coliform population varied considerably in different drug and water sampling sites. Coliform bacteria showed lower drug resistant viable count in sampling site-III (receiving treated wastewater) as compared to more polluted site-I and site-II. Viable count of coliform population obtained on both medium was recorded higher against erythromycin from sampling site-III. Lower viable count of coliforms was recorded against tetracycline in site-II and III. Similar resistance pattern was obtained in the frequency of E. coli and Enterobacter species from all the three sampling sites. Percentage of antibiotic resistant E. coli was observed higher than Enterobacter spp among the total coliforms against all antibiotics tested without Erythromycin and penicillin in site-I and II respectively. Isolates of E. coli and Enterobacter spp. showed their tolerance level (MIC) in the range of 2-100 against the antibiotics tested. Maximum number of isolates of both genus exhibited their MICs at lower concentration range 2-5µg/ml against ciprofloxacin, tetracyclin and amoxycillin. Abbreviations EMB - Eosin methylene blue, IMViC tests - Indole, Methyl Red, Voges Proskauer and Citrate Utilization Tests, MIC - Minimum inhibitory concentration. PMID:24966515
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Imdad, Aamer; Foster, Monique A; Iqbal, Junaid; Fonnesbeck, Christopher; Payne, Daniel C; Zhang, Chengxian; Chappell, James D; Halasa, Natasha; Gómez-Duarte, Oscar G
2018-06-01
Diarrheagenic Escherichia coli (DEC) is an important cause of acute gastroenteritis in children; however, there is limited information available on the epidemiology, phylogenetics, serotyping and antibiotic susceptibility of DEC in children in the United States. The aim of this study was to determine the molecular epidemiology of DEC among children with and without acute gastroenteritis in Davidson County, Tennessee. This prospective, frequency matched, case-control study recruited subjects 15 days to 17 years of age and detected DEC with polymerase chain reaction from stool samples. Additional testing was done to define phylogenetics and antibiotics resistance. Among 1267 participants, 857 cases and 410 controls, 5.5% were positive for at least one subtype of DEC. Enteroaggregative E. coli [n = 32 (45%)] was the most common subtype followed by enteropathogenic E. coli (EPEC) [n = 30 (43%)], Shiga toxin-producing E. coli [n = 4 (6%)] and diffusely adherent E. coli [n = 4 (6%)]. No significant difference in prevalence of DEC was found between cases (5%) and controls (7%) [odds ratio: 0.66 (95% confidence interval: 0.4-1.07)], and results were similar when data were stratified by subtypes and adjusted for age, sex, race and ethnicity. Substantial diversity was found among DEC isolates in terms of phylotypes and serotypes, and a large proportion was resistant to, at least, one antibiotic. Enteroaggregative E. coli and enteropathogenic E. coli were frequently found in both cases and controls in this study population. DNA-based methods for detection of these subtypes need further investigation to help differentiate between pathogenic and colonizing strains.
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Use of Nitrogen-15-Enriched Escherichia coli as a Bacterial Tracer in Karst Aquifers.
Ward, James W; Warden, John G; Bandy, Ashley M; Fryar, Alan E; Brion, Gail M; Macko, Stephen A; Romanek, Christopher S; Coyne, Mark S
2016-11-01
Karst aquifers are susceptible to contamination by microorganisms, but relatively few studies have used bacteria as tracers. We demonstrate the utility of Escherichia coli enriched in the stable isotope nitrogen-15 ( 15 N) as a novel bacterial tracer. Nonpathogenic E. coli from two springs in central Kentucky were grown on 15 N-enriched media. Survival of E. coli and persistence of the isotopic signal were assessed in two sets of laboratory experiments conducted with sterilized spring water in dark microcosms at 14 °C. First, isotopically labeled bacteria survived for 130 d at concentrations within one log unit of the average initial value, and there was no significant difference in δ 15 N values from Day 1 to Day 130. Second, water samples with E. coli were inoculated with either of two different species of protozoa (Tetrahymena pyriformis or Colpoda steinii). During 7 d, δ 15 N values increased in T. pyriformis while bacterial populations decreased. In a field test, following a 2.1-cm rainfall, 15 N-labeled E. coli, solutes (rhodamine WT dye and bromide), and latex microspheres were injected into a sinkhole approximately 530 m upgradient of a spring. Breakthrough of all tracers coincided, but microspheres were remobilized by subsequent storms, unlike other tracers. Enriched E. coli exhibited more tailing than solute tracers during the initial storm-flow recession. These results indicate that 15 N-enriched E. coli is a viable tracer of bacterial transport in karst aquifers, although predation may attenuate the isotopic signal in systems that are not rapidly flushed. © 2016, National Ground Water Association.
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Foreshore sand as a source of Escherichia coli in nearshore water of a Lake Michigan beach.
Whitman, Richard L; Nevers, Meredith B
2003-09-01
Swimming advisories due to excessive Escherichia coli concentrations are common at 63rd Street Beach, Chicago, Ill. An intensive study was undertaken to characterize the source and fate of E. coli in beach water and sand at the beach. From April through September 2000, water and sand samples were collected daily or twice daily at two depths on three consecutive days per week (water samples, n = 1,747; sand samples, n = 858); hydrometeorological conditions and bird and bather distributions were also recorded. E. coli concentrations in sand and water were significantly correlated, with the highest concentration being found in foreshore sand, followed by those in submerged sediment and water of increasing depth. Gull contributions to E. coli densities in sand and water were most apparent on the day following gull activity in a given area. E. coli recolonized newly placed foreshore sand within 2 weeks. Analysis of variance, correlation, cluster analyses, concentration gradients, temporal-spatial distribution, demographic patterns, and DNA fingerprinting suggest that E. coli may be able to sustain population density in temperate beach sand during summer months without external inputs. This research presents evidence that foreshore beach sand (i) plays a major role in bacterial lake water quality, (ii) is an important non-point source of E. coli to lake water rather than a net sink, (iii) may be environmentally, and perhaps hygienically, problematic, and (iv) is possibly capable of supporting an autochthonous, high density of indicator bacteria for sustained periods, independent of lake, human, or animal input.
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Mina, Petros; di Bernardo, Mario; Savery, Nigel J.; Tsaneva-Atanasova, Krasimira
2013-01-01
Population-level measurements of phenotypic behaviour in biological systems may not necessarily reflect individual cell behaviour. To assess qualitative changes in the behaviour of a single cell, when alone and when part of a community, we developed an agent-based model describing the metabolic states of a population of quorum-coupled cells. The modelling is motivated by published experimental work of a synthetic genetic regulatory network (GRN) used in Escherichia coli cells that exhibit oscillatory behaviour across the population. To decipher the mechanisms underlying oscillations in the system, we investigate the behaviour of the model via numerical simulation and bifurcation analysis. In particular, we study the effect of an increase in population size as well as the spatio-temporal behaviour of the model. Our results demonstrate that oscillations are possible only in the presence of a high concentration of the coupling chemical and are due to a time scale separation in key regulatory components of the system. The model suggests that the population establishes oscillatory behaviour as the system's preferred stable state. This is achieved via an effective increase in coupling across the population. We conclude that population effects in GRN design need to be taken into consideration and be part of the design process. This is important in planning intervention strategies or designing specific cell behaviours. PMID:23135248
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Mina, Petros; di Bernardo, Mario; Savery, Nigel J; Tsaneva-Atanasova, Krasimira
2013-01-06
Population-level measurements of phenotypic behaviour in biological systems may not necessarily reflect individual cell behaviour. To assess qualitative changes in the behaviour of a single cell, when alone and when part of a community, we developed an agent-based model describing the metabolic states of a population of quorum-coupled cells. The modelling is motivated by published experimental work of a synthetic genetic regulatory network (GRN) used in Escherichia coli cells that exhibit oscillatory behaviour across the population. To decipher the mechanisms underlying oscillations in the system, we investigate the behaviour of the model via numerical simulation and bifurcation analysis. In particular, we study the effect of an increase in population size as well as the spatio-temporal behaviour of the model. Our results demonstrate that oscillations are possible only in the presence of a high concentration of the coupling chemical and are due to a time scale separation in key regulatory components of the system. The model suggests that the population establishes oscillatory behaviour as the system's preferred stable state. This is achieved via an effective increase in coupling across the population. We conclude that population effects in GRN design need to be taken into consideration and be part of the design process. This is important in planning intervention strategies or designing specific cell behaviours.
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Seras-Franzoso, Joaquin; Affentranger, Roman; Ferrer-Navarro, Mario; Daura, Xavier; Villaverde, Antonio
2012-01-01
Escherichia coli β-galactosidase is probably the most widely used reporter enzyme in molecular biology, cell biology, and biotechnology because of the easy detection of its activity. Its large size and tetrameric structure make this bacterial protein an interesting model for crystallographic studies and atomic mapping. In the present study, we investigate a version of Escherichia coli β-galactosidase produced under oxidizing conditions, in the cytoplasm of an Origami strain. Our data prove the activation of this microbial enzyme under oxidizing conditions and clearly show the occurrence of a disulfide bond in the β-galactosidase structure. Additionally, the formation of this disulfide bond is supported by the analysis of a homology model of the protein that indicates that two cysteines located in the vicinity of the catalytic center are sufficiently close for disulfide bond formation. PMID:22286993
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Chen, Chih-Ming; Ke, Se-Chin; Li, Chia-Ru; Wu, Ying-Chen; Chen, Ter-Hsin; Lai, Chih-Ho; Wu, Xin-Xia; Wu, Lii-Tzu
2017-10-01
Multidrug-resistant Escherichia coli can contaminate food meat during processing and cause human infection. Phenotypic and genotypic characterization of the antimicrobial resistance were conducted for 45 multidrug-resistant E. coli isolates from 208 samples of beef carcasses. The mechanisms of resistance were evaluated using polymerase chain reaction and sequencing methods, and the clonal relationship among isolates was evaluated using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Different variants of bla, tet, flo, dfrA, and aadA genes were detected in most of the strains resistant to β-lactam, tetracycline, chloramphenicol, sulfonamides, and aminoglycosides, respectively. Extended-spectrum β-lactamase (ESBL)-producing E. coli was found in 42.2% of the 45 E. coli isolates and the most commonly detected ESBL genotypes were CTX-M group 1 and 9. Class 1 integrons with nine different arrangements of gene cassettes were present in 28 of 45 E. coli isolates. Twenty-nine PFGE groups and 24 MLST types were identified in their clonal structure. This study revealed that E. coli isolates from beef contained high diversity of antimicrobial resistance genes, integrons, and genotypes. These results highlighted the role of beef meat as a potential source for multidrug-resistant E. coli strains and the need for controlling beef safety.
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Massicotte, Richard; Mafu, Akier A.; Ahmad, Darakhshan; Deshaies, Francis; Pichette, Gilbert; Belhumeur, Pierre
2017-01-01
The present study was undertaken to compare the use of flow cytometry (FCM) and traditional culture methods for efficacy assessment of six disinfectants used in Quebec hospitals including: two quaternary ammonium-based, two activated hydrogen peroxide-based, one phenol-based, and one sodium hypochlorite-based. Four nosocomial bacterial species, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Vancomycin-resistant Enterococci faecalis, were exposed to minimum lethal concentrations (MLCs) and sublethal concentrations (1/2 MLCs) of disinfectants under study. The results showed a strong correlation between the two techniques for the presence of dead and live cell populations, as well as, evidence of injured populations with the FCM. The only exception was observed with sodium hypochlorite at higher concentrations where fluorescence was diminished and underestimating dead cell population. The results also showed that FCM can replace traditional microbiological methods to study disinfectant efficacy on bacteria. Furthermore, FCM profiles for E. coli and E. faecalis cells exposed to sublethal concentrations exhibited distinct populations of injured cells, opening a new aspect for future research and investigation to elucidate the role of injured, cultural/noncuturable/resuscitable cell populations in infection control. PMID:28217115
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Jang, Hyein; Matthews, Karl R
2018-06-01
Shiga toxin-producing Escherichia coli (STEC) has been associated with illnesses and outbreaks linked to fresh vegetables, prompting a growing public health concern. Most studies regarding interactions of STEC on fresh produce focused on E. coli O157:H7. Limited information is available about survival or fitness of E. coli O104:H4, non-O157 pathogen that was linked to one of the largest outbreaks of hemolytic uremic syndrome in 2011. In this study, survival of E. coli O104:H4 was evaluated on Arabidopsis thaliana plant and lettuce for 5 days compared with E. coli O157:H7, and expression of pathogenesis-realted gene (PR1; induction of plant defense response) was examined by reverse transcription quantitative PCR, and potential influence of capsular polysaccharide (CPS) on the bacterial fitness on plant was investigated. Populations of E. coli O104:H4 strains (RG1, C3493, and LpfA) on Arabidopsis and lettuce were significantly (P < 0.05) greater than those of E. coli O157:H7 strains (7386 and sakai) at day 5 post-inoculation, indicating E. coli O104:H4 may have better survival ability on the plants. In addition, the E. coli O104:H4 strains produced significantly (P < 0.05) higher amounts of CPS compared with the E. coli O157:H7 strains. RG1 strain (1.5-fold) initiated significantly (P < 0.05) lower expression of PR1 gene indicating induction of plant defense response compared with E. coli O157:H7 strains 7386 (2.9-fold) and sakai (2.7-fold). Collectively, the results in this study suggests that different level of CPS production and plant defense response initiated by each STEC strain might influence the bacterial survival or persistence on plants. The present study provides better understanding of survival behavior of STEC, particularly E. coli O104:H4, using a model plant and vegetable under pre-harvest conditions with plant defense response. Copyright © 2018 Elsevier Ltd. All rights reserved.
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Dautzenberg, M J D; Haverkate, M R; Bonten, M J M; Bootsma, M C J
2016-01-01
Objectives Observational studies have suggested that Escherichia coli sequence type (ST) 131 and Klebsiella pneumoniae ST258 have hyperendemic properties. This would be obvious from continuously high incidence and/or prevalence of carriage or infection with these bacteria in specific patient populations. Hyperendemicity could result from increased transmissibility, longer duration of infectiousness, and/or higher pathogenic potential as compared with other lineages of the same species. The aim of our research is to quantitatively estimate these critical parameters for E. coli ST131 and K. pneumoniae ST258, in order to investigate whether E. coli ST131 and K. pneumoniae ST258 are truly hyperendemic clones. Primary outcome measures A systematic literature search was performed to assess the evidence of transmissibility, duration of infectiousness, and pathogenicity for E. coli ST131 and K. pneumoniae ST258. Meta-regression was performed to quantify these characteristics. Results The systematic literature search yielded 639 articles, of which 19 data sources provided information on transmissibility (E. coli ST131 n=9; K. pneumoniae ST258 n=10)), 2 on duration of infectiousness (E. coli ST131 n=2), and 324 on pathogenicity (E. coli ST131 n=285; K. pneumoniae ST258 n=39). Available data on duration of carriage and on transmissibility were insufficient for quantitative assessment. In multivariable meta-regression E. coli isolates causing infection were associated with ST131, compared to isolates only causing colonisation, suggesting that E. coli ST131 can be considered more pathogenic than non-ST131 isolates. Date of isolation, location and resistance mechanism also influenced the prevalence of ST131. E. coli ST131 was 3.2 (95% CI 2.0 to 5.0) times more pathogenic than non-ST131. For K. pneumoniae ST258 there were not enough data for meta-regression assessing the influence of colonisation versus infection on ST258 prevalence. Conclusions With the currently available data, it cannot be confirmed nor rejected, that E. coli ST131 or K. pneumoniae ST258 are hyperendemic clones. PMID:26988349
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Ortega, Adriana; Bartolomé, Rosa; Bou, Germán; Conejo, Carmen; Fernández-Martínez, Marta; González-López, Juan José; Martínez-García, Laura; Martínez-Martínez, Luis; Merino, María; Miró, Elisenda; Mora, Marta; Oliver, Antonio; Pascual, Álvaro; Rodríguez-Baño, Jesús; Ruiz-Carrascoso, Guillermo; Ruiz-Garbajosa, Patricia; Zamorano, Laura; Bautista, Verónica; Pérez-Vázquez, María; Campos, José
2015-01-01
The aim of this study was to determine the impact of carbapenemase-producing Enterobacteriaceae (CPE) in Spain in 2013 by describing the prevalence, dissemination, and geographic distribution of CPE clones, and their population structure and antibiotic susceptibility. From February 2013 to May 2013, 83 hospitals (about 40,000 hospital beds) prospectively collected nonduplicate Enterobacteriaceae using the screening cutoff recommended by EUCAST. Carbapenemase characterization was performed by phenotypic methods and confirmed by PCR and sequencing. Multilocus sequencing types (MLST) were determined for Klebsiella pneumoniae and Escherichia coli. A total of 702 Enterobacteriaceae isolates met the inclusion criteria; 379 (54%) were CPE. OXA-48 (71.5%) and VIM-1 (25.3%) were the most frequent carbapenemases, and K. pneumoniae (74.4%), Enterobacter cloacae (10.3%), and E. coli (8.4%) were the species most affected. Susceptibility to colistin, amikacin, and meropenem was 95.5%, 81.3%, and 74.7%, respectively. The most prevalent sequence types (STs) were ST11 and ST405 for K. pneumoniae and ST131 for E. coli. Forty-five (54.1%) of the hospitals had at least one CPE case. For K. pneumoniae, ST11/OXA-48, ST15/OXA-48, ST405/OXA-48, and ST11/VIM-1 were detected in two or more Spanish provinces. ST11 isolates carried four carbapenemases (VIM-1, OXA-48, KPC-2, and OXA-245), but ST405 isolates carried OXA-48 only. A wide interregional spread of CPE in Spain was observed, mainly due to a few successful clones of OXA-48-producing K. pneumoniae (e.g., ST11 and ST405). The dissemination of OXA-48-producing E. coli is a new finding of public health concern. According to the susceptibilities determined in vitro, most of the CPE (94.5%) had three or more options for antibiotic treatment. PMID:25824224
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Stamper, David M.; Walch, Marianne; Jacobs, Rachel N.
2003-01-01
The bacterial population of a graywater treatment system was monitored over the course of 100 days, along with several wastewater biochemical parameters. The graywater treatment system employed an 1,800-liter membrane bioreactor (MBR) to process the waste, with essentially 100% recycling of the biomass. Graywater feed consisting of 10% galley water and 90% laundry water, selected to approximate the graywater composition on board U.S. Navy ships, was collected offsite. Five-day biological oxygen demand (BOD5), oils and greases (O/G), nitrogen, and phosphorus were monitored in the feed and were found to vary greatly day to day. Changes in the bacterial population were monitored by PCR amplification of region 332 to 518 (Escherichia coli numbering) of the 16S rRNA gene and denaturing gradient gel electrophoresis (DGGE) analysis of the resultant PCR products. DGGE analysis indicated a diverse and unstable bacterial population throughout the 100-day period, with spikes in feed strength causing significant changes in community structure. Long-term similarity between the communities was 0 to 25%, depending on the method of analysis. In spite of the unstable bacterial population, the MBR system was able to meet effluent quality parameters approximately 90% of the time. PMID:12571004
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Stamper, David M; Walch, Marianne; Jacobs, Rachel N
2003-02-01
The bacterial population of a graywater treatment system was monitored over the course of 100 days, along with several wastewater biochemical parameters. The graywater treatment system employed an 1,800-liter membrane bioreactor (MBR) to process the waste, with essentially 100% recycling of the biomass. Graywater feed consisting of 10% galley water and 90% laundry water, selected to approximate the graywater composition on board U.S. Navy ships, was collected offsite. Five-day biological oxygen demand (BOD(5)), oils and greases (O/G), nitrogen, and phosphorus were monitored in the feed and were found to vary greatly day to day. Changes in the bacterial population were monitored by PCR amplification of region 332 to 518 (Escherichia coli numbering) of the 16S rRNA gene and denaturing gradient gel electrophoresis (DGGE) analysis of the resultant PCR products. DGGE analysis indicated a diverse and unstable bacterial population throughout the 100-day period, with spikes in feed strength causing significant changes in community structure. Long-term similarity between the communities was 0 to 25%, depending on the method of analysis. In spite of the unstable bacterial population, the MBR system was able to meet effluent quality parameters approximately 90% of the time.
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Valentin, Lars; Sharp, Hannah; Hille, Katja; Seibt, Uwe; Fischer, Jennie; Pfeifer, Yvonne; Michael, Geovana Brenner; Nickel, Silke; Schmiedel, Judith; Falgenhauer, Linda; Friese, Anika; Bauerfeind, Rolf; Roesler, Uwe; Imirzalioglu, Can; Chakraborty, Trinad; Helmuth, Reiner; Valenza, Giuseppe; Werner, Guido; Schwarz, Stefan; Guerra, Beatriz; Appel, Bernd; Kreienbrock, Lothar; Käsbohrer, Annemarie
2014-10-01
Escherichia (E.) coli producing extended-spectrum beta-lactamases (ESBLs) are an increasing problem for public health. The success of ESBLs may be due to spread of ESBL-producing bacterial clones, transfer of ESBL gene-carrying plasmids or exchange of ESBL encoding genes on mobile elements. This makes it difficult to identify transmission routes and sources for ESBL-producing bacteria. The objectives of this study were to compare the distribution of genotypic and phenotypic properties of E. coli isolates from different animal and human sources collected in studies in the scope of the national research project RESET. ESBL-producing E. coli from two longitudinal and four cross-sectional studies in broiler, swine and cattle farms, a cross-sectional and a case-control study in humans and diagnostic isolates from humans and animals were used. In the RESET consortium, all laboratories followed harmonized methodologies for antimicrobial susceptibility testing, confirmation of the ESBL phenotype, specific PCR assays for the detection of bla(TEM), bla(CTX), and bla(SHV) genes and sequence analysis of the complete ESBL gene as well as a multiplex PCR for the detection of the four major phylogenetic groups of E. coli. Most ESBL genes were found in both, human and non-human populations but quantitative differences for distinct ESBL-types were detectable. The enzymes CTX-M-1 (63.3% of all animal isolates, 29.3% of all human isolates), CTX-M-15 (17.7% vs. 48.0%) and CTX-M-14 (5.3% vs. 8.7%) were the most common ones. More than 70% of the animal isolates and more than 50% of the human isolates contained the broadly distributed ESBL genes bla(CTX-M-1), bla(CTX-M-15), or the combinations bla(SHV-12)+bla(TEM) or bla(CTX-M-1)+bla(TEM). While the majority of animal isolates carried bla(CTX-M-1) (37.5%) or the combination bla(CTX-M-1)+bla(TEM) (25.8%), this was the case for only 16.7% and 12.6%, respectively, of the human isolates. In contrast, 28.2% of the human isolates carried bla(CTX-M-15) compared to 10.8% of the animal isolates. When grouping data by ESBL types and phylogroups bla(CTX-M-1) genes, mostly combined with phylogroup A or B1, were detected frequently in all settings. In contrast, bla(CTX-M-15) genes common in human and animal populations were mainly combined with phylogroup A, but not with the more virulent phylogroup B2 with the exception of companion animals, where a few isolates were detectable. When E. coli subtype definition included ESBL types, phylogenetic grouping and antimicrobial susceptibility data, the proportion of isolates allocated to common clusters was markedly reduced. Nevertheless, relevant proportions of same subtypes were detected in isolates from the human and livestock and companion animal populations included in this study, suggesting exchange of bacteria or bacterial genes between these populations or a common reservoir. In addition, these results clearly showed that there is some similarity between ESBL genes, and bacterial properties in isolates from the different populations. Finally, our current approach provides good insight into common and population-specific clusters, which can be used as a basis for the selection of ESBL-producing isolates from interesting clusters for further detailed characterizations, e.g. by whole genome sequencing. Copyright © 2014 The Authors. Published by Elsevier GmbH.. All rights reserved.
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NASA Astrophysics Data System (ADS)
Yang, Leyun; Xu, Yu; Chen, Yong; Ying, Hanjie
2018-01-01
New secretion vectors containing the synthetic signal sequence (OmpA’) was constructed for the secretory production of recombinant proteins in Escherichia coli. The E. coli Phospholipase D structural gene (Accession number:NC_018658) fused to various signal sequence were expressed from the Lac promoter in E. coli Rosetta strains by induction with 0.4mM IPTG at 28°C for 48h. SDS-PaGe analysis of expression and subcellular fractions of recombinant constructs revealed the translocation of Phospholipase D (PLD) not only to the medium but also remained in periplasm of E. coli with OmpA’ signal sequence at the N-terminus of PLD. Thus the study on the effects of various surfactants on PLD extracellular production in Escherichia coli in shake flasks revealed that optimal PLD extracellular production could be achieved by adding 0.4% Triton X-100 into the medium. The maximal extracellular PLD production and extracellular enzyme activity were 0.23mg ml-1 and 16U ml-1, respectively. These results demonstrate the possibility of efficient secretory production of recombinant PLD in E. coli should be a potential industrial applications.
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Palermo, D A; Evans, T M; Clark, V L
1987-01-01
A gonococcal gene bank maintained in Escherichia coli K-12 was screened by colony immunoblotting, and a transformant expressing a surface antigen reactive to anti-gonococcal outer membrane antiserum was isolated. The isolate carried a recombinant plasmid, pTME6, consisting of approximately 9 kilobases of Neisseria gonorrhoeae DNA inserted into the BamHI site of pBR322. Surface labeling of E. coli HB101(pTME6) confirmed that the antigen was expressed on the E. coli cell surface. The antigenic material was resistant to proteinase K digestion and sensitive to periodate oxidation, indicating that the material was carbohydrate. Purified lipopolysaccharide (LPS) from HB101(pTME6) produced a unique band on silver-stained polyacrylamide gels that contained immunoreactive material as seen on Western blots of LPS samples. Only two of three E. coli LPS mutant strains carrying pTME6 reacted with the antigonococcal antiserum, suggesting that a certain E. coli core structure is necessary for antigen expression. We conclude that pTME6 contains one or more gonococcal genes encoding an LPS core biosynthetic enzyme(s) which can modify E. coli core LPS to produce a gonococcuslike epitope(s). Images PMID:3117695
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Côté, Caroline; Quessy, Sylvain
2005-05-01
Liquid hog manure is routinely applied to farm land as a crop fertilizer. However, this practice raises food safety concerns, especially when manure is used on fruit and vegetable crops. The objectives of this project were to evaluate the persistence of Escherichia coli and Salmonella in surface soil after application of liquid hog manure to fields where pickling cucumbers were grown and to verify the microbiological quality of harvested cucumbers. Mineral fertilizers were replaced by liquid hog manure at various ratios in the production of pickling cucumbers in a 3-year field study. The experimental design was a randomized complete block comprising four replicates in sandy loam (years 1, 2, and 3) and loamy sand (year 3). Soil samples were taken at a depth of 20 cm every 2 weeks after June application of organic and inorganic fertilizers. Vegetable samples were also taken at harvest time. Liquid hog manure, soil, and vegetable (washed and unwashed) samples were analyzed for the presence of Salmonella and E. coli. An exponential decrease of E. coli populations was observed in surface soil after the application of manure. The estimated average time required to reach undetectable concentrations of E. coli in sandy loam varied from 56 to 70 days, whereas the absence of E. coli was estimated at 77 days in loamy sand. The maximal Salmonella persistence in soil was 54 days. E. coli and Salmonella were not detected in any vegetable samples.
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Mordhorst, Ines L; Claus, Heike; Ewers, Christa; Lappann, Martin; Schoen, Christoph; Elias, Johannes; Batzilla, Julia; Dobrindt, Ulrich; Wieler, Lothar H; Bergfeld, Anne K; Mühlenhoff, Martina; Vogel, Ulrich
2009-12-01
Escherichia coli K1 causes disease in humans and birds. Its polysialic acid capsule can be O-acetylated via phase-variable expression of the acetyltransferase NeuO encoded by prophage CUS-3. The role of capsule O-acetylation in ecological adaptation or pathogenic invasion of E. coli K1 is largely unclear. A population genetics approach was performed to study the distribution of neuO among E. coli K1 isolates from human and avian sources. Multilocus sequence typing revealed 39 different sequence types (STs) among 183 E. coli K1 strains. The proportion of the ST95 complex (STC95) was 44%. NeuO was found in 98% of the STC95 strains, but only in 24% of other STs. Grouping of STs and prophage genotypes revealed a segregation of prophage types according to STs, suggesting coevolution of CUS-3 and the E. coli K1 host. Within the STC95, which is known to harbour both human and avian pathogenic isolates, CUS-3 genotypes were shared irrespective of the host species. Functional analysis of a variety of strain pairs revealed that NeuO-mediated K1 capsule O-acetylation enhanced desiccation resistance. In contrast, NeuO expression led to a reduced biofilm formation in biofilm positive E. coli K1 isolates. These findings suggest a delicate ecological balance of neuO'on'/'off' switching.
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Ibekwe, A M; Murinda, Shelton E; DebRoy, Chitrita; Reddy, Gudigopura B
2016-02-01
Escherichia coli populations originating from swine houses through constructed wetlands were analyzed for potential pathogens, antimicrobial susceptibility patterns, and genotypic diversity. Escherichia coli isolates (n = 493) were screened for the presence of the following virulence genes: stx1, stx2 and eae (Shiga toxin-producing E. coli [STEC]), heat-labile enterotoxin (LT) genes and heat stable toxin STa and STb (enterotoxigenic E. coli (ETEC), cytotoxin necrotizing factors 1 and 2 (cnf1 and cnf2 [necrotoxigenic E. coli- NTEC]), as well as O and H antigens, and the presence of the antibiotic resistance genes blaTEM, blaSHV, blaCMY-2, tet A, tet B, tet C, mph(A), aadA, StrA/B, sul1, sul2 and sul3. The commensal strains were further screened for 16 antimicrobials and characterized by BOX AIR-1 PCR for unique genotypes. The highest antibiotic resistance prevalence was for tetracycline, followed by erythromycin, ampicillin, streptomycin, sulfisoxazole and kanamycin. Our data showed that most of the isolates had high distribution of single or multidrug-resistant (MDR) genotypes. Therefore, the occurrence of MDR E. coli in the wetland is a matter of great concern due to possible transfer of resistance genes from nonpathogenic to pathogenic strains or vice versa in the environment. Published by Oxford University Press on behalf of FEMS 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.
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Elongation factor Tu resistant to kirromycin in an Esherichia coli mutant altered in both tuf genes
Fischer, Eckhard; Wolf, Heinz; Hantke, Klaus; Parmeggiani, Andrea
1977-01-01
A mutant of Escherichia coli is described that displays kirromycin resistance in a cell-free system by virtue of an altered elongation factor Tu (EF-Tu). In poly(U)-directed poly(Phe) synthesis the kirromycin resistance of the crystallized enzyme ranged between a factor of 80 and 700, depending on temperature. Similarly, kirromycin-induced EF-Tu GTPase activity uncoupled from ribosomes and aminoacyl-tRNA required correspondingly higher concentrations of the antibiotic. Resistance of EF-Tu to kirromycin is a consequence of a modified enzyme structure as indicated by its altered fingerprint pattern. P1 transduction experiments showed that the kirromycin-resistant EF-Tu is coded by an altered tufB gene (tufB1). The known existence of two genes coding for EF-Tu would interfere with the recognition of a mutant altered in only one of those genes, if the mutation were recessive. Because kirromycin blocks EF-Tu release from the ribosome, kirromycin sensitivity is dominant, as shown by the failure of a mixed EF-Tu population to express resistance in vitro. Therefore, phenotypic expression of kirromycin resistance in vivo appears to be only possible if the EF-Tu mutant lacks an active tufA gene, a property likely to be inherited from the parental D22 strain. The observations that introduction of a tufA+ region makes the resistant strain sensitive to the antibiotic and that transduction of tufB1 into a recipient other than E. coli D22 yields kirromycin-sensitive progeny support these conclusions. Images PMID:337296
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Miller, Cortney; Heringa, Spencer; Kim, Jinkyung; Jiang, Xiuping
2013-06-01
This study analyzed various organic fertilizers for indicator microorganisms, pathogens, and antibiotic-resistant Escherichia coli, and evaluated the growth potential of E. coli O157:H7 and Salmonella in fertilizers. A microbiological survey was conducted on 103 organic fertilizers from across the United States. Moisture content ranged from approximately 1% to 86.4%, and the average pH was 7.77. The total aerobic mesophiles ranged from approximately 3 to 9 log colony-forming units (CFU)/g. Enterobacteriaceae populations were in the range of <1 to approximately 7 log CFU/g, while coliform levels varied from <1 to approximately 6 log CFU/g. Thirty samples (29%) were positive for E. coli, with levels reaching approximately 6 log CFU/g. There were no confirmed positives for E. coli O157:H7, Salmonella, or Listeria monocytogenes. The majority of E. coli isolates (n=73), confirmed by glutamate decarboxylase (gad) PCR, were from group B1 (48%) and group A (32%). Resistance to 16 antibiotics was examined for 73 E. coli isolates, with 11 isolates having resistance to at least one antibiotic, 5 isolates to ≥ 2 antibiotics, and 2 isolates to ≥ 10 antibiotics. In the presence of high levels of background aerobic mesophiles, Salmonella and E. coli O157:H7 grew approximately 1 log CFU/g within 1 day of incubation in plant-based compost and fish emulsion-based compost, respectively. With low levels of background aerobic mesophiles, Salmonella grew approximately 2.6, 3.0, 3.0, and 3.2 log CFU/g in blood, bone, and feather meals and the mixed-source fertilizer, respectively, whereas E. coli O157:H7 grew approximately 4.6, 4.0, 4.0, and 4.8 log CFU/g, respectively. Our results revealed that the microbiological quality of organic fertilizers varies greatly, with some fertilizers containing antibiotic resistant E. coli and a few supporting the growth of foodborne pathogens after reintroduction into the fertilizer.
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Lee, Sun-Young; Baek, Seung-Youb
2008-06-01
Escherichia coli O157:H7 contaminated spinach has recently caused several outbreaks of human illness in the USA and Canada. However, to date, there has been no study demonstrating an effective way to eliminate E. coli O157:H7 in spinach. Therefore, this study was conducted to investigate the effect of chemical sanitizers alone or in combination with packaging methods such as vacuum and modified atmosphere packaging (MAP) on inactivating E. coli O157:H7 in spinach during storage time. Spinach inoculated with E. coli O157:H7 was packaged in four different methods (air, vacuum, N(2) gas, and CO(2) gas packaging) following treatment with water, 100 ppm chlorine dioxide, or 100 ppm sodium hypochlorite for 5 min at room temperature and stored at 7+/-2 degrees C. Treatment with water did not significantly reduce levels of E. coli O157:H7 in spinach. However, treatment with chlorine dioxide and sodium hypochlorite significantly decreased levels of E. coli O157:H7 by 2.6 and 1.1 log(10)CFU/g, respectively. Levels of E. coli O157:H7 in samples packaged in air following treatments grew during storage time, whereas levels were maintained in samples packaged in other packaging methods (vacuum, N(2) gas, and CO(2) gas packaging). Therefore there were significant differences (about 3-4 log) of E. coli O157:H7 populations between samples packed in air and other packaging methods following treatment with chemical sanitizers after 7 days storage. These results suggest that the combination of treatment with chlorine dioxide and packaging methods such as vacuum and MAP may be useful for improving the microbial safety of spinach against E. coli O157:H7 during storage.