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1

Enteroaggregative Escherichia coli Related to Uropathogenic Clonal Group A  

PubMed Central

Enteroaggregative Escherichia coli (EAEC) are heterogeneous, diarrheagenic E. coli. Of EAEC strains from Nigeria, 10 independent antimicrobial-resistant isolates belonged to the multilocus sequence type 69 clonal complex, to which uropathogenic E. coli clonal group A belongs. This finding suggests a recent common ancestor for these distinct groups of pathogenic E. coli.

Wallace-Gadsden, Faith; Johnson, James R.; Wain, John

2007-01-01

2

Covert Operations of Uropathogenic Escherichia coli within the Urinary Tract  

Microsoft Academic Search

Entry into host cells is required for many bacterial patho- gens to effectively disseminate within a host, avoid immune detection and cause disease. In recent years, many ostensibly extracellular bacteria have been shown to act as opportunistic intracellular pathogens. Among these are strains of uropathogenic Escherichia coli (UPEC), the primary causative agents of urinary tract infections (UTIs). UPEC are able

Jean M. Bower; Danelle S. Eto; Matthew A. Mulvey

2005-01-01

3

Uropathogenic Escherichia coli Flagella Aid in Efficient Urinary Tract Colonization  

Microsoft Academic Search

In the murine model of urinary tract infections (UTI), cystitis by uropathogenic Escherichia coli (UPEC) occurs through an intimate relationship with the bladder superficial umbrella cell entailing cycles of adher- ence, invasion, intracellular bacterial community (IBC) formation, and dispersal (fluxing) from the intracel- lular environment. IBC dispersal is a key step that results in the spread of bacteria over the

Kelly J. Wright; Patrick C. Seed; Scott J. Hultgren

2005-01-01

4

Transcriptome of Uropathogenic Escherichia coli during Urinary Tract Infection  

Microsoft Academic Search

A uropathogenic Escherichia coli strain CFT073-specific DNA microarray that includes each open reading frame was used to analyze the transcriptome of CFT073 bacteria isolated directly from the urine of infected CBA\\/J mice. The in vivo expression profiles were compared to that of E. coli CFT073 grown statically to exponential phase in rich medium, revealing the strategies this pathogen uses in

Jennifer A. Snyder; Brian J. Haugen; Eric L. Buckles; C. Virginia Lockatell; David E. Johnson; Michael S. Donnenberg; Rodney A. Welch; Harry L. T. Mobley

2004-01-01

5

The Asymptomatic Bacteriuria Escherichia coli Strain 83972 Outcompetes Uropathogenic E. coli Strains in Human Urine  

Microsoft Academic Search

Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract. The prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically

Viktoria Roos; Glen C. Ulett; Mark A. Schembri; Per Klemm

2006-01-01

6

Instability of Pathogenicity Islands in Uropathogenic Escherichia coli 536  

PubMed Central

The uropathogenic Escherichia coli strain 536 carries at least five genetic elements on its chromosome that meet all criteria characteristic of pathogenicity islands (PAIs). One main feature of these distinct DNA regions is their instability. We applied the so-called island-probing approach and individually labeled all five PAIs of E. coli 536 with the counterselectable marker sacB to evaluate the frequency of PAI-negative colonies under the influence of different environmental conditions. Furthermore, we investigated the boundaries of these PAIs. According to our experiments, PAI II536 and PAI III536 were the most unstable islands followed by PAI I536 and PAI V536, whereas PAI IV536 was stable. In addition, we found that deletion of PAI II536 and PAI III536 was induced by several environmental stimuli. Whereas excision of PAI I536, PAI II536, and PAI V536 was based on site-specific recombination between short direct repeat sequences at their boundaries, PAI III536 was deleted either by site-specific recombination or by homologous recombination between two IS100-specific sequences. In all cases, deletion is thought to lead to the formation of nonreplicative circular intermediates. Such extrachromosomal derivatives of PAI II536 and PAI III536 were detected by a specific PCR assay. Our data indicate that the genome content of uropathogenic E. coli can be modulated by deletion of PAIs.

Middendorf, Barbara; Hochhut, Bianca; Leipold, Kristina; Dobrindt, Ulrich; Blum-Oehler, Gabriele; Hacker, Jorg

2004-01-01

7

Covert operations of uropathogenic Escherichia coli within the urinary tract.  

PubMed

Entry into host cells is required for many bacterial pathogens to effectively disseminate within a host, avoid immune detection and cause disease. In recent years, many ostensibly extracellular bacteria have been shown to act as opportunistic intracellular pathogens. Among these are strains of uropathogenic Escherichia coli (UPEC), the primary causative agents of urinary tract infections (UTIs). UPEC are able to transiently invade, survive and multiply within the host cells and tissues constituting the urinary tract. Invasion of host cells by UPEC is promoted independently by distinct virulence factors, including cytotoxic necrotizing factor, Afa/Dr adhesins, and type 1 pili. Here we review the diverse mechanisms and consequences of host cell invasion by UPEC, focusing also on the impact of these processes on the persistence and recurrence of UTIs. PMID:15569242

Bower, Jean M; Eto, Danelle S; Mulvey, Matthew A

2005-01-01

8

Transcriptome of Uropathogenic Escherichia coli during Urinary Tract Infection  

PubMed Central

A uropathogenic Escherichia coli strain CFT073-specific DNA microarray that includes each open reading frame was used to analyze the transcriptome of CFT073 bacteria isolated directly from the urine of infected CBA/J mice. The in vivo expression profiles were compared to that of E. coli CFT073 grown statically to exponential phase in rich medium, revealing the strategies this pathogen uses in vivo for colonization, growth, and survival in the urinary tract environment. The most highly expressed genes overall in vivo encoded translational machinery, indicating that the bacteria were in a rapid growth state despite specific nutrient limitations. Expression of type 1 fimbriae, a virulence factor involved in adherence, was highly upregulated in vivo. Five iron acquisition systems were all highly upregulated during urinary tract infection, as were genes responsible for capsular polysaccharide and lipopolysaccharide synthesis, drug resistance, and microcin secretion. Surprisingly, other fimbrial genes, such as pap and foc/sfa, and genes involved in motility and chemotaxis were downregulated in vivo. E. coli CFT073 grown in human urine resulted in the upregulation of iron acquisition, capsule, and microcin secretion genes, thus partially mimicking growth in vivo. On the basis of gene expression levels, the urinary tract appears to be nitrogen and iron limiting, of high osmolarity, and of moderate oxygenation. This study represents the first assessment of any E. coli pathotype's transcriptome in vivo and provides specific insights into the mechanisms necessary for urinary tract pathogenesis.

Snyder, Jennifer A.; Haugen, Brian J.; Buckles, Eric L.; Lockatell, C. Virginia; Johnson, David E.; Donnenberg, Michael S.; Welch, Rodney A.; Mobley, Harry L. T.

2004-01-01

9

Morphological plasticity promotes resistance to phagocyte killing of uropathogenic Escherichia coli  

PubMed Central

Uropathogenic Escherichia coli proceed through a complex intracellular developmental pathway that includes multiple morphological changes. During intracellular growth within Toll-like receptor 4-activated superficial bladder epithelial cells, a subpopulation of uropathogenic E. coli initiates SulA-mediated filamentation. In this study, we directly investigated the role of bacterial morphology in the survival of uropathogenic E. coli from killing by phagocytes. We initially determined that both polymorphonuclear neutrophils and macrophages are recruited to murine bladder epithelium at times coincident with extracellular bacillary and filamentous uropathogenic E. coli. We further determined that bacillary uropathogenic E. coli were preferentially destroyed when mixed uropathogenic E. coli populations were challenged with cultured murine macrophages in vitro. Consistent with studies using elliptical-shaped polymers, the initial point of contact between the phagocyte and filamentous uropathogenic E. coli influenced the efficacy of internalization. These findings demonstrate that filamentous morphology provides a selective advantage for uropathogenic E. coli evasion of killing by phagocytes and defines a mechanism for the essential role for SulA during bacterial cystitis. Thus, morphological plasticity can be viewed as a distinct class of mechanism used by bacterial pathogens to subvert host immunity.

Horvath, Dennis J.; Li, Birong; Casper, Travis; Partida-Sanchez, Santiago; Hunstad, David A.; Hultgren, Scott J.; Justice, Sheryl S.

2011-01-01

10

Defining Genomic Islands and Uropathogen-Specific Genes in Uropathogenic Escherichia coli?  

PubMed Central

Uropathogenic Escherichia coli (UPEC) strains are responsible for the majority of uncomplicated urinary tract infections, which can present clinically as cystitis or pyelonephritis. UPEC strain CFT073, isolated from the blood of a patient with acute pyelonephritis, was most cytotoxic and most virulent in mice among our strain collection. Based on the genome sequence of CFT073, microarrays were utilized in comparative genomic hybridization (CGH) analysis of a panel of uropathogenic and fecal/commensal E. coli isolates. Genomic DNA from seven UPEC (three pyelonephritis and four cystitis) isolates and three fecal/commensal strains, including K-12 MG1655, was hybridized to the CFT073 microarray. The CFT073 genome contains 5,379 genes; CGH analysis revealed that 2,820 (52.4%) of these genes were common to all 11 E. coli strains, yet only 173 UPEC-specific genes were found by CGH to be present in all UPEC strains but in none of the fecal/commensal strains. When the sequences of three additional sequenced UPEC strains (UTI89, 536, and F11) and a commensal strain (HS) were added to the analysis, 131 genes present in all UPEC strains but in no fecal/commensal strains were identified. Seven previously unrecognized genomic islands (>30 kb) were delineated by CGH in addition to the three known pathogenicity islands. These genomic islands comprise 672 kb of the 5,231-kb (12.8%) genome, demonstrating the importance of horizontal transfer for UPEC and the mosaic structure of the genome. UPEC strains contain a greater number of iron acquisition systems than do fecal/commensal strains, which is reflective of the adaptation to the iron-limiting urinary tract environment. Each strain displayed distinct differences in the number and type of known virulence factors. The large number of hypothetical genes in the CFT073 genome, especially those shown to be UPEC specific, strongly suggests that many urovirulence factors remain uncharacterized.

Lloyd, Amanda L.; Rasko, David A.; Mobley, Harry L. T.

2007-01-01

11

Bacteriophages with the Ability to Degrade Uropathogenic Escherichia Coli Biofilms  

PubMed Central

Escherichia coli-associated urinary tract infections (UTIs) are among the most common bacterial infections in humans. UTIs are usually managed with antibiotic therapy, but over the years, antibiotic-resistant strains of uropathogenic E. coli (UPEC) have emerged. The formation of biofilms further complicates the treatment of these infections by making them resistant to killing by the host immune system as well as by antibiotics. This has encouraged research into therapy using bacteriophages (phages) as a supplement or substitute for antibiotics. In this study we characterized 253 UPEC in terms of their biofilm-forming capabilities, serotype, and antimicrobial resistance. Three phages were then isolated (vB_EcoP_ACG-C91, vB_EcoM_ACG-C40 and vB_EcoS_ACG-M12) which were able to lyse 80.5% of a subset (42) of the UPEC strains able to form biofilms. Correlation was established between phage sensitivity and specific serotypes of the UPEC strains. The phages’ genome sequences were determined and resulted in classification of vB_EcoP_ACG-C91 as a SP6likevirus, vB_EcoM_ACG-C40 as a T4likevirus and vB_EcoS_ACG-M12 as T1likevirus. We assessed the ability of the three phages to eradicate the established biofilm of one of the UPEC strains used in the study. All phages significantly reduced the biofilm within 2–12 h of incubation.

Chibeu, Andrew; Lingohr, Erika J.; Masson, Luke; Manges, Amee; Harel, Josee; Ackermann, Hans-W.; Kropinski, Andrew M.; Boerlin, Patrick

2012-01-01

12

Bacteriophages with the ability to degrade uropathogenic Escherichia coli biofilms.  

PubMed

Escherichia coli-associated urinary tract infections (UTIs) are among the most common bacterial infections in humans. UTIs are usually managed with antibiotic therapy, but over the years, antibiotic-resistant strains of uropathogenic E. coli (UPEC) have emerged. The formation of biofilms further complicates the treatment of these infections by making them resistant to killing by the host immune system as well as by antibiotics. This has encouraged research into therapy using bacteriophages (phages) as a supplement or substitute for antibiotics. In this study we characterized 253 UPEC in terms of their biofilm-forming capabilities, serotype, and antimicrobial resistance. Three phages were then isolated (vB_EcoP_ACG-C91, vB_EcoM_ACG-C40 and vB_EcoS_ACG-M12) which were able to lyse 80.5% of a subset (42) of the UPEC strains able to form biofilms. Correlation was established between phage sensitivity and specific serotypes of the UPEC strains. The phages' genome sequences were determined and resulted in classification of vB_EcoP_ACG-C91 as a SP6likevirus, vB_EcoM_ACG-C40 as a T4likevirus and vB_EcoS_ACG-M12 as T1likevirus. We assessed the ability of the three phages to eradicate the established biofilm of one of the UPEC strains used in the study. All phages significantly reduced the biofilm within 2-12 h of incubation. PMID:22590682

Chibeu, Andrew; Lingohr, Erika J; Masson, Luke; Manges, Amee; Harel, Josée; Ackermann, Hans-W; Kropinski, Andrew M; Boerlin, Patrick

2012-04-10

13

Genomic Islands of Uropathogenic Escherichia coli Contribute to Virulence? †  

PubMed Central

Uropathogenic Escherichia coli (UPEC) strain CFT073 contains 13 large genomic islands ranging in size from 32 kb to 123 kb. Eleven of these genomic islands were individually deleted from the genome, and nine isogenic mutants were tested for their ability to colonize the CBA/J mouse model of ascending urinary tract infection. Three genomic island mutants (?PAI-aspV, ?PAI-metV, and ?PAI-asnT) were significantly outcompeted by wild-type CFT073 in the bladders and/or kidneys following transurethral cochallenge (P ? 0.0139). The PAI-metV mutant also showed significant attenuation in the ability to independently colonize the kidneys (P = 0.0011). Specific genes within these islands contributed to the observed phenotype, including a previously uncharacterized iron acquisition cluster, fbpABCD (c0294 to c0297 [c0294-97]), autotransporter, picU (c0350), and RTX family exoprotein, tosA (c0363) in the PAI-aspV island. The double deletion mutant with deletions in both copies of the fbp iron acquisition operon (?c0294-97 ?c2518-15) was significantly outcompeted by wild-type CFT073 in cochallenge. Strains with mutations in a type VI secretion system within the PAI-metV island did not show attenuation. The attenuation of the PAI-metV island was localized to genes c3405-10, encoding a putative phosphotransferase transport system, which is common to UPEC and avian pathogenic E. coli strains but absent from E. coli K-12. We have shown that, in addition to encoding virulence genes, genomic islands contribute to the overall fitness of UPEC strain CFT073 in vivo.

Lloyd, Amanda L.; Henderson, Tiffany A.; Vigil, Patrick D.; Mobley, Harry L. T.

2009-01-01

14

Conditioning of Uropathogenic Escherichia coli for Enhanced Colonization of Host? †  

PubMed Central

While in transit within and between hosts, uropathogenic Escherichia coli (UPEC) encounters multiple stresses, including substantial levels of nitric oxide and reactive nitrogen intermediates. Here we show that UPEC, the primary cause of urinary tract infections, can be conditioned to grow at higher rates in the presence of acidified sodium nitrite (ASN), a model system used to generate nitrosative stress. When inoculated into the bladder of a mouse, ASN-conditioned UPEC bacteria are far more likely to establish an infection than nonconditioned bacteria. Microarray analysis of ASN-conditioned bacteria suggests that several NsrR-regulated genes and other stress- and polyamine-responsive factors may be partially responsible for this effect. Compared to K-12 reference strains, most UPEC isolates have increased resistance to ASN, and this resistance can be substantially enhanced by addition of the polyamine cadaverine. Nitrosative stress, as generated by ASN, can stimulate cadaverine synthesis by UPEC, and growth of UPEC in cadaverine-supplemented broth in the absence of ASN can also promote UPEC colonization of the bladder. These results suggest that UPEC interactions with polyamines or stresses such as reactive nitrogen intermediates can in effect reprogram the bacteria, enabling them to better colonize the host.

Bower, Jean M.; Gordon-Raagas, Hannah B.; Mulvey, Matthew A.

2009-01-01

15

Uropathogenic Escherichia coli are less likely than paired fecal E. coli to have CRISPR loci.  

PubMed

CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats) are short fragments of DNA that act as an adaptive immune system protecting bacteria against invasion by phages, plasmids or other forms of foreign DNA. Bacteria without a CRISPR locus may more readily adapt to environmental changes by acquiring foreign genetic material. Uropathogenic Escherichia coli (UPEC) live in a number of environments suggesting an ability to rapidly adapt to new environments. If UPEC are more adaptive than commensal E. coli we would expect that UPEC would have fewer CRISPR loci, and - if loci are present - that they would harbor fewer spacers than CRISPR loci in fecal E. coli. We tested this in vivo by comparing the number of CRISPR loci and spacers, and sensitivity to antibiotics (resistance is often obtained via plasmids) among 81 pairs of UPEC and fecal E. coli isolated from women with urinary tract infection. Each pair included one uropathogen and one commensal (fecal) sample from the same female patient. Fecal isolates had more repeats (p=0.009) and more unique spacers (p<0.0001) at four CRISPR loci than uropathogens. By contrast, uropathogens were more likely than fecal E. coli to be resistant to ampicillin, cefazolin and trimethoprim/sulfamethoxazole. However, no consistent association between CRISPRs and antibiotic resistance was identified. To our knowledge, this is the first study to compare fecal E. coli and pathogenic E. coli from the same individuals, and to test the association of CRISPR loci with antibiotic resistance. Our results suggest that the absence of CRISPR loci may make UPEC more susceptible to infection by phages or plasmids and allow them to adapt more quickly to various environments. PMID:23891665

Dang, Trang Nguyen Doan; Zhang, Lixin; Zöllner, Sebastian; Srinivasan, Usha; Abbas, Khadija; Marrs, Carl F; Foxman, Betsy

2013-07-25

16

Structural and sequence diversity of the pathogenicity island of uropathogenic Escherichia coli which encodes the USP protein  

Microsoft Academic Search

A total of 321 uropathogenic Escherichia coli (UPEC) strains and 12 strains of E. coli isolated from stool samples of healthy individuals, which were previously shown to be positive in colony hybridization test using the usp (encoding for the uropathogenic-specific protein) DNA probe, were examined by PCR amplification to determine the size of the usp gene and the pathogenicity island

Masayuki Nakano; Shingo Yamamoto; Akito Terai; Osamu Ogawa; Sou-ichi Makino; Hideo Hayashi; G. Balakrish Nair; Hisao Kurazono

2001-01-01

17

Active Cytotoxic Necrotizing Factor 1 Associated with Outer Membrane Vesicles from Uropathogenic Escherichia coli  

Microsoft Academic Search

Cytotoxic necrotizing factor type 1 (CNF1) is one of the virulence factors produced by uropathogenic Escherichia coli (UPEC). How this toxin is translocated from the bacterial cytoplasm to the surrounding environment is not well understood. Our data suggest that CNF1 may be regarded as a secreted protein, since it could be detected in culture supernatants. Furthermore, we found that CNF1

J. Clavin Kouokam; Sun Nyunt Wai; Maria Fallman; Ulrich Dobrindt; Jorg Hacker; Bernt Eric Uhlin

2006-01-01

18

Impact of the RNA Chaperone Hfq on the Fitness and Virulence Potential of Uropathogenic Escherichia coli  

Microsoft Academic Search

Hfq is a bacterial RNA chaperone involved in the posttranscriptional regulation of many stress-inducible genes via small noncoding RNAs. Here, we show that Hfq is critical for the uropathogenic Escherichia coli (UPEC) isolate UTI89 to effectively colonize the bladder and kidneys in a murine urinary tract infection model system. The disruption of hfq did not affect bacterial adherence to or

Richard R. Kulesus; Karen Diaz-Perez; E. Susan Slechta; Danelle S. Eto; Matthew A. Mulvey

2008-01-01

19

Identification of Type 3 Fimbriae in Uropathogenic Escherichia coli Reveals a Role in Biofilm Formation  

Microsoft Academic Search

Catheter-associated urinary tract infection (CAUTI) is the most common nosocomial infection in the United States. Uropathogenic Escherichia coli (UPEC), the most common cause of CAUTI, can form biofilms on indwelling catheters. Here, we identify and characterize novel factors that affect biofilm formation by UPEC strains that cause CAUTI. Sixty-five CAUTI UPEC isolates were characterized for phenotypic markers of urovirulence, including

Cheryl-Lynn Y. Ong; Glen C. Ulett; Amanda N. Mabbett; Scott A. Beatson; Richard I. Webb; Wayne Monaghan; Graeme R. Nimmo; David F. Looke; Alastair G. McEwan; Mark A. Schembri

2008-01-01

20

Integrin-Mediated Host Cell Invasion by Type 1–Piliated Uropathogenic Escherichia coli  

Microsoft Academic Search

Uropathogenic Escherichia coli (UPEC), the primary causative agent of urinary tract infections, typically express filamentous adhesive organelles called type 1 pili that mediate both bacterial attachment to and invasion of bladder urothelial cells. Several host proteins have previously been identified as receptors for type 1 pili, but none have been conclusively shown to promote UPEC entry into host bladder cells.

Danelle S. Eto; Tiffani A. Jones; Jamie L. Sundsbak; Matthew A. Mulvey

2007-01-01

21

Multiple-Antibiotic Resistance Mediated by Plasmids and Integrons in Uropathogenic Escherichia coli and Klebsiella pneumoniae  

Microsoft Academic Search

Antibiotic resistance in urinary tract infection (UTI) is a growing public health problem in the world. In this study, a total of 182 uropathogens were isolated from patients with symptoms of urinary tract infection (UTI). Escherichia coli (88%) was the most prevalent isolate, while Klebsiella pneumoniae was recovered from 12% cases. The male\\/female ratio was 1:3. About 56% female and

Taslima Taher Lina; Sabita Rezwana Rahman; Donald James Gomes

2007-01-01

22

Oral Consumption of Cranberry Juice Cocktail Inhibits Molecular-Scale Adhesion of Clinical Uropathogenic Escherichia Coli  

Microsoft Academic Search

Cranberry juice cocktail (CJC) has been shown to inhibit the formation of biofilm by uropathogenic Escherichia coli. In order to investigate whether the anti-adhesive components could reach the urinary tract after oral consumption of CJC, a volunteer was given 16?oz of either water or CJC. Urine samples were collected at 0, 2, 4, 6, and 8 hours after consumption of

Yuanyuan Tao; Paola A. Pinzón-Arango; Amy B Howell; Terri A Camesano

2011-01-01

23

Extensive mosaic structure revealed by the complete genome sequence of uropathogenic Escherichia coli  

Microsoft Academic Search

We present the complete genome sequence of uropathogenic Escherichia coli, strain CFT073. A three-way genome comparison of the CFT073, enterohemorrhagic E. coli EDL933, and laboratory strain MG1655 reveals that, amazingly, only 39.2% of their combined (nonredundant) set of proteins actually are common to all three strains. The pathogen genomes are as different from each other as each pathogen is from

R. A. Welch; V. Burland; G. Plunkett III; P. Redford; P. Roesch; D. Rasko; E. L. Buckles; S.-R. Liou; A. Boutin; J. Hackett; D. Stroud; G. F. Mayhew; D. J. Rose; S. Zhou; D. C. Schwartz; N. T. Perna; H. L. T. Mobley; M. S. Donnenberg; F. R. Blattner

2002-01-01

24

Identification and Characterization of a Novel Uropathogenic Escherichia coli-Associated Fimbrial Gene Cluster  

Microsoft Academic Search

Received 15 January 2004\\/Returned for modification 2 March 2004\\/Accepted 24 March 2004 Recently, we identified a fimbrial usher gene in uropathogenic Escherichia coli strain CFT073 that is absent from an E. coli laboratory strain. Analysis of the CFT073 genome indicates that this fimbrial usher gene is part of a novel fimbrial gene cluster, aufABCDEFG. Analysis of a collection of pathogenic

Eric L. Buckles; Farah K. Bahrani-Mougeot; Anita Molina; C. Virgina Lockatell; David E. Johnson; Cinthia B. Drachenberg; Valerie Burland; Fred R. Blattner; Michael S. Donnenberg

2004-01-01

25

Isolation of Generalized Transducing Bacteriophages for Uropathogenic Strains of Escherichia coli?†  

PubMed Central

The traditional genetic procedure for random or site-specific mutagenesis in Escherichia coli K-12 involves mutagenesis, isolation of mutants, and transduction of the mutation into a clean genetic background. The transduction step reduces the likelihood of complications due to secondary mutations. Though well established, this protocol is not tenable for many pathogenic E. coli strains, such as uropathogenic strain CFT073, because it is resistant to known K-12 transducing bacteriophages, such as P1. CFT073 mutants generated via a technique such as lambda Red mutagenesis may contain unknown secondary mutations. Here we describe the isolation and characterization of transducing bacteriophages for CFT073. Seventy-seven phage isolates were acquired from effluent water samples collected from a wastewater treatment plant in Madison, WI. The phages were differentiated by a host sensitivity-typing scheme with a panel of E. coli strains from the ECOR collection and clinical uropathogenic isolates. We found 49 unique phage isolates. These were then examined for their ability to transduce antibiotic resistance gene insertions at multiple loci between different mutant strains of CFT073. We identified 4 different phages capable of CFT073 generalized transduction. These phages also plaque on the model uropathogenic E. coli strains 536, UTI89, and NU14. The highest-efficiency transducing phage, ?EB49, was further characterized by DNA sequence analysis, revealing a double-stranded genome 47,180 bp in length and showing similarity to other sequenced phages. When combined with a technique like lambda Red mutagenesis, the newly characterized transducing phages provide a significant development in the genetic tools available for the study of uropathogenic E. coli.

Battaglioli, E. J.; Baisa, G. A.; Weeks, A. E.; Schroll, R. A.; Hryckowian, A. J.; Welch, R. A.

2011-01-01

26

Isolation of generalized transducing bacteriophages for uropathogenic strains of Escherichia coli.  

PubMed

The traditional genetic procedure for random or site-specific mutagenesis in Escherichia coli K-12 involves mutagenesis, isolation of mutants, and transduction of the mutation into a clean genetic background. The transduction step reduces the likelihood of complications due to secondary mutations. Though well established, this protocol is not tenable for many pathogenic E. coli strains, such as uropathogenic strain CFT073, because it is resistant to known K-12 transducing bacteriophages, such as P1. CFT073 mutants generated via a technique such as lambda Red mutagenesis may contain unknown secondary mutations. Here we describe the isolation and characterization of transducing bacteriophages for CFT073. Seventy-seven phage isolates were acquired from effluent water samples collected from a wastewater treatment plant in Madison, WI. The phages were differentiated by a host sensitivity-typing scheme with a panel of E. coli strains from the ECOR collection and clinical uropathogenic isolates. We found 49 unique phage isolates. These were then examined for their ability to transduce antibiotic resistance gene insertions at multiple loci between different mutant strains of CFT073. We identified 4 different phages capable of CFT073 generalized transduction. These phages also plaque on the model uropathogenic E. coli strains 536, UTI89, and NU14. The highest-efficiency transducing phage, ?EB49, was further characterized by DNA sequence analysis, revealing a double-stranded genome 47,180 bp in length and showing similarity to other sequenced phages. When combined with a technique like lambda Red mutagenesis, the newly characterized transducing phages provide a significant development in the genetic tools available for the study of uropathogenic E. coli. PMID:21784916

Battaglioli, E J; Baisa, G A; Weeks, A E; Schroll, R A; Hryckowian, A J; Welch, R A

2011-07-22

27

Escherichia coli–Mediated Impairment of Ureteric Contractility Is Uropathogenic E. coli Specific  

PubMed Central

Background.?Ureters are fundamental for keeping kidneys free from uropathogenic Escherichia coli (UPEC), but we have shown that 2 strains (J96 and 536) can subvert this role and reduce ureteric contractility. To determine whether this is (1) a widespread feature of UPEC, (2) exhibited only by UPEC, and (3) dependent upon type 1 fimbriae, we analyzed strains representing epidemiologically important multilocus sequence types ST131, ST73, and ST95 and non-UPEC E. coli. Methods.?Contractility and calcium transients in intact rat ureters were compared between strains. Mannose and fim mutants were used to investigate the role of type 1 fimbriae. Results.?Non-UPEC had no significant effect on contractility, with a mean decrease after 8 hours of 8.8%, compared with 8.8% in controls. UPEC effects on contractility were strain specific, with decreases from 9.47% to 96.7%. Mannose inhibited the effects of the most potent strains (CFT073 and UTI89) but had variable effects among other UPEC strains. Mutation and complementation studies showed that the effects of the UTI89 cystitis isolate were fimH dependent. Conclusions.?We find that (1) non-UPEC do not affect ureteric contractility, (2) impairment of contractility is a common feature of UPEC, and (3) the mechanism varies between strains, but for the most potent UPEC type 1 fimbriae are involved.

Floyd, Rachel V.; Upton, Mathew; Hultgren, Scott J.; Wray, Susan; Burdyga, Theodor V.; Winstanley, Craig

2012-01-01

28

Prevalence and Persistence of Escherichia coli Strains with Uropathogenic Virulence Characteristics in Sewage Treatment Plants?  

PubMed Central

We investigated the prevalence and persistence of Escherichia coli strains in four sewage treatment plants (STPs) in a subtropical region of Queensland, Australia. In all, 264 E. coli strains were typed using a high-resolution biochemical fingerprinting method and grouped into either a single or a common biochemical phenotype (S-BPT and C-BPT, respectively). These strains were also tested for their phylogenetic groups and 12 virulence genes associated with intestinal and extraintestinal E. coli strains. Comparison of BPTs at various treatment stages indicated that certain BPTs were found in two or all treatment stages. These BPTs constituted the highest proportion of E. coli strains in each STP and belonged mainly to phylogenetic group B2 and, to a lesser extent, group D. No virulence genes associated with intestinal E. coli were found among the strains, but 157 (59.5%) strains belonging to 14 C-BPTs carried one or more virulence genes associated with uropathogenic strains. Of these, 120 (76.4%) strains belonged to seven persistent C-BPTs and were found in all four STPs. Our results indicate that certain clonal groups of E. coli with virulence characteristics of uropathogenic strains can survive the treatment processes of STPs. These strains were common to all STPs and constituted the highest proportion of the strains in different treatment tanks of each STP.

Anastasi, E. M.; Matthews, B.; Gundogdu, A.; Vollmerhausen, T. L.; Ramos, N. L.; Stratton, H.; Ahmed, W.; Katouli, M.

2010-01-01

29

The innate immune response to uropathogenic Escherichia coli involves IL-17A in a murine model of urinary tract infection.  

PubMed

Uropathogenic Escherichia coli is the causative agent for >80% of uncomplicated urinary tract infections (UTIs). Uropathogenic E. coli strains express a number of virulence and fitness factors that allow successful colonization of the mammalian bladder. To combat this, the host has distinct mechanisms to prevent adherence to the bladder wall and to detect and kill uropathogenic E. coli in the event of colonization. In this study, we investigated the role of IL-17A, an innate-adaptive immunomodulatory cytokine, during UTI using a murine model. Splenocytes isolated from mice infected by the transurethral route robustly expressed IL-17A in response to in vitro stimulation with uropathogenic E. coli Ags. Transcript expression of IL-17A in the bladders of infected mice correlated with a role in the innate immune response to UTI, and gammadelta cells seem to be a key source of IL-17A production. Although IL-17A seems to be dispensable for the generation of a protective response to uropathogenic E. coli, its importance in innate immunity is demonstrated by a defect in acute clearance of uropathogenic E. coli in IL-17A(-/-) mice. This clearance defect is likely a result of deficient cytokine and chemokine transcripts and impaired macrophage and neutrophil influx during infection. These results show that IL-17A is a key mediator for the innate immune response to UTIs. PMID:20083670

Sivick, Kelsey E; Schaller, Matthew A; Smith, Sara N; Mobley, Harry L T

2010-01-18

30

Uropathogenic Escherichia coli Strains Generally Lack Functional Trg and Tap Chemoreceptors Found in the Majority of E. coli Strains Strictly Residing in the Gut  

PubMed Central

The prevalence and function of four chemoreceptors, Tsr, Tar, Trg, and Tap, were determined for a collection of uropathogenic, fecal-commensal, and diarrheagenic Escherichia coli strains. tar and tsr were present or functional in nearly all isolates. However, trg and tap were significantly less prevalent or functional among the uropathogenic E. coli strains (both in 6% of strains) than among fecal-commensal strains (both in ?50% of strains) or diarrheal strains (both in ?75% of strains) (P < 0.02).

Lane, M. Chelsea; Lloyd, Amanda L.; Markyvech, Tiffany A.; Hagan, Erin C.; Mobley, Harry L. T.

2006-01-01

31

Oral consumption of cranberry juice cocktail inhibits molecular-scale adhesion of clinical uropathogenic Escherichia coli.  

PubMed

Cranberry juice cocktail (CJC) has been shown to inhibit the formation of biofilm by uropathogenic Escherichia coli. In order to investigate whether the anti-adhesive components could reach the urinary tract after oral consumption of CJC, a volunteer was given 16?oz of either water or CJC. Urine samples were collected at 0, 2, 4, 6, and 8 hours after consumption of a single dose. The ability of compounds in the urine to influence bacterial adhesion was tested for six clinical uropathogenic E. coli strains, including four P-fimbriated strains (B37, CFT073, BF1023, and J96) and two strains not expressing P-fimbriae but exhibiting mannose-resistant hemagglutination (B73 and B78). A non-fimbriated strain, HB101, was used as a control. Atomic force microscopy (AFM) was used to measure the adhesion force between a silicon nitride probe and bacteria treated with urine samples. Within 2 hours after CJC consumption, bacteria of the clinical strains treated with the corresponding urine sample demonstrated lower adhesion forces than those treated with urine collected before CJC consumption. The adhesion forces continued decreasing with time after CJC consumption over the 8-hour measurement period. The adhesion forces of bacteria after exposure to urine collected following water consumption did not change. HB101 showed low adhesion forces following both water and CJC consumption, and these did not change over time. The AFM adhesion force measurements were consistent with the results of a hemagglutination assay, confirming that oral consumption of CJC could act against adhesion of uropathogenic E. coli. PMID:21480803

Tao, Yuanyuan; Pinzón-Arango, Paola A; Howell, Amy B; Camesano, Terri A

2011-04-11

32

Oral Consumption of Cranberry Juice Cocktail Inhibits Molecular-Scale Adhesion of Clinical Uropathogenic Escherichia coli  

PubMed Central

Abstract Cranberry juice cocktail (CJC) has been shown to inhibit the formation of biofilm by uropathogenic Escherichia coli. In order to investigate whether the anti-adhesive components could reach the urinary tract after oral consumption of CJC, a volunteer was given 16?oz of either water or CJC. Urine samples were collected at 0, 2, 4, 6, and 8 hours after consumption of a single dose. The ability of compounds in the urine to influence bacterial adhesion was tested for six clinical uropathogenic E. coli strains, including four P-fimbriated strains (B37, CFT073, BF1023, and J96) and two strains not expressing P-fimbriae but exhibiting mannose-resistant hemagglutination (B73 and B78). A non-fimbriated strain, HB101, was used as a control. Atomic force microscopy (AFM) was used to measure the adhesion force between a silicon nitride probe and bacteria treated with urine samples. Within 2 hours after CJC consumption, bacteria of the clinical strains treated with the corresponding urine sample demonstrated lower adhesion forces than those treated with urine collected before CJC consumption. The adhesion forces continued decreasing with time after CJC consumption over the 8-hour measurement period. The adhesion forces of bacteria after exposure to urine collected following water consumption did not change. HB101 showed low adhesion forces following both water and CJC consumption, and these did not change over time. The AFM adhesion force measurements were consistent with the results of a hemagglutination assay, confirming that oral consumption of CJC could act against adhesion of uropathogenic E. coli.

Tao, Yuanyuan; Pinzon-Arango, Paola A.; Howell, Amy B.

2011-01-01

33

Type 1 Fimbriae, a Colonization Factor of Uropathogenic Escherichia coli, Are Controlled by the Metabolic Sensor CRP-cAMP  

Microsoft Academic Search

Type 1 fimbriae are a crucial factor for the virulence of uropathogenic Escherichia coli during the first steps of infection by mediating adhesion to epithelial cells. They are also required for the consequent colonization of the tissues and for invasion of the uroepithelium. Here, we studied the role of the specialized signal transduction system CRP-cAMP in the regulation of type

Claudia M. Müller; Anna Ĺberg; Jurate Straseviçiene; Levente Em?dy; Bernt Eric Uhlin; Carlos Balsalobre

2009-01-01

34

Polyamine-Mediated Resistance of Uropathogenic Escherichia coli to Nitrosative Stress  

PubMed Central

During the course of a urinary tract infection, substantial levels of nitric oxide and reactive nitrogen intermediates are generated. We have found that many uropathogenic strains of Escherichia coli display far greater resistance to nitrosative stress than the K-12 reference strain MG1655. By selecting and screening for uropathogenic E. coli transposon mutants that are unable to grow in the presence of acidified nitrite, the cadC gene product was identified as a key facilitator of nitrosative stress resistance. Mutation of cadC, or its transcriptional targets cadA and cadB, results in loss of significant production of the polyamine cadaverine and increased sensitivity to acidified nitrite. Exogenous addition of cadaverine or other polyamines rescues growth of cad mutants under nitrosative stress. In wild-type cells, the concentration of cadaverine produced per cell is substantially increased by exposure to acidified nitrite. The mechanism behind polyamine-mediated rescue from nitrosative stress is unclear, but it is not attributable solely to chemical quenching of reactive nitrogen species or reduction in mutation frequency.

Bower, Jean M.; Mulvey, Matthew A.

2006-01-01

35

Role of Uropathogenic Escherichia coli Virulence Factors in Development of Urinary Tract Infection and Kidney Damage  

PubMed Central

Uropathogenic Escherichia coli (UPEC) is a causative agent in the vast majority of urinary tract infections (UTIs), including cystitis and pyelonephritis, and infectious complications, which may result in acute renal failure in healthy individuals as well as in renal transplant patients. UPEC expresses a multitude of virulence factors to break the inertia of the mucosal barrier. In response to the breach by UPEC into the normally sterile urinary tract, host inflammatory responses are triggered leading to cytokine production, neutrophil influx, and the exfoliation of infected bladder epithelial cells. Several signaling pathways activated during UPEC infection, including the pathways known to activate the innate immune response, interact with calcium-dependent signaling pathways. Some UPEC isolates, however, might possess strategies to delay or suppress the activation of components of the innate host response in the urinary tract. Studies published in the recent past provide new information regarding how virulence factors of uropathogenic E. coli are involved in activation of the innate host response. Despite numerous host defense mechanisms, UPEC can persist within the urinary tract and may serve as a reservoir for recurrent infections and serious complications. Presentation of the molecular details of these events is essential for development of successful strategies for prevention of human UTIs and urological complications associated with UTIs.

Bien, Justyna; Sokolova, Olga; Bozko, Przemyslaw

2012-01-01

36

Diversity of Gene Cassette Promoter Variants of Class 1 Integrons in Uropathogenic Escherichia coli.  

PubMed

Class 1 integrons play important roles in the emergence and horizontal transfer of antibiotic resistance genes among bacteria. The gene cassette promoter variants Pc or Pc-P2 of class 1 integrons not only drive the transcription of downstream gene cassettes, they also correlate with the excision and integration efficiency of the capture exogenous gene cassettes. In this study, the diversity of Pc or Pc-P2 variants of class 1 integrons and their association with antibiotic resistance phenotypes were analyzed in 132 uropathogenic Escherichia coli strains. Class 1 integrons were detected in 95 (72 %) strains. Sixteen different gene cassettes, 11 different gene cassette arrays and six different Pc or Pc-P2 variants were detected. The most prevalent gene cassettes were those that conferred resistance to trimethoprim, aminoglycosides, and chloramphenicol. The most prevalent promoter was PcH1, a relatively weak promoter. Certain gene cassette arrays or gene cassettes were mainly associated with the same Pc or Pc-P2 in different strains. Strains harboring class 1 integrons with relatively strong promoters had higher resistance rates to, or higher MIC50 for, amikacin, chloramphenicol and tobramycin than those with relatively weak promoters. To the best of our knowledge, this is the first report of the diversity of class 1 integron Pc or Pc-P2 variants in uropathogenic E. coli strains. PMID:23743598

Wei, Quhao; Jiang, Xiaofei; Li, Min; Li, Gang; Hu, Qingfeng; Lu, Huoxiang; Chen, Guoqiang; Zhou, Yonglie; Lu, Yuan

2013-06-07

37

Distribution and Genetic Association of Putative Uropathogenic Virulence Factors Iron, iha, kpsMT, ompT and usp in Escherichia Coli Isolated From Urinary Tract Infections in Japan  

Microsoft Academic Search

PurposeMany virulence factors (VFs) have been reported in uropathogenic Escherichia coli. Recently we found a putative uropathogenic island including a gene encoding uropathogenic specific protein (USP). We have described the association between usp and other VFs reported previously. In the current study we examined epidemiological associations among 5 putative uropathogenic VFs.

SOJUN KANAMARU; HISAO KURAZONO; SATOSHI ISHITOYA; AKITO TERAI; TOMONORI HABUCHI; MASAYUKI NAKANO; OSAMU OGAWA; SHINGO YAMAMOTO

2003-01-01

38

Identification and Characterization of a Novel Uropathogenic Escherichia coli-Associated Fimbrial Gene Cluster  

PubMed Central

Recently, we identified a fimbrial usher gene in uropathogenic Escherichia coli strain CFT073 that is absent from an E. coli laboratory strain. Analysis of the CFT073 genome indicates that this fimbrial usher gene is part of a novel fimbrial gene cluster, aufABCDEFG. Analysis of a collection of pathogenic and commensal strains of E. coli and related species revealed that the auf gene cluster was significantly associated with uropathogenic E. coli isolates. For in vitro expression analysis of the auf gene cluster, RNA was isolated from CFT073 bacteria grown to the exponential or stationary phase in Luria-Bertani broth and reverse transcriptase PCR (RT-PCR) with oligonucleotide primers specific to the major subunit, aufA, was performed. We found that aufA is expressed in CFT073 only during the exponential growth phase; however, no expression of AufA protein was observed by Western blotting, indicating that under these conditions, the expression of the auf gene cluster is low. To determine if the auf gene cluster is expressed in vivo, RT-PCR was performed on bacteria from urine samples of mice infected with CFT073. Out of three independent experiments, we were able to detect expression of aufA at least once at 4, 24, and 48 h of infection, indicating that the auf gene cluster is expressed in the murine urinary tract. Furthermore, antisera from mice infected with CFT073 reacted with recombinant AufA in an enzyme-linked immunosorbent assay. To identify the structure encoded by the auf gene cluster, a recombinant plasmid containing the auf gene cluster under the T7 promoter was introduced into the E. coli BL-21 (AI) strain. Immunogold labeling using AufA antiserum revealed the presence of amorphous material extending from the surface of BL-21 cells. No hemagglutination or cellular adherence properties were detected in association with expression of AufA. Deletion of the entire auf gene cluster had no effect on the ability of CFT073 to colonize the kidney, bladder, or urine of mice. In addition, no significant histological differences between the parent and aufC mutant strain were observed. Therefore, Auf is a uropathogenic E. coli-associated structure that plays an uncertain role in the pathogenesis of urinary tract infections.

Buckles, Eric L.; Bahrani-Mougeot, Farah K.; Molina, Anita; Lockatell, C. Virgina; Johnson, David E.; Drachenberg, Cinthia B.; Burland, Valerie; Blattner, Fred R.; Donnenberg, Michael S.

2004-01-01

39

Roles of Putative Type II Secretion and Type IV Pilus Systems in the Virulence of Uropathogenic Escherichia coli  

Microsoft Academic Search

BackgroundType II secretion systems (T2SS) and the evolutionarily related type IV pili (T4P) are important virulence determinants in many Gram-negative bacterial pathogens. However, the roles of T2SS and T4P in the virulence of extraintestinal pathogenic Escherichia coli have not been determined.Methodology\\/Principal FindingsTo investigate the functions of putative T2SS and T4P gene clusters present in the model uropathogenic E. coli (UPEC)

Ritwij Kulkarni; Bijaya K. Dhakal; E. Susan Slechta; Zachary Kurtz; Matthew A. Mulvey; David G. Thanassi; Dagmar Beier

2009-01-01

40

The Serum Resistome of a Globally Disseminated Multidrug Resistant Uropathogenic Escherichia coli Clone  

PubMed Central

Escherichia coli ST131 is a globally disseminated, multidrug resistant clone responsible for a high proportion of urinary tract and bloodstream infections. The rapid emergence and successful spread of E. coli ST131 is strongly associated with antibiotic resistance; however, this phenotype alone is unlikely to explain its dominance amongst multidrug resistant uropathogens circulating worldwide in hospitals and the community. Thus, a greater understanding of the molecular mechanisms that underpin the fitness of E. coli ST131 is required. In this study, we employed hyper-saturated transposon mutagenesis in combination with multiplexed transposon directed insertion-site sequencing to define the essential genes required for in vitro growth and the serum resistome (i.e. genes required for resistance to human serum) of E. coli EC958, a representative of the predominant E. coli ST131 clonal lineage. We identified 315 essential genes in E. coli EC958, 231 (73%) of which were also essential in E. coli K-12. The serum resistome comprised 56 genes, the majority of which encode membrane proteins or factors involved in lipopolysaccharide (LPS) biosynthesis. Targeted mutagenesis confirmed a role in serum resistance for 46 (82%) of these genes. The murein lipoprotein Lpp, along with two lipid A-core biosynthesis enzymes WaaP and WaaG, were most strongly associated with serum resistance. While LPS was the main resistance mechanism defined for E. coli EC958 in serum, the enterobacterial common antigen and colanic acid also impacted on this phenotype. Our analysis also identified a novel function for two genes, hyxA and hyxR, as minor regulators of O-antigen chain length. This study offers novel insight into the genetic make-up of E. coli ST131, and provides a framework for future research on E. coli and other Gram-negative pathogens to define their essential gene repertoire and to dissect the molecular mechanisms that enable them to survive in the bloodstream and cause disease.

Phan, Minh-Duy; Peters, Kate M.; Sarkar, Sohinee; Lukowski, Samuel W.; Allsopp, Luke P.; Moriel, Danilo Gomes; Achard, Maud E. S.; Totsika, Makrina; Marshall, Vikki M.; Upton, Mathew; Beatson, Scott A.; Schembri, Mark A.

2013-01-01

41

The Serum Resistome of a Globally Disseminated Multidrug Resistant Uropathogenic Escherichia coli Clone.  

PubMed

Escherichia coli ST131 is a globally disseminated, multidrug resistant clone responsible for a high proportion of urinary tract and bloodstream infections. The rapid emergence and successful spread of E. coli ST131 is strongly associated with antibiotic resistance; however, this phenotype alone is unlikely to explain its dominance amongst multidrug resistant uropathogens circulating worldwide in hospitals and the community. Thus, a greater understanding of the molecular mechanisms that underpin the fitness of E. coli ST131 is required. In this study, we employed hyper-saturated transposon mutagenesis in combination with multiplexed transposon directed insertion-site sequencing to define the essential genes required for in vitro growth and the serum resistome (i.e. genes required for resistance to human serum) of E. coli EC958, a representative of the predominant E. coli ST131 clonal lineage. We identified 315 essential genes in E. coli EC958, 231 (73%) of which were also essential in E. coli K-12. The serum resistome comprised 56 genes, the majority of which encode membrane proteins or factors involved in lipopolysaccharide (LPS) biosynthesis. Targeted mutagenesis confirmed a role in serum resistance for 46 (82%) of these genes. The murein lipoprotein Lpp, along with two lipid A-core biosynthesis enzymes WaaP and WaaG, were most strongly associated with serum resistance. While LPS was the main resistance mechanism defined for E. coli EC958 in serum, the enterobacterial common antigen and colanic acid also impacted on this phenotype. Our analysis also identified a novel function for two genes, hyxA and hyxR, as minor regulators of O-antigen chain length. This study offers novel insight into the genetic make-up of E. coli ST131, and provides a framework for future research on E. coli and other Gram-negative pathogens to define their essential gene repertoire and to dissect the molecular mechanisms that enable them to survive in the bloodstream and cause disease. PMID:24098145

Phan, Minh-Duy; Peters, Kate M; Sarkar, Sohinee; Lukowski, Samuel W; Allsopp, Luke P; Moriel, Danilo Gomes; Achard, Maud E S; Totsika, Makrina; Marshall, Vikki M; Upton, Mathew; Beatson, Scott A; Schembri, Mark A

2013-10-03

42

Modulation of Host Innate Immune Response in the Bladder by Uropathogenic Escherichia coli?  

PubMed Central

Uropathogenic Escherichia coli (UPEC), the most frequent cause of urinary tract infection (UTI), is associated with an inflammatory response which includes the induction of cytokine/chemokine secretion by urothelial cells and neutrophil recruitment to the bladder. Recent studies indicate, however, that UPEC can evade the early activation of urothelial innate immune response in vitro. In this study, we report that infection with the prototypic UPEC strain NU14 suppresses tumor necrosis factor alpha (TNF-?)-mediated interleukin-8 (CXCL-8) and interleukin-6 (CXCL-6) secretion from urothelial cell cultures compared to infection with a type 1 piliated E. coli K-12 strain. Furthermore, examination of a panel of clinical E. coli isolates revealed that 15 of 17 strains also possessed the ability to suppress cytokine secretion. In a murine model of UTI, NU14 infection resulted in diminished levels of mRNAs encoding keratinocyte-derived chemokine, macrophage inflammatory peptide 2, and CXCL-6 in the bladder relative to infection with an E. coli K-12 strain. Furthermore, reduced stimulation of inflammatory chemokine production during NU14 infection correlated with decreased levels of bladder and urine myeloperoxidase and increased bacterial colonization. These data indicate that a broad phylogenetic range of clinical E. coli isolates, including UPEC, may evade the activation of innate immune response in the urinary tract, thereby providing a pathogenic advantage.

Billips, Benjamin K.; Forrestal, Sarah G.; Rycyk, Matthew T.; Johnson, James R.; Klumpp, David J.; Schaeffer, Anthony J.

2007-01-01

43

Use of optical mapping to sort uropathogenic Escherichia coli strains into distinct subgroups  

PubMed Central

Optical maps were generated for 33 uropathogenic Escherichia coli (UPEC) isolates. For individual genomes, the NcoI restriction fragments aligned into a unique chromosome map for each individual isolate, which was then compared with the in silico restriction maps of all of the sequenced E. coli and Shigella strains. All of the UPEC isolates clustered separately from the Shigella strains as well as the laboratory and enterohaemorrhagic E. coli strains. Moreover, the individual strains appeared to cluster into distinct subgroups based on the dendrogram analyses. Phylogenetic grouping of these 33 strains showed that 32/33 were the B2 subgroup and 1/33 was subgroup A. To further characterize the similarities and differences among the 33 isolates, pathogenicity island (PAI), haemolysin and virulence gene comparisons were performed. A strong correlation was observed between individual subgroups and virulence factor genes as well as haemolysis activity. Furthermore, there was considerable conservation of sequenced-strain PAIs in the specific subgroups. Strains with different antibiotic-resistance patterns also appeared to sort into separate subgroups. Thus, the optical maps distinguished the UPEC strains from other E. coli strains and further subdivided the strains into distinct subgroups. This optical mapping procedure holds promise as an alternative way to subgroup all E. coli strains, including those involved in infections outside of the intestinal tract and epidemic strains with distinct patterns of antibiotic resistance.

Schwan, William R.; Briska, Adam; Stahl, Buffy; Wagner, Trevor K.; Zentz, Emily; Henkhaus, John; Lovrich, Steven D.; Agger, William A.; Callister, Steven M.; DuChateau, Brian; Dykes, Colin W.

2010-01-01

44

Viability and survival capability of quinolone-resistant uropathogenic Escherichia coli  

Microsoft Academic Search

Uropathogenic strains of E. coli isolated from urine of patients with urinary tract infections were tested for antibiotic sensitivity using bio-Merieux kits\\u000a and ATB-UR 5 expression system. The virulence of strains was evaluated by serum bactericidal assay, macrophage “killing” and\\u000a bacterial adhesive tests. Survival capability of strains was assessed under starvation in saline. The results showed that\\u000a quinolone-resistant uropathogenic strains

Georgi Slavchev; Nadya Markova

2010-01-01

45

Uropathogenic Escherichia coli Outer Membrane Antigens Expressed during Urinary Tract Infection?  

PubMed Central

Uncomplicated urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) represents a prevalent and potentially severe infectious disease. In this study, we describe the application of an immunoproteomics approach to vaccine development that has been used successfully to identify vaccine targets in other pathogenic bacteria. Outer membranes were isolated from pyelonephritis strain E. coli CFT073 cultured under conditions that mimic the urinary tract environment, including iron limitation, osmotic stress, human urine, and exposure to uroepithelial cells. To identify antigens that elicit a humoral response during experimental UTI, outer membrane proteins were separated by two-dimensional gel electrophoresis and probed using pooled antisera from 20 CBA/J mice chronically infected with E. coli CFT073. In total, 23 outer membrane antigens, including a novel iron compound receptor, reacted with the antisera and were identified by mass spectrometry. These antigens also included proteins with known roles in UPEC pathogenesis, such as ChuA, IroN, IreA, Iha, IutA, and FliC. These data demonstrate that an antibody response is directed against these virulence-associated factors during UTI. We also show that the genes encoding ChuA, IroN, hypothetical protein c2482, and IutA are significantly more prevalent (P < 0.01) among UPEC strains than among fecal-commensal E. coli isolates. Thus, we suggest that the conserved outer membrane antigens identified in this study could be rational candidates for a UTI vaccine designed to elicit protective immunity against UPEC infection.

Hagan, Erin C.; Mobley, Harry L. T.

2007-01-01

46

Escherichia coli Uropathogenic-Specific Protein, Usp, Is a Bacteriocin-Like Genotoxin.  

PubMed

Background.?Bacterial genotoxins provoke DNA damage and carcinogenesis. The Escherichia coli uropathogenic-specific protein gene, usp, and its linked genes, imu1-3, are associated with strains from pyelonephritis, prostatitis, and bacteremia of urinary tract origin. While the Usp C-terminal domain exhibits similarity with DNase-like colicins and pyocins, its role and mechanisms of action, as well as those of the 3 associated proteins, is unknown. Methods.?We isolated Usp and Imu1-3 and examined their activity on plasmid DNA, human umbilical vein endothelial cells, and human embryonic kidney cells (cell line HEK293). The affect of Usp and Imu1-3 was assessed by MTT and Comet assays, infection assays, caspase 3/7 activity, fluorescently labeled actin staining, and Western blotting. Results.?Usp possesses DNase activity and, particularly when coapplied with Imu2, exhibits genotoxic activity in mammalian cells. Infection assays demonstrated that E. coli usp(+) imu1-3(+) affects the viability of mammalian cells, induces increased caspase 3/7 activity, and perturbs cell cytoskeleton structure. Conclusions.?Usp is a novel E. coli genotoxin active against mammalian cells. Optimal in vivo activity of Usp requires Imu2. Infection with E. coli usp(+) imu1-3(+) induces a response characteristic of apoptosis. PMID:23997234

Nipic, Damijan; Podlesek, Zdravko; Budic, Maruska; Crnigoj, Miha; Zgur-Bertok, Darja

2013-08-30

47

Medicinal plants extracts affect virulence factors expression and biofilm formation by the uropathogenic Escherichia coli.  

PubMed

Medicinal plants are an important source for the therapeutic remedies of various diseases including urinary tract infections. This prompted us to perform research in this area. We decided to focus on medicinal plants species used in urinary tract infections prevention. The aim of our study was to determine the influence of Betula pendula, Equisetum arvense, Herniaria glabra, Galium odoratum, Urtica dioica, and Vaccinium vitis-idaea extracts on bacterial survival and virulence factors involved in tissue colonization and biofilm formation of the uropathogenic Escherichia coli rods. Qualitative and quantitative analysis of plant extracts were performed. Antimicrobial assay relied on the estimation of the colony forming unit number. Hydrophobicity of cells was established by salt aggregation test. Using motility agar, the ability of bacteria to move was examined. The erythrocyte hemagglutination test was used for fimbriae P screening. Curli expression was determined using YESCA agar supplemented with congo red. Quantification of biofilm formation was carried out using a microtiter plate assay and a spectrophotometric method. The results of the study indicate significant differences between investigated extracts in their antimicrobial activities. The extracts of H. glabra and V. vitis-idaea showed the highest growth-inhibitory effects (p < 0.05). Surface hydrophobicity of autoaggregating E. coli strain changed after exposure to all plant extracts, except V. vitis-idaea (p > 0.05). The B. pendula and U. dioica extracts significantly reduced the motility of the E. coli rods (p < 0.05). All the extracts exhibited the anti-biofilm activity. PMID:22915095

Wojnicz, Dorota; Kucharska, Alicja Z; Sokó?-??towska, Anna; Kicia, Marta; Tichaczek-Goska, Dorota

2012-08-23

48

Multilocus sequence typing of uropathogenic ESBL-producing Escherichia coli isolated in a Brazilian community.  

PubMed

In the present study, multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and polymerase chain reaction detection of three resistance genes were combined to characterize seven uropathogenic E. coli isolated from outpatients. Selected portions of seven housekeeping and three antibiotic-resistance genes of the isolates were sequenced. The seven isolates were classified into four different sequence types (STs) by MLST and five PGFE types. Three isolates had a novel allelic profile representing a new ST designated as ST528 and showed the same PFGE and resistance genes. Two isolates, both characterized as ST359, were differentiated by PFGE and shared only one of the antibiotic-resistance genes studied. Comparison of MLST results with those of PFGE and resistance genes demonstrated that Escherichia coli had acquired different antibiotic-resistance genes and DNA rearrangements, causing alterations in PFGE patterns but maintaining the same ST. Furthermore, this article also reports the first detection of a CTX-M-2 ESBL E. coli and SHV-5 in a Brazilian community. PMID:17899265

Minarini, Luciene A R; Camargo, Ilana L B C; Pitondo-Silva, André; Darini, Ana Lúcia C

2007-09-25

49

Virulence factors and genetic variability of uropathogenic Escherichia coli isolated from dogs and cats in Italy  

PubMed Central

In this study, the association between virulence genotypes and phylogenetic groups among Escherichia (E.) coli isolates obtained from pet dogs and cats with cystitis was detected, and fingerprinting methods were used to explore the relationship among strains. Forty uropathogenic E. coli (UPEC) isolated from dogs (n = 30) and cats (n = 10) in Italy were analysed by polymerase chain reaction (PCR) for the presence of virulence factors and their classification into phylogenetic groups. The same strains were characterized by repetitive extragenic palindromic (REP)- and enterobacterial repetitive intergenic consensus (ERIC)-PCR techniques. We found a high number of virulence factors such as fimbriae A, S fimbriae (sfa) and cytotoxic necrotizing factor 1 (cnf1) significantly associated with phylogenetic group B2. We demonstrated a high correlation between ?-hemolysin A and pyelonephritis C, sfa, and cnf1 operons, confirming the presence of pathogenicity islands in these strains. In addition, UPEC belonging to group B2 harboured a greater number of virulence factors than strains from phylogenetic groups A, B1, and D. REP- and ERIC-PCR grouped the UPEC isolates into two major clusters, the former grouping E. coli strains belonging to phylogenetic group B2 and D, the latter grouping those belonging to groups A and B1. Given the significant genetic variability among the UPEC strains found in our study, it can be hypothesized that no specific genotype is responsible for cystitis in cats or dogs.

Tramuta, Clara; Nucera, Daniele; Robino, Patrizia; Salvarani, Sara

2011-01-01

50

Avian P1 antigens inhibit agglutination mediated by P fimbriae of uropathogenic Escherichia coli.  

PubMed Central

Whole egg white from pigeon, dove, and cockatiel eggs, as well as the ovomucoid fraction of pigeon egg white, exhibited strong P1 antigenic activities and inhibited agglutination of human P1 erythrocytes and of digalactoside-coated latex beads by P-fimbriated Escherichia coli strains. In contrast, chicken egg white exhibited only weak P1 antigenic activity and had little impact on P-fimbrial agglutination. These preparations did not affect hemagglutination by E. coli strains expressing mannose-resistant adhesins other than P fimbriae, i.e., Dr, F1845, and S adhesins. Human anti-P1 serum diminished the P-fimbrial inhibitory activities of pigeon egg white and pigeon ovomucoid. Pigeon ovomucoid was equipotent on a molar basis with globoside, and the pigeon, dove, and cockatiel egg white preparations were equipotent with each other in P-fimbrial inhibition. Incubation of p erythrocytes in whole egg whites or in pigeon ovomucoid did not render them agglutinable by P-fimbriated bacteria, whereas incubation in globoside did. These data demonstrate that whole egg whites (and their ovomucoid fraction) from members of the families Columbidae (pigeons and doves) and Psittacidae (parrots) specifically and potently inhibit P-fimbrial agglutination, probably by providing P1 antigen as a receptor for the P-fimbrial adhesin. Avian egg white preparations may facilitate adhesin characterization of wild-type uropathogenic strains and may useful in preventing upper urinary tract infections due to P-fimbriated E. coli.

Johnson, J R; Swanson, J L; Neill, M A

1992-01-01

51

Tetracycline Rapidly Reaches All the Constituent Cells of Uropathogenic Escherichia coli Biofilms  

PubMed Central

We have developed a method for visualizing Escherichia coli cells that are exposed to tetracycline in a biofilm, based on a previous report that liposomes containing the E. coli TetR(B) protein fluoresce when exposed to this antibiotic. By our method, cells devoid of TetR(B) also exhibited tetracycline-dependent fluorescence. At 50 ?g of tetracycline ml?1, planktonic cells of a uropathogenic E. coli (UPEC) strain developed maximal fluorescence after 7.5 to 10 min of exposure. A similar behavior was exhibited by cells in a 24- or 48-h UPEC biofilm, as examined by confocal laser microscopy, regardless of whether they lined empty spaces or occupied densely packed regions. Further, a comparison of phase-contrast and fluorescent images of corresponding biofilm zones showed that all the cells fluoresced. Thus, all the biofilm cells were exposed to tetracycline and there were no pockets within the biofilm where the antibiotic failed to reach. It also appeared unlikely that niches of reduced exposure to the antibiotic existed within the biofilms.

Stone, G.; Wood, P.; Dixon, L.; Keyhan, M.; Matin, A.

2002-01-01

52

The antibiotic susceptibility patterns of uropathogenic Escherichia coli, with special reference to the fluoroquinolones.  

PubMed

Context: The emergence of drug resistance to trimethoprim-sulfamethoxazole, the penicillins, cephalosporins, and fluoroquinolones by Uropathogenic Escherichia coli (UPEC) has limited the options for selecting the appropriate antibiotic for the treatment of urinary tract infections. Aims: The The E. coli isolates, which were obtained from the culture of urine samples,were studied for their antibiotic resistance patterns, with special reference to the antimicrobial activity of the fluoroquinolones and the production of the extended spectrum ?-lactamases. (ESBL), Settings and Design: This was a hospital based, prospective study which was done for a period of eighteen months. Material and Methods: This study was done by using the standard culture techniques for urine samples, the modified Kirby-Bauer disk diffusion method for the antibiotic susceptibility testing and the disk diffusion method to confirm the ESBL production by the clinical isolates of E. coli in urine. The sensitivity pattern was correlated with the clinical condition and the presence of the risk factors. The statistical analysis which was used: The statistical analysis was done by using the proportions of sensitive, resistant and intermediates. Descriptive statistics like the total, mean and percentage were done by using the Statistical Package for the Social Sciences (SPSS), version 15.0. Results: The hospital isolates showed high degrees of resistance to the penicillins, cephalosporins, nalidixic acid and the fluoroquinolones, with 59% of the isolates being ESBL producers. Conclusions: The incidence of the multidrug resistant strains of Escherichia coli has been steadily increasing over the past few years. The knowledge on the resistance pattern of the bacterial strains in a geographical area will help in guiding the appropriate and the judicious use of antibiotics. Also, the formulation of an appropriate hospital antibiotic policy will go a long way in controlling these infections. PMID:23905095

Shariff V A, Abdul Rahaman; Shenoy M, Suchitra; Yadav, Taruna; M, Radhakrishna

2013-06-01

53

The structure of cranberry proanthocyanidins which inhibit adherence of uropathogenic P-fimbriated Escherichia coli in vitro  

Microsoft Academic Search

Ethyl acetate extracts of Sephadex LH20-purified proanthocyanidins of American cranberry (Vaccinium macrocarpon Ait.) exhibited potent biological activity by inhibiting adherence of uropathogenic isolates of P-fimbriated Escherichia coli bacteria to cellular surfaces containing ?-Gal(1 ? 4)?-Gal receptor sequences similar to those on epithelial cells in the urinary tract. The chemical structures of the proanthocyanidins were determined by 13C NMR, electrospray mass

Lai Yeap Foo; Yinrong Lu; Amy B Howell; Nicholi Vorsa

2000-01-01

54

Two pathogenicity islands in uropathogenic Escherichia coli J96: cosmid cloning and sample sequencing.  

PubMed Central

Many of the virulence genes of pathogenic strains of Escherichia coli are carried in large multigene chromosomal segments called pathogenicity islands (PAIs) that are absent from normal fecal and laboratory K-12 strains of this bacterium. We are studying PAIs in order to better understand factors that govern virulence and to assess how such DNA segments are gained or lost during evolution. The isolation and sample sequencing of a set of 11 cosmid clones that cover all of one and much of a second large PAI in the uropathogenic E. coli J96 are described. These PAIs were mapped to the 64- and 94-min regions of the E. coli K-12 chromosome, which differ from the locations of three PAIs identified in other pathogenic E. coli strains. Analysis of the junction sequences with E. coli K-12-like DNAs showed that the insert at 94 min is within the 3' end of a phenylalanine tRNA gene, pheR, and is flanked by a 135-bp imperfect direct repeat. Analysis of the one junction recovered from the insert at 64 min indicated that it lies near another tRNA gene, pheV. To identify possible genes unique to these PAIs, 100 independent subclones of the cosmids were made by PstI digestion and ligation into a pBS+ plasmid and used in one-pass sample DNA sequencing from primer binding sites at the cloning site in the vector DNA. Database searches of the J96 PAI-specific sequences identified numerous instances in which the cloned DNAs shared significant sequence similarities to adhesins, toxins, and other virulence determinants of diverse pathogens. Several likely insertion sequence elements (IS100, IS630, and IS911) and conjugative R1 plasmid and P4 phage genes were also found. We propose that such mobile genetic elements may have facilitated the spread of virulence determinants within PAIs among bacteria.

Swenson, D L; Bukanov, N O; Berg, D E; Welch, R A

1996-01-01

55

Possible Involvement of Mycoplasma hominis in Inhibiting the Formation of Biofilms by Uropathogenic Escherichia coli (UPEC).  

PubMed

Here we examined the involvement of Mycoplasma hominis in the formation of biofilms by uropathogenic Escherichia coli (UPEC) strain CFT073. Initially, we thought that M. hominis does not affect the fitness of UPEC, including the growth and production of signaling molecules, such as autoinducer-2 and indole. We found, however, that the presence of M. hominis significantly decreased the degree of biofilm formation by UPEC CFT073 (approximately a 60% reduction for 10(5) ccu/mL of M. hominis as compared with UPEC alone). We also found that it had a slight effect in inhibiting the attachment and cytotoxicity of UPEC CFT073. These findings are specific to these UPEC strains rather than to enterohemorrhagic E. coli (EHEC) strains, found in normal intestinal flora. In addition, we performed whole-transcriptome profiling and quantitative real-time polymerase chain reaction (qRT-PCR) analysis. This indicated that the PhoPQ system and the anti-termination protein (encoded by ybcQ) were involved in the reduction of biofilm formation by M. hominis (corroborated by qRT-PCR). Furthermore, our results indicate that M. hominis raises the degree of transcription of toxin genes, including hha and pasT. Hence, we suggest a possible role of M. hominis in affecting the formation of biofilms by UPEC in the urinary tract. PMID:24096662

Oh, Sangnam; Go, Gwang-Woong; Choi, Nag-Jin; Oh, Sejong; Kim, Younghoon

2013-10-07

56

Comparison of Adhesin Genes and Antimicrobial Susceptibilities between Uropathogenic and Intestinal Commensal Escherichia coli Strains  

PubMed Central

The presence of adhesins is arguably an important determinant of pathogenicity for Uropathogenic Escherichia coli (UPEC). Antimicrobial susceptibilities were tested by agar dilution method, fifteen adhesin genes were detected by polymerase chain reaction, and multilocus sequence typing (MLST) was analyzed in 70 UPEC isolates and 41 commensal E. coli strains. Extended-spectrum ?-lactamase (ESBL) was determined with confirmatory test. The prevalence of ESBL-producers in UPEC (53%, 37/70) was higher than the commensal intestinal isolates (7%, 3/41), and 97% (36/37) of the ESBL-producing UPEC harbored blaCTX-M genes. afa was present in 36% (10/28) UPEC isolates from recurrent lower urinary tract infection (UTI), and none in the acute pyelonephritis, acute uncomplicated cystitis or commensal strains (P<0.0001). papG was detected in 28% (20/70) of UPEC isolates, while 5% (2/41) of the commensal strains were papG positive (P?=?0.0025), and the prevalence of papG was significantly higher in acute pyelonephritis group (71%) than the other two UTI groups (P<0.0001). The prevalence of flu, yqi, yadN and ygiL was significantly higher in UPEC isolates than in the commensal strains. ESBL-producing UPEC showed a lower prevalence of adhesin genes compared with non-ESBL-producing strains. The MLST profiles were different between UPEC and commensal strains, with ST131 (19%, 13/70) and ST10 (20%, 8/41) being the most common MLSTs, respectively. This study demonstrated that several adhesin genes were more prevalent in UPEC isolates than in commensal E. coli, and afa may be associated with recurrent lower UTI whereas papG is more frequently associated with acute pyelonephritis.

Qin, Xiaohua; Hu, Fupin; Wu, Shi; Ye, Xinyu; Zhu, Demei; Zhang, Ying; Wang, Minggui

2013-01-01

57

Characterization of a dipartite iron uptake system from uropathogenic Escherichia coli strain F11.  

PubMed

In the uropathogenic Escherichia coli strain F11, in silico genome analysis revealed the dicistronic iron uptake operon fetMP, which is under iron-regulated control mediated by the Fur regulator. The expression of fetMP in a mutant strain lacking known iron uptake systems improved growth under iron depletion and increased cellular iron accumulation. FetM is a member of the iron/lead transporter superfamily and is essential for iron uptake by the Fet system. FetP is a periplasmic protein that enhanced iron uptake by FetM. Recombinant FetP bound Cu(II) and the iron analog Mn(II) at distinct sites. The crystal structure of the FetP dimer reveals a copper site in each FetP subunit that adopts two conformations: CuA with a tetrahedral geometry composed of His(44), Met(90), His(97), and His(127), and CuB, a second degenerate octahedral geometry with the addition of Glu(46). The copper ions of each site occupy distinct positions and are separated by ?1.3 ?. Nearby, a putative additional Cu(I) binding site is proposed as an electron source that may function with CuA/CuB displacement to reduce Fe(III) for transport by FetM. Together, these data indicate that FetMP is an additional iron uptake system composed of a putative iron permease and an iron-scavenging and potentially iron-reducing periplasmic protein. PMID:21596746

Koch, Doreen; Chan, Anson C K; Murphy, Michael E P; Lilie, Hauke; Grass, Gregor; Nies, Dietrich H

2011-05-19

58

Characterization of a Dipartite Iron Uptake System from Uropathogenic Escherichia coli Strain F11*  

PubMed Central

In the uropathogenic Escherichia coli strain F11, in silico genome analysis revealed the dicistronic iron uptake operon fetMP, which is under iron-regulated control mediated by the Fur regulator. The expression of fetMP in a mutant strain lacking known iron uptake systems improved growth under iron depletion and increased cellular iron accumulation. FetM is a member of the iron/lead transporter superfamily and is essential for iron uptake by the Fet system. FetP is a periplasmic protein that enhanced iron uptake by FetM. Recombinant FetP bound Cu(II) and the iron analog Mn(II) at distinct sites. The crystal structure of the FetP dimer reveals a copper site in each FetP subunit that adopts two conformations: CuA with a tetrahedral geometry composed of His44, Met90, His97, and His127, and CuB, a second degenerate octahedral geometry with the addition of Glu46. The copper ions of each site occupy distinct positions and are separated by ?1.3 ?. Nearby, a putative additional Cu(I) binding site is proposed as an electron source that may function with CuA/CuB displacement to reduce Fe(III) for transport by FetM. Together, these data indicate that FetMP is an additional iron uptake system composed of a putative iron permease and an iron-scavenging and potentially iron-reducing periplasmic protein.

Koch, Doreen; Chan, Anson C. K.; Murphy, Michael E. P.; Lilie, Hauke; Grass, Gregor; Nies, Dietrich H.

2011-01-01

59

Active cytotoxic necrotizing factor 1 associated with outer membrane vesicles from uropathogenic Escherichia coli.  

PubMed

Cytotoxic necrotizing factor type 1 (CNF1) is one of the virulence factors produced by uropathogenic Escherichia coli (UPEC). How this toxin is translocated from the bacterial cytoplasm to the surrounding environment is not well understood. Our data suggest that CNF1 may be regarded as a secreted protein, since it could be detected in culture supernatants. Furthermore, we found that CNF1 was tightly associated to outer membrane vesicles, suggesting that such vesicles play a role in the secretion of this protein. Interestingly, vesicle samples containing CNF1 could exert the effects known for this protein on HeLa cell cultures, showing that CNF1 is transported by vesicles in its active form. Taken together, our results strongly suggest that outer membrane vesicles could be a means for the bacteria to deliver CNF1 to the environment and to the infected tissue. In addition, our results indicate that the histone-like nucleoid structuring protein H-NS has a role in the downregulation of CNF1 production and that it affects the outer membrane vesicle release in UPEC strain J96. PMID:16552031

Kouokam, J Clavin; Wai, Sun Nyunt; Fällman, Maria; Dobrindt, Ulrich; Hacker, Jörg; Uhlin, Bernt Eric

2006-04-01

60

In Vitro Adhesion of Uropathogenic Escherichia coli to Human Periurethral Cells  

PubMed Central

The in vitro adhesion of three uropathogenic strains of Escherichia coli to epithelial cells from the periurethral area (area surrounding the urethral orifice) of women with and without a history of recurrent urinary tract infections was investigated. All strains showed a specific mannose-resistant hemagglutination restricted to human erythrocytes. Since only a few hundred periurethral cells were used in each test, gentle methods were required. Optimal results were obtained with bacteria grown for 16 h at 37°C in nutrient broth without shaking. The binding of bacteria seemed to be irreversible under the conditions studied, since repeated washings of the epithelial cells after incubation did not decrease the number of adhering bacteria. Chloramphenicol was used to control the number of added bacteria in the incubation system. A difference in the adhesive capacity of periurethral cells of infection-prone and healthy individuals was most evident at concentrations of 2.5 × 109 bacteria/ml. Electron microscope studies indicated that pili mediated the adhesion. Adhesion was correlated with the mannose-resistant hemagglutination of human erythrocytes, indicating that the pili were not type 1 pili. Day-to-day variations in the adhesiveness of the bacteria were reduced by selecting well-adhering bacteria with the aid of in vitro passage on periurethral cells or human erythrocytes, and by exclusion of bacteria with low hemagglutination ability. ImagesFig. 1Fig. 4

Kallenius, Gunilla; Mollby, Roland; Winberg, Jan

1980-01-01

61

Waging War against Uropathogenic Escherichia coli: Winning Back the Urinary Tract?  

PubMed Central

Urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) is a substantial economic and societal burden—a formidable public health issue. Symptomatic UTI causes significant discomfort in infected patients, results in lost productivity, predisposes individuals to more serious infections, and usually necessitates antibiotic therapy. There is no licensed vaccine available for prevention of UTI in humans in the United States, likely due to the challenge of targeting a relatively heterogeneous group of pathogenic strains in a unique physiological niche. Despite significant advances in the understanding of UPEC biology, mechanistic details regarding the host response to UTI and full comprehension of genetic loci that influence susceptibility require additional work. Currently, there is an appreciation for the role of classic innate immune responses—from pattern receptor recognition to recruitment of phagocytic cells—that occur during UPEC-mediated UTI. There is, however, a clear disconnect regarding how factors involved in the innate immune response to UPEC stimulate acquired immunity that facilitates enhanced clearance upon reinfection. Unraveling the molecular details of this process is vital in the development of a successful vaccine for prevention of human UTI. Here, we survey the current understanding of host responses to UPEC-mediated UTI with an eye on molecular and cellular factors whose activity may be harnessed by a vaccine that stimulates lasting and sterilizing immunity.

Sivick, Kelsey E.; Mobley, Harry L. T.

2010-01-01

62

The Cpx Stress Response System Potentiates the Fitness and Virulence of Uropathogenic Escherichia coli  

PubMed Central

Strains of uropathogenic Escherichia coli (UPEC) are the primary cause of urinary tract infections, representing one of the most widespread and successful groups of pathogens on the planet. To colonize and persist within the urinary tract, UPEC must be able to sense and respond appropriately to environmental stresses, many of which can compromise the bacterial envelope. The Cpx two-component envelope stress response system is comprised of the inner membrane histidine kinase CpxA, the cytosolic response regulator CpxR, and the periplasmic auxiliary factor CpxP. Here, by using deletion mutants along with mouse and zebrafish infection models, we show that the Cpx system is critical to the fitness and virulence of two reference UPEC strains, the cystitis isolate UTI89 and the urosepsis isolate CFT073. Specifically, deletion of the cpxRA operon impaired the ability of UTI89 to colonize the murine bladder and greatly reduced the virulence of CFT073 during both systemic and localized infections within zebrafish embryos. These defects coincided with diminished host cell invasion by UTI89 and increased sensitivity of both strains to complement-mediated killing and the aminoglycoside antibiotic amikacin. Results obtained with the cpxP deletion mutants were more complicated, indicating variable strain-dependent and niche-specific requirements for this well-conserved auxiliary factor.

Debnath, Irina; Norton, J. Paul; Barber, Amelia E.; Ott, Elizabeth M.; Dhakal, Bijaya K.; Kulesus, Richard R.

2013-01-01

63

Distribution of drb Genes Coding for Dr Binding Adhesins among Uropathogenic and Fecal Escherichia coli Isolates and Identification of New Subtypes  

Microsoft Academic Search

The Dr family of related adherence structures, some fimbriated and others afimbriated, bind to decay- accelerating factor molecules on human cells. Dr is associated with recurring urinary tract infection (UTI), but the distribution of Dr subtypes among uropathogenic Escherichia coli causing UTI among otherwise healthy women has yet to be described. A total of 787 UTI and fecal E. coli

LIXIN ZHANG; BETSY FOXMAN; PAT TALLMAN; EDUARDO CLADERA; CHANTAL LE BOUGUENEC; CARL F. MARRS

1997-01-01

64

Functional Heterogeneity of the UpaH Autotransporter Protein from Uropathogenic Escherichia coli  

PubMed Central

Uropathogenic Escherichia coli (UPEC) is responsible for the majority of urinary tract infections (UTI). To cause a UTI, UPEC must adhere to the epithelial cells of the urinary tract and overcome the shear flow forces of urine. This function is mediated primarily by fimbrial adhesins, which mediate specific attachment to host cell receptors. Another group of adhesins that contributes to UPEC-mediated UTI is autotransporter (AT) proteins. AT proteins possess a range of virulence properties, such as adherence, aggregation, invasion, and biofilm formation. One recently characterized AT protein of UPEC is UpaH, a large adhesin-involved-in-diffuse-adherence (AIDA-I)-type AT protein that contributes to biofilm formation and bladder colonization. In this study we characterized a series of naturally occurring variants of UpaH. We demonstrate that extensive sequence variation exists within the passenger-encoding domain of UpaH variants from different UPEC strains. This sequence variation is associated with functional heterogeneity with respect to the ability of UpaH to mediate biofilm formation. In contrast, all of the UpaH variants examined retained a conserved ability to mediate binding to extracellular matrix (ECM) proteins. Bioinformatic analysis of the UpaH passenger domain identified a conserved region (UpaHCR) and a hydrophobic region (UpaHHR). Deletion of these domains reduced biofilm formation but not the binding to ECM proteins. Despite variation in the upaH sequence, the transcription of upaH was repressed by a conserved mechanism involving the global regulator H-NS, and mutation of the hns gene relieved this repression. Overall, our findings shed new light on the regulation and functions of the UpaH AT protein.

Allsopp, Luke P.; Beloin, Christophe; Moriel, Danilo Gomes; Totsika, Makrina; Ghigo, Jean-Marc

2012-01-01

65

Population Dynamics and Niche Distribution of Uropathogenic Escherichia coli during Acute and Chronic Urinary Tract Infection ? †  

PubMed Central

Urinary tract infections (UTIs) have complex dynamics, with uropathogenic Escherichia coli (UPEC), the major causative agent, capable of colonization from the urethra to the kidneys in both extracellular and intracellular niches while also producing chronic persistent infections and frequent recurrent disease. In mouse and human bladders, UPEC invades the superficial epithelium, and some bacteria enter the cytoplasm to rapidly replicate into intracellular bacterial communities (IBCs) comprised of ?104 bacteria each. Through IBC formation, UPEC expands in numbers while subverting aspects of the innate immune response. Within 12 h of murine bladder infection, half of the bacteria are intracellular, with 3 to 700 IBCs formed. Using mixed infections with green fluorescent protein (GFP) and wild-type (WT) UPEC, we discovered that each IBC is clonally derived from a single bacterium. Genetically tagged UPEC and a multiplex PCR assay were employed to investigate the distribution of UPEC throughout urinary tract niches over time. In the first 24 h postinfection (hpi), the fraction of tags dramatically decreased in the bladder and kidney, while the number of CFU increased. The percentage of tags detected at 6 hpi correlated to the number of IBCs produced, which closely matched a calculated multinomial distribution based on IBC clonality. The fraction of tags remaining thereafter depended on UTI outcome, which ranged from resolution of infection with or without quiescent intracellular reservoirs (QIRs) to the development of chronic cystitis as defined by persistent bacteriuria. Significantly more tags remained in mice that developed chronic cystitis, arguing that during the acute stages of infection, a higher number of IBCs precedes chronic cystitis than precedes QIR formation.

Schwartz, Drew J.; Chen, Swaine L.; Hultgren, Scott J.; Seed, Patrick C.

2011-01-01

66

Kinetics of Uropathogenic Escherichia coli Metapopulation Movement during Urinary Tract Infection  

PubMed Central

ABSTRACT 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.

Walters, Matthew S.; Lane, M. Chelsea; Vigil, Patrick D.; Smith, Sara N.; Walk, Seth T.; Mobley, Harry L. T.

2012-01-01

67

Naturally occurring bacteriophages lyse a large proportion of canine and feline uropathogenic Escherichia coli isolates in vitro.  

PubMed

We investigated the feasibility of bacteriophage therapy to combat canine and feline Escherichia coli urinary tract infections (UTIs) by testing the in vitro lytic ability of 40 naturally occurring bacteriophages on 53 uropathogenic E. coli (UPEC). The mean number of UPEC strains lysed by an individual bacteriophage was 21/53 (40%, range 17-72%). In total, 50/53 (94%) of the UPEC strains were killed by one or more of the bacteriophages. Ten bacteriophages lysed 51% of UPEC strains individually and 92% of UPEC strains as a group. Electron microscopy and DNA sequencing of 5 'promising' bacteriophages revealed that 4 bacteriophages belonged to the lytic T4-like genus, while one displayed morphologic similarity to temperate P2-like bacteriophages. Overall, these results indicate that the majority of UPEC are susceptible to lysis by naturally occurring bacteriophages. Thus, bacteriophages show promise as therapeutic agents for treatment of canine and feline E. coli UTIs. PMID:17959211

Freitag, T; Squires, R A; Schmid, J

2007-10-23

68

Role of Histone-Like Proteins H-NS and StpA in Expression of Virulence Determinants of Uropathogenic Escherichia coli  

Microsoft Academic Search

The histone-like protein H-NS is a global regulator in Escherichia coli that has been intensively studied in nonpathogenic strains. However, no comprehensive study on the role of H-NS and its paralogue, StpA, in gene expression in pathogenic E. coli has been carried out so far. Here, we monitored the global effects of H-NS and StpA in a uropathogenic E. coli

Claudia M. Muller; Ulrich Dobrindt; Gabor Nagy; Levente Emody; Bernt Eric Uhlin; Jorg Hacker

2006-01-01

69

Induction of a State of Iron Limitation in Uropathogenic Escherichia coli CFT073 by Cranberry-Derived Proanthocyanidins as Revealed by Microarray Analysis ?  

PubMed Central

Transcriptional profiles of uropathogenic Escherichia coli CFT073 exposed to cranberry-derived proanthocyanidins (PACs) were determined. Our results indicate that bacteria grown on media supplemented with PACs were iron deprived. To our knowledge, this is the first time that PACs have been shown to induce a state of iron limitation in this bacterium.

Hidalgo, Gabriela; Ponton, Andre; Fatisson, Julien; O'May, Che; Asadishad, Bahareh; Schinner, Tim; Tufenkji, Nathalie

2011-01-01

70

Uropathogenic specific protein gene, highly distributed in extraintestinal uropathogenic Escherichia coli, encodes a new member of H-N-H nuclease superfamily  

PubMed Central

Background The uropathogenic specific protein (Usp) and three OrfU proteins (OrfU1, OrfU2 and OrfU3) are encoded in the putative small pathogenicity island which is closely associated with Uropathogenic Escherichia coli. Although homology search revealed that Usp and OrfUs have a homology with nuclease-type bacteriocins, which possess H-N-H nuclease motif, and immunity proteins respectively, the molecular activity of these proteins was never investigated. In this study, we try to over-express Usp in E. coli, purify Usp and characterize its molecular activity. Method Recombinant Usp protein was expressed in E. coli BL21(DE3) cells together with 6× Histidine tagged OrfU1 (OrfU1-His) protein, and purified with affinity chromatography using Ni2+ chelating agarose. The nuclease activity of the purified Usp was examined in vitro by using plasmid DNA as a substrate. The importance of H-N-H motif in nuclease activity of Usp was examined by site-directed mutagenesis study. Results We revealed that pET expression vector encoding Usp alone could not be maintained in E. coli BL21(DE3), and insertion of the orfUs as well as usp in the constructed plasmid diminished the toxic effect, suggesting that co-expressed OrfUs masked the activity of Usp. To purify Usp protein, we employed the expression vector encoding untagged Usp together with OrfU1-His. A tight complex formation could be observed between Usp and OrfU1-His, which allowed the purification of Usp in a single chromatographic step: binding of Usp/OrfU1-His complex to Ni2+ chelating agarose followed by elution of Usp from the complex with denaturing reagent. The purified free Usp was found to have the nuclease activity, and the activity was constitutively higher than Usp/OrfU1-His complex. H-N-H motif, which is found in various types of nucleases including a subfamily of nuclease-type bacteriocin, had been identified in the C-terminal region of Usp. Site-directed mutagenesis study showed that the H-N-H motif in Usp is indispensable for its nuclease activity. Conclusion This is the first evidence of the molecular activity of the new member of H-N-H superfamily and lays the foundation for the biological characterization of Usp and its inhibitor protein, OrfUs.

2013-01-01

71

Human Bladder Uroepithelial Cells Synergize with Monocytes to Promote IL-10 Synthesis and Other Cytokine Responses to Uropathogenic Escherichia coli  

PubMed Central

Urinary tract infections are a major source of morbidity for women and the elderly, with Uropathogenic Escherichia coli (UPEC) being the most prevalent causative pathogen. Studies in recent years have defined a key anti-inflammatory role for Interleukin-10 (IL-10) in urinary tract infection mediated by UPEC and other uropathogens. We investigated the nature of the IL-10-producing interactions between UPEC and host cells by utilising a novel co-culture model that incorporated lymphocytes, mononuclear and uroepithelial cells in histotypic proportions. This co-culture model demonstrated synergistic IL-10 production effects between monocytes and uroepithelial cells following infection with UPEC. Membrane inserts were used to separate the monocyte and uroepithelial cell types during infection and revealed two synergistic IL-10 production effects based on contact-dependent and soluble interactions. Analysis of a comprehensive set of immunologically relevant biomarkers in monocyte-uroepithelial cell co-cultures highlighted that multiple cytokine, chemokine and signalling factors were also produced in a synergistic or antagonistic fashion. These results demonstrate that IL-10 responses to UPEC occur via multiple interactions between several cells types, implying a complex role for infection-related IL-10 during UTI. Development and application of the co-culture model described in this study is thus useful to define the degree of contact dependency of biomarker production to UPEC, and highlights the relevance of histotypic co-cultures in studying complex host-pathogen interactions.

Duell, Benjamin L.; Carey, Alison J.; Dando, Samantha J.; Schembri, Mark A.; Ulett, Glen C.

2013-01-01

72

Human Bladder Uroepithelial Cells Synergize with Monocytes to Promote IL-10 Synthesis and Other Cytokine Responses to Uropathogenic Escherichia coli.  

PubMed

Urinary tract infections are a major source of morbidity for women and the elderly, with Uropathogenic Escherichia coli (UPEC) being the most prevalent causative pathogen. Studies in recent years have defined a key anti-inflammatory role for Interleukin-10 (IL-10) in urinary tract infection mediated by UPEC and other uropathogens. We investigated the nature of the IL-10-producing interactions between UPEC and host cells by utilising a novel co-culture model that incorporated lymphocytes, mononuclear and uroepithelial cells in histotypic proportions. This co-culture model demonstrated synergistic IL-10 production effects between monocytes and uroepithelial cells following infection with UPEC. Membrane inserts were used to separate the monocyte and uroepithelial cell types during infection and revealed two synergistic IL-10 production effects based on contact-dependent and soluble interactions. Analysis of a comprehensive set of immunologically relevant biomarkers in monocyte-uroepithelial cell co-cultures highlighted that multiple cytokine, chemokine and signalling factors were also produced in a synergistic or antagonistic fashion. These results demonstrate that IL-10 responses to UPEC occur via multiple interactions between several cells types, implying a complex role for infection-related IL-10 during UTI. Development and application of the co-culture model described in this study is thus useful to define the degree of contact dependency of biomarker production to UPEC, and highlights the relevance of histotypic co-cultures in studying complex host-pathogen interactions. PMID:24155979

Duell, Benjamin L; Carey, Alison J; Dando, Samantha J; Schembri, Mark A; Ulett, Glen C

2013-10-14

73

Biofilm formation and virulence of uropathogenic Escherichia coli in urine after consumption of cranberry-lingonberry juice.  

PubMed

Cranberry-lingonberry juice (CLJ) was effective in preventing urinary tract infections (UTIs) in our earlier randomized clinical trial. We aimed to test whether consumption of CLJ at a similar dose to earlier reduces the biofilm formation and virulence of uropathogenic Escherichia coli in urine. Twenty healthy women drank 100 ml of CLJ daily for two weeks. Urine samples were obtained 2-4 hours after the last dose. Control samples were taken after a one-week period without berry consumption. Biofilm formation of 20 E. coli strains was measured at 72 hours by the polystyrene microtitre plate method. Quantitative real-time PCR analyses were performed for selected genes. Four of the 20 clinical strains produced more biofilm in urine after CLJ consumption (P < 0.05) and one produced less. Expression levels of the pga, cpxA, fimA and papF genes did not differ between bacteria grown in control urine and urine obtained after CLJ consumption, except for pga gene expression, which was reduced in one strain after CLJ (P = 0.04). It appears that the effect of CLJ in preventing UTIs is not explained by mechanisms that reduce biofilm formation or the expression of selected virulence genes of Escherichia coli in urine. PMID:21822564

Tapiainen, T; Jauhiainen, H; Jaakola, L; Salo, J; Sevander, J; Ikäheimo, I; Pirttilä, A M; Hohtola, A; Uhari, M

2011-08-07

74

UpaG, a new member of the trimeric autotransporter family of adhesins in uropathogenic Escherichia coli.  

PubMed

The ability of Escherichia coli to colonize both intestinal and extraintestinal sites is driven by the presence of specific virulence factors, among which are the autotransporter (AT) proteins. Members of the trimeric AT adhesin family are important virulence factors for several gram-negative pathogens and mediate adherence to eukaryotic cells and extracellular matrix (ECM) proteins. In this study, we characterized a new trimeric AT adhesin (UpaG) from uropathogenic E. coli (UPEC). Molecular analysis of UpaG revealed that it is translocated to the cell surface and adopts a multimeric conformation. We demonstrated that UpaG is able to promote cell aggregation and biofilm formation on abiotic surfaces in CFT073 and various UPEC strains. In addition, UpaG expression resulted in the adhesion of CFT073 to human bladder epithelial cells, with specific affinity to fibronectin and laminin. Prevalence analysis revealed that upaG is strongly associated with E. coli strains from the B2 and D phylogenetic groups, while deletion of upaG had no significant effect on the ability of CFT073 to colonize the mouse urinary tract. Thus, UpaG is a novel trimeric AT adhesin from E. coli that mediates aggregation, biofilm formation, and adhesion to various ECM proteins. PMID:18424525

Valle, Jaione; Mabbett, Amanda N; Ulett, Glen C; Toledo-Arana, Alejandro; Wecker, Karine; Totsika, Makrina; Schembri, Mark A; Ghigo, Jean-Marc; Beloin, Christophe

2008-04-18

75

Temperature control of molecular circuit switch responsible for virulent phenotype expression in uropathogenic Escherichia coli  

NASA Astrophysics Data System (ADS)

The behavior and fate of biological organisms are to a large extent dictated by their environment, which can be often viewed as a collection of features and constraints governed by physics laws. Since biological systems comprise networks of molecular interactions, one such key physical property is temperature, whose variations directly affect the rates of biochemical reactions involved. For instance, temperature is known to control many gene regulatory circuits responsible for pathogenicity in bacteria. One such example is type 1 fimbriae (T1F) -- the foremost virulence factor in uropathogenic E. coli (UPEC), which accounts for 80-90% of all community-acquired urinary tract infections (UTIs). The expression of T1F is randomly `phase variable', i.e. individual cells switch between virulent/fimbriate and avirulent/afimbriate phenotypes, with rates regulated by temperature. Our computational investigation of this process, which is based on FimB/FimE recombinase-mediated inversion of fimS DNA element, offers new insights into its discrete-stochastic kinetics. In particular, it elucidates the logic of T1F control optimization to the host temperature and contributes further understanding toward the development of novel therapeutic approaches to UPEC-caused UTIs.

Samoilov, Michael

2010-03-01

76

In vitro adherence of type 1-fimbriated uropathogenic Escherichia coli to human ureteral mucosa.  

PubMed Central

Type 1-fimbriated Escherichia coli isolated from patients with urinary tract infections adhered in vitro to the epithelial cell surface of an excised human ureter. The bacteria also adhered to a mucous coating and to Formalin-fixed human ureteral mucosa. D-Mannose strongly inhibited such adherence. The bacteria in their nonfimbriated phase lacked the ability to adhere. We concluded that type 1 fimbriae play a role, at least in part, in upper urinary tract infections in humans. Images

Fujita, K; Yamamoto, T; Yokota, T; Kitagawa, R

1989-01-01

77

Occurrence of Antibiotic-Resistant Uropathogenic Escherichia coli Clonal Group A in Wastewater Effluents  

Microsoft Academic Search

Received 21 September 2006\\/Accepted 27 April 2007 Isolates of Escherichia coli belonging to clonal group A (CGA), a recently described disseminated cause of drug-resistant urinary tract infections in humans, were present in four of seven sewage effluents collected from geographically dispersed areas of the United States. All 15 CGA isolates (1% of the 1,484 isolates analyzed) exhibited resistance to trimethoprim-sulfamethoxazole

Laura A. Boczek; Eugene W. Rice; Brian Johnston; James R. Johnson

2007-01-01

78

Uropathogenic Escherichia coli AL511 requires flagellum to enter renal collecting duct cells.  

PubMed

Escherichia coli is the leading cause of urinary tract infections, but the mechanisms governing renal colonization by this bacterium remain poorly understood. We investigated the ability of 13 E. coli strains isolated from the urine of patients with pyelonephritis and cystitis and normal stools to invade collecting duct cells, which constitute the first epithelium encountered by bacteria ascending from the bladder. The AL511 clinical isolate adhered to mouse collecting duct mpkCCD(cl4) cells, used as a model of renal cell invasion, and was able to enter and persist within these cells. Previous studies have shown that bacterial flagella play an important role in host urinary tract colonization, but the role of flagella in the interaction of E. coli with renal epithelial cells remains unclear. An analysis of the ability of E. coli AL511 mutants to invade renal cells showed that flagellin played a key role in bacterial entry. Both flagellum filament assembly and the motor proteins MotA and MotB appeared to be required for E. coli AL511 uptake into collecting duct cells. These findings indicate that pyelonephritis-associated E. coli strains may invade renal collecting duct cells and that flagellin may act as an invasin in this process. PMID:19134121

Pichon, Christophe; Héchard, Céline; du Merle, Laurence; Chaudray, Christelle; Bonne, Isabelle; Guadagnini, Stéphanie; Vandewalle, Alain; Le Bouguénec, Chantal

2009-01-07

79

[Inhibition of bacterial adhesion of uropathogenic Escherichia coli strains by the urine of patients treated with nitroxoline].  

PubMed

The present study evaluates the effects of sub-inhibitory concentrations of nitroxoline, (oxyquinoline derivative) widely used in the treatment of uncomplicated, urinary tract infections, on the adherence of uropathogenic strains of Escherichia coli. These bacterial strains showed mannose sensitive and/or mannose resistant hemagglutinating activity (HA). In the presence of nitroxoline and at sub-MIC concentrations, inhibition of adherence is 90% (MIC/4), 87% (MIC/8), and 70% (MIC/16), whatever HA's are expressed by the E. coli strains. The inhibitory effect on adherence is also observed in the urine after oral administration of 400 mg of nitroxoline. The concentrations of nitroxoline in the urine are determined by microbiological assay (anti-bacterial activity) and by physico-chemical assay (total nitroxoline and free nitroxoline). The percentages of inhibition are related to the concentrations of free and conjugated nitroxoline. For a 1/16 dilution of urine, the inhibitory effect is 70% and 87% respectively 1 h 30 and 2 h 30 after oral administration of nitroxoline. After 5 h, a similar inhibitory effect is observed for a 1/2 dilution of urine. These results justify the performance of a clinical trial on the prophylaxis of recurrent urinary tract infections by nitroxoline. PMID:3043342

Karam, D; Amgar, A; Bourlioux, P

1988-05-01

80

Structure-based virtual screening for plant-derived SdiA-selective ligands as potential antivirulent agents against uropathogenic Escherichia coli.  

PubMed

The uropathogenic Escherichia coli pathogenecity is affected by quorum sensing transcriptional regulator SdiA. In this study, in vitro characterization of the active principles that could potentially antagonize with SdiA from the Melia dubia bark extracts has been described. After in vitro assays carried out to evaluate the inhibitory activities against the uropathogenic E. coli, the ethanolic extract (30 mg/ml) which showed the strongest suppression of haemolysis, swarming motility, hydrophobicity and biofilm formation, was subjected to GC-MS analysis and an array of 40 unrelated compounds was identified. Docking studies was conducted to screen for plant-based SdiA inhibitors. Five hits were assessed for their binding profiles and 7-(1-bromoethyl)-3, 3-dimethyl-bicyclo [4.1.0]heptan-2-one showed 66.95% binding ability with respect to C(8)HSL. PMID:22209416

Ravichandiran, Vinothkannan; Shanmugam, Karthi; Anupama, K; Thomas, Sabu; Princy, Adline

2011-12-16

81

Influence of fluoroquinolones on expression and function of P fimbriae in uropathogenic Escherichia coli.  

PubMed Central

P fimbriae are the major adhesins mediating attachment of pyelonephritogenic Escherichia coli to urinary tract tissues, and they therefore constitute a recognized virulence factor. In this work, the effect of fluoroquinolones on P fimbria expression and function in E. coli SS142 and C1212 was assessed. Ciprofloxacin, fleroxacin, and norfloxacin were compared with their precursor nalidixic acid and with trimethoprim in sublethal concentrations ranging from 1/32 to 1/4 of the MIC. Fimbria function was assessed in a standard hemagglutination assay and in a parallel hemagglutination inhibition assay in which the tier of antifimbrial antiserum necessary to inhibit hemagglutination by SS142 was determined. Adhesion of antibiotic-exposed bacteria to human uroma T24 cells in suspension was also measured. Fimbria production was quantitated in an inhibition enzyme-linked immunosorbent assay. Trimethoprim produced a dose-dependent decrease of three to four hemagglutination titers for both strains and a decline in the antiserum titer from 1:16 (control) to 1:128 (1/4 MIC) for E. coli SS142. Adherence exhibited similar decrements from 130 +/- 28 (control) to 16 +/- 3 (1/4 MIC) and from 83 +/- 19 (control) to 30 +/- 11 (1/4 MIC) E. coli cells per uroepithelial cell (mean +/- standard error) for SS142 and C1212, respectively (P less than 0.015). By enzyme-linked immunosorbent assay, the inhibition following exposure decreased in a dose-dependent manner from 31% (control) to 8% (1/4 MIC). By contrast, none of the quinolones produced significant changes in the parameters assessed above. At sublethal concentrations, trimethoprim decreased fimbria production. Following exposure to fluoroquinolones, however, E. coli expressed morphologically and functionally intact P fimbriae.

Kovarik, J M; Hoepelman, I M; Verhoef, J

1989-01-01

82

A novel two-component signaling system facilitates uropathogenic Escherichia coli's ability to exploit abundant host metabolites.  

PubMed

Two-component signaling systems (TCSs) are major mechanisms by which bacteria adapt to environmental conditions. It follows then that TCSs would play important roles in the adaptation of pathogenic bacteria to host environments. However, no pathogen-associated TCS has been identified in uropathogenic Escherichia coli (UPEC). Here, we identified a novel TCS, which we termed KguS/KguR (KguS: ?-ketoglutarate utilization sensor; KguR: ?-ketoglutarate utilization regulator) in UPEC CFT073, a strain isolated from human pyelonephritis. kguS/kguR was strongly associated with UPEC but was found only rarely among other E. coli including commensal and intestinal pathogenic strains. An in vivo competition assay in a mouse UTI model showed that deletion of kguS/kguR in UPEC CFT073 resulted in a significant reduction in its colonization of the bladders and kidneys of mice, suggesting that KguS/KguR contributed to UPEC fitness in vivo. Comparative proteomics identified the target gene products of KguS/KguR, and sequence analysis showed that TCS KguS/KguR and its targeted-genes, c5032 to c5039, are encoded on a genomic island, which is not present in intestinal pathogenic E. coli. Expression of the target genes was induced by ?-ketoglutarate (?-KG). These genes were further shown to be involved in utilization of ?-KG as a sole carbon source under anaerobic conditions. KguS/KguR contributed to the regulation of the target genes with the direct regulation by KguR verified using an electrophoretic mobility shift assay. In addition, oxygen deficiency positively modulated expression of kguS/kguR and its target genes. Taken altogether, this study describes the first UPEC-associated TCS that functions in controlling the utilization of ?-ketoglutarate in vivo thereby facilitating UPEC adaptation to life inside the urinary tract. PMID:23825943

Cai, Wentong; Wannemuehler, Yvonne; Dell'anna, Giuseppe; Nicholson, Bryon; Barbieri, Nicolle L; Kariyawasam, Subhashinie; Feng, Yaping; Logue, Catherine M; Nolan, Lisa K; Li, Ganwu

2013-06-27

83

The Repeat-In-Toxin Family Member TosA Mediates Adherence of Uropathogenic Escherichia coli and Survival during Bacteremia  

PubMed Central

Uropathogenic Escherichia coli (UPEC) is responsible for the majority of uncomplicated urinary tract infections (UTI) and represents the most common bacterial infection in adults. UPEC utilizes a wide range of virulence factors to colonize the host, including the novel repeat-in-toxin (RTX) protein TosA, which is specifically expressed in the host urinary tract and contributes significantly to the virulence and survival of UPEC. tosA, found in strains within the B2 phylogenetic subgroup of E. coli, serves as a marker for strains that also contain a large number of well-characterized UPEC virulence factors. The presence of tosA in an E. coli isolate predicts successful colonization of the murine model of ascending UTI, regardless of the source of the isolate. Here, a detailed analysis of the function of tosA revealed that this gene is transcriptionally linked to genes encoding a conserved type 1 secretion system similar to other RTX family members. TosA localized to the cell surface and was found to mediate (i) adherence to host cells derived from the upper urinary tract and (ii) survival in disseminated infections and (iii) to enhance lethality during sepsis (as assessed in two different animal models of infection). An experimental vaccine, using purified TosA, protected vaccinated animals against urosepsis. From this work, it was concluded that TosA belongs to a novel group of RTX proteins that mediate adherence and host damage during UTI and urosepsis and could be a novel target for the development of therapeutics to treat ascending UTIs.

Vigil, Patrick D.; Wiles, Travis J.; Engstrom, Michael D.; Prasov, Lev; Mulvey, Matthew A.

2012-01-01

84

Molecular characterization of UpaB and UpaC, two new autotransporter proteins of uropathogenic Escherichia coli CFT073.  

PubMed

Uropathogenic Escherichia coli (UPEC) is the primary cause of urinary tract infection (UTI) in the developed world. The major factors associated with virulence of UPEC are fimbrial adhesins, which mediate specific attachment to host receptors and trigger innate host responses. Another group of adhesins is represented by the autotransporter (AT) subgroup of proteins. The genome-sequenced prototype UPEC strain CFT073 contains 11 putative AT-encoding genes. In this study, we have performed a detailed molecular characterization of two closely related AT adhesins from CFT073: UpaB (c0426) and UpaC (c0478). PCR screening revealed that the upaB and upaC AT-encoding genes are common in E. coli. The upaB and upaC genes were cloned and characterized in a recombinant E. coli K-12 strain background. This revealed that they encode proteins located at the cell surface but possess different functional properties: UpaB mediates adherence to several ECM proteins, while UpaC expression is associated with increased biofilm formation. In CFT073, upaB is expressed while upaC is transcriptionally repressed by the global regulator H-NS. In competitive colonization experiments employing the mouse UTI model, CFT073 significantly outcompeted its upaB (but not upaC) isogenic mutant strain in the bladder. This attenuated phenotype was also observed in single-challenge experiments, where deletion of the upaB gene in CFT073 significantly reduced early colonization of the bladder. PMID:21930758

Allsopp, Luke P; Beloin, Christophe; Ulett, Glen C; Valle, Jaione; Totsika, Makrina; Sherlock, Orla; Ghigo, Jean-Marc; Schembri, Mark A

2011-09-19

85

Salmochelins, siderophores of Salmonella enterica and uropathogenic Escherichia coli strains, are recognized by the outer membrane receptor IroN  

PubMed Central

Members of a family of catecholate siderophores, called salmochelins, were isolated by reversed-phase HPLC from Salmonella enterica serotype Typhimurium and structurally characterized by Fourier transform ion cyclotron resonance–MS/MS and GC–MS. The tentative structure of salmochelin 1 contained two 2,3- dihydroxybenzoylserine moieties bridged by a glucose residue, bound to the serine hydroxyl group of one moiety and the carboxylate of the second moiety. Salmochelin 2 contained in addition a second glucose residue linked to a third 2,3-dihydroxybenzoylserine moiety. Salmochelins were not produced by an iroBC mutant, which indicated that the IroB protein might be responsible for the glucosyl transfer predicted by sequence similarities to known glycosyltransferases. Uptake experiments with radiolabeled 55Fe-salmochelin and growth promotion tests with salmochelins showed that the IroN outer membrane receptor, encoded in the iroA locus of S. enterica and uropathogenic Escherichia coli strains, was the main receptor for ferric salmochelin transport.

Hantke, K.; Nicholson, G.; Rabsch, W.; Winkelmann, G.

2003-01-01

86

Aberrant Community Architecture and Attenuated Persistence of Uropathogenic Escherichia coli in the Absence of Individual IHF Subunits  

PubMed Central

Uropathogenic Escherichia coli (UPEC) utilizes a complex community-based developmental pathway for growth within superficial epithelial cells of the bladder during cystitis. Extracellular DNA (eDNA) is a common matrix component of organized bacterial communities. Integration host factor (IHF) is a heterodimeric protein that binds to double-stranded DNA and produces a hairpin bend. IHF-dependent DNA architectural changes act both intrabacterially and extrabacterially to regulate gene expression and community stability, respectively. We demonstrate that both IHF subunits are required for efficient colonization of the bladder, but are dispensable for early colonization of the kidney. The community architecture of the intracellular bacterial communities (IBCs) is quantitatively different in the absence of either IhfA or IhfB in the murine model for human urinary tract infection (UTI). Restoration of Type 1 pili by ectopic production does not restore colonization in the absence of IhfA, but partially compensates in the absence of IhfB. Furthermore, we describe a binding site for IHF that is upstream of the operon that encodes for the P-pilus. Taken together, these data suggest that both IHF and its constituent subunits (independent of the heterodimer), are able to participate in multiple aspects of the UPEC pathogenic lifestyle, and may have utility as a target for treatment of bacterial cystitis.

Justice, Sheryl S.; Li, Birong; Downey, Jennifer S.; Dabdoub, Shareef M.; Brockson, M. Elizabeth; Probst, G. Duane; Ray, William C.; Goodman, Steven D.

2012-01-01

87

Heme acquisition is facilitated by a novel receptor Hma and required by uropathogenic Escherichia coli for kidney infection  

PubMed Central

SUMMARY Iron acquisition, mediated by specific outer membrane receptors, is critical for colonization of the urinary tract by uropathogenic Escherichia coli (UPEC). The role of specific iron sources in vivo, however, remains largely unknown. In this study, we identified a 79 kDa heme receptor, heme acquisition protein Hma, and established that it functions independently of ChuA to mediate hemin uptake by UPEC strain CFT073. We demonstrated that expression of hma promotes TonB-dependent hemin utilization and the Hma protein binds hemin with high affinity (Kd=8 ?M). Hma, however, lacks conserved His residues shown to mediate heme uptake by other bacterial receptors. In contrast, we identified Tyr126 as a residue necessary for Hmamediated hemin utilization. In a murine co-infection model of UTI, an isogenic hma mutant was outcompeted by wildtype CFT073 in the kidneys (P<0.001) and spleens (P<0.0001) of infected mice, indicating its expression provided a competitive advantage in these organs. Furthermore, a hma chuA double mutant, which is unable to utilize hemin, was unable to colonize the kidneys to wildtype levels during independent infection (P=0.02). Thus, we demonstrate that UPEC requires heme for kidney colonization and that uptake of this iron source is mediated, in part, by the novel receptor, Hma.

Hagan, Erin C.; Mobley, Harry L.T.

2009-01-01

88

Immune Modulation by Group B Streptococcus Influences Host Susceptibility to Urinary Tract Infection by Uropathogenic Escherichia coli  

PubMed Central

Urinary tract infection (UTI) is most often caused by uropathogenic Escherichia coli (UPEC). UPEC inoculation into the female urinary tract (UT) can occur through physical activities that expose the UT to an inherently polymicrobial periurethral, vaginal, or gastrointestinal flora. We report that a common urogenital inhabitant and opportunistic pathogen, group B Streptococcus (GBS), when present at the time of UPEC exposure, undergoes rapid UPEC-dependent exclusion from the murine urinary tract, yet it influences acute UPEC-host interactions and alters host susceptibility to persistent outcomes of bladder and kidney infection. GBS presence results in increased UPEC titers in the bladder lumen during acute infection and reduced inflammatory responses of murine macrophages to live UPEC or purified lipopolysaccharide (LPS), phenotypes that require GBS mimicry of host sialic acid residues. Taken together, these studies suggest that despite low titers, the presence of GBS at the time of polymicrobial UT exposure may be an overlooked risk factor for chronic pyelonephritis and recurrent UTI in susceptible groups, even if it is outcompeted and thus absent by the time of diagnosis.

Kline, Kimberly A.; Schwartz, Drew J.; Gilbert, Nicole M.

2012-01-01

89

Decreased Expression of Type 1 Fimbriae by a pst Mutant of Uropathogenic Escherichia coli Reduces Urinary Tract Infection  

PubMed Central

The pstSCAB-phoU operon encodes the phosphate-specific transport system (Pst). Loss of Pst constitutively activates the Pho regulon and decreases bacterial virulence. However, specific mechanisms underlying decreased bacterial virulence through inactivation of Pst are poorly understood. In uropathogenic Escherichia coli (UPEC) strain CFT073, inactivation of pst decreased urinary tract colonization in CBA/J mice. The pst mutant was deficient in production of type 1 fimbriae and showed decreased expression of the fimA structural gene which correlated with differential expression of the fimB, fimE, ipuA, and ipbA genes, encoding recombinases, mediating inversion of the fim promoter. The role of fim downregulation in attenuation of the pst mutant was confirmed using a fim phase-locked-on derivative, which demonstrated a significant gain in virulence. In addition, the pst mutant was less able to invade human bladder epithelial cells. Since type 1 fimbriae contribute to UPEC virulence by promoting colonization and invasion of bladder cells, the reduced bladder colonization by the pst mutant is predominantly attributed to downregulation of these fimbriae. Elucidation of mechanisms mediating the control of type 1 fimbriae through activation of the Pho regulon in UPEC may open new avenues for therapeutics or prophylactics against urinary tract infections.

Crepin, Sebastien; Houle, Sebastien; Charbonneau, Marie-Eve; Mourez, Michael; Harel, Josee

2012-01-01

90

Urinary tract infection drives genome instability in uropathogenic Escherichia coli and necessitates translesion synthesis DNA polymerase IV for virulence  

PubMed Central

Uropathogenic Escherichia coli (UPEC) produces ?80% of community-acquired UTI, the second most common infection in humans. During UTI, UPEC has a complex life cycle, replicating and persisting in intracellular and extracellular niches. Host and environmental stresses may affect the integrity of the UPEC genome and threaten its viability. We determined how the host inflammatory response during UTI drives UPEC genome instability and evaluated the role of multiple factors of genome replication and repair for their roles in the maintenance of genome integrity and thus virulence during UTI. The urinary tract environment enhanced the mutation frequency of UPEC ?100-fold relative to in vitro levels. Abrogation of inflammation through a host TLR4-signaling defect significantly reduced the mutation frequency, demonstrating in the importance of the host response as a driver of UPEC genome instability. Inflammation induces the bacterial SOS response, leading to the hypothesis that the UPEC SOS-inducible translesion synthesis (TLS) DNA polymerases would be key factors in UPEC genome instability during UTI. However, while the TLS DNA polymerases enhanced in vitro, they did not increase in vivo mutagenesis. Although it is not a source of enhanced mutagenesis in vivo, the TLS DNA polymerase IV was critical for the survival of UPEC during UTI during an active inflammatory assault. Overall, this study provides the first evidence of a TLS DNA polymerase being critical for UPEC survival during urinary tract infection and points to independent mechanisms for genome instability and the maintenance of genome replication of UPEC under host inflammatory stress.

Gawel, Damian

2011-01-01

91

Urinary tract infection drives genome instability in uropathogenic Escherichia coli and necessitates translesion synthesis DNA polymerase IV for virulence.  

PubMed

Uropathogenic Escherichia coli (UPEC) produces ~80% of community-acquired UTI, the second most common infection in humans. During UTI, UPEC has a complex life cycle, replicating and persisting in intracellular and extracellular niches. Host and environmental stresses may affect the integrity of the UPEC genome and threaten its viability. We determined how the host inflammatory response during UTI drives UPEC genome instability and evaluated the role of multiple factors of genome replication and repair for their roles in the maintenance of genome integrity and thus virulence during UTI. The urinary tract environment enhanced the mutation frequency of UPEC ~100-fold relative to in vitro levels. Abrogation of inflammation through a host TLR4-signaling defect significantly reduced the mutation frequency, demonstrating in the importance of the host response as a driver of UPEC genome instability. Inflammation induces the bacterial SOS response, leading to the hypothesis that the UPEC SOS-inducible translesion synthesis (TLS) DNA polymerases would be key factors in UPEC genome instability during UTI. However, while the TLS DNA polymerases enhanced in vitro, they did not increase in vivo mutagenesis. Although it is not a source of enhanced mutagenesis in vivo, the TLS DNA polymerase IV was critical for the survival of UPEC during UTI during an active inflammatory assault. Overall, this study provides the first evidence of a TLS DNA polymerase being critical for UPEC survival during urinary tract infection and points to independent mechanisms for genome instability and the maintenance of genome replication of UPEC under host inflammatory stress. PMID:21597325

Gawel, Damian; Seed, Patrick C

2011-05-01

92

Molecular Epidemiologic Approaches to Urinary Tract Infection Gene Discovery in Uropathogenic Escherichia coli  

PubMed Central

Urinary tract infection (UTI) is one of the most frequently acquired bacterial infections. The vast majority of UTIs are caused by a large, genetically heterogeneous group of Escherichia coli. This genetic diversity has hampered identification of UTI-related genes. A three-step experimental strategy was used to identify genes potentially involved in E. coli UTI transmission or virulence: epidemiologic pairing of a UTI-specific strain with a fecal control, differential cloning to isolated UTI strain-specific DNA, and epidemiologic screening to identify sequences among isolated DNAs that are associated with UTI. The 37 DNA sequences initially isolated were physically located all over the tester strain genome. Only two hybridized to the total DNA of the sequenced E. coli K-12 strain; eight sequences were present significantly more frequently in UTI isolates than in fecal isolates. Three of the eight sequences matched to genes for multidrug efflux proteins, usher proteins, and pathogenicity island insertion sites, respectively. Using population characteristics to direct gene discovery and evaluation is a productive strategy applicable to any system.

Zhang, Lixin; Foxman, Betsy; Manning, Shannon D.; Tallman, Patricia; Marrs, Carl F.

2000-01-01

93

Genetic analysis of the gene cluster encoding nonfimbrial adhesin I from an Escherichia coli uropathogen.  

PubMed Central

The chromosomally encoded nonfimbrial adhesion I (NFA-I) from Escherichia coli urinary tract isolate 827 (O83:K1:H4) mediates agglutination of human erythrocytes. Subclones were constructed from an NFA-I-expressing recombinant E. coli K-12 clone, derived from a genomic library of E. coli 827. Minicell analysis and nucleotide sequencing revealed that proteins of 30.5, 9, 80, 15, and 19 kDa encoded on a stretch of approximately 6 kb are involved in the expression of NFA-I. NFA-I exhibits a polymeric structure, which disintegrates with elevated temperature into a 19-kDa monomer but with some relatively stable dimers. By using gold-conjugated monoclonal antibodies directed against NFA-I in electron microscopy, the adhesin could be localized on the outer surface of the recombinant E. coli K-12 bacteria. The nucleotide sequence of the nfaA gene encoding the monomeric structural subunit of the adhesin was determined. An open reading frame of 184 amino acids encoding the NfaA precursor, which is processed to the mature protein, was found; it consisted of 156 amino acids with a calculated molecular weight of 16,000. Peptide sequencing of the NFA-I subunit protein confirmed that this open reading frame corresponds to the NfaA coding locus. Furthermore, the nucleotide sequence of the open reading frame termed NfaE, located at the proximal part of the DNA stretch responsible for NFA-I expression, was elaborated. NfaE consists of 247 amino acids, including a presumptive 29-amino-acid signal peptide, leading to a molecular weight of 24,000 for the mature protein. The nfaE sequence shares homology with the 27-kDa CS3 protein, which is involved in the assembly of CS3 fibrillae, and might encode the 30.5-kDa protein, detected in minicells. Images

Ahrens, R; Ott, M; Ritter, A; Hoschutzky, H; Buhler, T; Lottspeich, F; Boulnois, G J; Jann, K; Hacker, J

1993-01-01

94

Haemolytic Escherichia coli isolated from dogs with diarrhea have characteristics of both uropathogenic and necrotoxigenic strains.  

PubMed

Twenty-four haemolytic Escherichia coli strains were isolated from dogs with diarrhea. The strains were serotyped and analysed by polymerase chain reaction (PCR) for genes encoding virulence factors associated with E. coli that cause diarrhea in animals. Adhesion antigen production was deduced from haemagglutination experiments. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of heat extracts was also used as an indication for the production of adhesive structures. The majority of the strains was shown to produce this type of virulence factor. Adhesion and invasion tests of the strains and Caco-2 cells showed that all strains adhered and that two were invasive. The two invasive strains were positive in the intimin PCR and one of them also contained genes encoding CS31A. The PCR for heat stable toxin (ST) was positive in only four strains, as was the presence of F17 fimbrial genes. Surprisingly, 19 strains had intact P fimbrial operons, coding for an adhesin involved in urinary tract infection (UTI). The cytotoxic necrotising factor 1 (CNF1) gene, also mainly found in UTI was likewise detected in these 19 strains. Cytolethal distending toxin (Cdt) genes were found in five strains. The high number of strains positive for CNF1 and P fimbriae prompted us to test the strains in a multiplex PCR used to test E. coli isolated from UTI in various species for 30 virulence associated genes. The data showed that the majority of the diarrhea isolates have virulence factor profiles highly similar to UTI E. coli isolates from dogs. This raises the question whether these isolates are real intestinal pathogens or "innocent bystanders". However, since CNF1 producing necrotoxic E. coli (NTEC) strains isolated from humans, pigs and calves with diarrhea appear to be highly related to our strains, it might be that in dogs this type of isolate is capable of causing not only UTI, but also diarrhea. If this is the case and this type of isolate is "bifunctional", domestic animals likely constitute a reservoir of NTEC strains which can be also pathogenic for humans. PMID:11856586

Starcic, Marjanca; Johnson, James R; Stell, Adam L; van der Goot, Jeanet; Hendriks, Henno G C J M; van Vorstenbosch, Camillo; van Dijk, Linda; Gaastra, Wim

2002-04-01

95

Roles of Putative Type II Secretion and Type IV Pilus Systems in the Virulence of Uropathogenic Escherichia coli  

PubMed Central

Background Type II secretion systems (T2SS) and the evolutionarily related type IV pili (T4P) are important virulence determinants in many Gram-negative bacterial pathogens. However, the roles of T2SS and T4P in the virulence of extraintestinal pathogenic Escherichia coli have not been determined. Methodology/Principal Findings To investigate the functions of putative T2SS and T4P gene clusters present in the model uropathogenic E. coli (UPEC) strains UTI89 and CFT073, we deleted the secretin gene present in each cluster. The secretin forms a channel in the outer membrane that is essential for the function of T2S and T4P systems. We compared the secretin deletion mutants with their wild type counterparts using tissue culture assays and the CBA/J mouse model of ascending urinary tract infection. No deficiencies were observed with any of the mutants in adherence, invasion or replication in human bladder or kidney cell lines, but UTI89 ?hofQ and UTI89 ?gspD exhibited approximately 2-fold defects in fluxing out of bladder epithelial cells. In the mouse infection model, each of the knockout mutants was able to establish successful infections in the bladder and kidneys by day one post-infection. However, UTI89 ?hofQ and a CFT073 ?hofQ ?yheF double mutant both exhibited defects in colonizing the kidneys by day seven post-infection. Conclusions/Significance Based on our results, we propose that the putative T4P and T2S systems are virulence determinants of UPEC important for persistence in the urinary tract, particularly in renal tissues.

Kulkarni, Ritwij; Dhakal, Bijaya K.; Slechta, E. Susan; Kurtz, Zachary; Mulvey, Matthew A.; Thanassi, David G.

2009-01-01

96

Cytotoxic Necrotizing Factor 1 and Hemolysin from Uropathogenic Escherichia coli Elicit Different Host Responses in the Murine Bladder  

PubMed Central

Cytotoxic necrotizing factor 1 (CNF1) and hemolysin (HlyA1) are toxins produced by uropathogenic Escherichia coli (UPEC). We previously showed that these toxins contribute to the inflammation and tissue damage seen in a mouse model of ascending urinary tract infection. CNF1 constitutively activates small Rho GTPases by deamidation of a conserved glutamine residue, and HlyA1 forms pores in eukaryotic cell membranes. In this study, we used cDNA microarrays of bladder tissue isolated from mice infected intraurethrally with wild-type CP9, CP9cnf1, or CP9?hlyA to further evaluate the role that each toxin plays in the host response to UPEC. Regardless of the strain used, we found that UPEC itself elicited a significant change in host gene expression 24 h after inoculation. The largest numbers of upregulated genes were in the cytokine and chemokine signaling and Toll-like receptor signaling pathways. CNF1 exerted a strong positive influence on expression of genes involved in innate immunity and signal transduction and a negative impact on metabolism- and transport-associated genes. HlyA1 evoked an increase in expression of genes that encode innate immunity factors and a decrease in expression of genes involved in cytoskeletal and metabolic processes. Multiplex cytokine and myeloperoxidase assays corroborated our finding that a strong proinflammatory response was elicited by all strains tested. Bladders challenged intraurethrally with purified CNF1 displayed pathology similar to but significantly less intense than the pathology that we observed in CP9-challenged mice. Our data demonstrate substantial roles for CNF1 and HlyA1 in initiation of a strong proinflammatory response to UPEC in the bladder.

Garcia, Tamako A.; Ventura, Christy L.; Smith, Mark A.; Merrell, D. Scott

2013-01-01

97

Adenylate Cyclase and the Cyclic AMP Receptor Protein Modulate Stress Resistance and Virulence Capacity of Uropathogenic Escherichia coli  

PubMed Central

In many bacteria, the second messenger cyclic AMP (cAMP) interacts with the transcription factor cAMP receptor protein (CRP), forming active cAMP-CRP complexes that can control a multitude of cellular activities, including expanded carbon source utilization, stress response pathways, and virulence. Here, we assessed the role of cAMP-CRP as a regulator of stress resistance and virulence in uropathogenic Escherichia coli (UPEC), the principal cause of urinary tract infections worldwide. Deletion of genes encoding either CRP or CyaA, the enzyme responsible for cAMP synthesis, attenuates the ability of UPEC to colonize the bladder in a mouse infection model, dependent on intact innate host defenses. UPEC mutants lacking cAMP-CRP grow normally in the presence of glucose but are unable to utilize alternate carbon sources like amino acids, the primary nutrients available to UPEC within the urinary tract. Relative to the wild-type UPEC isolate, the cyaA and crp deletion mutants are sensitive to nitrosative stress and the superoxide generator methyl viologen but remarkably resistant to hydrogen peroxide (H2O2) and acid stress. In the mutant strains, H2O2 resistance correlates with elevated catalase activity attributable in part to enhanced translation of the alternate sigma factor RpoS. Acid resistance was promoted by both RpoS-independent and RpoS-dependent mechanisms, including expression of the RpoS-regulated DNA-binding ferritin-like protein Dps. We conclude that balanced input from many cAMP-CRP-responsive elements, including RpoS, is critical to the ability of UPEC to handle the nutrient limitations and severe environmental stresses present within the mammalian urinary tract.

Donovan, Grant T.; Norton, J. Paul; Bower, Jean M.

2013-01-01

98

Identification of In Vivo-Induced Antigens Including an RTX Family Exoprotein Required for Uropathogenic Escherichia coli Virulence ?  

PubMed Central

Uncomplicated urinary tract infections (UTI) are caused most commonly by uropathogenic Escherichia coli (UPEC). Whole-genome screening approaches, including transcriptomic, proteomic, and signature-tagged mutagenesis, have shown that UPEC highly expresses or requires genes for translational machinery, capsule, lipopolysaccharide, type 1 fimbriae, and iron acquisition systems during UTI. To identify additional genes expressed by UPEC during UTI, an immunoscreening approach termed in vivo-induced antigen technology (IVIAT) was employed to identify antigens produced during experimental infection that are not produced during in vitro culture. An inducible protein expression library, constructed from genomic DNA isolated from UPEC strain CFT073, was screened using exhaustively adsorbed pooled sera from 20 chronically infected female CBA/J mice. Using this approach, we identified 93 antigens induced by UPEC in vivo. A representative subset of these genes was tested by quantitative PCR for expression by CFT073 in vivo and during growth in human urine or LB medium in vitro; proWX, narJI, lolA, lolD, tosA (upxA), c2432, katG, ydhX, kpsS, and yddQ were poorly expressed in vitro but highly expressed in vivo. Of these, tosA, a gene encoding a predicted repeat-in-toxin family member, was expressed exclusively during UTI. Deletion of tosA in UPEC strain CFT073 resulted in significant attenuation in bladder and kidney infections during ascending UTI. By screening for in vivo-induced antigens, we identified a novel UPEC virulence factor and additional proteins that could be useful as potential vaccine targets.

Vigil, Patrick D.; Alteri, Christopher J.; Mobley, Harry L. T.

2011-01-01

99

Adenylate cyclase and the cyclic AMP receptor protein modulate stress resistance and virulence capacity of uropathogenic Escherichia coli.  

PubMed

In many bacteria, the second messenger cyclic AMP (cAMP) interacts with the transcription factor cAMP receptor protein (CRP), forming active cAMP-CRP complexes that can control a multitude of cellular activities, including expanded carbon source utilization, stress response pathways, and virulence. Here, we assessed the role of cAMP-CRP as a regulator of stress resistance and virulence in uropathogenic Escherichia coli (UPEC), the principal cause of urinary tract infections worldwide. Deletion of genes encoding either CRP or CyaA, the enzyme responsible for cAMP synthesis, attenuates the ability of UPEC to colonize the bladder in a mouse infection model, dependent on intact innate host defenses. UPEC mutants lacking cAMP-CRP grow normally in the presence of glucose but are unable to utilize alternate carbon sources like amino acids, the primary nutrients available to UPEC within the urinary tract. Relative to the wild-type UPEC isolate, the cyaA and crp deletion mutants are sensitive to nitrosative stress and the superoxide generator methyl viologen but remarkably resistant to hydrogen peroxide (H(2)O(2)) and acid stress. In the mutant strains, H(2)O(2) resistance correlates with elevated catalase activity attributable in part to enhanced translation of the alternate sigma factor RpoS. Acid resistance was promoted by both RpoS-independent and RpoS-dependent mechanisms, including expression of the RpoS-regulated DNA-binding ferritin-like protein Dps. We conclude that balanced input from many cAMP-CRP-responsive elements, including RpoS, is critical to the ability of UPEC to handle the nutrient limitations and severe environmental stresses present within the mammalian urinary tract. PMID:23115037

Donovan, Grant T; Norton, J Paul; Bower, Jean M; Mulvey, Matthew A

2012-10-31

100

Identification of in vivo-induced antigens including an RTX family exoprotein required for uropathogenic Escherichia coli virulence.  

PubMed

Uncomplicated urinary tract infections (UTI) are caused most commonly by uropathogenic Escherichia coli (UPEC). Whole-genome screening approaches, including transcriptomic, proteomic, and signature-tagged mutagenesis, have shown that UPEC highly expresses or requires genes for translational machinery, capsule, lipopolysaccharide, type 1 fimbriae, and iron acquisition systems during UTI. To identify additional genes expressed by UPEC during UTI, an immunoscreening approach termed in vivo-induced antigen technology (IVIAT) was employed to identify antigens produced during experimental infection that are not produced during in vitro culture. An inducible protein expression library, constructed from genomic DNA isolated from UPEC strain CFT073, was screened using exhaustively adsorbed pooled sera from 20 chronically infected female CBA/J mice. Using this approach, we identified 93 antigens induced by UPEC in vivo. A representative subset of these genes was tested by quantitative PCR for expression by CFT073 in vivo and during growth in human urine or LB medium in vitro; proWX, narJI, lolA, lolD, tosA (upxA), c2432, katG, ydhX, kpsS, and yddQ were poorly expressed in vitro but highly expressed in vivo. Of these, tosA, a gene encoding a predicted repeat-in-toxin family member, was expressed exclusively during UTI. Deletion of tosA in UPEC strain CFT073 resulted in significant attenuation in bladder and kidney infections during ascending UTI. By screening for in vivo-induced antigens, we identified a novel UPEC virulence factor and additional proteins that could be useful as potential vaccine targets. PMID:21422188

Vigil, Patrick D; Alteri, Christopher J; Mobley, Harry L T

2011-03-21

101

The Analysis of Multiple Genome Comparisons in Genus Escherichia and Its Application to the Discovery of Uncharacterised Metabolic Genes in Uropathogenic Escherichia coli CFT073.  

PubMed

A survey of a complete gene synteny comparison has been carried out between twenty fully sequenced strains from the genus Escherichia with the aim of finding yet uncharacterised genes implicated in the metabolism of uropathogenic strains of E. coli (UPEC). Several sets of adjacent colinear genes have been identified which are present in all four UPEC included in this study (CFT073, F11, UTI89, and 536), annotated with putative metabolic functions, but are not found in any other strains considered. An operon closely homologous to that encoding the L-sorbose degradation pathway in Klebsiella pneumoniae has been identified in E. coli CFT073; this operon is present in all of the UPEC considered, but only in 7 of the other 16 strains. The operon's function has been confirmed by cloning the genes into E. coli DH5alpha and testing for growth on L-sorbose. The functional genomic approach combining in silico and in vitro work presented here can be used as a basis for the discovery of other uncharacterised genes contributing to bacterial survival in specific environments. PMID:20204180

Bryant, William A; Krabben, Preben; Baganz, Frank; Zhou, Yuhong; Ward, John M

2010-03-02

102

Bacteriocin synthesis in uropathogenic and commensal Escherichia coli: colicin E1 is a potential virulence factor  

Microsoft Academic Search

BACKGROUND: Bacteriocin production is an important characteristic of E. coli strains of human origin. To date, 26 colicin and 9 microcin types have been analyzed on a molecular level allowing molecular detection of the corresponding genes. The production incidence of 29 bacteriocin types and E. coli phylogroups were tested in a set of 361 E. coli strains isolated from human

David Šmajs; Lenka Micenková; Jan Šmarda; Martin Vrba; Alena Šev?íková; Zuzana Vališová; Vladana Woznicová

2010-01-01

103

A FimH Inhibitor Prevents Acute Bladder Infection and Treats Chronic Cystitis Caused by Multidrug-Resistant Uropathogenic Escherichia coli ST131.  

PubMed

Background.?Escherichia coli O25b:H4-ST131 represents a predominant clone of multidrug-resistant uropathogens currently circulating worldwide in hospitals and the community. Urinary tract infections (UTIs) caused by E. coli ST131 are typically associated with limited treatment options and are often recurrent. Methods.?Using established mouse models of acute and chronic UTI, we mapped the pathogenic trajectory of the reference E. coli ST131 UTI isolate, strain EC958. Results.?We demonstrated that E. coli EC958 can invade bladder epithelial cells and form intracellular bacterial communities early during acute UTI. Moreover, E. coli EC958 persisted in the bladder and established chronic UTI. Prophylactic antibiotic administration failed to prevent E. coli EC958-mediated UTI. However, 1 oral dose of a small-molecular-weight compound that inhibits FimH, the type 1 fimbriae adhesin, significantly reduced bacterial colonization of the bladder and prevented acute UTI. Treatment of chronically infected mice with the same FimH inhibitor lowered their bladder bacterial burden by >1000-fold. Conclusions.?In this study, we provide novel insight into the pathogenic mechanisms used by the globally disseminated E. coli ST131 clone during acute and chronic UTI and establish the potential of FimH inhibitors as an alternative treatment against multidrug-resistant E. coli. PMID:23737602

Totsika, Makrina; Kostakioti, Maria; Hannan, Thomas J; Upton, Mathew; Beatson, Scott A; Janetka, James W; Hultgren, Scott J; Schembri, Mark A

2013-06-03

104

Persistence of uropathogenic Escherichia coli strains in the host for long periods of time: relationship between phylogenetic groups and virulence factors.  

PubMed

Escherichia coli cause the majority of urinary tract infections (UTIs). Virulence plays an important role in the initial stages of interaction with the host, facilitating colonization of the urinary tract tissue. The purpose of this study was to assess whether there is a relationship between virulence and antibiotic resistance in the persistence of uropathogenic E. coli strains. This study included five patients with UTI between 2001 and 2009. The antibiotic resistance phenotype of 29 E. coli isolates was determined by the disk diffusion method. Clonal relationship was determined through M13 polymerase chain reaction (PCR) fingerprinting. Phylogeny, virulence factors, ?-lactamases, and replicon typing were studied through PCR. Antibiogram profiles were found from different patients and corresponded to CTX-M-2, CTX-M-15, CTX-M-32, and TEM-52 enzymes. Plasmids belonged essentially to incompatibility group IncF. No clonal relationship was observed among isolates from different patients, except for patients 4 and 5. Phylogenetic group A was predominant. Our work showed that commensal group A possesses the same virulence factors as the pathogenic groups B1 and D. E. coli common pilus and type 1 fimbriae could play an important role in the persistence in the host and in symptomatic UTI, respectively, which, combined with extended-spectrum ?-lactamases (ESBLs), are a cause of the dissemination of microorganisms in the hospital and the community. PMID:21990017

Narciso, A; Nunes, F; Amores, T; Lito, L; Melo-Cristino, J; Duarte, A

2011-10-12

105

UpaG, a New Member of the Trimeric Autotransporter Family of Adhesins in Uropathogenic Escherichia coli  

Microsoft Academic Search

The ability of Escherichia coli to colonize both intestinal and extraintestinal sites is driven by the presence of specific virulence factors, among which are the autotransporter (AT) proteins. Members of the trimeric AT adhesin family are important virulence factors for several gram-negative pathogens and mediate adherence to eukaryotic cells and extracellular matrix (ECM) proteins. In this study, we characterized a

Jaione Valle; Amanda N. Mabbett; Glen C. Ulett; Alejandro Toledo-Arana; Karine Wecker; Makrina Totsika; Mark A. Schembri; Jean-Marc Ghigo; Christophe Beloin

2008-01-01

106

The type 1 pili regulator gene fimX and pathogenicity island PAI-X as molecular markers of uropathogenic Escherichia coli.  

PubMed

Uropathogenic Escherichia coli (UPEC) fall within a larger group of isolates producing extraintestinal disease. UPEC express type 1 pili as a critical virulence determinant mediating adherence to and invasion into urinary tract tissues. Type 1 pili expression is under regulation by a family of site-specific recombinases, including FimX, which is encoded from a genomic island called PAI-X for pathogenicity island of FimX. Using a new multiplex PCR, fimX and the additional PAI-X genes were found to be highly associated with UPEC (144/173?=?83.2?%), and more prevalent in UPEC of lower urinary tract origin (105/120?=?87.5?%) than upper urinary tract origin (39/53?=?74?%; P<0.05) or commensal isolates (28/78?=?36?%; P?0.0001). The Fim-like recombinase gene fimX is the only family member that has a significant association with UPEC compared to commensal isolates. Our results indicate PAI-X genes, including the type 1 pili regulator gene fimX, are highly prevalent among UPEC isolates and have a strong positive correlation with genomic virulence factors, suggesting a potential role for PAI-X in the extraintestinal pathogenic E. coli lifestyle. PMID:23744903

Bateman, Stacey L; Stapleton, Ann E; Stamm, Walter E; Hooton, Thomas M; Seed, Patrick C

2013-06-06

107

Role of histone-like proteins H-NS and StpA in expression of virulence determinants of uropathogenic Escherichia coli.  

PubMed

The histone-like protein H-NS is a global regulator in Escherichia coli that has been intensively studied in nonpathogenic strains. However, no comprehensive study on the role of H-NS and its paralogue, StpA, in gene expression in pathogenic E. coli has been carried out so far. Here, we monitored the global effects of H-NS and StpA in a uropathogenic E. coli isolate by using DNA arrays. Expression profiling revealed that more than 500 genes were affected by an hns mutation, whereas no effect of StpA alone was observed. An hns stpA double mutant showed a distinct gene expression pattern that differed in large part from that of the hns single mutant. This suggests a direct interaction between the two paralogues and the existence of distinct regulons of H-NS and an H-NS/StpA heteromeric complex. hns mutation resulted in increased expression of alpha-hemolysin, fimbriae, and iron uptake systems as well as genes involved in stress adaptation. Furthermore, several other putative virulence genes were found to be part of the H-NS regulon. Although the lack of H-NS, either alone or in combination with StpA, has a huge impact on gene expression in pathogenic E. coli strains, its effect on virulence is ambiguous. At a high infection dose, hns mutants trigger more sudden lethality due to their increased acute toxicity in murine urinary tract infection and sepsis models. At a lower infectious dose, however, mutants lacking H-NS are attenuated through their impaired growth rate, which can only partially be compensated for by the higher expression of numerous virulence factors. PMID:16855232

Müller, Claudia M; Dobrindt, Ulrich; Nagy, Gábor; Emödy, Levente; Uhlin, Bernt Eric; Hacker, Jörg

2006-08-01

108

Assessment of the significance of virulence factors of uropathogenic Escherichia coli in experimental urinary tract infection in mice.  

PubMed

Four Escherichia coli strains, isolated from cystitis patients, belonging to serotype 02:H- and possessing different combinations of urovirulence factors were examined in an experimental pyelonephritis mouse model to assess the relative importance of virulence factors in causation of urinary tract infections (UTI). The results suggest not only that the each virulence factor has a role in causation of UTI but also that the presence of P fimbriae and production of hemolysin significantly reduced the LD50 and ID50 of the strains in the mouse model. The results also demonstrate that the presence of additional virulence factors acts in an additive or synergetic fashion enhancing the cumulative impact of the strain. PMID:8908603

Yamamoto, S; Nakata, K; Yuri, K; Katae, H; Terai, A; Kurazono, H; Takeda, Y; Yoshida, O

1996-01-01

109

Uropathogenic Escherichia coli CFT073 Is Adapted to Acetatogenic Growth but Does Not Require Acetate during Murine Urinary Tract Infection? §  

PubMed Central

In vivo accumulation of d-serine by Escherichia coli CFT073 leads to elevated expression of PAP fimbriae and hemolysin by an unknown mechanism. Loss of d-serine catabolism by CFT073 leads to a competitive advantage during murine urinary tract infection (UTI), but loss of both d- and l-serine catabolism results in attenuation. Serine is the first amino acid to be consumed in closed tryptone broth cultures and precedes the production of acetyl phosphate, a high-energy molecule involved in intracellular signaling, and the eventual secretion of acetate. We propose that the colonization defect associated with the loss of serine catabolism is due to perturbations of acetate metabolism. CFT073 grows more rapidly on acetogenic substrates than does E. coli K-12 isolate MG1655. As shown by transcription microarray results, d-serine is catabolized into acetate via the phosphotransacetylase (pta) and acetate kinase (ackA) genes while downregulating expression of acetyl coenzyme A synthase (acs). CFT073 acs, which is unable to reclaim secreted acetate, colonized mouse bladders and kidneys in the murine model of UTI indistinguishably from the wild type. Both pta and ackA are involved in the maintenance of intracellular acetyl phosphate. CFT073 pta and ackA mutants were screened to investigate the role of acetyl phosphate in UTI pathogenesis. Both single mutants are at a competitive disadvantage relative to the wild type in the kidneys but normally colonize the bladder. CFT073 ackA pta was attenuated in both the bladder and the kidneys. Thus, we demonstrate that CFT073 is adapted to acetate metabolism as a result of requiring a proper cycling of the acetyl phosphate pathway for colonization of the upper urinary tract.

Anfora, Andrew T.; Halladin, David K.; Haugen, Brian J.; Welch, Rodney A.

2008-01-01

110

Necrosis is the dominant cell death pathway in uropathogenic Escherichia coli elicited epididymo-orchitis and is responsible for damage of rat testis.  

PubMed

Male infertility is a frequent medical condition, compromising approximately one in twenty men, with infections of the reproductive tract constituting a major etiological factor. Bacterial epididymo-orchitis results in acute inflammation most often caused by ascending canalicular infections from the urethra via the continuous male excurrent ductal system. Uropathogenic Escherichia coli (UPEC) represent a relevant pathogen in urogenital tract infections. To explore how bacteria can cause damage and cell loss and thus impair fertility, an in vivo epididymo-orchitis model was employed in rats by injecting UPEC strain CFT073 into the vas deference in close proximity to the epididymis. Seven days post infection bacteria were found predominantly in the testicular interstitial space. UPEC infection resulted in severe impairment of spermatogenesis by germ cell loss, damage of testicular somatic cells, a decrease in sperm numbers and a significant increase in TUNEL (+) cells. Activation of caspase-8 (extrinsic apoptotic pathway), caspase-3/-6 (intrinsic apoptotic pathway), caspase-1 (pyroptosis pathway) and the presence of 180 bp DNA fragments, all of which serve as indicators of the classical apoptotic pathway, were not observed in infected testis. Notably, electron microscopical examination revealed degenerative features of Sertoli cells (SC) in UPEC infected testis. Furthermore, the passive release of high mobility group protein B1 (HMGB1), as an indication of necrosis, was observed in vivo in infected testis. Thus, necrosis appears to be the dominant cell death pathway in UPEC infected testis. Substantial necrotic changes seen in Sertoli cells will contribute to impaired spermatogenesis by loss of function in supporting the dependent germ cells. PMID:23301002

Lu, Yongning; Bhushan, Sudhanshu; Tchatalbachev, Svetlin; Marconi, Marcelo; Bergmann, Martin; Weidner, Wolfgang; Chakraborty, Trinad; Meinhardt, Andreas

2013-01-02

111

Necrosis Is the Dominant Cell Death Pathway in Uropathogenic Escherichia coli Elicited Epididymo-Orchitis and Is Responsible for Damage of Rat Testis  

PubMed Central

Male infertility is a frequent medical condition, compromising approximately one in twenty men, with infections of the reproductive tract constituting a major etiological factor. Bacterial epididymo-orchitis results in acute inflammation most often caused by ascending canalicular infections from the urethra via the continuous male excurrent ductal system. Uropathogenic Escherichia coli (UPEC) represent a relevant pathogen in urogenital tract infections. To explore how bacteria can cause damage and cell loss and thus impair fertility, an in vivo epididymo-orchitis model was employed in rats by injecting UPEC strain CFT073 into the vas deference in close proximity to the epididymis. Seven days post infection bacteria were found predominantly in the testicular interstitial space. UPEC infection resulted in severe impairment of spermatogenesis by germ cell loss, damage of testicular somatic cells, a decrease in sperm numbers and a significant increase in TUNEL (+) cells. Activation of caspase-8 (extrinsic apoptotic pathway), caspase-3/?6 (intrinsic apoptotic pathway), caspase-1 (pyroptosis pathway) and the presence of 180 bp DNA fragments, all of which serve as indicators of the classical apoptotic pathway, were not observed in infected testis. Notably, electron microscopical examination revealed degenerative features of Sertoli cells (SC) in UPEC infected testis. Furthermore, the passive release of high mobility group protein B1 (HMGB1), as an indication of necrosis, was observed in vivo in infected testis. Thus, necrosis appears to be the dominant cell death pathway in UPEC infected testis. Substantial necrotic changes seen in Sertoli cells will contribute to impaired spermatogenesis by loss of function in supporting the dependent germ cells.

Lu, Yongning; Bhushan, Sudhanshu; Tchatalbachev, Svetlin; Marconi, Marcelo; Bergmann, Martin; Weidner, Wolfgang; Chakraborty, Trinad; Meinhardt, Andreas

2013-01-01

112

A structural and biochemical basis for PAPS-independent sulfuryl transfer by aryl sulfotransferase from uropathogenic Escherichia coli.  

PubMed

Sulfotransferases are a versatile class of enzymes involved in numerous physiological processes. In mammals, adenosine 3'-phosphate-5'-phosphosulfate (PAPS) is the universal sulfuryl donor, and PAPS-dependent sulfurylation of small molecules, including hormones, sugars, and antibiotics, is a critical step in hepatic detoxification and extracellular signaling. In contrast, little is known about sulfotransferases in bacteria, which make use of sulfurylated molecules as mediators of cell-cell interactions and host-pathogen interactions. Bacterial arylsulfate sulfotransferases (also termed aryl sulfotransferases), in contrast to PAPS-dependent sulfotransferases, transfer sulfuryl groups exclusively among phenolic compounds in a PAPS-independent manner. Here, we report the crystal structure of the virulence factor arylsulfate sulfotransferase (ASST) from the prototypic, pyelonephritogenic Escherichia coli strain CFT073 at 2.0-A resolution, and 2 catalytic intermediates, at 2.1-A and 2.4-A resolution, with substrates bound in the active site. ASST is one of the largest periplasmic enzymes and its 3D structure differs fundamentally from all other structurally characterized sulfotransferases. Each 63.8-kDa subunit of the ASST homodimer comprises a 6-bladed beta-propeller domain and a C-terminal beta-sandwich domain. The active sites of the dimer are situated at the center of the channel formed by each beta-propeller and are defined by the side chains of His-252, His-356, Arg-374, and His-436. We show that ASST follows a ping-pong bi-bi reaction mechanism, in which the catalytic residue His-436 undergoes transient sulfurylation, a previously unreported covalent protein modification. The data provide a framework for understanding PAPS-independent sulfotransfer and a basis for drug design targeting this bacterial virulence factor. PMID:19036922

Malojci?, Goran; Owen, Robin L; Grimshaw, John P A; Brozzo, Maurice S; Dreher-Teo, Hiang; Glockshuber, Rudi

2008-11-26

113

Micropatterned Surfaces for Reducing the Risk of Catheter-Associated Urinary Tract Infection: An In Vitro Study on the Effect of Sharklet Micropatterned Surfaces to Inhibit Bacterial Colonization and Migration of Uropathogenic Escherichia coli  

PubMed Central

Abstract Background and Purpose Catheter-associated urinary tract infection (CAUTI) is the most common device-associated infection and can result in serious medical consequences. We studied the efficacy of a novel microscopic physical surface modification (Sharklet) for preventing bacterial colonization and migration of uropathogenic Escherichia coli on silicone elastomer. Materials and Methods In vitro growth assays evaluated E coli colonization using three variations of micropatterned silicone surfaces vs a smooth silicone control. Enumeration techniques included quantification of colonies on surfaces and analysis of bacterial area coverage and colony size. In vitro migration assays involved placement of micropatterned and smooth silicone rod segments between two agar islands to measure incidence of migration. Results All three variations of the Sharklet micropattern outperformed the control surfaces in inhibiting E coli colonization. On average, 47% reduction in colony-forming units (CFUs) and bacterial area coverage plus 77% reduction in colony size were achieved with the Sharklet surfaces in tryptic soy broth and artificial urine compared with the control nonpatterned surfaces. The incidence of E coli migration over the rod segments was reduced by more than 80% for the Sharklet transverse patterned rods compared with the unpatterned control rods. Conclusion The Sharklet micropattern is effective at inhibiting colonization and migration of a common uropathogen. This performance is achieved through a physical surface modification without the use of any antimicrobial agents. Because deterrence of bacterial colonization and migration is a critical step to prevent CAUTI, the Sharklet micropattern offers a novel concept in addressing this important problem.

Chung, Kenneth K.; McDaniel, Clinton J.; Darouiche, Rabih O.; Landman, Jaime; Brennan, Anthony B.

2011-01-01

114

Cloning of fimH and fliC and expression of the fusion protein FimH/FliC from Uropathogenic Escherichia coli (UPEC) isolated in Iran  

PubMed Central

Background and Objectives Urinary tract infection (UTI) is one of the most common infections in the world. The majority of UTIs are caused by Uropathogenic Escherichia coli (UPEC) strains. FimH and FliC are the most important virulence factors of UPEC. To date, any ideal vaccine against UTI has not been approved for human use and we need to test new targets to develop an ideal vaccine against UTI. In this study, we constructed fusion fimH/fliC of UPEC as a novel vaccine candidate against UTI. Material and Methods PCR amplification of fimH and fliC genes of the UPEC isolates was performed by specific primers designed for this purpose. Construction of fimH/fliC hybrid gene was performed by overlap PCR. The fimH, fliC and fimH/fliC were cloned in pET28a vector. The confirmation of expression of the proteins was done by SDS-PAGE and Western blot. Results The fliC and fimH genes were amplified in all of the UPEC isolates tested. The fimH showed significant homology with the sequences in GenBank. We generated a fusion consisting of the fimH linked to the N-terminal end of fliC. Sequencing of the fusion fimH/fliC showed that fusion was constructed correctly. SDS-PAGE and western blot confirmed the expression of the proteins in optimized condition. Conclusion Urinary tract infection is a huge burden on healthcare system in many countries. UPEC is isolated in around 80% of UTI cases. Antibiotic therapy resulted in the emergence of antibiotic resistance in UPEC strains. This is the major cause for an increasing requirement for a vaccine to prevent UTI. This work describes for the first time the construction of a novel fusion protein from Iranian UPEC isolates. Further immunological studies are required for evaluation of this protein as a novel and safe vaccine candidate against UTI caused by UPEC.

Asadi, Karam MR; Oloomi, M; Habibi, M; Bouzari, S

2012-01-01

115

Microcins and urovirulence in Escherichia coli  

Microsoft Academic Search

Urinary tract infections are among the most common infectious diseases encountered in humans and Escherichia coli is their leading etiologic agent. Uropathogenic E. coli encompasses a group of bacteria possessing a variable virulence gene assortment. It is generally agreed that many urovirulence factors remain to be discovered and that this information is required to gain knowledge on the pathogenic processes

María F. Azpiroz; María Eloisa Poey; Magela Lavińa

2009-01-01

116

ESCHERICHIA COLI  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli is a major commensal of the human intestine, and for years, the organism was regarded as having low virulence. In the 1920's, E. coli was recognized as a cause of urinary tract infections and in the 1940's as a cause of gastroenteritis in infants. The identification of a wide rang...

117

Mobilisation and remobilisation of a large archetypal pathogenicity island of uropathogenic Escherichia coli in vitro support the role of conjugation for horizontal transfer of genomic islands  

PubMed Central

Background A substantial amount of data has been accumulated supporting the important role of genomic islands (GEIs) - including pathogenicity islands (PAIs) - in bacterial genome plasticity and the evolution of bacterial pathogens. Their instability and the high level sequence similarity of different (partial) islands suggest an exchange of PAIs between strains of the same or even different bacterial species by horizontal gene transfer (HGT). Transfer events of archetypal large genomic islands of enterobacteria which often lack genes required for mobilisation or transfer have been rarely investigated so far. Results To study mobilisation of such large genomic regions in prototypic uropathogenic E. coli (UPEC) strain 536, PAI II536 was supplemented with the mobRP4 region, an origin of replication (oriVR6K), an origin of transfer (oriTRP4) and a chloramphenicol resistance selection marker. In the presence of helper plasmid RP4, conjugative transfer of the 107-kb PAI II536 construct occured from strain 536 into an E. coli K-12 recipient. In transconjugants, PAI II536 existed either as a cytoplasmic circular intermediate (CI) or integrated site-specifically into the recipient's chromosome at the leuX tRNA gene. This locus is the chromosomal integration site of PAI II536 in UPEC strain 536. From the E. coli K-12 recipient, the chromosomal PAI II536 construct as well as the CIs could be successfully remobilised and inserted into leuX in a PAI II536 deletion mutant of E. coli 536. Conclusions Our results corroborate that mobilisation and conjugal transfer may contribute to evolution of bacterial pathogens through horizontal transfer of large chromosomal regions such as PAIs. Stabilisation of these mobile genetic elements in the bacterial chromosome result from selective loss of mobilisation and transfer functions of genomic islands.

2011-01-01

118

The innate immune response to Uropathogenic Escherichia coli involves IL-17A in a murine model of urinary tract infection1  

PubMed Central

Uropathogenic E. coli (UPEC)3 is the causative agent for greater than 80% of uncomplicated urinary tract infections (UTIs). UPEC strains express a number of virulence and fitness factors that allow successful colonization of the mammalian bladder. To combat this, the host has distinct mechanisms, not only to prevent adherence to the bladder wall, but to detect and kill UPEC in the event of colonization. In this study, we investigated the role of IL-17A, an innate-adaptive immunomodulatory cytokine, during UTI using a murine model. Splenocytes, isolated from mice infected by the transurethral route, robustly expressed IL-17A in response to in vitro stimulation with UPEC antigens. Transcript expression of IL-17A in the bladders of infected mice correlated with a role in the innate immune response to UTI, and ??-positive cells appear to be a key source of IL-17A production. While IL-17A appears to be dispensable for the generation of a protective response to UPEC, its importance in innate immunity is demonstrated by a defect in acute clearance of UPEC in IL-17A?/? mice. This clearance defect is likely a result of deficient cytokine and chemokine transcripts and impaired macrophage and neutrophil influx during infection. These results show that IL-17A is a key mediator for the innate immune response to UTI.

Sivick, Kelsey E.; Schaller, Matthew A.; Smith, Sara N.; Mobley, Harry L.T.

2009-01-01

119

Escherichia Coli  

ERIC Educational Resources Information Center

|Diverse biological data may be used to create illustrations of molecules in their cellular context. I describe the scientific results that support a recent textbook illustration of an "Escherichia coli cell". The image magnifies a portion of the bacterium at one million times, showing the location and form of individual macromolecules. Results…

Goodsell, David S.

2009-01-01

120

Molecular organisation of the genes involved in the production of F7 2 fimbriae, causing mannose resistant haemagglutination, of a uropathogenic Escherichia coli 06:K2:H1:F7 strain  

Microsoft Academic Search

The genes responsible for the formation of the F72 fimbriae of the uropathogenic E. coli strain AD110 (O6:K2:H1:F7) have been cloned on the recombinant plasmid pPIL110-35 (Van Die et al. 1983). The F72 fimbriae, like the F71 fimbriae of AD110, are responsible for mannose resistant haemagglutination (MRHA).

Irma van Die; Ingrid van Megen; Wiel Hoekstra; Hans Bergmans

1984-01-01

121

The DraC usher in Dr fimbriae biogenesis of uropathogenic E. coli Dr + strains  

Microsoft Academic Search

Biogenesis of Dr fimbriae encoded by the dra gene cluster of uropathogenic Escherichia coli strains requires the chaperone-usher pathway. This secretion system is based on two non-structural assembly components, the\\u000a DraB periplasmic chaperone and DraC outer-membrane usher. The DraB controls the folding of DraE subunits, and DraC forms the\\u000a assembly and secretion platform for polymerization of subunits in linear fibers.

Beata Zalewska-Pi?tek; Marta Kur; Sabina Wilkanowicz; Rafa? Pi?tek; Józef Kur

2010-01-01

122

Molecular analysis of type 3 fimbrial genes from Escherichia coli, Klebsiella and Citrobacter species  

Microsoft Academic Search

BACKGROUND: Catheter-associated urinary tract infection (CAUTI) is the most common nosocomial infection in the United States and is caused by a range of uropathogens. Biofilm formation by uropathogens that cause CAUTI is often mediated by cell surface structures such as fimbriae. In this study, we characterised the genes encoding type 3 fimbriae from CAUTI strains of Escherichia coli, Klebsiella pneumoniae,

Cheryl-lynn Y Ong; Scott A Beatson; Makrina Totsika; Christiane Forestier; Alastair G McEwan; Mark A Schembri

2010-01-01

123

Target analysis of ?-alkylidene-?-butyrolactones in uropathogenic E. coli.  

PubMed

?-Alkylidene-?-butyrolactones are quite common in nature and exhibit a broad spectrum of biological activities. We therefore synthesized a small library of xanthatine inspired ?-alkylidene-?-butyrolactones to screen non-pathogenic and uropathogenic E. coli strains by activity based protein profiling (ABPP). The identified targets are involved in cellular redox processes and give first insight into the preferred binding sites of this privileged motif. Furthermore the gene of one protein, c2450, which was only identified in uropathogenic E. coli belongs to a genomic island which encodes a hybrid polyketide/non-ribosomal peptide synthetase (PKS/NRPS). This system is responsible for the synthesis of colibactin, a natural product which causes DNA double strand breaks in eukaryotic cells leading to the activation of the DNA damage checkpoint pathway and subsequent cell cycle arrest. While the role of several proteins that are involved in the colibactin synthesis has been elucidated, the function of c2450 remains elusive. Investigation of the binding site showed that c2450 is modified at a cysteine residue which may be important for the catalytic activity. PMID:22990910

Kunzmann, Martin H; Sieber, Stephan A

2012-09-18

124

Difference in the regulation of IL8 expression induced by uropathogenic E. coli between two kinds of urinary tract epithelial cells  

Microsoft Academic Search

Bacterial adherence to epithelial cells is a key virulence trait of pathogenic bacteria. The type 1 fimbriae and the P-fimbriae of uropathogenic Escherichia coli (UPEC) have both been described to be important for the establishment of urinary tract infections (UTI). To explore the interactions between the host and bacterium responsible for the different environments of UPEC invasion, we examined the

Kun-Wei Tsai; Hong-Thih Lai; Tzung-Chieh Tsai; Yi-Chien Wu; Ya-Ting Yang; Kwei-Yi Chen; Chun-Ming Chen; Yi-Shuan J Li; Cheng-Nan Chen

2009-01-01

125

The Genome Sequence of Avian Pathogenic Escherichia coli Strain O1:K1:H7 Shares Strong Similarities with Human Extraintestinal Pathogenic E. coli Genomes  

Microsoft Academic Search

Escherichia coli strains that cause disease outside the intestine are known as extraintestinal pathogenic E. coli (ExPEC) and include human uropathogenic E. coli (UPEC) and avian pathogenic E. coli (APEC). Regard- less of host of origin, ExPEC strains share many traits. It has been suggested that these commonalities may enable APEC to cause disease in humans. Here, we begin to

Timothy J. Johnson; Subhashinie Kariyawasam; Yvonne Wannemuehler; Paul Mangiamele; Sara J. Johnson; Curt Doetkott; Jerod A. Skyberg; Aaron M. Lynne; James R. Johnson; Lisa K. Nolan

2007-01-01

126

Pathogenic Escherichia coli  

Microsoft Academic Search

Few microorganisms are as versatile as Escherichia coli. An important member of the normal intestinal microflora of humans and other mammals, E. coli has also been widely exploited as a cloning host in recombinant DNA technology. But E. coli is more than just a laboratory workhorse or harmless intestinal inhabitant; it can also be a highly versatile, and frequently deadly,

James P. Nataro; Harry L. T. Mobley; James B. Kaper

2004-01-01

127

Role of enteroaggregative Escherichia coli virulence factors in uropathogenesis.  

PubMed

A multiresistant clonal Escherichia coli O78:H10 strain qualifying molecularly as enteroaggregative Escherichia coli (EAEC) was recently shown to be the cause of a community-acquired outbreak of urinary tract infection (UTI) in greater Copenhagen, Denmark, in 1991. This marks the first time EAEC has been associated with an extraintestinal disease outbreak. Importantly, the outbreak isolates were recovered from the urine of patients with symptomatic UTI, strongly implying urovirulence. Here, we sought to determine the uropathogenic properties of the Copenhagen outbreak strain and whether these properties are conferred by the EAEC-specific virulence factors. We demonstrated that through expression of aggregative adherence fimbriae, the principal adhesins of EAEC, the outbreak strain exhibited pronouncedly increased adherence to human bladder epithelial cells compared to prototype uropathogenic strains. Moreover, the strain was able to produce distinct biofilms on abiotic surfaces, including urethral catheters. These findings suggest that EAEC-specific virulence factors increase uropathogenicity and may have played a significant role in the ability of the strain to cause a community-acquired outbreak of UTI. Thus, inclusion of EAEC-specific virulence factors is warranted in future detection and characterization of uropathogenic E. coli. PMID:23357383

Boll, Erik J; Struve, Carsten; Boisen, Nadia; Olesen, Bente; Stahlhut, Steen G; Krogfelt, Karen A

2013-01-28

128

Role of Enteroaggregative Escherichia coli Virulence Factors in Uropathogenesis  

PubMed Central

A multiresistant clonal Escherichia coli O78:H10 strain qualifying molecularly as enteroaggregative Escherichia coli (EAEC) was recently shown to be the cause of a community-acquired outbreak of urinary tract infection (UTI) in greater Copenhagen, Denmark, in 1991. This marks the first time EAEC has been associated with an extraintestinal disease outbreak. Importantly, the outbreak isolates were recovered from the urine of patients with symptomatic UTI, strongly implying urovirulence. Here, we sought to determine the uropathogenic properties of the Copenhagen outbreak strain and whether these properties are conferred by the EAEC-specific virulence factors. We demonstrated that through expression of aggregative adherence fimbriae, the principal adhesins of EAEC, the outbreak strain exhibited pronouncedly increased adherence to human bladder epithelial cells compared to prototype uropathogenic strains. Moreover, the strain was able to produce distinct biofilms on abiotic surfaces, including urethral catheters. These findings suggest that EAEC-specific virulence factors increase uropathogenicity and may have played a significant role in the ability of the strain to cause a community-acquired outbreak of UTI. Thus, inclusion of EAEC-specific virulence factors is warranted in future detection and characterization of uropathogenic E. coli.

Boll, Erik J.; Struve, Carsten; Boisen, Nadia; Olesen, Bente; Stahlhut, Steen G.

2013-01-01

129

Microcins and urovirulence in Escherichia coli.  

PubMed

Urinary tract infections are among the most common infectious diseases encountered in humans and Escherichia coli is their leading etiologic agent. Uropathogenic E. coli encompasses a group of bacteria possessing a variable virulence gene assortment. It is generally agreed that many urovirulence factors remain to be discovered and that this information is required to gain knowledge on the pathogenic processes underlying the different clinical presentations of urinary tract infections. The production of higher-molecular-mass microcins, a group of ribosomally-synthesized peptide antibiotics comprising microcins H47, I47, E492, M and ColV, has been proposed as a virulence trait of some uropathogenic E. coli. To study this possibility, clones producing any of these microcins were selected from a collection of 160 Gram-negative clinical isolates from urine cultures and their virulence profile was analyzed. The study consisted in surveying genetic loci known to be relevant to urinary tract infection caused by E. coli. Depending on the type of microcin produced, different virulence patterns were observed which seemed to be determined by the degree of compatibility between virulence and microcin loci. In conclusion, results pointed to a relationship between higher-molecular-mass microcins and urovirulence. PMID:19744552

Azpiroz, María F; Poey, María Eloisa; Lavińa, Magela

2009-09-08

130

Physical Properties of Escherichia coli P Pili Measured by Optical Tweezers  

Microsoft Academic Search

The mechanical behavior of individual P pili of uropathogenic Escherichia coli has been investigated using optical tweezers. P pili, whose main part constitutes the PapA rod, composed of ?103 PapA subunits in a helical arrangement, are distributed over the bacterial surface and mediate adhesion to host cells. They are particularly important in the pathogenesis of E. coli colonizing the upper

Jana Jass; Staffan Schedin; Erik Fällman; Jörgen Ohlsson; Ulf J. Nilsson; Bernt Eric Uhlin; Ove Axner

2004-01-01

131

Comparison of Escherichia coli isolates implicated in human urinary tract infection and avian colibacillosis  

Microsoft Academic Search

Since avian pathogenic Escherichia coli (APEC) and human uropathogenic E. coli (UPEC) may encounter similar challenges when establishing infection in extraintestinal locations, they may share a similar content of virulence genes and capacity to cause disease. In the present study, 524 APEC and 200 UPEC isolates were compared by their content of virulence genes, phylogenetic group, and other traits. The

Kylie E. Rodriguez-Siek; Catherine W. Giddings; Curt Doetkott; Timothy J. Johnson; Mohamed K. Fakhr; Lisa K. Nolan

2005-01-01

132

Diarrheagenic Escherichia coli  

PubMed Central

Escherichia coli is the predominant nonpathogenic facultative flora of the human intestine. Some E. coli strains, however, have developed the ability to cause disease of the gastrointestinal, urinary, or central nervous system in even the most robust human hosts. Diarrheagenic strains of E. coli can be divided into at least six different categories with corresponding distinct pathogenic schemes. Taken together, these organisms probably represent the most common cause of pediatric diarrhea worldwide. Several distinct clinical syndromes accompany infection with diarrheagenic E. coli categories, including traveler’s diarrhea (enterotoxigenic E. coli), hemorrhagic colitis and hemolytic-uremic syndrome (enterohemorrhagic E. coli), persistent diarrhea (enteroaggregative E. coli), and watery diarrhea of infants (enteropathogenic E. coli). This review discusses the current level of understanding of the pathogenesis of the diarrheagenic E. coli strains and describes how their pathogenic schemes underlie the clinical manifestations, diagnostic approach, and epidemiologic investigation of these important pathogens.

Nataro, James P.; Kaper, James B.

1998-01-01

133

Screening of SdiA inhibitors from Melia dubia seeds extracts towards the hold back of uropathogenic E.coli quorum sensing-regulated factors.  

PubMed

Plants have always been a supreme source of drugs and India is endowed with a wide variety of them with high medicinal values. The Quorum Sensing (QS) quenching efficiency of various solvent extracts of Melia dubia seeds was investigated against uropathogenic Escherichia coli (UPEC) to screen the competitive inhibitor of SdiA, a transcriptional activator of quorum sensing in E. coli. In this study, potentiality of five different extracts of Melia dubia seeds for quorum sensing inhibitory activity was investigated against uropathogenic Escherichia coli (UPEC). Assays such as cell density, swarming motility, protein, protease, hemolysis, hemagglutination, hydrophobicity and biofilm inhibition were performed. Biofilm, hemolysis and swarming motility were found to be inhibited by 92.1%, 20.9 % and 48.52% respectively, when the medium was supplemented with 30 mg/ml of the ethanolic extract. GC-MS spectrum of the ethanolic extract showed an array of 27 structurally unlinked compounds with natural ligand C8HSL. The docking against QS transcriptional regulator SdiA was predicted by in silico studies and the ligand C6 showed significant activity with -10.8 GScore. In vitro and in silico docking analysis showed fairly a good correlation, suggesting that the ethanolic extract showed potency to attenuate quorum sensing of uropathogenic E. coli. Further studies by in vitro and in vivo strategies are necessary to foresee the quorum quenching effect of the ligands. PMID:23210902

Ravichandiran, Vinothkannan; Shanmugam, Karthi; Solomon, Adline Princy

2013-09-01

134

PATHOGENIC ESCHERICHIA COLI  

EPA Science Inventory

Escherichia coli is a bacterial species which inhabits the gastrointestinal tract of man and warm-blooded animals. Because of the ubiquity of this bacterium in the intestinal flora, it serves as an important indicator organism of fecal contamination. E. coli, aside from serving a...

135

Expression of the Escherichia coli IrgA homolog adhesin is regulated by the ferric uptake regulation protein  

Microsoft Academic Search

The IrgA homolog adhesin (Iha) is an adherence-conferring outer membrane protein of Escherichia coli associated with enterohemorrhagic and uropathogenic strains. Here, we used primer extension analysis to identify iha promoters in O157:H7 and uropathogenic E. coli strains. Transcriptional fusions demonstrated that iha transcription is repressed by iron. Gel shifts using purified ferric uptake regulator protein (Fur) demonstrated that repression involves

Rebecca A. Rashid; Phillip I. Tarr; Steve L. Moseley

2006-01-01

136

The IrgA Homologue Adhesin Iha Is an Escherichia coli Virulence Factor in Murine Urinary Tract Infection  

Microsoft Academic Search

The role of the Escherichia coli iron-regulated gene homologue adhesin (Iha) in the pathogenesis of urinary tract infections (UTIs) is unknown. We performed a series of complementary analyses to confirm or refute the hypothesis that Iha is a virulence factor in uropathogenic E. coli. Fecal E. coli isolates exhibited significantly lower prevalences of iha (range, 14 to 22%) than did

James R. Johnson; Srdjan Jelacic; Laura M. Schoening; Connie Clabots; Nurmohammad Shaikh; Harry L. T. Mobley; Phillip I. Tarr

2005-01-01

137

Escherichia coli Diarrhea  

Microsoft Academic Search

\\u000a During the 1940s and 1950s, a series of outbreaks of diarrhea in hospital newborn nurseries were reported in which the etiologic\\u000a agent appeared to be Escherichia coli identified by serotype. These strains became known as enteropathogenic E. coli (EPEC). Since the Second International Symposium on EPEC in 1995, EPEC strains have been renamed typical EPEC (tEPEC) to\\u000a distinguish them from

Herbert L. DuPont; M. Teresa Estrada-Garcia; Zhi-Dong Jiang

138

Genetic recombination. [Escherichia coli  

SciTech Connect

The molecular pathways of gene recombination are explored and compared in studies of the model organisms, Escherichia coli and phase lambda. In the discussion of data from these studies it seems that recombination varies with the genetic idiosyncrasies of the organism and may also vary within a single organism.

Stahl, F.W.

1987-02-01

139

Uropathogenic E. coli Promote a Paracellular Urothelial Barrier Defect Characterized by Altered Tight Junction Integrity, Epithelial Cell Sloughing and Cytokine Release  

PubMed Central

Summary The urinary bladder is a common site of bacterial infection with a majority of cases attributed to uropathogenic Escherichia coli. Sequels of urinary tract infections (UTIs) include the loss of urothelial barrier function and subsequent clinical morbidity secondary to the permeation of urine potassium, urea and ammonia into the subepithelium. To date there has been limited research describing the mechanism by which this urothelial permeability defect develops. The present study models acute uropathogenic E. coli infection in vitro using intact canine bladder mucosa mounted in Ussing chambers to determine whether infection induces primarily a transcellular or paracellular permeability defect. The Ussing chamber sustains tissue viability while physically separating submucosal and lumen influences, so this model is ideal for quantitative measurement of transepithelial electrical resistance (TER) to assess alterations of urothelial barrier function. Using this model, changes in both tissue ultrastructure and TER indicated that uropathogenic E. coli infection promotes a paracellular permeability defect associated with the failure of umbrella cell tight junction formation and umbrella cell sloughing. In addition, bacterial interaction with the urothelium promoted secretion of cytokines from the urinary bladder with bioactivity capable of modulating epithelial barrier function including tumour necrosis factor-?, interleukin (IL)-6 and IL-15. IL-15 secretion by the infected bladder mucosa is a novel finding and, because IL-15 plays key roles in reconstitution of tight junction function in damaged intestine, this study points to a potential role for IL-15 in UTI-induced urothelial injury.

Wood, M. W.; Breitschwerdt, E. B.; Nordone, S. K.; Linder, K. E.; Gookin, J. L.

2013-01-01

140

Study on the influence of cranberry extract ?uravit S·O·S(®) on the properties of uropathogenic Escherichia coli strains, their ability to form biofilm and its antioxidant properties.  

PubMed

Consumption of cranberries is known to exert positive health effects, especially against urinary tract infections. For this reason, presumably, they are widely used in folk medicine. Different aspects of cranberry phenolics activity were studied in individual papers but complex study in this matter is missing. The aim of the present study is to provide complex data concerning various aspects of cranberry extract activity. We studied the effects of subinhibitory concentrations of commercially available extract (?uravit S·O·S(®)) against two Escherichia coli strains isolated from urine of patients with pyelonephritis. Additionally the main extract anthocyanins were characterized. The activity of extract against lipid peroxidation and its radical scavenging ability were also assessed. ?uravit S·O·S(®) decreased the hydrophobicity of one of the studied E. coli strains, reduced swimming motility and adhesion to epithelial cells of both studied strains, it also limited the ability of bacteria to form biofilm. Expression of curli was not affected by cranberry extract, the assessment of P fimbriae expression was not reliable due to extract-induced agglutination of erythrocytes. Cranberry extract caused filamentation in both studied E. coli strains. It also showed pronounced antioxidant and radical scavenging properties. The properties of the studied cranberry extract show that it could be effectively used in prevention and/or elimination of urinary tract infections, specially the recurrent ones. PMID:22306419

Wojnicz, Dorota; Sycz, Zuzanna; Walkowski, Stefan; Gabrielska, Janina; Aleksandra, W?och; Alicja, Kucharska; Anna, Sokó?-??towska; Hendrich, Andrzej B

2012-02-04

141

In vitro binding of type 1-fimbriated Escherichia coli to uroplakins Ia and Ib: Relation to urinary tract infections  

Microsoft Academic Search

Urinary tract infections, caused mainly by Escherichia coli, are among the most common infectious diseases. Most isolates of the uropathogenic E. coli can express type 1 and P fimbriae containing adhesins that recognize cell receptors. While P fimbriae recognize kidney glycolipid receptors and are involved in pyelonephritis, the urothelial receptors for type 1 fimbriae were not identified. We show that

Xue-Ru Wu; Tung-Tien Sun

1996-01-01

142

Incidence of colicinogenic strains among human Escherichia coli.  

PubMed

During the years 1993-1999, altogether 1,043 Escherichia coli strains from colons of different persons were screened for colicinogeny using a most susceptible procedure and indicator system. In control persons (with healthy colons), 41.37% producers of colicins were found. In patients suffering from salmonelloses, the proportion of colicinogenic Escherichia coli was the same. In patients with non-specific inflammatory colon diseases, the proportion of colicinogenic Escherichia coli strains appeared slightly though weakly, significantly or unsignificantly increased: to 47.50% in morbus Crohn and to 56.10% in colitis ulcerosa. These results suggest some sort of engagement of colicinogeny in the pathogenesis thereof. In malignant tumours of the colon, the incidence of colicinogenic Escherichia coli was not altered (40.58%). This does not indicate any colicin participation in the pathology of malignant tumours. In colitis ulcerosa, the incidence of colicinogenic Escherichia coli strains inhibiting Shigella sonei 17 (the indicator for colicin Js which generally inhibits interoinvasive strains of both species) increased from 21.94% (control samples) to 41.46%. Uropathogenic Escherichia coli strains shared the same incidence of colicinogeny as controls (42.08%), if they were not haemolytic; haemolytic ones were colicinogenic with only 22.37%. This difference was highly significant. The patterns of some colicin activities in the set of five indicator strains used suggested that several wild strains produced new, so far unknown types of colicins and/or combinations thereof. PMID:11802547

Smarda, J; Obdrzálek, V

2001-01-01

143

Multiple drug resistance patterns in various phylogenetic groups of uropathogenic E.coli isolated from Faisalabad region of Pakistan  

PubMed Central

The objective of this work was the phylogenetic characterization of local clinical isolates of uropathogenic E. coli with respect to drug resistance. A total of 59 uropathogenic E. coli responsible for community acquired urinary tract infections were included in this study. A triplex PCR was employed to segregate each isolate into four different phylogenetic groups (A, B1, B2 and D). Drug resistance was evaluated by disc diffusion method. The drugs used were ampicillin, aztreonam, cefixime, cefoperazone, ceftriaxone, cephradine among ?-lactam group; amikacin, gentamicin, and streptomycin among aminoglycosides; nalidixic acid and ciprofloxacin from quinolones; trimethoprim-sulfomethoxazole, and tetracycline. Among 59 uropathogenic E. coli isolates majority belonged to phylogenetic group B2 (50%) where as 19% each belonged to groups A and B1, and 12% to group D. All the isolates were multiple drug resistant (MDR). Most effective drugs against Group A, B1, and B2 were gentamicin, amikacin and cefixime; ceftriaxone and quinolones; and ceftriaxone and amikacin, respectively. Group D isolates were found to be highly resistant to all drugs. Our results have shown emergence of MDR isolates among uropathogenic E. coli with dominance of phylogenetic group B2. However, it was found that group D isolates were though less frequent, more drug resistant as compared with group B2. Groups A and B1 were relatively uncommon. Amikacin, ceftriaxone and gentamicin were the most effective drugs in general.

Bashir, Saira; Sarwar, Yasra; Ali, Aamir; Mohsin, Mashkoor; Saeed, Muhammad Azeem; Tariq, Ayesha; Haque, Abdul

2011-01-01

144

Differential Stability and Trade-Off Effects of Pathoadaptive Mutations in the Escherichia coli FimH Adhesin  

Microsoft Academic Search

FimH is the tip adhesin of mannose-specific type 1 fimbriae of Escherichia coli, which are critical to the pathogenesis of urinary tract infections. Point FimH mutations increasing monomannose (1M)-specific uro- epithelial adhesion are commonly found in uropathogenic strains of E. coli. Here, we demonstrate the emer- gence of a mixed population of clonally identical E. coli strains in the urine

Scott J. Weissman; Viktoriya Beskhlebnaya; Veronika Chesnokova; Sujay Chattopadhyay; W. E. Stamm; T. M. Hooton; E. V. Sokurenko

2007-01-01

145

Expression of the Escherichia coli IrgA homolog adhesin is regulated by the ferric uptake regulation protein.  

PubMed

The IrgA homolog adhesin (Iha) is an adherence-conferring outer membrane protein of Escherichia coli associated with enterohemorrhagic and uropathogenic strains. Here, we used primer extension analysis to identify iha promoters in O157:H7 and uropathogenic E. coli strains. Transcriptional fusions demonstrated that iha transcription is repressed by iron. Gel shifts using purified ferric uptake regulator protein (Fur) demonstrated that repression involves a direct interaction between Fur and the iha promoter. We identified strain-dependent differences in iha expression and determined that single nucleotide polymorphisms upstream of the iha promoter, in particular position -85, contribute to differences in expression levels. PMID:16954050

Rashid, Rebecca A; Tarr, Phillip I; Moseley, Steve L

2006-09-06

146

Structural and Functional Integrity of Spermatozoa Is Compromised as a Consequence of Acute Uropathogenic E. coli-Associated Epididymitis.  

PubMed

Uropathogenic Escherichia coli (UPEC)-associated epididymitis is commonly diagnosed in outpatient settings. Although the infection can be successfully cleared using antimicrobial medications, 40% of patients unexplainably show persistent impaired semen parameters even after treatment. Our aim was to investigate whether pathogenic UPEC and its associated virulence factor hemolysin (hlyA) perturb the structural and functional integrity of both the epididymis and sperm, actions that may be responsible for the observed impairment and possibly a reduction of fertilization capabilities. Semen collected from patients diagnosed with E. coli-only related epididymitis showed that sperm counts were low 14 days postantimicrobial treatment regardless of hlyA status. At Day 84 following treatment, hlyA production correlated with approximately 4-fold lower sperm concentrations than in men with hlyA-negative strains. In vivo experiments with the hlyA-producing UPEC CFT073 strain in a murine epididymitis model showed that just 3 days postinfection, structural damage to the epididymis (epithelial damage, leukocyte infiltration, and edema formation) was present. This was more severe in UPEC CFT073 compared to nonpathogenic E. coli (NPEC 470) infection. Moreover, pathogenic UPEC strains prematurely activated the acrosome in vivo and in vitro. Raman microspectroscopy revealed that UPEC CFT073 undermined sperm integrity by inducing nuclear DNA damage. Consistent with these observations, the in vitro fertilization capability of hlyA-treated mouse sperm was completely abolished, although sperm were motile. These findings provide new insights into understanding the possible processes underlying clinical manifestations of acute epididymitis. PMID:23843239

Lang, Tali; Dechant, Maria; Sanchez, Victoria; Wistuba, Joachim; Boiani, Michele; Pilatz, Adrian; Stammler, Angelika; Middendorff, Ralf; Schuler, Gerhard; Bhushan, Sudhanshu; Tchatalbachev, Svetlin; Wübbeling, Frank; Burger, Martin; Chakraborty, Trinad; Mallidis, Con; Meinhardt, Andreas

2013-09-19

147

Evolution of the iss gene in Escherichia coli.  

PubMed

The increased serum survival gene iss has long been recognized for its role in extraintestinal pathogenic Escherichia coli (ExPEC) virulence. iss has been identified as a distinguishing trait of avian ExPEC but not of human ExPEC. This gene has been localized to large virulence plasmids and shares strong similarities with the bor gene from bacteriophage lambda. Here, we demonstrate that three alleles of iss occur among E. coli isolates that appear to have evolved from a common lambda bor precursor. In addition to the occurrence of iss on the ColV/BM virulence plasmids, at least two iss alleles occur within the E. coli chromosome. One of these alleles (designated type 3) was found to occur in the genomes of all currently sequenced ExPEC strains on a similar prophage element that also harbors the Sit iron and manganese transport system. When the prevalence of the three iss types was examined among 487 E. coli isolates, the iss type 3 gene was found to occur at a high frequency among ExPEC isolates, irrespective of the host source. The plasmid-borne iss allele (designated type 1) was highly prevalent among avian pathogenic E. coli and neonatal meningitis-associated E. coli isolates but not among uropathogenic E. coli isolates. This study demonstrates the evolution of iss in E. coli and provides an additional tool for discriminating among E. coli pathotypes through the differentiation of the three iss allele types and bor. PMID:18281426

Johnson, Timothy J; Wannemuehler, Yvonne M; Nolan, Lisa K

2008-02-15

148

Role of the rapA Gene in Controlling Antibiotic Resistance of Escherichia coli Biofilms  

Microsoft Academic Search

By using a high-throughput screening method, a mutant of a uropathogenic Escherichia coli strain affected in the rapA gene was isolated. The mutant formed normal-architecture biofilms but showed decreased peni- cillin G resistance, although the mutation did not affect planktonic cell resistance. Transcriptome analysis showed that 22 genes were down-regulated in the mutant biofilm. One of these genes was yhcQ,

S. V. Lynch; L. Dixon; M. R. Benoit; E. L. Brodie; M. Keyhan; P. Hu; D. F. Ackerley; G. L. Andersen; A. Matin

2007-01-01

149

Effects of subinhibitory concentrations of nitroxoline on the surface properties of Escherichia coli  

Microsoft Academic Search

Nitroxoline (5-nitro-8-quinolinol; NIQ) at subinhibitory concentrations (sub-MIC) decreased the adherence of uropathogenicEscherichia coli to catheter surface and significantly enhanced cell surface hydrophobicity. The surface hydrophobicity increased in the presence\\u000a of sub-MIC of NIQ and also in an excess of Mg2+. The effect of NIQ on the cell surface was not related to the bacteriostatic effect of this agent. The increase

H. Latrache; P. Bourlioux; M. Karroua; H. Zahir; A. Hakkou

2000-01-01

150

Isolation and comparison of Escherichia coli strains from canine and human patients with urinary tract infections.  

PubMed Central

We analyzed Escherichia coli strains isolated from dogs with urinary tract infections (UTIs) in an attempt to determine if any of these strains were similar to E. coli isolated from humans with UTIs. Using genotypic and phenotypic traits, we identified four canine and six human E. coli UTI isolates that all appeared to be closely related or identical. All isolates shared similar DNA sequences for pyelonephritis-associated pili (pap), alpha-hemolysin (hly), and insertion sequence 5 (IS5), on the basis of Southern blot analysis. Similar outer membrane protein, pilin, and plasmid profiles were obtained for each of the isolates, although minor heterogeneity was observed. All of these isolates expressed a neuraminidase-sensitive binding phenotype in contrast to the majority of human isolates, which are known to express an adhesin that recognizes terminal digalactoside residues. Taken together, these results suggest that similar E. coli uropathogens may be capable of infecting both dogs and humans. To determine if the intestinal tracts of dogs were a reservoir for uropathogenic E. coli, eight paired rectal and urine pap+ E. coli strains were cultured from dogs with UTIs. By using the same genotypic and phenotypic criteria described above as a basis for strain identity, seven of eight urine-rectal pairs showed intrapair identity. However, each urine-rectal pair displayed a unique overall profile and could be distinguished from the other pairs. We conclude that the uropathogen colonizing the bladders of dog can also be the predominant strain colonizing the intestinal tracts. Images

Low, D A; Braaten, B A; Ling, G V; Johnson, D L; Ruby, A L

1988-01-01

151

Uropathogenic E. coli induce different immune response in testicular and peritoneal macrophages: implications for testicular immune privilege.  

PubMed

Infertility affects one in seven couples and ascending bacterial infections of the male genitourinary tract by Escherichia coli are an important cause of male factor infertility. Thus understanding mechanisms by which immunocompetent cells such as testicular macrophages (TM) respond to infection and how bacterial pathogens manipulate defense pathways is of importance. Whole genome expression profiling of TM and peritoneal macrophages (PM) infected with uropathogenic E. coli (UPEC) revealed major differences in regulated genes. However, a multitude of genes implicated in calcium signaling pathways was a common feature which indicated a role of calcium-dependent nuclear factor of activated T cells (NFAT) signaling. UPEC-dependent NFAT activation was confirmed in both cultured TM and in TM in an in vivo UPEC infectious rat orchitis model. Elevated expression of NFATC2-regulated anti-inflammatory cytokines was found in TM (IL-4, IL-13) and PM (IL-3, IL-4, IL-13). NFATC2 is activated by rapid influx of calcium, an activity delineated to the pore forming toxin alpha-hemolysin by bacterial mutant analysis. Alpha-hemolysin suppressed IL-6 and TNF-? cytokine release from PM and caused differential activation of MAP kinase and AP-1 signaling pathways in TM and PM leading to reciprocal expression of key pro-inflammatory cytokines in PM (IL-1?, IL-1?, IL-6 downregulated) and TM (IL-1?, IL-6 upregulated). In addition, unlike PM, LPS-treated TM were refractory to NF?B activation shown by the absence of degradation of I?B? and lack of pro-inflammatory cytokine secretion (IL-6, TNF-?). Taken together, these results suggest a mechanism to the conundrum by which TM initiate immune responses to bacteria, while maintaining testicular immune privilege with its ability to tolerate neo-autoantigens expressed on developing spermatogenic cells. PMID:22164293

Bhushan, Sudhanshu; Hossain, Hamid; Lu, Yongning; Geisler, Andreas; Tchatalbachev, Svetlin; Mikulski, Zbigniew; Schuler, Gerhard; Klug, Jörg; Pilatz, Adrian; Wagenlehner, Florian; Chakraborty, Trinad; Meinhardt, Andreas

2011-12-02

152

Multidrug-Resistance and Extended Spectrum Beta-Lactamase Production in Uropathogenic E. Coli which were Isolated from Hospitalized Patients in Kolkata, India.  

PubMed

Background and Objective: Urinary Tract Infections (UTIs) are mostly caused by Escherichia coli. The appropriate therapy demands a current knowledge on the antimicrobial susceptibility pattern amongst these pathogens, as an inappropriate use of antibiotics may lead to complications and treatment failure. The UTIs which are caused by multidrug resistant Extended-Spectrum Beta-Lactamase (ESBL) producing bacteria further pose a severe problem, as the treatment options are limited. The aim of this study was to identify the pattern of multi drug resistance amongst the uropathogenic E. coli (UPEC) isolates which were obtained from hospitalized patients. Materials and Methods: Forty UPEC were isolated from 200 urine samples of hospitalized patients who were clinically suspected for UTIs. Antimicrobial susceptibility screening was performed by using 16 antibiotics, by the Kirby Bauer disk diffusion technique. The isolates which were resistant to the third generation cephalosporins were subjected to the ESBL confirmatory test by using drug and drug-inhibitor combination disks by following the CLSI guidelines. Results: All the 40 isolates except three were multidrug resistant. They showed the highest sensitivities for nitrofurantoin (72.5%) and amikacin (70%). A high level of resistance was observed against ampicillin (97.5%), nalidixic acid and cefelexin (95%), amoxicillin (92.5%), cotrimoxazole (82.5%) and ciprofloxacin (80%) respectively. Thirty different antibiotic resistance patterns were observed against the different antibiotics. Twenty-eight out of the 40 isolates were resistant to the third generation cephalosporins. However, the phenotypic test for the ESBL confirmation indicated that eighteen out of the twenty-eight isolates were ESBL producers and that eleven different drug resistance patterns were observed amongst them. Conclusions: Therefore, this study accounts for the varied multidrug resistance pattern amongst the uropathogenic E. coli which were isolated from hospitalized patients in Kolkata, an eastern region of India. Nitrofurantoin and amikacin should be assigned as potent drugs to treat this infection in this region of the country. These varied resistance patterns present major therapeutic and infection control challenges and they suggest a heterogeneous population of the uropathogenic E. coli isolates which circulate in this sector of India. PMID:23634394

Mukherjee, Mandira; Basu, Shreya; Mukherjee, Sandip Kumar; Majumder, Monalisa

2013-03-01

153

Multidrug-Resistance and Extended Spectrum Beta-Lactamase Production in Uropathogenic E. Coli which were Isolated from Hospitalized Patients in Kolkata, India  

PubMed Central

Background and Objective: Urinary Tract Infections (UTIs) are mostly caused by Escherichia coli. The appropriate therapy demands a current knowledge on the antimicrobial susceptibility pattern amongst these pathogens, as an inappropriate use of antibiotics may lead to complications and treatment failure. The UTIs which are caused by multidrug resistant Extended-Spectrum Beta-Lactamase (ESBL) producing bacteria further pose a severe problem, as the treatment options are limited. The aim of this study was to identify the pattern of multi drug resistance amongst the uropathogenic E. coli (UPEC) isolates which were obtained from hospitalized patients. Materials and Methods: Forty UPEC were isolated from 200 urine samples of hospitalized patients who were clinically suspected for UTIs. Antimicrobial susceptibility screening was performed by using 16 antibiotics, by the Kirby Bauer disk diffusion technique. The isolates which were resistant to the third generation cephalosporins were subjected to the ESBL confirmatory test by using drug and drug-inhibitor combination disks by following the CLSI guidelines. Results: All the 40 isolates except three were multidrug resistant. They showed the highest sensitivities for nitrofurantoin (72.5%) and amikacin (70%). A high level of resistance was observed against ampicillin (97.5%), nalidixic acid and cefelexin (95%), amoxicillin (92.5%), cotrimoxazole (82.5%) and ciprofloxacin (80%) respectively. Thirty different antibiotic resistance patterns were observed against the different antibiotics. Twenty-eight out of the 40 isolates were resistant to the third generation cephalosporins. However, the phenotypic test for the ESBL confirmation indicated that eighteen out of the twenty-eight isolates were ESBL producers and that eleven different drug resistance patterns were observed amongst them. Conclusions: Therefore, this study accounts for the varied multidrug resistance pattern amongst the uropathogenic E. coli which were isolated from hospitalized patients in Kolkata, an eastern region of India. Nitrofurantoin and amikacin should be assigned as potent drugs to treat this infection in this region of the country. These varied resistance patterns present major therapeutic and infection control challenges and they suggest a heterogeneous population of the uropathogenic E. coli isolates which circulate in this sector of India.

Mukherjee, Mandira; Basu, Shreya; Mukherjee, Sandip Kumar; Majumder, Monalisa

2013-01-01

154

EXTRAINTESTINAL PATHOGENIC ESCHERICHIA COLI (EXPEC)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Extraintestinal pathogenic Escherichia coli (ExPEC) possess virulence traits that allow them to invade, colonize, and induce disease in bodily sites outside of the gastrointestinal tract. Human diseases caused by ExPEC include urinary tract infections, neonatal meningitis, sepsis, pneumonia, surgic...

155

Genetic analysis of Escherichia coli urease genes: evidence for two distinct loci.  

PubMed Central

Studies with two uropathogenic urease-producing Escherichia coli strains, 1021 and 1440, indicated that the urease genes of each are distinct. Recombinant plasmids encoding urease activity from E. coli 1021 and 1440 differed in their restriction endonuclease cleavage sites and showed minimal DNA hybridization under stringent conditions. The polypeptides encoded by the DNA fragments containing the 1021 and 1440 urease loci differed in electrophoretic mobility under reducing conditions. Regulation of urease gene expression differed in the two ureolytic E. coli. The E. coli 1021 locus is probably chromosomally encoded and has DNA homology to Klebsiella, Citrobacter, Enterobacter, and Serratia species and to about one-half of the urease-producing E. coli tested. The E. coli 1440 locus is plasmid encoded; plasmids with DNA homology to the 1440 locus probe were found in urease-producing Salmonella spp., Providencia stuartii, and two E. coli isolates. In addition, the 1440 urease probe was homologous to Proteus mirabilis DNA. Images

Collins, C M; Falkow, S

1990-01-01

156

Draft Genome Sequence of Escherichia coli Strain ATCC 23506 (Serovar O10:K5:H4).  

PubMed

We report the 5.101-Mbp high-quality draft assembly of the Escherichia coli strain ATCC 23506 (serovar O10:K5:H4, also known as NCDC Bi 8337-41) genome. This uropathogenic strain, commonly referred to as E. coli K5, produces N-acetyl heparosan, a glycosaminoglycan-like capsular polysaccharide and precursor to the anticoagulant pharmaceutical heparin. Metabolic reconstruction of this genome will enable the prediction of gene deletions and overexpressions that lead to increased heparosan production. PMID:23516192

Cress, Brady F; Greene, Zachary R; Linhardt, Robert J; Koffas, Mattheos A G

2013-02-28

157

Molecular Variations in Klebsiella pneumoniae and Escherichia coli FimH Affect Function and Pathogenesis in the Urinary Tract  

Microsoft Academic Search

Type 1 pili mediate binding, invasion, and biofilm formation of uropathogenic Escherichia coli (UPEC) in the host urothelium during urinary tract infection (UTI) via the adhesin FimH. In this study, we characterized the molecular basis of functional differences between FimH of the UPEC isolate UTI89 and the Klebsiella pneu- moniae cystitis isolate TOP52. Type 1 pili characteristically mediate mannose-sensitive hemagglutination

David A. Rosen; Jerome S. Pinkner; Jennifer N. Walker; Jennifer Stine Elam; Jennifer M. Jones; Scott J. Hultgren

2008-01-01

158

21 CFR 866.3255 - Escherichia coli serological reagents.  

Code of Federal Regulations, 2010 CFR

...reagents consist of Escherichia coli antisera conjugated with a...used to identify Escherichia coli directly from clinical...microorganism. Although Escherichia coli constitutes the greater...notification procedures in subpart E of part 807 of this chapter...

2009-04-01

159

21 CFR 866.3255 - Escherichia coli serological reagents.  

Code of Federal Regulations, 2010 CFR

...reagents consist of Escherichia coli antisera conjugated with a...used to identify Escherichia coli directly from clinical...microorganism. Although Escherichia coli constitutes the greater...notification procedures in subpart E of part 807 of this chapter...

2010-04-01

160

21 CFR 866.3255 - Escherichia coli serological reagents.  

Code of Federal Regulations, 2013 CFR

...reagents consist of Escherichia coli antisera conjugated with a...used to identify Escherichia coli directly from clinical...microorganism. Although Escherichia coli constitutes the greater...notification procedures in subpart E of part 807 of this chapter...

2013-04-01

161

Early severe inflammatory responses to uropathogenic E. coli predispose to chronic and recurrent urinary tract infection.  

PubMed

Chronic infections are an increasing problem due to the aging population and the increase in antibiotic resistant organisms. Therefore, understanding the host-pathogen interactions that result in chronic infection is of great importance. Here, we investigate the molecular basis of chronic bacterial cystitis. We establish that introduction of uropathogenic E. coli (UPEC) into the bladders of C3H mice results in two distinct disease outcomes: resolution of acute infection or development of chronic cystitis lasting months. The incidence of chronic cystitis is both host strain and infectious dose-dependent. Further, development of chronic cystitis is preceded by biomarkers of local and systemic acute inflammation at 24 hours post-infection, including severe pyuria and bladder inflammation with mucosal injury, and a distinct serum cytokine signature consisting of elevated IL-5, IL-6, G-CSF, and the IL-8 analog KC. Mice deficient in TLR4 signaling or lymphocytes lack these innate responses and are resistant, to varying degrees, to developing chronic cystitis. Treatment of C3H mice with the glucocorticoid anti-inflammatory drug dexamethasone prior to UPEC infection also suppresses the development of chronic cystitis. Finally, individuals with a history of chronic cystitis, lasting at least 14 days, are significantly more susceptible to redeveloping severe, chronic cystitis upon bacterial challenge. Thus, we have discovered that the development of chronic cystitis in C3H mice by UPEC is facilitated by severe acute inflammatory responses early in infection, which subsequently are predisposing to recurrent cystitis, an insidious problem in women. Overall, these results have significant implications for our understanding of how early host-pathogen interactions at the mucosal surface determines the fate of disease. PMID:20811584

Hannan, Thomas J; Mysorekar, Indira U; Hung, Chia S; Isaacson-Schmid, Megan L; Hultgren, Scott J

2010-08-12

162

Escherichia coli Isolates That Carry vat, fyuA, chuA, and yfcV Efficiently Colonize the Urinary Tract  

PubMed Central

Extraintestinal Escherichia coli (ExPEC), a heterogeneous group of pathogens, encompasses avian, neonatal meningitis, and uropathogenic E. coli strains. While several virulence factors are associated with ExPEC, there is no core set of virulence factors that can be used to definitively differentiate these pathotypes. Here we describe a multiplex of four virulence factor-encoding genes, yfcV, vat, fyuA, and chuA, highly associated with uropathogenic E. coli strains that can distinguish three groups of E. coli: diarrheagenic and animal-associated E. coli strains, human commensal and avian pathogenic E. coli strains, and uropathogenic and neonatal meningitis E. coli strains. Furthermore, human intestinal isolates that encode all four predictor genes express them during exponential growth in human urine and colonize the bladder in the mouse model of ascending urinary tract infection in higher numbers than human commensal strains that do not encode the four predictor genes (P = 0.02), suggesting that the presence of the predictors correlates with uropathogenic potential.

Spurbeck, Rachel R.; Dinh, Paul C.; Walk, Seth T.; Stapleton, Ann E.; Hooton, Thomas M.; Nolan, Lisa K.; Kim, Kwang Sik; Johnson, James R.

2012-01-01

163

Virulence factors in Escherichia coli urinary tract infection.  

PubMed Central

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

Johnson, J R

1991-01-01

164

Assembly proteins of CS1 pili of enterotoxigenic Escherichia coli.  

PubMed

Some strains of enterotoxigenic Escherichia coli associated with human diarrhoeal disease produce a class of pili represented by those called CS1. For the assembly of the major-pilin subunit, CooA, into pili, each of four linked genes, cooB, A, C, and D, is required. In this study, we have determined the subcellular localization of CooB, C and D, and investigated the molecular interactions of these proteins using specific antisera. CooD appears to be an integral pilus protein because it co-purifies with, and is strongly associated with, CS1 pili. In keeping with its role as an assembly protein, the CooD minor pilin (when overexpressed in CS1-piliated strains) was detected in periplasmic intermolecular complexes with the major-pilin subunit CooA. CooB is an assembly protein found exclusively in the periplasm of CS1-piliated strains. CooB also forms periplasmic intermolecular complexes with CooA, but does not constitute part of the final pilus structure. Immunoblot analysis of cell fractions showed that CooC is an outer membrane protein of CS1-piliated E. coli. Based on this information, we have proposed a model for CS1-pilus assembly which is very similar to the model for polymerization of the PapA pilin of uropathogenic E. coli. As the assembly proteins of Pap and CS1 pili are structurally unrelated, this may represent a case of convergent evolution. PMID:8866477

Sakellaris, H; Balding, D P; Scott, J R

1996-08-01

165

SEROLOGICAL CROSS-REACTIONS BETWEEN ESCHERICHIA COLI 0157 AND OTHER SPECIES OF THE GENUS ESCHERICHIA  

EPA Science Inventory

Escherichia hermannii, a sorbitol-negative species of the genus Escherichia, has been reported to be agglutinated by Escherichia coli 0157 and four sorbitol-negative species of the genus Escherichia: . hermannii (24 isolates), Escherichia fergusonii (12 isolates), Escherichia vul...

166

Effects of subinhibitory concentrations of nitroxoline on the surface properties of Escherichia coli.  

PubMed

Nitroxoline (5-nitro-8-quinolinol; NIQ) at subinhibitory concentrations (sub-MIC) decreased the adherence of uropathogenic Escherichia coli to catheter surface and significantly enhanced cell surface hydrophobicity. The surface hydrophobicity increased in the presence of sub-MIC of NIQ and also in an excess of Mg2+. The effect of NIQ on the cell surface was not related to the bacteriostatic effect of this agent. The increase in nitrogen and decrease in phosphate content in the cell surface was found in the presence of NIQ. NIQ did not inhibit the expression of fimbriae. PMID:11501411

Latrache, H; Bourlioux, P; Karroua, M; Zahir, H; Hakkou, A

2000-01-01

167

Robust growth of Escherichia coli  

PubMed Central

Summary The quantitative study of the cell growth [1-5] has led to many fundamental insights in our understanding of a wide range of subjects from cell cycle [6-9] to senescence [10]. Of particular importance is the growth rate, whose constancy represents a physiological steady state of an organism. Recent studies, however, suggest that the rate of elongation during exponential growth of bacterial cells decreases cumulatively with replicative age for both asymmetrically [11] and symmetrically [12,13] dividing organisms, implying that a “steady-state” population consists of individual cells that are never in a steady state of growth. To resolve this seeming paradoxical observation, we studied the long-term growth and division patterns of Escherichia coli cells by employing a microfluidic device designed to follow steady state growth and division of a large number of cells at a defined reproductive age. Our analysis of ~105 individual cells reveals a remarkable stability of growth of the mother cell inheriting the same pole for hundreds of generations. We further show that death of E. coli is not purely stochastic but is the result of accumulating damages. We conclude that E. coli, unlike all other aging model systems studied to date, has a robust mechanism of growth that is decoupled from cell death.

Wang, Ping; Robert, Lydia; Pelletier, James; Dang, Wei Lien; Taddei, Francois; Wright, Andrew; Jun, Suckjoon

2010-01-01

168

Effect of 2,4-Dichlorophenoxyacetic acid herbicide Escherichia coli growth, chemical, composition, and cellular envelope  

USGS Publications Warehouse

2,4-Dichlorophenoxyacetic acid (2,4-D) is a herbicide widely used in the world and mainly excreted by the renal route in exposed humans and animals. Herbicides can affect other nontarget organisms, such as Escherichia coli. We observed that a single exposure to 1 mM 2,4-D diminished growth and total protein content in all E. coli strains tested in vitro. In addition, successive exposures to 0.01 mM 2,4-D had a toxic effect decreasing growth up to early stationary phase. Uropathogenic E. coli adhere to epithelial cells mediated by fimbriae, adhesins, and hydrophobic properties. 2,4-D exposure of uropathogenic E. coli demonstrated altered hydrophobicity and fimbriation. Hydrophobicity index values obtained by partition in p-xylene/water were 300-420% higher in exposed cells than in control ones. Furthermore, values of hemagglutination titer, protein contents in fimbrial crude extract, and electron microscopy demonstrated a significant diminution of fimbriation in treated cells. Other envelope alterations could be detected, such as lipoperoxidation, evidenced by decreased polyunsaturated fatty acids and increased lipid degradation products (malonaldehyde), and motility diminution. These alterations decreased cell adherence to erythrocytes, indicating a diminished pathogenic capacity of the 2,4-D-exposed E. coli. ?? 2001 by John Wiley & Sons, Inc.

Carr, R. S.; Biedenbach, J. M.; Hooten, R. L.

2001-01-01

169

DETECTION AND CHARACTERIZATION OF PATHOGENIC ESCHERICHIA COLI  

Technology Transfer Automated Retrieval System (TEKTRAN)

A comparison was made of the relative efficiencies of three enrichment media, Rapid-Chek E. coli O157:H7 Enrichment Broth (REB), BCM Escherichia coli O157:H7 Enrichment Broth (BCM), and modified E. coli broth containing novobiocin (mEC+n), and four selective plating media for detection/isolation of...

170

Nonchemotactic Mutants of Escherichia coli  

PubMed Central

We have isolated 40 mutants of Escherichia coli which are nonchemotactic as judged by their failure to swarm on semisolid tryptone plates or to make bands in capillary tubes containing tryptone broth. All the mutants have normal flagella, a fact shown by their shape and reaction with antiflagella serum. All are fully motile under the microscope and all are sensitive to the phage chi. Unlike its parent, one of the mutants, studied in greater detail, failed to show chemotaxis toward oxygen, glucose, serine, threonine, or aspartic acid. The failure to exhibit chemotaxis does not result from a failure to use the chemicals. The swimming of this mutant was shown to be random. The growth rate was normal under several conditions, and the growth requirements were unchanged. Images

Armstrong, John B.; Adler, Julius; Dahl, Margaret M.

1967-01-01

171

Negative Chemotaxis in Escherichia coli  

PubMed Central

Several methods for detecting or measuring negative chemotaxis are described. Using these, we have surveyed a number of chemicals for their ability to repel Escherichia coli. Although most of the repellents are harmful compounds, harmfulness is neither necessary nor sufficient to make a compound a repellent. The repellents can be grouped into at least nine classes according to (i) competition experiments, (ii) mutants lacking certain of the negative taxes, and (iii) their chemical structure. The specificity of each class was studied. It is suggested that each class corresponds to a distinct chemoreceptor. Generally, non-chemotactic mutants lack both positive and negative chemotaxis, and l-methionine is required for both kinds of taxis. Repellents at very low concentrations are not attractants, and attractants at very high concentrations are not repellents. Images

Tso, Wung-Wai; Adler, Julius

1974-01-01

172

Comparative Genomics of Escherichia coli Strains Causing Urinary Tract Infections ? †  

PubMed Central

The virulence determinants of uropathogenic Escherichia coli have been studied extensively over the years, but relatively little is known about what differentiates isolates causing various types of urinary tract infections. In this study, we compared the genomic profiles of 45 strains from a range of different clinical backgrounds, i.e., urosepsis, pyelonephritis, cystitis, and asymptomatic bacteriuria (ABU), using comparative genomic hybridization analysis. A microarray based on 31 complete E. coli sequences was used. It emerged that there is little correlation between the genotypes of the strains and their disease categories but strong correlation between the genotype and the phylogenetic group association. Also, very few genetic differences may exist between isolates causing symptomatic and asymptomatic infections. Only relatively few genes that could potentially differentiate between the individual disease categories were identified. Among these were two genomic islands, namely, pathogenicity island (PAI)-CFT073-serU and PAI-CFT073-pheU, which were significantly more associated with the pyelonephritis and urosepsis isolates than with the ABU and cystitis isolates. These two islands harbor genes encoding virulence factors, such as P fimbriae (pyelonephritis-associated fimbriae) and an important immunomodulatory protein, TcpC. It seems that both urovirulence and growth fitness can be attributed to an assortment of genes rather than to a specific gene set. Taken together, urovirulence and fitness are the results of the interplay of a mixture of factors taken from a rich menu of genes.

Vejborg, Rebecca Munk; Hancock, Viktoria; Schembri, Mark A.; Klemm, Per

2011-01-01

173

Peptidoglycan Hydrolases of Escherichia coli  

PubMed Central

Summary: The review summarizes the abundant information on the 35 identified peptidoglycan (PG) hydrolases of Escherichia coli classified into 12 distinct families, including mainly glycosidases, peptidases, and amidases. An attempt is also made to critically assess their functions in PG maturation, turnover, elongation, septation, and recycling as well as in cell autolysis. There is at least one hydrolytic activity for each bond linking PG components, and most hydrolase genes were identified. Few hydrolases appear to be individually essential. The crystal structures and reaction mechanisms of certain hydrolases having defined functions were investigated. However, our knowledge of the biochemical properties of most hydrolases still remains fragmentary, and that of their cellular functions remains elusive. Owing to redundancy, PG hydrolases far outnumber the enzymes of PG biosynthesis. The presence of the two sets of enzymes acting on the PG bonds raises the question of their functional correlations. It is difficult to understand why E. coli keeps such a large set of PG hydrolases. The subtle differences in substrate specificities between the isoenzymes of each family certainly reflect a variety of as-yet-unidentified physiological functions. Their study will be a far more difficult challenge than that of the steps of the PG biosynthesis pathway.

van Heijenoort, Jean

2011-01-01

174

Molecular epidemiology of 3 putative virulence genes for Escherichia coli urinary tract infection-usp, iha, and iroN(E. coli).  

PubMed

This study describes the epidemiological association of 3 putative genes for virulence of uropathogenic Escherichia coli; uropathogenic specific protein (usp), a Vibrio cholerae zot gene homologue; IrgA homologue adhesin (iha), a nonhemagglutinating adhesin; and iroN(E. coli), a catechole siderophore receptor homologue. We compared the relative frequency in urinary tract infection (UTI) isolates (n=508), compared with non-UTI isolates (n=416). iroN(E. coli) occurred 2.1-3.6 times more frequently in UTI isolates than in rectal isolates (P=1.1x10-18 to P=2.7x10-5) and was associated with several uropathogenic virulence genes found on pathogenicity islands. usp occurred more frequently in isolates from patients with pyelonephritis (P=3.6x10-9), in periurethral isolates (P=.001), and in isolates from patients with UTI who were aged 40-65 years (P=.004), when compared with the rectal isolates; iha was not associated with UTI in this study. PMID:11992291

Bauer, Richard J; Zhang, Lixin; Foxman, Betsy; Siitonen, Anja; Jantunen, Maria E; Saxen, Harri; Marrs, Carl F

2002-04-30

175

Strategies for Protein Overproduction in Escherichia coli.  

ERIC Educational Resources Information Center

|Examines heterologous expression in Escherichia coli and the role of regulatory sequences which control gene expression at transcription resulting in abundant production of messenger RNA and regulatory sequences in mRNA which promote efficient translation. Also examines the role of E. coli cells in stabilizing mRNA and protein that is…

Mott, John E.

1984-01-01

176

MANURE DECREASES ESCHERICHIA COLI ATTACHMENT TO SOIL  

Technology Transfer Automated Retrieval System (TEKTRAN)

Attachment of bacteria to soil is an important component of bacterial fate and transport. Escherichia. coli are commonly used as indicators of fecal contamination in the environment. Despite the fact that E. coli are derived exclusively from feces/manure, relatively little is known about the effect...

177

Clinical Characteristics of Adult Escherichia coli Meningitis  

Microsoft Academic Search

SUMMARY: The clinical characteristics and therapeutic outcomes of adult meningitis due to Escherichia coli alone have not been examined adequately. In this study, we analyzed the clinical and laboratory data of 15 adult patients with monomicrobial E. coli meningitis. The 15 patients, collected over a period of 18 years (January 1986 - December 2003), included 7 men and 8 women,

Tzu-Ming Yang; Cheng-Hsien Lu; Chi-Ren Huang; Hui-Hong Tsai; Nai-Wen Tsai; Ping-Yu Lee; Chun-Chih Chien; Wen-Neng Chang

178

Natural plasmid transformation in Escherichia coli  

Microsoft Academic Search

AlthoughEscherichia coli does not have a natural transformation process, strains ofE. coli can incorporate extracellular plasmids into cytoplasm ‘naturally’ at low frequencies. A standard method was developed in which stationary phase cells were concentrated, mixed with plasmids, and then plated on agar plates with nutrients which allowed cells to grow. Transformed cells could then be selected by harvesting cells and

Suh-Der Tsen; Suh-Sen Fang; Mei-Jye Chen; Jun-Yi Chien; Chih-Chun Lee; Darwin Han-Lin Tsen

2002-01-01

179

Natural Plasmid Transformation in Escherichia coli  

Microsoft Academic Search

Although Escherichia coli does not have a natural transformation process, strains of E. coli can incorporate extracellular plasmids into cytoplasm ‘naturally’ at low frequencies. A standard method was developed in which stationary phase cells were concentrated, mixed with plasmids, and then plated on agar plates with nutrients which allowed cells to grow. Transformed cells could then be selected by harvesting

Suh-Der Tsen; Suh-Sen Fang; Mei-Jye Chen; Jun-Yi Chien; Chih-Chun Lee; Darwin Han-Lin Tsen

2002-01-01

180

Phenotypic Dissociation in an Escherichia coli Population  

Microsoft Academic Search

It was shown in the preceding work [1] that Escherichia coli colonies have an elaborate spatial structure. This structure is arbitrarily divided into four zones. Two cell forms of E. coli (coccobacteria and long rodshaped bacteria) are observed in growing colonies. Formation of long rods (filaments) can be induced by mutations and chemical agents [2]. The goal of this work

V. V. Kravchenko; A. B. Medvinskii; G. R. Ivanitskii

2000-01-01

181

Transcriptional proofreading in Escherichia coli.  

PubMed Central

A novel transcriptional proofreading mechanism associated with the beta-subunit of wild-type RNA polymerase from Escherichia coli is suggested from the following data. The purified holoenzyme contains an NTPase activity which specifically converts noncognate NTPs to their corresponding NDP in a template-dependent manner during in vitro transcription of synthetic single- and double-stranded templates. In contrast, purified enzyme from an rpoB mutant which shows increased transcriptional error lacked template-dependent NTP hydrolytic activity. The NTP hydrolytic activity of wild-type enzyme was critically dependent on the integrity of the initiation complex, and required continued transcriptional elongation. Transcription and translation of the lacZ gene proceeded 17% faster in the mutant than in its wild-type parent. These results are discussed in terms of a proofreading model in which the rate of transcription is limited by proofreading events that involve recognition and hydrolysis of noncognate NTPs before they can be misincorporated into RNA. Images

Libby, R T; Nelson, J L; Calvo, J M; Gallant, J A

1989-01-01

182

Succinate production in Escherichia coli.  

PubMed

Succinate has been recognized as an important platform chemical that can be produced from biomass. While a number of organisms are capable of succinate production naturally, this review focuses on the engineering of Escherichia coli for the production of four-carbon dicarboxylic acid. Important features of a succinate production system are to achieve an optimal balance of reducing equivalents generated by consumption of the feedstock, while maximizing the amount of carbon channeled into the product. Aerobic and anaerobic production strains have been developed and applied to production from glucose and other abundant carbon sources. Metabolic engineering methods and strain evolution have been used and supplemented by the recent application of systems biology and in silico modeling tools to construct optimal production strains. The metabolic capacity of the production strain, the requirement for efficient recovery of succinate, and the reliability of the performance under scaleup are important in the overall process. The costs of the overall biorefinery-compatible process will determine the economic commercialization of succinate and its impact in larger chemical markets. PMID:21932253

Thakker, Chandresh; Martínez, Irene; San, Ka-Yiu; Bennett, George N

2011-09-20

183

Urinary bactericidal activity of single doses (250, 500, 750 and 1000 mg) of levofloxacin against fluoroquinolone-resistant strains of Escherichia coli  

Microsoft Academic Search

Increasing resistance to fluoroquinolones in uropathogens has become a clinical concern. The purpose of this study was to analyse the urinary bactericidal activity (UBA) of levofloxacin against fluoroquinolone-resistant strains of Escherichia coli. Ten healthy adult subjects (aged 23–60 years) received single doses of levofloxacin (250, 500, 750 and 1000mg) and then blood and urine samples were collected in intervals (0–1.5,

Gary E. Stein; Sharon L. Schooley; David P. Nicolau

2008-01-01

184

Virulence factors in Escherichia coli urinary tract infection.  

PubMed

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. PMID:1672263

Johnson, J R

1991-01-01

185

Iron induces bimodal population development by Escherichia coli  

PubMed Central

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.

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

186

Adhesive threads of extraintestinal pathogenic Escherichia coli  

PubMed Central

The ability to adhere to host surfaces is by far the most vital step in the successful colonization by microbial pathogens. Colonization begins with the attachment of the bacterium to receptors expressed by cells forming the lining of the mucosa. Long hair like extracellular appendages called fimbriae, produced by most Gram-negative pathogens, mediate specific attachment to the epithelial cell surface. Associated with the fimbriae is a protein called an adhesin, which directs high-affinity binding to specific cell surface components. In the last couple of years, an enormous amount of research has been undertaken that deals with understanding how bacterial pathogens adhere to host cells. E. coli in all probability is one of the best studied free-living organisms. A group of E. coli called Extraintestinal pathogenic E. coli (ExPEC) including both human and animal pathogens like Uropathogenic E. coli (UPEC), Newborn meningitic E. coli (NMEC) and Avian pathogenic E. coli (APEC), have been found to harbour many fimbriae including Type 1 fimbriae, P fimbriae, curli fibres, S fimbriae, F1C fimbriae, Dr fimbriae, afimbrial adhesins, temperature-sensitive haemagglutinin and many novel adhesin gene clusters that have not yet been characterized. Each of these adhesins is unique due to the recognition of an adhesin-specific receptor, though as a group these adhesins share common genomic organization. A newly identified putative adhesin temporarily termed ExPEC Adhesin I, encoded by gene yqi, has been recently found to play a significant role in the pathogenesis of APEC infection, thus making it an interesting candidate for future research. The aim of this review is to describe the role of ExPEC adhesins during extraintestinal infections known till date, and to suggest the idea of investigating their potential role in the colonization of the host gut which is said to be a reservoir for ExPEC.

2009-01-01

187

Growth rate of Escherichia coli.  

PubMed Central

It should be possible to predict the rate of growth of Escherichia coli of a given genotype in a specified environment. The idea that the rate of synthesis of ATP determines the rate of growth and that the yield of ATP determines the yield of growth is entrenched in bacterial physiology, yet this idea is inconsistent with experimental results. In minimal media the growth rate and yield vary with the carbon source in a manner independent of the rate of formation and yield of ATP. With acetate as the carbon source, anapleurotic reactions, not ATP synthesis, limit the growth rate. For acetate and other gluconeogenic substrates the limiting step appears to be the formation of triose phosphate. I conclude that the rate of growth is controlled by the rate of formation of a precursor metabolite and, thus, of monomers such as amino acids derived from it. The protein-synthesizing system is regulated according to demand for protein synthesis. I examine the conjecture that the signal for this regulation is the ratio of uncharged tRNA to aminoacyl-tRNA, that this signal controls the concentration of guanosine tetraphosphate, and that the concentration of guanosine tetraphosphate controls transcription of rrn genes. Differential equations describing this system were solved numerically for steady states of growth; the computed values of ribosomes and guanosine tetraphosphate and the maximal growth rate agree with experimental values obtained from the literature of the past 35 years. These equations were also solved for dynamical states corresponding to nutritional shifts up and down.

Marr, A G

1991-01-01

188

Clinical Implications of Enteroadherent Escherichia coli  

PubMed Central

Pathogenic Escherichia coli that colonize the small intestine primarily cause gastrointestinal illness in infants and travelers. The main categories of pathogenic E. coli that colonize the epithelial lining of the small intestine are enterotoxigenic E. coli enteropathogenic E. coli and enteroaggregative E. coli. These organisms accomplish their pathogenic process by a complex, coordinated multistage strategy, including non-intimate adherence mediated by various adhesins. These so called “enteroadherent E. coli ” categories subsequently produced toxins or effector proteins that are either secreted to the milieu or injected to the host cell. Finally, destruction of the intestinal microvilli results from the intimate adherence or the toxic effect exerted over the epithelia, resulting in water secretion and diarrhea. In this review, we summarize the current state of knowledge regarding these enteroadherent E. coli strains and the present clinical understanding of how these organisms colonize the human intestine and cause disease.

Arenas-Hernandez, Margarita M.P.; Martinez-Laguna, Ygnacio; Torres, Alfredo G.

2012-01-01

189

Pathogenic Escherichia coli Found in Sewage Treatment Plants and Environmental Waters  

PubMed Central

We previously demonstrated that some Escherichia coli strains with uropathogenic properties survived treatment stages of sewage treatment plants (STPs), suggesting that they may be released into the environment. We investigated the presence of such strains in the surrounding environmental waters of four STPs from which these persistent strains were isolated. In all, 264 E. coli isolates were collected from 129 receiving water sites in a 20-km radius surrounding STPs. We also included 93 E. coli strains collected from 18 animal species for comparison. Isolates were typed using a high-resolution biochemical fingerprinting method (the PhPlate system), and grouped into common (C) types. One hundred forty-seven (56%) environmental isolates were identical to strains found in STPs' final effluents. Of these, 140 (95%) carried virulence genes (VGs) associated with intestinal pathogenic E. coli (IPEC) or uropathogenic E. coli (UPEC) and were found in a variety of sites within areas sampled. Of the remaining 117 environmental strains not identical to STP strains, 105 belonged to 18 C types and 102 of them carried VGs found among IPEC or UPEC strains. These strains belonged mainly to phylogenetic groups A (A0 and A1) and B1 and to a lesser extent B22, B23, D1, and D2. Eight of 18 environmental C types, comprising 50 isolates, were also identical to bird strains. The presence of a high percentage of environmental E. coli in waters near STPs carrying VGs associated with IPEC and UPEC suggests that they may have derived from STP effluents and other nonpoint sources.

Anastasi, E. M.; Matthews, B.; Stratton, H. M.

2012-01-01

190

BAM: Diarrheagenic Escherichia coli  

Center for Food Safety and Applied Nutrition (CFSAN)

... a small loopful of growth from TSAYE ... Coliforms, fecal coliforms, Escherichia coli and enteropathogenic E ... Escherichia coli and the Coliform Bacteria. ... More results from www.fda.gov/food/foodscienceresearch/laboratorymethods

191

Escherichia coli growth under modeled reduced gravity  

Microsoft Academic Search

Bacteria exhibit varying responses to modeled reduced gravity that can be simulated by clino-rotation. WhenEscherichia coli was subjected to different rotation speeds during clino-rotation, significant differences between modeled reduced gravity\\u000a and normal gravity controls were observed only at higher speeds (30–50 rpm). There was no apparent affect of removing samples\\u000a on the results obtained. WhenE. coli was grown in minimal

Paul W. Baker; Michelle L. Meyer; Laura G. Leff

2004-01-01

192

Native valve Escherichia coli endocarditis following urosepsis  

PubMed Central

Gram-negative organisms are a rare cause of infective endocarditis. Escherichia coli, the most common cause of urinary tract infection and gram-negative septicemia involves endocardium rarely. In this case report, we describe infection of native mitral valve by E. coli following septicemia of urinary tract origin in a diabetic male; subsequently, he required prosthetic tissue valve replacement indicated by persistent sepsis and congestive cardiac failure.

Rangarajan, D.; Ramakrishnan, S.; Patro, K. C.; Devaraj, S.; Krishnamurthy, V.; Kothari, Y.; Satyaki, N.

2013-01-01

193

Expanding the Genetic Code of Escherichia coli  

Microsoft Academic Search

A unique transfer RNA (tRNA)\\/aminoacyl-tRNA synthetase pair has been generated that expands the number of genetically encoded amino acids in Escherichia coli. When introduced into E. coli, this pair leads to the in vivo incorporation of the synthetic amino acid O-methyl-L-tyrosine into protein in response to an amber nonsense codon. The fidelity of translation is greater than 99%, as determined

Lei Wang; Ansgar Brock; Brad Herberich; Peter G. Schultz

2001-01-01

194

Inactivation of Escherichia coli by photocatalytic oxidation  

Microsoft Academic Search

The inactivation of Escherichia coli (Ecoli) was studied in presterilized surface water sample using titanium dioxide as the photocatalyst under irradiation of BLF Fluorescent lamps. Inactivation of E. coli ( 103 CFU\\/mL) was achieved in 60 min in the presence of 1.0 mg Ti02 \\/ mL. Photocatalytic inactivation data was evaluated in terms of first order rate equation N\\/N0 =

Miray Bekbölet; Claudia V. Araz

1996-01-01

195

Uropathogenic E. coli Induce Different Immune Response in Testicular and Peritoneal Macrophages: Implications for Testicular Immune Privilege  

Microsoft Academic Search

Infertility affects one in seven couples and ascending bacterial infections of the male genitourinary tract by Escherichia coli are an important cause of male factor infertility. Thus understanding mechanisms by which immunocompetent cells such as testicular macrophages (TM) respond to infection and how bacterial pathogens manipulate defense pathways is of importance. Whole genome expression profiling of TM and peritoneal macrophages

Sudhanshu Bhushan; Hamid Hossain; Yongning Lu; Andreas Geisler; Svetlin Tchatalbachev; Zbigniew Mikulski; Gerhard Schuler; Jörg Klug; Adrian Pilatz; Florian Wagenlehner; Trinad Chakraborty; Andreas Meinhardt

2011-01-01

196

In vitro binding of type 1-fimbriated Escherichia coli to uroplakins Ia and Ib: relation to urinary tract infections.  

PubMed Central

Urinary tract infections, caused mainly by Escherichia coli, are among the most common infectious diseases. Most isolates of the uropathogenic E.coli can express type 1 and P fimbriae containing adhesins that recognize cell receptors. While P fimbriae recognize kidney glycolipid receptors and are involved in peyelonephritis, the urothelial for type 1 fimbriae were not identified. We show that type 1-fimbriated E. coli recognize uroplakins Ia and Ib, two major glycoproteins of urothelial apical plaques. Anchorage of E. coli to urothelial surface via type 1 fimbriae-uroplakin I interactions may play a role in its bladder colonization and eventual ascent through the ureters, against urine flow, to invade the kidneys. Images Fig. 5

Wu, X R; Sun, T T; Medina, J J

1996-01-01

197

Endogenous endophthalmitis caused by Escherichia coli.  

PubMed

Endophthalmitis is a rare complication of Escherichia coli-induced septicemia. Nine cases of endogenous endophthalmitis caused by E. coli have been reported previously, all except one in patients with diabetes. The most common primary site of infection is the urinary tract. The course of illness is rapidly progressive with a poor visual prognosis. Concurrent systemic morbidity, including body abscesses and endocarditis, is high. We report an additional case of endogenous endophthalmitis from E. coli in a diabetic woman. Enucleation was required despite aggressive topical and systemic treatment. The pertinent literature is reviewed. PMID:8460886

Park, S B; Searl, S S; Aquavella, J V; Erdey, R A

1993-03-01

198

Lysis of Escherichia coli by Marine Microorganisms  

Microsoft Academic Search

INVESTIGATIONS of the lethal effect of seawater on Escherichia coli, the common indicator organism for pollution by intestinal pathogens, have suggested a variety of possible mechanisms1-3. The negative effect of heat sterilization of seawater on its specific bactericidal action indicates a biological interaction which has been neither confirmed nor disproved. We attempt to define here the role of the native

R. Mitchell; Shlomit Yankofsky; H. W. JANNASCH

1967-01-01

199

Regulation of Alcohol Fermentation by Escherichia Coli.  

National Technical Information Service (NTIS)

The purpose of this project is to elucidate the way in which the fermentative synthesis of ethanol is regulated in the facultative anaerobe Escherichia coli. Focus is on the two final steps in alcohol synthesis, which are catalyzed by alcohol dehydrogenas...

D. P. Clark

1986-01-01

200

Transcriptional Response of Escherichia coli to TPEN  

PubMed Central

DNA microarrays were used to probe the transcriptional response of Escherichia coli to N,N,N?,N?-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN). Fifty-five transcripts were significantly up-regulated, including all of the genes that are regulated by Zur and many that are regulated by Fur. In the same TPEN-treated cells, 46 transcripts were significantly down-regulated.

Sigdel, Tara K.; Easton, J. Allen; Crowder, Michael W.

2006-01-01

201

Escherichia coli O157 and Children  

MedlinePLUS

... toddlers who may fall down frequently. Avoid hand-to-mouth behaviors. Do not let children use pacifiers or sippy cups while in a ... shared, sold, traded, exchanged, or rented. Please refer to The JAMA Network's Privacy Policy for ... Escherichia coli O157 and Children. Arch Pediatr Adolesc Med. 2009;163(1):96. ...

202

Development of Bacteriophage in Escherichia coli B  

Microsoft Academic Search

EXAMINATION of living cultures of Salmonella typhimurium by phase-contrast illumination has revealed the presence of characteristic changes when this organism is infected with different bacteriophages1. The corresponding changes which occur in infected Escherichia coli B. have now been studied by the same method. The seven members of the `T' series of coliphages2 have been classified in terms of serological characters,

J. S. K. Boyd

1949-01-01

203

Prevalence of Multiple Drug Resistant Escherichia coli Serotypes in a Tropical Estuary, India.  

PubMed

A total of eighty-one Escherichia coli isolates belongs to forty-three different serotypes including several pathogenic strains such as enterotoxigenic E. coli (ETEC), enterohaemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC) and uropathogenic E. coli (UPEC) isolated from a tropical estuary were tested against 12 antibiotics to determine the prevalence of multiple antibiotic resistance (MAR), antimicrobial resistance profiles and also to find out high risk source of contamination by MAR indexing. The results revealed that more than 95% of the isolates were multiple antibiotic resistant (resistant to more than three antibiotics). Resistance to vancomycin, novobiocin, kanamycin, oxytetracycline, tetracycline, streptomycin was high (>80%), resistance to other antibiotics was relatively less. The MAR indexing of the isolates showed that all these strains were originated from high risk source of contamination. The incidence of multiple antibiotic resistant E. coli especially the pathogenic strains in natural water will pose a serious health risk to the human population and also act as a `manmade' reservoir of resistance genes for (potentially) pathogenic bacteria. The determination of antibiotic susceptibility/resistance patterns of isolated microbes is a part of the microbial monitoring process of the water which would be important for the meaningful interpretation of sanitary water quality data. PMID:21558702

Chandran, Abhirosh; Hatha, A A Mohamed; Varghese, Sherin; Sheeja, K Mony

2008-01-01

204

Increased Expression of Type-1 Fimbriae by Nonpathogenic Escherichia coli 83972 Results in an Increased Capacity for Catheter Adherence and Bacterial Interference  

PubMed Central

Background In vitro, urinary catheter colonization by avirulent Escherichia coli 83972 impedes subsequent catheter colonization by a variety of uropathogenic organisms. However, E. coli 83972 shows a low efficacy of adherence to silicone urinary catheter material, possibly because the fim operon encoding adhesive type 1 fimbriae is incomplete. We hypothesized that improving the catheter adherence of E. coli 83972 would improve its bacterial interference properties. Methods We created adhesive mutants by transforming wild-type E. coli 83972 with fim+ plasmids. Adherence to urinary catheters and ability to prevent uropathogenic E. coli from colonizing urinary catheters were studied by use of a sonication assay. Results The addition of a single-copy fim+ plasmid increased adherence to urinary catheters 10-fold, and addition of an 18-copy fim+ plasmid increased adherence 100-fold. The more adherent 18-copy fim+ plasmid strain was more effective at blocking catheter colonization by pathogenic E. coli than was the wild-type parental strain. Neither ?fim nor fim+ E. coli 83972 adhered to shed urinary epithelial cells. Conclusions Our results indicate that improving urinary catheter adherence augments the bacterial interference capabilities of benign E. coli 83972. Increased expression of type-1 fimbriae may enhance bacterial interference without conferring virulence on E. coli 83972.

Trautner, Barbara W.; Cevallos, Manuel E.; Li, Huaiguang; Riosa, Sarah; Hull, Richard A.; Hull, Sheila I.; Tweardy, David J.; Darouiche, Rabih O.

2010-01-01

205

Mechanisms accounting for fluoroquinolone multidrug resistance Escherichia coli isolated from companion animals.  

PubMed

Multidrug resistance (MDR) is associated with fluoroquinolone (FQ) resistance in companion animal Escherichia coli (E. coli). In this study, gyrA, gyrB, parC, and parE quinolone resistance determining regions (QRDR) were sequenced among uropathogenic E. coli isolates with different resistant phenotypes. Also determined were porin, efflux pump and regulatory gene expression based on quantitative real-time reverse transcriptase PCR (qRT-PCR), the impact of efflux pump inhibition (Phe-Arg-?-naphthylamide) and the presence of plasmid-mediated quinolone resistance (PMQR). Using enrofloxacin as the prototypic FQ, we found that (i) the number of mutations in target genes correlate well with minimum inhibitory concentrations (MICs). A single mutation (Ser83Leu) in gyrA increases FQ MIC in susceptible isolates; subsequent mutations result in resistance that increases from low (enrofloxacin MICs 4-16 ?g/ml) to high level (enrofloxacin MICs?128 ?g/ml) with each progressive mutation. (ii) as MIC increase, acrB activity and the number of drug classes contributing to the MDR phenotype increases; (iii) a consistent relationship between regulatory gene expression and MIC could not be identified; and (iv) qnrS and aac(6')-Ib-cr gene were detected in 14 and 5 ENR(R)-MDR isolates containing the target mutation, respectively. Of 13 isolates expressing PDR isolates, 10 (77%) were positive for qnrS gene, and 4 (40%) carried both qnrS and aac(6')-Ib-cr gene. These findings demonstrated that MDR-associated FQ resistance in canine and feline uropathogenic E. coli reflects a combination of point mutations, enhanced efflux pump activities, and PMQR mechanisms. Point mutations in DNA gyrase, however, are necessary to achieve a clinical level of FQ resistance. PMID:22877517

Liu, Xiaoqiang; Boothe, Dawn M; Thungrat, Kamoltip; Aly, Sherine

2012-07-20

206

Serological Cross-Reactions between 'Escherichia coli' O157 and other Species of the Genus 'Escherichia'.  

National Technical Information Service (NTIS)

The antigenic relatedness of Escherichia coli O157 and four sorbitol-negative species of the genus Escherichia was examined. Isolates of Escherichia hermannii, E. fergusonii, E. vulneris, and E. blattae were tested in the tube agglutination assay by using...

E. W. Rice E. G. Sowers C. H. Johnson M. E. Dunnigan N. A. Strockbine

1992-01-01

207

FTIR nanobiosensors for Escherichia coli detection  

PubMed Central

Summary Infections due to enterohaemorrhagic E. coli (Escherichia coli) have a low incidence but can have severe and sometimes fatal health consequences, and thus represent some of the most serious diseases due to the contamination of water and food. New, fast and simple devices that monitor these pathogens are necessary to improve the safety of our food supply chain. In this work we report on mesoporous titania thin-film substrates as sensors to detect E. coli O157:H7. Titania films treated with APTES ((3-aminopropyl)triethoxysilane) and GA (glutaraldehyde) were functionalized with specific antibodies and the absorption properties monitored. The film-based biosensors showed a detection limit for E. coli of 1 × 102 CFU/mL, constituting a simple and selective method for the effective screening of water samples.

Greppi, Gianfranco; Marongiu, Maria Laura; Roggero, Pier Paolo; Ravindranath, Sandeep P; Mauer, Lisa J; Schibeci, Nicoletta; Perria, Francesco; Piccinini, Massimo; Innocenzi, Plinio; Irudayaraj, Joseph

2012-01-01

208

Infectious endocarditis caused by Escherichia coli.  

PubMed

Although Escherichia coli is among the most common causes of Gram-negative bacteraemia, infectious endocarditis (IE) due to this pathogen is rare. A 67-y-old male without a previous medical history presented with a new mitral regurgitation murmur and persisting E. coli bacteraemia in spite of broad-spectrum intravenous antibiotics. Transthoracic and transoesophageal echocardiography revealed a severe mitral endocarditis. E. coli DNA was identified from the mitral valve and the vegetation, and no other pathogen was found. The case was further complicated by spondylodiscitis and bilateral endophthalmitis. Extra-intestinal pathogenic E. coli (ExPEC) are able to colonize tissue outside the gastrointestinal tract and contain a variety of virulence factors that may enable the pathogens to invade and induce infections in the cardiac endothelia. In these cases echocardiography as the imaging technology is of paramount importance for the correct diagnosis and treatment. PMID:21309637

Lauridsen, Trine Kiilerich; Arpi, Magnus; Fritz-Hansen, Thomas; Frimodt-Mřller, Niels; Bruun, Niels Eske

2011-02-10

209

FTIR nanobiosensors for Escherichia coli detection.  

PubMed

Infections due to enterohaemorrhagic E. coli (Escherichia coli) have a low incidence but can have severe and sometimes fatal health consequences, and thus represent some of the most serious diseases due to the contamination of water and food. New, fast and simple devices that monitor these pathogens are necessary to improve the safety of our food supply chain. In this work we report on mesoporous titania thin-film substrates as sensors to detect E. coli O157:H7. Titania films treated with APTES ((3-aminopropyl)triethoxysilane) and GA (glutaraldehyde) were functionalized with specific antibodies and the absorption properties monitored. The film-based biosensors showed a detection limit for E. coli of 1 × 10(2) CFU/mL, constituting a simple and selective method for the effective screening of water samples. PMID:23019542

Mura, Stefania; Greppi, Gianfranco; Marongiu, Maria Laura; Roggero, Pier Paolo; Ravindranath, Sandeep P; Mauer, Lisa J; Schibeci, Nicoletta; Perria, Francesco; Piccinini, Massimo; Innocenzi, Plinio; Irudayaraj, Joseph

2012-07-03

210

Escherichia coli genosensor based on polyaniline.  

PubMed

Avidin-modified polyaniline (PANI) electrochemically deposited onto a Pt disk electrode has been utilized for direct detection of Escherichia coli by immobilizing a 5'-biotin-labeled E. coli probe (BdE) using a differential pulse voltammetric technique in the presence of methylene blue as a DNA hybridization indicator. Depending on the target sample and the sonication time, this BdE-avidin-PANI bioelectrode can be utilized to electrochemically detect a complementary target probe (0.009 ng/microL), E. coli genomic DNA (0.01 ng/microL) and 11 E. coli cells/mL in 60 s to 14 min (hybridization time) without using PCR and can be used 5-7 times at temperatures of 30-45 degrees C. PMID:17630719

Arora, Kavita; Prabhakar, Nirmal; Chand, Subhash; Malhotra, B D

2007-07-14

211

Escherichia coli Biofilms Have an Organized and Complex Extracellular Matrix Structure  

PubMed Central

ABSTRACT Bacterial biofilms are ubiquitous in nature, and their resilience is derived in part from a complex extracellular matrix that can be tailored to meet environmental demands. Although common developmental stages leading to biofilm formation have been described, how the extracellular components are organized to allow three-dimensional biofilm development is not well understood. Here we show that uropathogenic Escherichia coli (UPEC) strains produce a biofilm with a highly ordered and complex extracellular matrix (ECM). We used electron microscopy (EM) techniques to image floating biofilms (pellicles) formed by UPEC. EM revealed intricately constructed substructures within the ECM that encase individual, spatially segregated bacteria with a distinctive morphology. Mutational and biochemical analyses of these biofilms confirmed curli as a major matrix component and revealed important roles for cellulose, flagella, and type 1 pili in pellicle integrity and ECM infrastructure. Collectively, the findings of this study elucidated that UPEC pellicles have a highly organized ultrastructure that varies spatially across the multicellular community.

Hung, Chia; Zhou, Yizhou; Pinkner, Jerome S.; Dodson, Karen W.; Crowley, Jan R.; Heuser, John; Chapman, Matthew R.; Hadjifrangiskou, Maria; Henderson, Jeffrey P.; Hultgren, Scott J.

2013-01-01

212

Escherichia coli Uropathogenesis In Vitro: Invasion, Cellular Escape, and Secondary Infection Analyzed in a Human Bladder Cell Infection Model  

PubMed Central

Uropathogenic Escherichia coli (UPEC) strains are capable of invading bladder epithelial cells (BECs) on the bladder luminal surface. Based primarily on studies in mouse models, invasion is proposed to trigger an intracellular uropathogenic cascade involving intracellular bacterial proliferation followed by escape of elongated, filamentous bacteria from colonized BECs. UPEC filaments on the mouse bladder epithelium are able to revert to rod-shaped bacteria, which are believed to invade neighboring cells to initiate new rounds of intracellular colonization. So far, however, these late-stage infection events have not been replicated in vitro. We have established an in vitro model of human bladder cell infection by the use of a flow chamber (FC)-based culture system, which allows investigation of steps subsequent to initial invasion. Short-term bacterial colonization on the FC-BEC layer led to intracellular colonization. Exposing invaded BECs to a flow of urine, i.e., establishing conditions similar to those faced by UPEC reemerging on the bladder luminal surface, led to outgrowth of filamentous bacteria similar to what has been reported to occur in mice. These filaments were capable of reverting to rods that could invade other BECs. Hence, under growth conditions established to resemble those present in vivo, the elements of the proposed uropathogenic cascade were inducible in a human BEC model system. Here, we describe the model and show how these characteristics are reproduced in vitro.

Khandige, Surabhi; Madelung, Michelle; Brewer, Jonathan; Kolmos, Hans J.

2012-01-01

213

Predation of Escherichia coli by Colpoda steinii.  

PubMed Central

A study of single-stage chemostat cultures of Colpoda steinii. Escherichia coli, and glucose is reported here. Two levels of glucose were fed as the limiting nutrient to the chemostat cultures. The cultures were studied at three holding times. Oscillations developed at short holding time and damped oscillations developed a long-residence times that approached steady-state conditions of populations of C. steinii and E. coli and concentrations of glucose. The experimental data are fitted to and compared with Jost's model.

Drake, J F; Tsuchiya, H M

1976-01-01

214

Predation of Escherichia coli by Colpoda steinii.  

PubMed

A study of single-stage chemostat cultures of Colpoda steinii. Escherichia coli, and glucose is reported here. Two levels of glucose were fed as the limiting nutrient to the chemostat cultures. The cultures were studied at three holding times. Oscillations developed at short holding time and damped oscillations developed a long-residence times that approached steady-state conditions of populations of C. steinii and E. coli and concentrations of glucose. The experimental data are fitted to and compared with Jost's model. PMID:820258

Drake, J F; Tsuchiya, H M

1976-06-01

215

Escherichia coli Field Contamination of Pecan Nuts  

PubMed Central

More pecan samples collected from grazed orchards were contaminated with Escherichia coli than were samples from nongrazed orchards. No differences in frequency of contamination between mechanically and manually harvested nuts occurred. Nutmeats from whole uncracked pecans that were soaked for 24 h in a lactose broth solution containing E. coli did not become contaminated. Twentyfour percent of the whole pecans soaked in water for 48 h to simulate standing in a rain puddle developed openings along shell suture lines which did not completely close when the nuts were redried.

Marcus, Karen A.; Amling, H. J.

1973-01-01

216

Torus generated by Escherichia coli  

NASA Astrophysics Data System (ADS)

The bioluminescence images of unstirred cultures show that lux reporter E. coli (0.10 mg biomass per ml of the broth medium) in 6.4-10 mm diameter circular containers induce center-fluid-rising toroidal convection of ?1 mm/min. The bioconvective torus is stable in a Teflon vessel and is deformed by 3.2-4.4 mm wavelength azimuthal waves in polystyrene or glass vessels.

Šimkus, R.; Kirejev, V.; Meškien?, R.; Meškys, R.

2009-02-01

217

FdeC, a Novel Broadly Conserved Escherichia coli Adhesin Eliciting Protection against Urinary Tract Infections  

PubMed Central

ABSTRACT The increasing antibiotic resistance of pathogenic Escherichia coli species and the absence of a pan-protective vaccine pose major health concerns. We recently identified, by subtractive reverse vaccinology, nine Escherichia coli antigens that protect mice from sepsis. In this study, we characterized one of them, ECOK1_0290, named FdeC (factor adherence E. coli) for its ability to mediate E. coli adhesion to mammalian cells and extracellular matrix. This adhesive propensity was consistent with the X-ray structure of one of the FdeC domains that shows a striking structural homology to Yersinia pseudotuberculosis invasin and enteropathogenic E. coli intimin. Confocal imaging analysis revealed that expression of FdeC on the bacterial surface is triggered by interaction of E. coli with host cells. This phenotype was also observed in bladder tissue sections derived from mice infected with an extraintestinal strain. Indeed, we observed that FdeC contributes to colonization of the bladder and kidney, with the wild-type strain outcompeting the fdeC mutant in cochallenge experiments. Finally, intranasal mucosal immunization with recombinant FdeC significantly reduced kidney colonization in mice challenged transurethrally with uropathogenic E. coli, supporting a role for FdeC in urinary tract infections.

Nesta, Barbara; Spraggon, Glen; Alteri, Christopher; Gomes Moriel, Danilo; Rosini, Roberto; Veggi, Daniele; Smith, Sara; Bertoldi, Isabella; Pastorello, Ilaria; Ferlenghi, Ilaria; Fontana, Maria Rita; Frankel, Gad; Mobley, Harry L. T.; Rappuoli, Rino; Pizza, Mariagrazia; Serino, Laura; Soriani, Marco

2012-01-01

218

Production of glycoprotein vaccines in Escherichia coli  

Microsoft Academic Search

BACKGROUND: Conjugate vaccines in which polysaccharide antigens are covalently linked to carrier proteins belong to the most effective and safest vaccines against bacterial pathogens. State-of-the art production of conjugate vaccines using chemical methods is a laborious, multi-step process. In vivo enzymatic coupling using the general glycosylation pathway of Campylobacter jejuni in recombinant Escherichia coli has been suggested as a simpler

Julian Ihssen; Michael Kowarik; Sandro Dilettoso; Cyril Tanner; Michael Wacker; Linda Thöny-Meyer

2010-01-01

219

Engineering the Escherichia coli Fermentative Metabolism  

Microsoft Academic Search

\\u000a Fermentative metabolism constitutes a fundamental cellular capacity for industrial biocatalysis. Escherichia coli is an important microorganism in the field of metabolic engineering for its well-known molecular characteristics and its\\u000a rapid growth. It can adapt to different growth conditions and is able to grow in the presence or absence of oxygen. Through\\u000a the use of metabolic pathway engineering and bioprocessing techniques,

M. Orencio-Trejo; J. Utrilla; M. Fernández-Sandoval; G. Huerta-Beristain; G. Gosset; A. Martinez

2010-01-01

220

Intermediary Metabolite Levels in Escherichia coli  

Microsoft Academic Search

SUMMARY The intra- and extracellular concentrations of a number of phosphorylated inter- mediary metabolites in Escherichia coli were measured radiochemically during growth in low phosphate (0.75 mM) media containing (32P)Pi. Distribution studies showed that most of the monophosphate metabolites were present in the super- natant medium outside the bacteria. This was much less marked for the di- and triphosphates, and

V. MOSES; PAMELA B. SHARP

1972-01-01

221

Suppressor of phosphofructokinase mutations of Escherichia coli.  

PubMed

The known locus of fructose-6-phosphate kinase mutations (pfkA) in Escherichia coli is at 76 min on the genetic map. We have now found another gene, pfkB, at 33 min, mutation of which suppresses pfkA mutations. The suppression is not informational, and pfkB may be a second gene for fructose-6-phosphate kinase activity. PMID:4263401

Morrissey, A T; Fraenkel, D G

1972-10-01

222

Quorum sensing in Escherichia coli and Salmonella  

Microsoft Academic Search

Quorum sensing in Escherichia coli and Salmonella has been an elusive topic for a long time. However, in the past 8 years, several research groups have demonstrated that these bacteria use several quorum-sensing systems, such as: the luxS\\/AI-2, AI-3\\/epinephrine\\/norepinephrine, indole, and the LuxR homolog SdiA to achieve intercellular signaling. The majority of these signaling systems are involved in interspecies communication,

Matthew Walters; Vanessa Sperandio

2006-01-01

223

Action of sodium deoxycholate on Escherichia coli  

SciTech Connect

Sodium deoxycholate is used in a number of bacteriological media for the isolation and classification of gram-negative bacteria from food and the environment. Initial experiments to study the effect of deoxycholate on the growth parameters of Escherichia coli showed an increase in the lag time constant and generation time and a decrease in the growth rate constant total cell yield of this microorganisms. Cell fractionation studies indicated that sodium deoxycholate at levels used in bacteriological media interferes with the incorporation of (U-/sup 14/C)glucose into the cold-trichloroacetic acid-soluble, ethanol-soluble, and trypsin-soluble cellular fractions of E. coli. Finally, sodium deoxycholate interfered with the flagellation and motility of Proteus mirabilis and E. coli. It would appear then that further improvement of the deoxycholate medium may be in order.

D'Mello, A.; Yotis, W.W.

1987-08-01

224

DNA Ligase Mutants of Escherichia coli  

PubMed Central

A procedure is described for the isolation of Escherichia coli mutants with either excess or deficient DNA ligase activity. A mutant that overproduces DNA ligase supports the growth of ligase-defective (gene 30 mutant) T4 phages. Even T4 rII-gene 30 double mutants, which are able to grow in normal E. coli, cannot grow in cells deficient in DNA ligase. A functional DNA ligase, supplied either by the phage or the host, thus seems to be required for T4 growth. An E. coli strain that makes a temperature-sensitive DNA ligase becomes radiation-sensitive at high temperature, but otherwise grows normally and shows no obvious defect in DNA replication.

Gellert, Martin; Bullock, Minnie L.

1970-01-01

225

The lumicins: novel bacteriocins from Photorhabdus luminescens with similarity to the uropathogenic-specific protein (USP) from uropathogenic Escherichia coli  

Microsoft Academic Search

Bacteriocins are proteins produced by bacteria to destroy other bacteria occupying their ecological niche. Photorhabdus luminescens is an insect pathogenic bacterium carried by an entomopathogenic nematode and occupies several different niches in its life cycle. The nematode enters the insect and releases a single strain of P. luminescens. The bacteria then kill the host and the bacteria and nematodes replicate

Sadhana Sharma; Nicholas Waterfield; David Bowen; Thomas Rocheleau; Lisa Holland; Richard James; Richard ffrench-Constant

2002-01-01

226

Clonal and pathotypic analysis of archetypal Escherichia coli cystitis isolate NU14.  

PubMed

Escherichia coli NU14, a cystitis isolate used to study the pathogenesis of cystitis and to develop a FimH (type 1 fimbrial adhesin) vaccine, was assessed for extended virulence genotype, phylogenetic background, and FimH sequence and binding phenotype(s). NU14 exhibited the same virulence genotype and was derived from the same (meningitis- and cystitis-associated) subclone of E. coli O18:K1:H7 as the archetypal neonatal bacterial meningitis (NBM) isolate RS218. NU14 also displayed the same Ser62Ala FimH polymorphism as did NBM isolates RS218 and IHE3034-conferring both collagen binding and a distinct monomannose binding capability (which characterizes uropathogenic but not commensal E. coli and dramatically increases adherence to uroepithelial cells). These findings establish that strain NU14 exhibits numerous urovirulence-associated traits and derives from the single most prevalent clonal group in acute cystitis. They provide further evidence of clonal and pathotypic similarities between cystitis and NBM isolates of E. coli O18:K1:H7. PMID:11740731

Johnson, J R; Weissman, S J; Stell, A L; Trintchina, E; Dykhuizen, D E; Sokurenko, E V

2001-11-01

227

Extensive Genomic Diversity in Pathogenic Escherichia coli and Shigella Strains Revealed by Comparative Genomic Hybridization Microarray †  

PubMed Central

Escherichia coli, including the closely related genus Shigella, is a highly diverse species in terms of genome structure. Comparative genomic hybridization (CGH) microarray analysis was used to compare the gene content of E. coli K-12 with the gene contents of pathogenic strains. Missing genes in a pathogen were detected on a microarray slide spotted with 4,071 open reading frames (ORFs) of W3110, a commonly used wild-type K-12 strain. For 22 strains subjected to the CGH microarray analyses 1,424 ORFs were found to be absent in at least one strain. The common backbone of the E. coli genome was estimated to contain about 2,800 ORFs. The mosaic distribution of absent regions indicated that the genomes of pathogenic strains were highly diversified becasue of insertions and deletions. Prophages, cell envelope genes, transporter genes, and regulator genes in the K-12 genome often were not present in pathogens. The gene contents of the strains tested were recognized as a matrix for a neighbor-joining analysis. The phylogenic tree obtained was consistent with the results of previous studies. However, unique relationships between enteroinvasive strains and Shigella, uropathogenic, and some enteropathogenic strains were suggested by the results of this study. The data demonstrated that the CGH microarray technique is useful not only for genomic comparisons but also for phylogenic analysis of E. coli at the strain level.

Fukiya, Satoru; Mizoguchi, Hiroshi; Tobe, Toru; Mori, Hideo

2004-01-01

228

Comparative Resistance of 'Escherichia coli' and Enterococci to Chlorination.  

National Technical Information Service (NTIS)

Pure cultures of Escherichia coli and Enterococcus faecium were inactivated by free chlorine and monochloramine. Indigenous E. coli and enterococci in wastewater effluents were also inactivated. Selective bacteriological media specifically designed for th...

E. W. Rice T. C. Covert D. K. Wild D. Berman S. A. Johnson

1992-01-01

229

Cation Transport in Escherichia coli  

PubMed Central

Methods have been developed to study the intracellular Na and K concentrations in E. coli, strain K-12. These intracellular cation concentrations have been shown to be functions of the extracellular cation concentrations and the age of the bacterial culture. During the early logarithmic phase of growth, the intracellular K concentration greatly exceeds that of the external medium, whereas the intracellular Na concentration is lower than that of the growth medium. As the age of the culture increases, the intracellular K concentration falls and the intracellular Na concentration rises, changes which are related to the fall in the pH of the medium and to the accumulation of the products of bacterial metabolism. When stationary phase cells, which are rich in Na and poor in K, are resuspended in fresh growth medium, there is a rapid reaccumulation of K and extrusion of Na. These processes represent oppositely directed net ion movements against concentration gradients, and have been shown to be dependent upon the presence of an intact metabolic energy supply.

Schultz, Stanley G.; Solomon, A. K.

1961-01-01

230

A-type cranberry proanthocyanidins and uropathogenic bacterial anti-adhesion activity  

Microsoft Academic Search

Clinical, epidemiological and mechanistic studies support the role of cranberry (Vaccinium macrocarpon Ait.) in maintaining urinary tract health. Cranberry proanthocyanidins contain A-type linkages and have been associated with preventing adhesion of P-fimbriated uropathogenic Escherichia coli to uroepithelial cells. It is not known if the presence of the A-type linkage is a prerequisite for anti-adhesion activity. Other commercial sources of proanthocyanidins

Amy B. Howell; Jess D. Reed; Christian G. Krueger; Ranee Winterbottom; David G. Cunningham; Marge Leahy

2005-01-01

231

Profiling of Escherichia coli Chromosome database.  

PubMed

The Profiling of Escherichia coli Chromosome (PEC) database (http://www.shigen.nig.ac.jp/ecoli/pec/) is designed to allow E. coli researchers to efficiently access information from functional genomics studies. The database contains two principal types of data: gene essentiality and a large collection of E. coli genetic research resources. The essentiality data are based on data compilation from published single-gene essentiality studies and on cell growth studies of large-deletion mutants. Using the circular and linear viewers for both whole genomes and the minimal genome, users can not only gain an overview of the genome structure but also retrieve information on contigs, gene products, mutants, deletions, and so forth. In particular, genome-wide exhaustive mutants are an essential resource for studying E. coli gene functions. Although the genomic database was constructed independently from the genetic resources database, users may seamlessly access both types of data. In addition to these data, the PEC database also provides a summary of homologous genes of other bacterial genomes and of protein structure information, with a comprehensive interface. The PEC is thus a convenient and useful platform for contemporary E. coli researchers. PMID:18392982

Yamazaki, Yukiko; Niki, Hironori; Kato, Jun-ichi

2008-01-01

232

A subset of mucosa-associated Escherichia coli isolates from patients with colon cancer, but not Crohn's disease, share pathogenicity islands with urinary pathogenic E. coli.  

PubMed

Adherent and invasive mucosa-associated Escherichia coli have been implicated in the pathogenesis of colon cancer and inflammatory bowel diseases. It has been reported that such isolates share features of extraintestinal E. coli (ExPEC) and particularly uropathogenic E. coli (UPEC). We used suppression subtractive hybridization (SSH) to subtract the genome of E. coli K-12 from that of a colon cancer mucosal E. coli isolate. Of the subtracted sequences, 53 % were present in the genomes of one or more of three sequenced UPEC strains but absent from the genome of an enterohaemorrhagic E. coli (EHEC) strain. Of the subtracted sequences, 80 % matched at least one UPEC genome, whereas only 4 % were absent from the UPEC genomes but present in the genome of the EHEC strain. A further genomic subtraction against the UPEC strain 536 enriched for sequences matching mobile genetic elements, other ExPEC strains, and other UPEC strains or commensals, rather than strains associated with gastrointestinal disease. We analysed the distribution of selected subtracted sequences and UPEC-associated pathogenicity islands (PAIs) amongst a panel of mucosa-associated E. coli isolated from colonoscopic biopsies of patients with colon cancer, patients with Crohn's disease and controls. This enabled us to identify a group of isolates from colon cancer (30-40 %) carrying multiple genes previously categorized as UPEC-specific and implicated in virulence. PMID:18227261

Bronowski, Christina; Smith, Shirley L; Yokota, Kyoko; Corkill, John E; Martin, Helen M; Campbell, Barry J; Rhodes, Jonathan M; Hart, C Anthony; Winstanley, Craig

2008-02-01

233

Yersinia High Pathogenicity Island genes modify the Escherichia coli primary metabolome independently of siderophore production  

PubMed Central

Bacterial siderophores may enhance pathogenicity by scavenging iron but their expression has been proposed to exert a substantial metabolic cost. Here we describe a combined metabolomic-genetic approach to determine how mutations affecting the virulence-associated siderophore yersiniabactin affect the Escherichia coli primary metabolome. Contrary to expectations, we did not find yersiniabactin biosynthesis to correspond to consistent metabolomic shifts. Instead, we found that targeted deletion of ybtU or ybtA, dissimilar genes with similar roles in regulating yersiniabactin expression, were associated with a specific shift in arginine pathway metabolites during growth in minimal media. This interaction was associated with high arginine levels in the model uropathogen Escherichia coli UTI89 compared to its ybtU and ybtA mutants and the K12 strain MG1655, which lacks yersiniabactin-associated genes. Because arginine is not a direct yersiniabactin biosynthetic substrate, these findings show that virulence-associated secondary metabolite systems may shape bacterial primary metabolism independently of substrate consumption.

Lv, Haitao; Henderson, Jeffrey P

2013-01-01

234

Shear-enhanced binding of intestinal colonization factor antigen I of enterotoxigenic Escherichia coli  

PubMed Central

SUMMARY In the intestine, enterotoxigenic Escherichia coli works against peristaltic forces, adhering to the epithelium via the CFA/I fimbrial adhesin CfaE. The CfaE adhesin is similar in localization and tertiary (but not primary) structure to FimH, the type 1 fimbrial adhesin of uropathogenic Escherichia coli, which shows shear-dependent binding to epithelial receptors by an allosteric catch-bond mechanism. Thus, we speculated that CfaE is also capable of shear-enhanced binding. Indeed, bovine erythrocytes coursing over immobilized CFA/I fimbriae in flow-chambers exhibited low accumulation levels and fast rolling at low shear, but an 80-fold increase in accumulation and 3-fold decrease in rolling velocity at elevated shear. This effect was reversible and abolished by pre-incubation of fimbriae with anti-CfaE antibody. Erythrocytes bound to whole CfaE in the same shear-enhanced manner, but to CfaE adhesin domain in a shear-inhibitable fashion. Residue replacements designed to disrupt CfaE interdomain interaction decreased the shear-dependency of adhesion and increased binding under static conditions to human intestinal epithelial cells. These findings indicate that close interaction between adhesive and anchoring pilin domains of CfaE keeps the former in a low-affinity state that toggles into a high-affinity state upon separation of two domains, all consistent with an allosteric catch-bond mechanism of CfaE binding.

Tchesnokova, Veronika; McVeigh, Annette L.; Kidd, Brian; Yakovenko, Olga; Thomas, Wendy E.; Sokurenko, Evgeni V.; Savarino, Stephen J.

2010-01-01

235

Identification of a Gene Encoding Heat-Resistant Agglutinin in Escherichia coli as a Putative Virulence Factor in Urinary Tract Infection  

PubMed Central

Escherichia coli causes the vast majority of urinary tract infections (UTI) in both ambulatory and hospital patients. Several uropathogenic virulence factors have been identified, but half of all E. coli isolates that cause UTI have none or only one of the known virulence factors. Thus, it is reasonable to presume that other bacterial factors may be important in UTI pathogenesis. In order to find additional uropathogenic E. coli genes, we used genomic subtraction to identify DNA regions present in a uropathogenic strain of E. coli (1128-11). Genomic subtraction yielded 40 tester-specific fragments, including a novel heat-resistant agglutinin (hra) gene fragment. hra occurred in 55% of 486 UTI strains compared to 28% of 165 rectal strains (P = 0.001). The hra gene in 1128-11 was cloned, sequenced, and found to have 91% homology to the hra gene from E. coli meningitis strain RS218. The genetic organization of genes flanking hra in 1128-11 is distinct from the hra found in E. coli strains J96 and RS218. In our UTI and rectal specimen collections, hra was positively associated with a number of known virulence genes, including pathogenicity island genes hly and cnf, which are absent in 1128-11. The presence of hra in 1128-11 independent of hly/cnf suggests multiple mechanisms by which hra can be acquired by pathogenic E. coli strains. The flanking genes suggest that in 1128-11, hra may be part of a novel variant of a pathogenicity island V.

Srinivasan, Usha; Foxman, Betsy; Marrs, Carl F.

2003-01-01

236

Molecular analysis of type 3 fimbrial genes from Escherichia coli, Klebsiella and Citrobacter species  

PubMed Central

Background Catheter-associated urinary tract infection (CAUTI) is the most common nosocomial infection in the United States and is caused by a range of uropathogens. Biofilm formation by uropathogens that cause CAUTI is often mediated by cell surface structures such as fimbriae. In this study, we characterised the genes encoding type 3 fimbriae from CAUTI strains of Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter koseri and Citrobacter freundii. Results Phylogenetic analysis of the type 3 fimbrial genes (mrkABCD) from 39 strains revealed they clustered into five distinct clades (A-E) ranging from one to twenty-three members. The majority of sequences grouped in clade A, which was represented by the mrk gene cluster from the genome sequenced K. pneumoniae MGH78578. The E. coli and K. pneumoniae mrkABCD gene sequences clustered together in two distinct clades, supporting previous evidence for the occurrence of inter-genera lateral gene transfer. All of the strains examined caused type 3 fimbriae mediated agglutination of tannic acid treated human erythrocytes despite sequence variation in the mrkD-encoding adhesin gene. Type 3 fimbriae deletion mutants were constructed in 13 representative strains and were used to demonstrate a direct role for type 3 fimbriae in biofilm formation. Conclusions The expression of functional type 3 fimbriae is common to many Gram-negative pathogens that cause CAUTI and is strongly associated with biofilm growth. Our data provides additional evidence for the spread of type 3 fimbrial genes by lateral gene transfer. Further work is now required to substantiate the clade structure reported here by examining more strains as well as other bacterial genera that make type 3 fimbriae and cause CAUTI.

2010-01-01

237

Both Host and Pathogen Factors Predispose to Escherichia coli Urinary-Source Bacteremia in Hospitalized Patients  

PubMed Central

Background.?The urinary tract is the most common source for Escherichia coli bacteremia. Mortality from E. coli urinary-source bacteremia is higher than that from urinary tract infection. Predisposing factors for urinary-source E. coli bacteremia are poorly characterized. Methods.?In order to identify urinary-source bacteremia risk factors, we conducted a 12-month prospective cohort study of adult inpatients with E. coli bacteriuria that were tested for bacteremia within ±1 day of the bacteriuria. Patients with bacteremia were compared with those without bacteremia. Bacterial isolates from urine were screened for 16 putative virulence genes using high-throughput dot-blot hybridization. Results.?Twenty-four of 156 subjects (15%) had E. coli bacteremia. Bacteremic patients were more likely to have benign prostatic hyperplasia (56% vs 19%; P = .04), a history of urogenital surgery (63% vs 28%; P = .001), and presentation with hesitancy/retention (21% vs 4%; P = .002), fever (63% vs 38%; P = .02), and pyelonephritis (67% vs 41%; P = .02). The genes kpsMT (group II capsule) (17 [71%] vs 62 [47%]; P = .03) and prf (P-fimbriae family) (13 [54%] vs 40 [30%]; P = .02) were more frequent in the urinary strains from bacteremic patients. Symptoms of hesitancy/retention (odds ratio [OR], 7.8; 95% confidence interval [CI], 1.6–37), history of a urogenital procedure (OR, 5.4; 95% CI, 2–14.7), and presence of kpsMT (OR, 2.9; 95% CI, 1–8.2) independently predicted bacteremia. Conclusions.?Bacteremia secondary to E. coli bacteriuria was frequent (15%) in those tested for it. Urinary stasis, surgical disruption of urogenital tissues, and a bacterial capsule characteristic contribute to systemic invasion by uropathogenic E. coli.

Marschall, Jonas; Zhang, Lixin; Foxman, Betsy; Warren, David K.; Henderson, Jeffrey P.

2012-01-01

238

Engineering Desiccation Tolerance in Escherichia coli  

PubMed Central

Recombinant sucrose-6-phosphate synthase (SpsA) was synthesized in Escherichia coli BL21DE3 by using the spsA gene of the cyanobacterium Synechocystis sp. strain PCC 6803. Transformants exhibited a 10,000-fold increase in survival compared to wild-type cells following either freeze-drying, air drying, or desiccation over phosphorus pentoxide. The phase transition temperatures and vibration frequencies (P 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 O stretch) in phospholipids suggested that sucrose maintained membrane fluidity during cell dehydration.

Billi, Daniela; Wright, Deborah J.; Helm, Richard F.; Prickett, Todd; Potts, Malcolm; Crowe, John H.

2000-01-01

239

Pathogenesis of adherent-invasive Escherichia coli.  

PubMed

The etiology of Crohn's disease (CD) is complex and involves both host susceptibility factors (i.e., the presence of particular genetic alleles) and environmental factors, including bacteria. In this regard, adherent-invasive Escherichia coli (AIEC), have recently emerged as an exciting potential etiological agent of CD. AIEC are distinguished from commensal strains of E. coli through their ability to adhere to and invade epithelial cells and replicate in macrophages. Recent molecular analyses have identified genes required for both invasion of epithelial cells and replication in the macrophage. However, these genetic studies, in combination with recent genome sequencing projects, have revealed that the pathogenesis of this group of bacteria cannot be explained by the presence of AIEC-specific genes. In this article, we review the role of AIEC as a pathobiont in the pathology of CD. We also describe the emerging link between AIEC and autophagy, and we propose a model for AIEC pathogenesis. PMID:24059919

Smith, Emma J; Thompson, Aoife P; O'Driscoll, Adam; Clarke, David J

2013-10-01

240

Transient fluorescence in synchronously dividing Escherichia coli.  

PubMed Central

Using a spectrometer equipped with an optical multichannel analyzer as the detector, we observed the Stokes laser-Raman spectra of metabolically synchronous Escherichia coli from 100 to 2100 cm-1. After more than 400 separate recordings, at cell concentrations of 10(7)-10(8) per ml, no Raman lines attributable to the metabolic process nor to the cells themselves were found. However, we did find that synchronous E. coli cultures become more fluorescent during a limited phase of the division cycle. This transient increase in fluorescence may be ascribed to a variation in the redox state of a chemical species within the bacteria or to a variation of the intracellular optical field. The effect is reproducible in synchronous cultures and it is not seen in asynchronous ones. The results suggest that spectral features seen in previous laser-Raman spectra of synchronous bacteria (taken with scanning monochromators) are due to a time-dependent variation in bacterial fluorescence.

Layne, S P; Bigio, I J; Scott, A C; Lomdahl, P S

1985-01-01

241

Transient fluorescence in synchronously dividing Escherichia coli.  

PubMed

Using a spectrometer equipped with an optical multichannel analyzer as the detector, we observed the Stokes laser-Raman spectra of metabolically synchronous Escherichia coli from 100 to 2100 cm-1. After more than 400 separate recordings, at cell concentrations of 10(7)-10(8) per ml, no Raman lines attributable to the metabolic process nor to the cells themselves were found. However, we did find that synchronous E. coli cultures become more fluorescent during a limited phase of the division cycle. This transient increase in fluorescence may be ascribed to a variation in the redox state of a chemical species within the bacteria or to a variation of the intracellular optical field. The effect is reproducible in synchronous cultures and it is not seen in asynchronous ones. The results suggest that spectral features seen in previous laser-Raman spectra of synchronous bacteria (taken with scanning monochromators) are due to a time-dependent variation in bacterial fluorescence. PMID:3906649

Layne, S P; Bigio, I J; Scott, A C; Lomdahl, P S

1985-11-01

242

Inhibition of Escherichia coli B by Homoarginine  

PubMed Central

Homoarginine inhibits the growth of Escherichia coli B, but not of E. coli K-12. These two strains also differ in regard to repressibility of the arginine-forming enzymes. In K-12, arginine acts as a repressor whereas in B it does not. The latter difference is determined by different alleles of a regulator gene, arg R. In K-12 × B crosses, it was shown that the genetic determinant for homoarginine sensitivity is closely linked to or identical with arg R. Homoarginine-resistant mutants of B were isolated. The biochemical mechanism of homoarginine inhibition is not known. However, whether or not a strain is sensitive to homoarginine seems to depend on the intracellular level of arginine. In B this level is relatively low and inflexible as a result of the action of a repressor whose formation is determined by the B-specific allele of arg R.

Peyru, Graciela M.; Maas, Werner K.

1967-01-01

243

Natural DNA uptake by Escherichia coli.  

PubMed

Escherichia coli has homologues of the competence genes other species use for DNA uptake and processing, but natural competence and transformation have never been detected. Although we previously showed that these genes are induced by the competence regulator Sxy as in other gamma-proteobacteria, no conditions are known that naturally induce sxy expression. We have now tested whether the competence gene homologues encode a functional DNA uptake machinery and whether DNA uptake leads to recombination, by investigating the effects of plasmid-borne sxy expression on natural competence in a wide variety of E. coli strains. High- and low-level sxy expression alone did not induce transformation in any of the strains tested, despite varying the transforming DNA, its concentration, and the incubation conditions used. Direct measurements of uptake of radiolabelled DNA were below the limit of detection, however transformants were readily detected when recombination functions were provided by the lambda Red recombinase. This is the first demonstration that E. coli sxy expression can induce natural DNA uptake and that E. coli's competence genes do encode a functional uptake machinery. However, the amount of transformation cells undergo is limited both by low levels of DNA uptake and by inefficient DNA processing/recombination. PMID:22532864

Sinha, Sunita; Redfield, Rosemary J

2012-04-19

244

Chemoreceptors of Escherichia coli CFT073 Play Redundant Roles in Chemotaxis toward Urine  

PubMed Central

Community-acquired urinary tract infections (UTIs) are commonly caused by uropathogenic Escherichia coli (UPEC). We hypothesize that chemotaxis toward ligands present in urine could direct UPEC into and up the urinary tract. Wild-type E. coli CFT073 and chemoreceptor mutants with tsr, tar, or aer deletions were tested for chemotaxis toward human urine in the capillary tube assay. Wild-type CFT073 was attracted toward urine, and Tsr and Tar were the chemoreceptors mainly responsible for mediating this response. The individual components of urine including L-amino acids, D-amino acids and various organic compounds were also tested in the capillary assay with wild-type CFT073. Our results indicate that CFT073 is attracted toward some L- amino acids and possibly toward some D-amino acids but not other common compounds found in urine such as urea, creatinine and glucuronic acid. In the murine model of UTI, the loss of any two chemoreceptors did not affect the ability of the bacteria to compete with the wild-type strain. Our data suggest that the presence of any strong attractant and its associated chemoreceptor might be sufficient for colonization of the urinary tract and that amino acids are the main chemoattractants for E. coli strain CFT073 in this niche.

Raterman, Erica L.; Welch, Rodney A.

2013-01-01

245

Comparative Structure-Function Analysis of Mannose-Specific FimH Adhesins from Klebsiella pneumoniae and Escherichia coli?  

PubMed Central

FimH, the adhesive subunit of type 1 fimbriae expressed by many enterobacteria, mediates mannose-sensitive binding to target host cells. At the same time, fine receptor-structural specificities of FimH from different species can be substantially different, affecting bacterial tissue tropism and, as a result, the role of the particular fimbriae in pathogenesis. In this study, we compared functional properties of the FimH proteins from Escherichia coli and Klebsiella pneumoniae, which are both 279 amino acids in length but differ by some ?15% of residues. We show that K. pneumoniae FimH is unable to mediate adhesion in a monomannose-specific manner via terminally exposed Man?(1-2) residues in N-linked oligosaccharides, which are the structural basis of the tropism of E. coli FimH for uroepithelial cells. However, K. pneumoniae FimH can bind to the terminally exposed Man?(1-3)Man?(1-4)GlcNAc?1 trisaccharide, though only in a shear-dependent manner, wherein the binding is marginal at low shear force but enhanced sevenfold under increased shear. A single mutation in the K. pneumoniae FimH, S62A, converts the mode of binding from shear dependent to shear independent. This mutation has occurred naturally in the course of endemic circulation of a nosocomial uropathogenic clone and is identical to a pathogenicity-adaptive mutation found in highly virulent uropathogenic strains of E. coli, in which it also eliminates the dependence of E. coli binding on shear. The shear-dependent binding properties of the K. pneumoniae and E. coli FimH proteins are mediated via an allosteric catch bond mechanism. Thus, despite differences in FimH structure and fine receptor specificity, the shear-dependent nature of FimH-mediated adhesion is highly conserved between bacterial species, supporting its remarkable physiological significance.

Stahlhut, Steen G.; Tchesnokova, Veronika; Struve, Carsten; Weissman, Scott J.; Chattopadhyay, Sujay; Yakovenko, Olga; Aprikian, Pavel; Sokurenko, Evgeni V.; Krogfelt, Karen Angeliki

2009-01-01

246

Comparative structure-function analysis of mannose-specific FimH adhesins from Klebsiella pneumoniae and Escherichia coli.  

PubMed

FimH, the adhesive subunit of type 1 fimbriae expressed by many enterobacteria, mediates mannose-sensitive binding to target host cells. At the same time, fine receptor-structural specificities of FimH from different species can be substantially different, affecting bacterial tissue tropism and, as a result, the role of the particular fimbriae in pathogenesis. In this study, we compared functional properties of the FimH proteins from Escherichia coli and Klebsiella pneumoniae, which are both 279 amino acids in length but differ by some approximately 15% of residues. We show that K. pneumoniae FimH is unable to mediate adhesion in a monomannose-specific manner via terminally exposed Manalpha(1-2) residues in N-linked oligosaccharides, which are the structural basis of the tropism of E. coli FimH for uroepithelial cells. However, K. pneumoniae FimH can bind to the terminally exposed Manalpha(1-3)Manbeta(1-4)GlcNAcbeta1 trisaccharide, though only in a shear-dependent manner, wherein the binding is marginal at low shear force but enhanced sevenfold under increased shear. A single mutation in the K. pneumoniae FimH, S62A, converts the mode of binding from shear dependent to shear independent. This mutation has occurred naturally in the course of endemic circulation of a nosocomial uropathogenic clone and is identical to a pathogenicity-adaptive mutation found in highly virulent uropathogenic strains of E. coli, in which it also eliminates the dependence of E. coli binding on shear. The shear-dependent binding properties of the K. pneumoniae and E. coli FimH proteins are mediated via an allosteric catch bond mechanism. Thus, despite differences in FimH structure and fine receptor specificity, the shear-dependent nature of FimH-mediated adhesion is highly conserved between bacterial species, supporting its remarkable physiological significance. PMID:19734306

Stahlhut, Steen G; Tchesnokova, Veronika; Struve, Carsten; Weissman, Scott J; Chattopadhyay, Sujay; Yakovenko, Olga; Aprikian, Pavel; Sokurenko, Evgeni V; Krogfelt, Karen Angeliki

2009-09-04

247

[Frequency of Escherichia coli resistance in Switzerland].  

PubMed

Monitoring the drug resistance of bacteria is necessary at regional, national and international levels. Over a two-week period in October 1978, 2561 strains of Escherichia coli and coliforms were isolated from stool specimens obtained from 19 civilian institutions (1338 strains) and from 9 army training camps (1223 strains) located all over Switzerland. Only a few of the donors had undergone recent antimicrobial therapy. The bacterial strains were rapidly distributed among 7 Swiss army microbiological field laboratories and tested for resistance against ampicillin, gentamycin, tetracycline and cotrimoxazole by standard disc diffusion techniques. Criteria for the interpretation of inhibition zones were adapted from WHO and NCCLS guidelines. E. coli ATCC 25922 served as a control strain. The overall resistance rates of E. coli and coliforms were 18% for ampicillin, 0.3% for gentamycin, 33% for tetracycline and 4% for cotrimoxazole. Multiple drug resistance patterns involving these four drugs plus sulfisoxazole, streptomycin, kanamycin, chloramphenicol, cefalothin and colistin were analyzed. Many combinations of drug resistances occurred in far higher numbers than was expected from individual drug resistance frequencies, a fact which suggested linkage of resistance genes. The resistance frequencies observed were shown by several tests of reproducibility to be subject to a modest overall error of approximately 20%. PMID:7022622

Braun, R; Fitzi, K; Gutzwiller, F; Hohl, H R; van der Linde, F; Gelzer, J

1981-07-01

248

Regulation of alcohol fermentation by Escherichia coli  

SciTech Connect

The purpose of this project is to elucidate the way in which the synthesis of ethanol and related fermentation products are regulated in the facultative anaerobe Escherichia coli. We are also investigating the control of other genes required for anaerobic growth. We have isolated both structural and regulatory mutations affecting the expression of alcohol dehydrogenase, the enzyme responsible for the final step in alcohol synthesis. Some of these regulatory mutations also affect other anaerobically induced genes. The adh gene has been cloned and sequenced. The ADH protein is one of the largest highly expressed proteins in E. coli and requires approximately 2700bp of DNA for its coding sequence. We have also isolated mutations affecting the fermentative lactate dehydrogenase and have recently cloned the ldh gene. In consequence it is now possible to construct E. coli strains defective in the production of any one or more of their normal fermentation products (i.e. formate, acetate, lactate, ethanol and succinate). The factors affecting ratio of fermentation products are being investigated by in vivo NMR spectroscopy.

Clark, D.P.

1990-01-01

249

Inactivation of Escherichia coli with ozone: chemical and inactivation kinetics  

Microsoft Academic Search

The apparent chemical and inactivation reactions taking place during the disinfection of Escherichia coli with ozone in the presence of humic acid were investigated with continuous-flow tubular reactors. The apparent decomposition of dissolved ozone in the presence of humic acid and E. coli cells was modeled successfully with mixed second-order rate expressions within a time scale relevant to E. coli

Nimrata K Hunt; Benito J Marińas

1999-01-01

250

Escherichia coli resistance to quinolones at a comprehensive cancer center  

Microsoft Academic Search

As part of Meropenem Yearly Susceptibility Test Information Collection\\/USA Surveillance Programme, we monitored the occurrence of quinolone resistance in Escherichia coli over a 10-year period. A total of 271 E. coli isolates from our institution were tested over a 10-year period. Screening for quinolone resistance (qnr) gene was performed. A decline in susceptibility of E. coli isolates to quinolones and

Coralia N. Mihu; Paul R. Rhomberg; Ronald N. Jones; Elizabeth Coyle; Randall A. Prince; Kenneth V. Rolston

2010-01-01

251

Antimicrobial activity of Nutmeg against Escherichia coli O157  

Microsoft Academic Search

We examined the difference between Escherichia coli O157 and non-pathogenic E. coli in their tolerance to spices. Various spices (5 g each) were homogenized at 25°C for 10 min with 5 ml of 70% ethyl alcohol, and the supernatant solutions obtained by centrifugation were used as spice extracts. When the E. coli strains were incubated with each spice extract at

Akiko Takikawa; Keiko Abe; Makiko Yamamoto; Shoko Ishimaru; Mari Yasui; Yoko Okubo; Kumio Yokoigawa

2002-01-01

252

Risk factors of ciprofloxacin resistance in urinary Escherichia coli isolates  

Microsoft Academic Search

Background and Purpose: Increasing rates of fluoroquinolone resistance among Escherichia coli have been reported in Taiwan and worldwide. We aimed to identify the risk factors of ciprofloxacin resistance in urinary E. coli isolates. Methods: Patients with positive urine culture result for E. coli and resistance to ciprofloxacin between Septem- ber 1, 1999 and December 31, 1999 were prospectively identified as

Chun-Yu Lin; Shu-Hua Huang; Tun-Chieh Chen; Po-Liang Lu; Wei-Ru Lin; Yen-Hsu Chen

2008-01-01

253

Vibrio parahaemolyticus, enterotoxigenic Escherichia coli, enterohemorrhagic Escherichia coli and Vibrio cholerae  

PubMed Central

This review highlighted the following: (i) pathogenic mechanism of the thermostable direct hemolysin produced by Vibrio parahaemolyticus, especially on its cardiotoxicity, (ii) heat-labile and heat-stable enterotoxins produced by enterotoxigenic Escherichia coli, especially structure–activity relationship of heat-stable enterotoxin, (iii) RNA N-glycosidase activity of Vero toxins (VT1 and VT2) produced by enterohemorrhagic Escherichia coli O157:H7, (iv) discovery of Vibrio cholerae O139, (v) isolation of new variant of Vibrio cholerae O1 El Tor that carries classical ctxB, and production of high concentration of cholera toxin by these strains, and (vi) conversion of viable but nonculturable (VBNC) Vibrio cholerae to culturable state by co-culture with eukaryotic cells.

TAKEDA, Yoshifumi

2011-01-01

254

Indole transport across Escherichia coli membranes.  

PubMed

Indole has many, diverse roles in bacterial signaling. It regulates the transition from exponential to stationary phase, it is involved in the control of plasmid stability, and it influences biofilm formation, virulence, and stress responses (including antibiotic resistance). Its role is not restricted to bacteria, and recently it has been shown to include mutually beneficial signaling between enteric bacteria and their mammalian hosts. In many respects indole behaves like the signaling component of a quorum-sensing system. Indole synthesized within the producer bacterium is exported into the surroundings where its accumulation is detected by sensitive cells. A view often repeated in the literature is that in Escherichia coli the AcrEF-TolC and Mtr transporter proteins are involved in the export and import, respectively, of indole. However, the evidence for their involvement is indirect, and it has been known for a long time that indole can pass directly through a lipid bilayer. We have combined in vivo and in vitro approaches to examine the relative importance of protein-mediated transport and direct passage across the E. coli membrane. We conclude that the movement of indole across the E. coli membrane under normal physiological conditions is independent of AcrEF-TolC and Mtr. Furthermore, direct observation of individual liposomes shows that indole can rapidly cross an E. coli lipid membrane without the aid of any proteinaceous transporter. These observations not only enhance our understanding of indole signaling in bacteria but also provide a simple explanation for the ability of indole to signal between biological kingdoms. PMID:21296966

Pińero-Fernandez, S; Chimerel, C; Keyser, U F; Summers, D K

2011-02-04

255

Indole Transport across Escherichia coli Membranes ?  

PubMed Central

Indole has many, diverse roles in bacterial signaling. It regulates the transition from exponential to stationary phase, it is involved in the control of plasmid stability, and it influences biofilm formation, virulence, and stress responses (including antibiotic resistance). Its role is not restricted to bacteria, and recently it has been shown to include mutually beneficial signaling between enteric bacteria and their mammalian hosts. In many respects indole behaves like the signaling component of a quorum-sensing system. Indole synthesized within the producer bacterium is exported into the surroundings where its accumulation is detected by sensitive cells. A view often repeated in the literature is that in Escherichia coli the AcrEF-TolC and Mtr transporter proteins are involved in the export and import, respectively, of indole. However, the evidence for their involvement is indirect, and it has been known for a long time that indole can pass directly through a lipid bilayer. We have combined in vivo and in vitro approaches to examine the relative importance of protein-mediated transport and direct passage across the E. coli membrane. We conclude that the movement of indole across the E. coli membrane under normal physiological conditions is independent of AcrEF-TolC and Mtr. Furthermore, direct observation of individual liposomes shows that indole can rapidly cross an E. coli lipid membrane without the aid of any proteinaceous transporter. These observations not only enhance our understanding of indole signaling in bacteria but also provide a simple explanation for the ability of indole to signal between biological kingdoms.

Pinero-Fernandez, S.; Chimerel, C.; Keyser, U. F.; Summers, D. K.

2011-01-01

256

Escherichia coli malate dehydrogenase, a novel solubility enhancer for heterologous proteins synthesized in Escherichia coli  

Microsoft Academic Search

Using 2-dimensional gel electrophoresis, the Escherichia coli proteome response to a heat-shock stress was analyzed and a 1.6-fold increase of malate dehydrogenase was observed even under\\u000a the heat-shock condition where the total number of soluble proteins decreased by about 5%. We subsequently demonstrated that,\\u000a as an N-terminus fusion expression partner, malate dehydrogenase facilitated the folding of, and dramatically increased the

Jin-Seung Park; Kyung-Yeon Han; Jong-Am Song; Keum-Young Ahn; Hyuk-Seong Seo; Jeewon Lee

2007-01-01

257

Mutations Affecting Iron Transport in Escherichia coli  

PubMed Central

A mutant of Escherichia coli K-12 unable to form an essential component of the enterochelin-dependent iron transport system has been isolated. This strain carries a mutation in a gene designated fep, mapping close to two genes, entA and entD, concerned with enterochelin synthesis. Strain AN102, which carries the fep? allele, accumulates large quantities of enterochelin and gives a growth response to sodium citrate. The cytochrome b1 and total iron content, and the measurement of the uptake of 55Fe3+, indicate an impairment of the enterochelin-dependent iron transport system. The growth response to sodium citrate is related to the presence, in strain AN102, of an inducible citrate-dependent iron transport system. Images

Cox, G. B.; Gibson, F.; Luke, R. K. J.; Newton, N. A.; O'Brien, I. G.; Rosenberg, H.

1970-01-01

258

Ribonuclease Sensitivity of Escherichia coli Ribosomes  

PubMed Central

Santer, Melvin (Haverford College, Haverford, Pa.), and Josephine R. Smith. Ribonuclease sensitivity of Escherichia coli ribosomes. J. Bacteriol. 92:1099–1110. 1966.—The ribonucleic acid (RNA) contained in 70S ribosomes and in 50S and 30S subunits was hydrolyzed by pancreatic ribonuclease. A 7% amount of the RNA was removed from the 70S particle; at 10?4m magnesium concentration, a maximum of 24 and 30% of the RNA in the 50S and the 30S fractions, respectively, was removed by ribonuclease. At the two lower magnesium ion concentrations, 50S ribosomes did not lose any protein, whereas 30S ribosomes lost protein as a result of ribonuclease treatment. A number of proteins were removed from the 30S particles by ribonuclease, and these proteins were antigenically related to proteins present in 50S ribosomes. The differential effect of ribonuclease on 50S and 30S ribosomes suggested that they have structural dissimilarities. Images

Santer, Melvin; Smith, Josephine R.

1966-01-01

259

l-Serine Deaminase of Escherichia coli  

PubMed Central

The native l-serine deaminase (l-serine hydrolyase, deaminating, EC 4.2.1.13) of Escherichia coli K-12, which seems to be a very labile protein, is rather stable in concentrated solution. Dilution rapidly inactivates it, but in the presence of a saturating concentration of l-serine the molecule is protected from inactivation. It is a very specific enzyme; l-serine is the sole substrate with a Km value of 6.60 × 10?3m. d-Serine and l-cysteine are competitive inhibitors. Substrate saturation curves of the native enzyme show sigmoid shape, whereas the enzyme liberated from the bacteria in the presence of l-serine exhibits normal Michaelis-Menten kinetics.

Alfoldi, Lajos; Rasko, Istvan; Kerekes, Erzsebet

1968-01-01

260

Direct upstream motility in Escherichia coli.  

PubMed

We provide an experimental demonstration of positive rheotaxis (rapid and continuous upstream motility) in wild-type Escherichia coli freely swimming over a surface. This hydrodynamic phenomenon is dominant below a critical shear rate and robust against Brownian motion and cell tumbling. We deduce that individual bacteria entering a flow system can rapidly migrate upstream (>20 ?m/s) much faster than a gradually advancing biofilm. Given a bacterial population with a distribution of sizes and swim speeds, local shear rate near the surface determines the dominant hydrodynamic mode for motility, i.e., circular or random trajectories for low shear rates, positive rheotaxis for moderate flow, and sideways swimming at higher shear rates. Faster swimmers can move upstream more rapidly and at higher shear rates, as expected. Interestingly, we also find on average that both swim speed and upstream motility are independent of cell aspect ratio. PMID:22500751

Kaya, Tolga; Koser, Hur

2012-04-03

261

Anaerobic iron uptake by Escherichia coli.  

PubMed Central

Assimilation and uptake of iron in anaerobic cultures of Escherichia coli were supported by iron supplied as ferrienterobactin, ferrichrome, and ferrous ascorbate; however, as in the aerobic cultures, ferrichrome A was a poor iron source. Albomycin inhibited both aerobically and anaerobically grown cells. The siderophore outer membrane receptor proteins FepA and FhuA were produced under anaerobic iron-deficient conditions. Anaerobic transport of ferrienterobactin and ferrichrome was inhibited by KCN and dinitrophenol. The Km for ferrienterobactin uptake in anaerobically grown cells was 0.8 microM, and the Vmax was 38 pmol/min per mg, compared with 0.1 microM and 80 pmol/min per mg, respectively, in aerobically grown cells.

Lodge, J S; Emery, T

1984-01-01

262

Phosphoglucomutase Mutants of Escherichia coli K-12  

PubMed Central

Bacteria with strongly depressed phosphoglucomutase (EC 2.7.5.1) activity are found among the mutants of Escherichia coli which, when grown on maltose, accumulate sufficient amylose to be detectable by iodine staining. These pgm mutants grow poorly on galactose but also accumulate amylose on this carbon source. Growth on lactose does not produce high amylose but, instead, results in the induction of the enzymes of maltose metabolism, presumably by accumulation of maltose. These facts suggest that the catabolism of glucose-1-phosphate is strongly depressed in pgm mutants, although not completely abolished. Anabolism of glucose-1-phosphate is also strongly depressed, since amino acid- or glucose-grown pgm mutants are sensitive to phage C21, indicating a deficiency in the biosynthesis of uridine diphosphoglucose or uridine diphosphogalactose, or both. All pgm mutations isolated map at about 16 min on the genetic map, between purE and the gal operon.

Adhya, Sankar; Schwartz, Maxime

1971-01-01

263

Direct Upstream Motility in Escherichia coli  

PubMed Central

We provide an experimental demonstration of positive rheotaxis (rapid and continuous upstream motility) in wild-type Escherichia coli freely swimming over a surface. This hydrodynamic phenomenon is dominant below a critical shear rate and robust against Brownian motion and cell tumbling. We deduce that individual bacteria entering a flow system can rapidly migrate upstream (>20 ?m/s) much faster than a gradually advancing biofilm. Given a bacterial population with a distribution of sizes and swim speeds, local shear rate near the surface determines the dominant hydrodynamic mode for motility, i.e., circular or random trajectories for low shear rates, positive rheotaxis for moderate flow, and sideways swimming at higher shear rates. Faster swimmers can move upstream more rapidly and at higher shear rates, as expected. Interestingly, we also find on average that both swim speed and upstream motility are independent of cell aspect ratio.

Kaya, Tolga; Koser, Hur

2012-01-01

264

Enzymatic properties of Escherichia coli peptide deformylase.  

PubMed Central

Since its discovery in crude extracts in the late sixties, Escherichia coli peptide deformylase activity could not be further characterized because of an apparent extreme instability. We show that this behavior was caused by an inadequate activity assay, involving substrate concentration inhibition and substrate precipitation in crude extracts. The homogeneous protein, as it was previously purified (T. Meinnel and S. Blanquet J. Bacteriol. 175:7737-7740, 1993), had actually retained its initial activity. The influence on the deformylation reaction of several factors was studied and used to improve the activity assay. Pure peptide deformylase proves to act only on peptide substrates with an N-formylmethionyl moiety. In agreement with the occurrence of zinc in the enzyme, peptide deformylase activity is inhibited by 1,10-phenanthroline.

Meinnel, T; Blanquet, S

1995-01-01

265

Aerobic TMAO respiration in Escherichia coli.  

PubMed

In the absence of oxygen, Escherichia coli can use alternative exogenous electron acceptors, including trimethylamine oxide (TMAO), to generate energy. In this study, we showed that in contrast to the other anaerobic respiratory systems, the TMAO reductase (Tor) system was expressed during both aerobiosis and anaerobiosis. By using a torA-lacZ fusion and quantitative reverse transcription polymerase chain reaction, we established that the torCAD operon encoding the Tor system was induced in the presence of TMAO mainly during exponential phase, and that optimal induction required a certain level of DNA supercoiling. We also showed that the presence of oxygen prevented neither the biogenesis of the Tor system nor the reduction of TMAO. The physiological role of TMAO reduction during aerobiosis has not been yet established, but our experiments suggest that alkaline TMA production could enhance the growth conditions by increasing the pH of the culture. PMID:17850256

Ansaldi, Mireille; Théraulaz, Laurence; Baraquet, Claudine; Panis, Gaël; Méjean, Vincent

2007-09-10

266

Dispensability of Escherichia coli's latent pathways  

PubMed Central

Gene-knockout experiments on single-cell organisms have established that expression of a substantial fraction of genes is not needed for optimal growth. This problem acquired a new dimension with the recent discovery that environmental and genetic perturbations of the bacterium Escherichia coli are followed by the temporary activation of a large number of latent metabolic pathways, which suggests the hypothesis that temporarily activated reactions impact growth and hence facilitate adaptation in the presence of perturbations. Here, we test this hypothesis computationally and find, surprisingly, that the availability of latent pathways consistently offers no growth advantage and tends, in fact, to inhibit growth after genetic perturbations. This is shown to be true even for latent pathways with a known function in alternate conditions, thus extending the significance of this adverse effect beyond apparently nonessential genes. These findings raise the possibility that latent pathway activation is in fact derivative of another, potentially suboptimal, adaptive response.

Cornelius, Sean P.; Lee, Joo Sang; Motter, Adilson E.

2011-01-01

267

T-even-related bacteriophages as candidates for treatment of Escherichia coli urinary tract infections.  

PubMed

Multidrug-resistant uropathogenic Escherichia coli (UPEC) is increasing gradually on a worldwide scale. We therefore examined the possibility of bacteriophage (phage) therapy for urinary tract infections (UTIs) caused by the UPEC strains as an alternative to chemotherapy. In addition to the well-known T4 phage, KEP10, which was newly isolated, was used as a therapeutic phage candidate. KEP10 showed a broader bacteriolytic spectrum (67%) for UPEC strains than T4 (14%). Morphological and genetic analyses showed that KEP10 resembles phage T4. Phages T4 and KEP10 injected into the peritoneal cavity of mice were distributed immediately to all organs examined and maintained a high titer for at least 24 h. They were stable in the urine of both mice and humans for 24 h at 37 degrees C. Administration of these phages into the peritoneal cavity caused a marked decrease in the mortality of mice inoculated transurethrally with a UPEC strain, whereas most of the control mice died within a few days of bacterial infection. Inoculation with phage alone produced no adverse effects attributable to the phage per se. The present study experimentally demonstrated the therapeutic potential of phage for E. coli-induced UTIs, and T-even-related phages may be suitable candidates with which to treat them. PMID:18188500

Nishikawa, H; Yasuda, M; Uchiyama, J; Rashel, M; Maeda, Y; Takemura, I; Sugihara, S; Ujihara, T; Shimizu, Y; Shuin, T; Matsuzaki, S

2008-01-08

268

Shear-enhanced binding of intestinal colonization factor antigen I of enterotoxigenic Escherichia coli.  

PubMed

In the intestine, enterotoxigenic Escherichia coli works against peristaltic forces, adhering to the epithelium via the colonization factor antigen I (CFA/I) fimbrial adhesin CfaE. The CfaE adhesin is similar in localization and tertiary (but not primary) structure to FimH, the type 1 fimbrial adhesin of uropathogenic E. coli, which shows shear-dependent binding to epithelial receptors by an allosteric catch-bond mechanism. Thus, we speculated that CfaE is also capable of shear-enhanced binding. Indeed, bovine erythrocytes coursing over immobilized CFA/I fimbriae in flow chambers exhibited low accumulation levels and fast rolling at low shear, but an 80-fold increase in accumulation and threefold decrease in rolling velocity at elevated shear. This effect was reversible and abolished by pre-incubation of fimbriae with anti-CfaE antibody. Erythrocytes bound to whole CfaE in the same shear-enhanced manner, but to CfaE adhesin domain in a shear-inhibitable fashion. Residue replacements designed to disrupt CfaE interdomain interaction decreased the shear dependency of adhesion and increased binding under static conditions to human intestinal epithelial cells. These findings indicate that close interaction between adhesive and anchoring pilin domains of CfaE keeps the former in a low-affinity state that toggles into a high-affinity state upon separation of two domains, all consistent with an allosteric catch-bond mechanism of CfaE binding. PMID:20345656

Tchesnokova, Veronika; McVeigh, Annette L; Kidd, Brian; Yakovenko, Olga; Thomas, Wendy E; Sokurenko, Evgeni V; Savarino, Stephen J

2010-03-25

269

Tuning Escherichia coli for membrane protein overexpression.  

PubMed

A simple generic method for optimizing membrane protein overexpression in Escherichia coli is still lacking. We have studied the physiological response of the widely used "Walker strains" C41(DE3) and C43(DE3), which are derived from BL21(DE3), to membrane protein overexpression. For unknown reasons, overexpression of many membrane proteins in these strains is hardly toxic, often resulting in high overexpression yields. By using a combination of physiological, proteomic, and genetic techniques we have shown that mutations in the lacUV5 promoter governing expression of T7 RNA polymerase are key to the improved membrane protein overexpression characteristics of the Walker strains. Based on this observation, we have engineered a derivative strain of E. coli BL21(DE3), termed Lemo21(DE3), in which the activity of the T7 RNA polymerase can be precisely controlled by its natural inhibitor T7 lysozyme (T7Lys). Lemo21(DE3) is tunable for membrane protein overexpression and conveniently allows optimizing overexpression of any given membrane protein by using only a single strain rather than a multitude of different strains. The generality and simplicity of our approach make it ideal for high-throughput applications. PMID:18796603

Wagner, Samuel; Klepsch, Mirjam M; Schlegel, Susan; Appel, Ansgar; Draheim, Roger; Tarry, Michael; Högbom, Martin; van Wijk, Klaas J; Slotboom, Dirk J; Persson, Jan O; de Gier, Jan-Willem

2008-09-16

270

Peptidase-deficient mutants of Escherichia coli.  

PubMed

Mutant derivatives of Escherichia coli K-12 deficient in several peptidases have been obtained. Mutants lacking a naphthylamidase, peptidase N, were isolated by screening for colonies unable to hydrolyze L-alanine beta-naphthylamide. Other mutants were isolated using positive selections for resistance to valine peptides. Mutants lacking peptidase A, a broad-specificity aminopeptidase, were obtained by selection for resistance to L-valyl-L-leucine amide. Mutants lacking a dipeptidase, peptidase D, were isolated from a pepN pepA strain by selection for resistance to L-valyl-glycine. Starting with a pepN pepA pepD strain, selection for resistance to L-valyl-glycyl-glycine or several other valine peptides produced mutants deficient in another aminopeptidase, peptidase B. Mutants resistant to L-valyl-L-proline lack peptidase Q, an activity capable of rapid hydrolysis of X-proline dipeptides. Using these selection procedures, a strain (CM89) lacking five different peptidases has been isolated. Although still sensitive to valine, this strain is resistant to a variety of valine di- and tripeptides. The ability of this strain to use peptides as sources of amino acids is much more restricted than that of wild-type E. coli strains. Strains containing only one of the five peptidases missing in CM89 have been constructed by transduction. The peptide utilization profiles of these strains show that each of the five peptidases can function during growth in the catabolism of peptides. PMID:355237

Miller, C G; Schwartz, G

1978-08-01

271

Peptidase-deficient mutants of Escherichia coli.  

PubMed Central

Mutant derivatives of Escherichia coli K-12 deficient in several peptidases have been obtained. Mutants lacking a naphthylamidase, peptidase N, were isolated by screening for colonies unable to hydrolyze L-alanine beta-naphthylamide. Other mutants were isolated using positive selections for resistance to valine peptides. Mutants lacking peptidase A, a broad-specificity aminopeptidase, were obtained by selection for resistance to L-valyl-L-leucine amide. Mutants lacking a dipeptidase, peptidase D, were isolated from a pepN pepA strain by selection for resistance to L-valyl-glycine. Starting with a pepN pepA pepD strain, selection for resistance to L-valyl-glycyl-glycine or several other valine peptides produced mutants deficient in another aminopeptidase, peptidase B. Mutants resistant to L-valyl-L-proline lack peptidase Q, an activity capable of rapid hydrolysis of X-proline dipeptides. Using these selection procedures, a strain (CM89) lacking five different peptidases has been isolated. Although still sensitive to valine, this strain is resistant to a variety of valine di- and tripeptides. The ability of this strain to use peptides as sources of amino acids is much more restricted than that of wild-type E. coli strains. Strains containing only one of the five peptidases missing in CM89 have been constructed by transduction. The peptide utilization profiles of these strains show that each of the five peptidases can function during growth in the catabolism of peptides. Images

Miller, C G; Schwartz, G

1978-01-01

272

Genes under positive selection in Escherichia coli  

PubMed Central

We used a comparative genomics approach to identify genes that are under positive selection in six strains of Escherichia coli and Shigella flexneri, including five strains that are human pathogens. We find that positive selection targets a wide range of different functions in the E. coli genome, including cell surface proteins such as beta barrel porins, presumably because of the involvement of these genes in evolutionary arms races with other bacteria, phages, and/or the host immune system. Structural mapping of positively selected sites on trans-membrane beta barrel porins reveals that the residues under positive selection occur almost exclusively in the extracellular region of the proteins that are enriched with sites known to be targets of phages, colicins, or the host immune system. More surprisingly, we also find a number of other categories of genes that show very strong evidence for positive selection, such as the enigmatic rhs elements and transposases. Based on structural evidence, we hypothesize that the selection acting on transposases is related to the genomic conflict between transposable elements and the host genome.

Petersen, Lise; Bollback, Jonathan P.; Dimmic, Matt; Hubisz, Melissa; Nielsen, Rasmus

2007-01-01

273

Biosynthesis of ethylene glycol in Escherichia coli.  

PubMed

Ethylene glycol (EG) is an important platform chemical with steadily expanding global demand. Its commercial production is currently limited to fossil resources; no biosynthesis route has been delineated. Herein, a biosynthesis route for EG production from D-xylose is reported. This route consists of four steps: D-xylose???D-xylonate???2-dehydro-3-deoxy-D-pentonate???glycoaldehyde???EG. Respective enzymes, D-xylose dehydrogenase, D-xylonate dehydratase, 2-dehydro-3-deoxy-D-pentonate aldolase, and glycoaldehyde reductase, were assembled. The route was implemented in a metabolically engineered Escherichia coli, in which the D-xylose???D-xylulose reaction was prevented by disrupting the D-xylose isomerase gene. The most efficient construct produced 11.7 g?L(-1) of EG from 40.0 g?L(-1) of D-xylose. Glycolate is a carbon-competing by-product during EG production in E. coli; blockage of glycoaldehyde???glycolate reaction was also performed by disrupting the gene encoding aldehyde dehydrogenase, but from this approach, EG productivity was not improved but rather led to D-xylonate accumulation. To channel more carbon flux towards EG than the glycolate pathway, further systematic metabolic engineering and fermentation optimization studies are still required to improve EG productivity. PMID:23233208

Liu, Huaiwei; Ramos, Kristine Rose M; Valdehuesa, Kris Nińo G; Nisola, Grace M; Lee, Won-Keun; Chung, Wook-Jin

2012-12-12

274

5-Aminolevulinic acid synthesis in Escherichia coli.  

PubMed Central

A hemA mutant of Escherichia coli containing a multicopy plasmid which complemented the mutation excreted 5-aminolevulinic acid (ALA) into the medium. [1-14C]glutamate was substantially incorporated into ALA by this strain, whereas [2-14C]glycine was not. Periodate degradation of labeled ALA showed that C-5 of ALA was derived from C-1 of glutamate. The synthesis of ALA by two sonicate fractions which had been processed by gel filtration and dialysis, respectively, was dependent on glutamate, ATP, NADPH, tRNA(Glu), and pyridoxal phosphate. tRNA(Glu) stimulated ALA synthesis in a concentration-dependent manner. Pretreatment with RNase reduced this stimulation. The amino acid sequence of the cloned insert, derived from the nucleotide sequence (J.-M. Li, C. S. Russell, and S. D. Cosloy, J. Cell Biol. 107:617a, 1988), showed no homology with any ALA synthase sequenced to date. These results suggest that E. coli synthesizes ALA by the C5 pathway from the intact five-carbon chain of glutamate.

Li, J M; Brathwaite, O; Cosloy, S D; Russell, C S

1989-01-01

275

Nucleotide excision repair in Escherichia coli.  

PubMed Central

One of the best-studied DNA repair pathways is nucleotide excision repair, a process consisting of DNA damage recognition, incision, excision, repair resynthesis, and DNA ligation. Escherichia coli has served as a model organism for the study of this process. Recently, many of the proteins that mediate E. coli nucleotide excision have been purified to homogeneity; this had led to a molecular description of this repair pathway. One of the key repair enzymes of this pathway is the UvrABC nuclease complex. The individual subunits of this enzyme cooperate in a complex series of partial reactions to bind to and incise the DNA near a damaged nucleotide. The UvrABC complex displays a remarkable substrate diversity. Defining the structural features of DNA lesions that provide the specificity for damage recognition by the UvrABC complex is of great importance, since it represents a unique form of protein-DNA interaction. Using a number of in vitro assays, researchers have been able to elucidate the action mechanism of the UvrABC nuclease complex. Current research is devoted to understanding how these complex events are mediated within the living cell.

Van Houten, B

1990-01-01

276

PfkA locus of Escherichia coli.  

PubMed

pfkA was know, on the basis of three mutants, as the likely locus of phosphofructokinase in Escherichia coli, and the unlinked pfkB1 mutation suppressed these mutations by restoring some enzyme activity (Morrissey and Fraenkel, 1972). We now report a new search for the complete inactivation of pfkA (e.g., by deletion or amber mutation), done to assess whether the pfkB1 suppression is by an independent enzyme, phosphofructokinase activity 2 (Fraenkel, Kotlarz, and Buc, 1973). Ten new phosphofructokinase mutants all were at pfkA, rather than at pfkB or pfkC. One of them (pfkA9) gave temperature-sensitive reverants with heat-labile enzyme. Another (pfkA11) proved genetically to be a nonsense mutation, but showed no restored activity when suppressed by supF. However, even unsuppressed it was found to contain an enzyme related to phosphofructokinase activity 1 kinetically (more allosteric), physically (almot identical subunit), and antigenically. All the pfkA mutants apparently contained cross-reacting material to activity 1. All (including pfkA11) were suppressed by the pfkB1 mutation. Several results support the idea that pfkA is the structural gene for the main phosphofructokinase of E. coli (activity 1), but that there is some restriction to its complete inactivation. PMID:125265

Vinopal, R T; Clifton, D; Fraenkel, D G

1975-06-01

277

Indole enhances acid resistance in Escherichia coli.  

PubMed

As a stationary-phase signal, indole is secreted in large quantities by Escherichia coli on enriched media and has been shown to control several genes; however, its impact on acid resistance remains to be studied in detail. Real-time quantitative reverse transcription-polymerase chain reaction analysis revealed that indole increases the expression of the glutamine decarboxylase system that includes genes such as gadA, gadB, and gadC genes with no effect on the expression of other acid resistance systems such as arginine decarboxylase (adiA) and lysine decarboxylase (cadA, cadB, cadC, and ldcC). Indole also induces yhiE (gadE) that encodes the regulator required for expression of gadA, gadB, and gadC. These results suggest that indole enhances the survival of E. coli under acidic conditions by increasing the expression of acid resistance genes of the glutamine decarboxylase system, thus increasing its acid resistance. PMID:20470880

Hirakawa, Hidetada; Hayashi-Nishino, Mitsuko; Yamaguchi, Akihito; Nishino, Kunihiko

2010-05-12

278

Identification of pseudouridine methyltransferase in Escherichia coli  

PubMed Central

In ribosomal RNA, modified nucleosides are found in functionally important regions, but their function is obscure. Stem–loop 69 of Escherichia coli 23S rRNA contains three modified nucleosides: pseudouridines at positions 1911 and 1917, and N3 methyl-pseudouridine (m3?) at position 1915. The gene for pseudouridine methyltransferase was previously not known. We identified E. coli protein YbeA as the methyltransferase methylating ?1915 in 23S rRNA. The E. coli ybeA gene deletion strain lacks the N3 methylation at position 1915 of 23S rRNA as revealed by primer extension and nucleoside analysis by HPLC. Methylation at position 1915 is restored in the ybeA deletion strain when recombinant YbeA protein is expressed from a plasmid. In addition, we show that purified YbeA protein is able to methylate pseudouridine in vitro using 70S ribosomes but not 50S subunits from the ybeA deletion strain as substrate. Pseudouridine is the preferred substrate as revealed by the inability of YbeA to methylate uridine at position 1915. This shows that YbeA is acting at the final stage during ribosome assembly, probably during translation initiation. Hereby, we propose to rename the YbeA protein to RlmH according to uniform nomenclature of RNA methyltransferases. RlmH belongs to the SPOUT superfamily of methyltransferases. RlmH was found to be well conserved in bacteria, and the gene is present in plant and in several archaeal genomes. RlmH is the first pseudouridine specific methyltransferase identified so far and is likely to be the only one existing in bacteria, as m3?1915 is the only methylated pseudouridine in bacteria described to date.

Ero, Rya; Peil, Lauri; Liiv, Aivar; Remme, Jaanus

2008-01-01

279

Frequency of enterovirulent Escherichia coli in diarrhoeal disease in The Netherlands  

Microsoft Academic Search

To assess the role of enterovirulentEscherichia coli in The Netherlands, faecal samples of 279 patients (108 children, 171 adults) with diarrhoea and 100 healthy controls were investigated in a prospective study. EnterovirulentEscherichia coli were identified by hybridization with five different non-radioactively labelled DNA probes specific for enteropathogenicEscherichia coli (EPEC), verocytotoxin producingEscherichia coli (VTEC) and enterotoxigenicEscherichia coli (ETEC). The rate of

C. M. A. Rademaker; A. C. Fluit; M. Jansze; W. H. Jansen; J. H. Glerum; J. Verhoef

1993-01-01

280

The IrgA homologue adhesin Iha is an Escherichia coli virulence factor in murine urinary tract infection.  

PubMed

The role of the Escherichia coli iron-regulated gene homologue adhesin (Iha) in the pathogenesis of urinary tract infections (UTIs) is unknown. We performed a series of complementary analyses to confirm or refute the hypothesis that Iha is a virulence factor in uropathogenic E. coli. Fecal E. coli isolates exhibited significantly lower prevalences of iha (range, 14 to 22%) than did clinical isolates from cases of pediatric cystitis or pyelonephritis, adult pyelonephritis or urosepsis, or bacteremia (range, 38 to 74%). Recombinant Iha from E. coli pyelonephritis isolate CFT073 conferred upon nonadherent E. coli ORN172 the ability to adhere to cultured T-24 human uroepithelial cells. In a well-established mouse model of ascending UTI, CFT073 and its derivative UPEC76 (a pap [P fimbriae] mutant version of strain CFT073) each significantly outcompeted their respective iha deletion mutants in CBA/J mice 48 h after bladder challenge (P < 0.03 for urine, both kidneys, and bladders of both constructs, except for bladders of mice challenged with UPEC76 and its deletion mutant, where P = 0.11). These data suggest that Iha(CFT073) is a virulence factor and might be a target for anti-UTI interventions. PMID:15664939

Johnson, James R; Jelacic, Srdjan; Schoening, Laura M; Clabots, Connie; Shaikh, Nurmohammad; Mobley, Harry L T; Tarr, Phillip I

2005-02-01

281

The IrgA Homologue Adhesin Iha Is an Escherichia coli Virulence Factor in Murine Urinary Tract Infection  

PubMed Central

The role of the Escherichia coli iron-regulated gene homologue adhesin (Iha) in the pathogenesis of urinary tract infections (UTIs) is unknown. We performed a series of complementary analyses to confirm or refute the hypothesis that Iha is a virulence factor in uropathogenic E. coli. Fecal E. coli isolates exhibited significantly lower prevalences of iha (range, 14 to 22%) than did clinical isolates from cases of pediatric cystitis or pyelonephritis, adult pyelonephritis or urosepsis, or bacteremia (range, 38 to 74%). Recombinant Iha from E. coli pyelonephritis isolate CFT073 conferred upon nonadherent E. coli ORN172 the ability to adhere to cultured T-24 human uroepithelial cells. In a well-established mouse model of ascending UTI, CFT073 and its derivative UPEC76 (a pap [P fimbriae] mutant version of strain CFT073) each significantly outcompeted their respective iha deletion mutants in CBA/J mice 48 h after bladder challenge (P < 0.03 for urine, both kidneys, and bladders of both constructs, except for bladders of mice challenged with UPEC76 and its deletion mutant, where P = 0.11). These data suggest that IhaCFT073 is a virulence factor and might be a target for anti-UTI interventions.

Johnson, James R.; Jelacic, Srdjan; Schoening, Laura M.; Clabots, Connie; Shaikh, Nurmohammad; Mobley, Harry L. T.; Tarr, Phillip I.

2005-01-01

282

Improvements In Ethanologenic Escherichia Coli and Klebsiella Oxytoca. (Final Report).  

National Technical Information Service (NTIS)

The current Verenium cellulosic ethanol process is based on the dilute-acid pretreatment of a biomass feedstock, followed by a two-stage fermentation of the pentose sugar-containing hydrolysate by a genetically modified ethanologenic Escherichia coli stra...

D. Nunn

2010-01-01

283

Structure Stabilization in Escherichia Coli Transfer Ribonucleic Acid.  

National Technical Information Service (NTIS)

Formaldehyde treatment of Escherichia coli B transfer ribonucleic acid (tRNA) appreciably changes hydrodynamic and optical properties. The increase in intrinsic viscosity, decrease in sedimentation coefficient coupled with the change in absorbance melting...

D. B. Millar M. MacKenzie

1967-01-01

284

76 FR 58157 - Shiga Toxin-Producing Escherichia coli  

Federal Register 2010, 2011, 2012, 2013

...Escherichia coli in Certain Raw Beef Products AGENCY: Food Safety and Inspection Service...documented, particularly in daycare settings and nursing homes, where there...In addition, FSIS will...for-cause food safety assessment...

2011-09-20

285

Effects of Protease Inhibitors on Protein Breakdown in 'Escherichia coli'.  

National Technical Information Service (NTIS)

In an attempt to learn more about the proteolytic enzymes responsible for protein turnover in cells, the effects of various protease inhibitors on protein catabolism in Escherichia coli were examined. Diisopropyl fluorophosphate, phenylmethane sulfonyl fl...

W. F. Prouty A. L. Goldberg

1971-01-01

286

Infected hepatic Echinococcus cyst presenting as recurrent Escherichia coli empyema.  

PubMed

An 81-year-old man, previously a shepherd in Italy, presented with recurrent Escherichia coli empyema over an 8-month period. His empyema was caused by an infected, nonviable hepatic Echinococcus cyst that eroded the diaphragm and led to intermittent spillage and pleural seeding. This case demonstrates that when dealing with Escherichia coli empyema, a subdiaphragmatic source ought to be suspected, and among immigrants from areas with prevalent hydatid disease, infected hepatic Echinococcus cyst might rarely be the cause. PMID:8452451

Chang, R; Higgins, M; DiLisio, R; Hawasli, A; Camaro, L G; Khatib, R

1993-03-01

287

Polymorphisms in the umuDC region of Escherichia species. [Escherichia coli; Escherichia alkalescens; Escherichia dispar; Escherichia aurescens  

SciTech Connect

The umuDC operon of Escherichia coli encodes mutagenic DNA repair. The umuDC regions of multiple isolates of E. coli, E. alkalescens, and E. dispar and a single stock of E. aurescens were mapped by nucleotide hybridization. umuDC is located at one end of a conserved tract of restriction endonuclease sites either 12.5 or 14 kilobase pairs long. Rearrangements, including possible deletions, were seen in the polymorphic DNA flanking the conserved tract. Restriction site polymorphisms were not found around the DNA repair gene recA or polA. The junctions of the conserved region contain direct repeats of nucleotide sequences resembling the termini of the Tn3 group of transposons. Possible mechanisms for the generation of these variants are discussed.

Sedgwick, S.G.; Robson, M.; Malik, F.

1988-04-01

288

EFFECT OF MANURE ON ESCHERICHIA COLI ATTACHMENT TO SOIL FRACTIONS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli are commonly used as indicators of fecal contamination in the environment. Attachment of bacteria to soil and sediment is an important retardation factor of bacterial transport with runoff water. Despite the fact that E. coli are derived exclusively from feces/manure, the effect of ...

289

RAPID GLUTAMATE DECARBOXYLASE ASSAY FOR THE DETECTION OF ESCHERICHIA COLI  

EPA Science Inventory

A rapid test procedure for the enzyme glutamate decarboxylase was developed for the detection of Escherichia coli. he assay procedure was able to confirm the presence of E. coli in enteric broth cultures with a 95 percent specificity for both pure cultures and environmental sampl...

290

Reduction of Aerobic Acetate Production by Escherichia coli  

Microsoft Academic Search

Acetate excretion by Escherichia coli during aerobic growth on glucose is a major obstacle to enhanced recombinant protein production. We report here that the fraction of carbon flux through the anaplerotic pathways is one of the factors influencing acetate excretion. Flux analysis of E. coli central metabolic pathways predicts that increasing the fraction of carbon flux through the phosphoenolpyruvate carboxylase

William R. Farmer; James C. Liao

1997-01-01

291

Relationship among fecal coliforms and Escherichia coli in various foods  

Microsoft Academic Search

For much of the twentieth century, coliform bacteria and especially Escherichia coli have been used as indicators of possible post-processing contamination and the presence of E. coli as an indicator of fecal contamination in foods. In this study, 500 foods in 10 different groups, mainly dairy products, delicatessen products, salads, spices, cream cakes and fresh fruit and vegetable samples, were

Hilal B. Do?an-Halkman; ?brahim Çak?r; Fikret Keven; Randy W. Worobo; A. Kadir Halkman

2003-01-01

292

Genome Sequence of Enterohemorrhagic Escherichia coli NCCP15658  

PubMed Central

Enterohemorrhagic Escherichia coli causes severe food-borne disease in the guts of humans and animals. Here, we report the high-quality draft genome sequence of E. coli NCCP15658 isolated from a patient in the Republic of Korea. Its genome size was determined to be 5.46 Mb, and its genomic features, including genes encoding virulence factors, were analyzed.

Song, Ju Yeon; Yoo, Ran Hee; Jang, Song Yee; Seong, Won-Keun; Kim, Seon-Young; Jeong, Haeyoung; Kang, Sung Gyun; Kim, Byung Kwon; Kwon, Soon-Kyeong; Lee, Choong Hoon; Yu, Dong Su; Park, Mi-Sun

2012-01-01

293

Interaction of Escherichia coli and Soil Particles in Runoff  

Microsoft Academic Search

A laboratory-scale model system was developed to investigate the transport mechanisms involved in the horizontal movement of bacteria in overland flow across saturated soils. A suspension of Escherichia coli and bromide tracer was added to the model system, and the bromide concentration and number of attached and unattached E. coli cells in the overland flow were measured over time. Analysis

Richard William Muirhead; Robert Peter Collins; Philip James Bremer

2006-01-01

294

Directed Evolution of Ionizing Radiation Resistance in Escherichia coli  

Microsoft Academic Search

We have generated extreme ionizing radiation resistance in a relatively sensitive bacterial species, Esche- richia coli, by directed evolution. Four populations of Escherichia coli K-12 were derived independently from strain MG1655, with each specifically adapted to survive exposure to high doses of ionizing radiation. D37 values for strains isolated from two of the populations approached that exhibited by Deinococcus radiodurans.

Dennis R. Harris; Steve V. Pollock; Elizabeth A. Wood; Reece J. Goiffon; Audrey J. Klingele; Eric L. Cabot; Wendy Schackwitz; Joel Martin; Julie Eggington; Timothy J. Durfee; Christina M. Middle; Jason E. Norton; Michael C. Popelars; Hao Li; Sarit A. Klugman; Lindsay L. Hamilton; Lukas B. Bane; Len A. Pennacchio; Thomas J. Albert; Nicole T. Perna; Michael M. Cox; John R. Battista

2009-01-01

295

Enterotoxigenic Escherichia coli Multilocus Sequence Types in Guatemala and Mexico  

PubMed Central

The genetic backgrounds of 24 enterotoxigenic Escherichia coli (ETEC) strains from Mexico and Guatemala expressing heat-stable toxin (ST) and coli surface antigen 6 (CS6) were analyzed. US travelers to these countries and resident children in Guatemala were infected by ETEC strains of sequence type 398, expressing STp and carrying genetically identical CS6 sequences.

Klena, John; Rodas, Claudia; Bourgeois, August Louis; Torres, Olga; Svennerholm, Ann-Mari; Sjoling, Asa

2010-01-01

296

Repair System for Noncanonical Purines in Escherichia coli  

Microsoft Academic Search

Exposure of Escherichia coli strains deficient in molybdopterin biosynthesis (moa) to the purine base N-6-hydroxylaminopurine (HAP) is mutagenic and toxic. We show that moa mutants exposed to HAP also exhibit elevated mutagenesis, a hyperrecombination phenotype, and increased SOS induction. The E. coli rdgB gene encodes a protein homologous to a deoxyribonucleotide triphosphate pyrophosphatase from Methanococ- cus jannaschii that shows a

Nicholas E. Burgis; Jason J. Brucker; Richard P. Cunningham

2003-01-01

297

Instability of repeated DNAs during transformation in Escherichia coli  

Microsoft Academic Search

Escherichia coli has provided an important model system for understanding the molecular basis for genetic instabilities associated with repeated DNA. Changes in triplet repeat length during growth following transformation in E. coli have been used as a measure of repeat instability. However, very little is known about the molecular and biological changes that may occur on transformation. Since only a

Vera I. Hashem; Elzbieta A. Klysik; William A. Rosche; Richard R. Sinden

2002-01-01

298

Transformation of Escherichia coli by a specific DNA restriction fragment  

Microsoft Academic Search

Specific transformation of a rifampicin sensitive strain of Escherichia coli to rifampicin resistance has been performed by a single, defined DNA restriction fragment carrying the genetic information for the ß subunit of E. coli RNA polymerase. In this transformation the transforming genetic character has been substituted for the corresponding recipient gene locus by recombination. The value of the described transformation

Silvia M. Schweitzer; Hans Matzura

1977-01-01

299

CNF producing Escherichia coli isolated from cattle in Northern Ireland  

Microsoft Academic Search

Tissue culture assays were used to investigate the incidence of cytotoxic necrotising factors (CNFs) 1 and 2 in Escherichia coli strains from cattle. E. coli cultures were obtained from faeces collected from 223 cases of diarrhoea and from 113 healthy animals. In addition, strains cultured from 62 cases of mastitis, 66 cases of septicaemia and 68 cases of abortion were

A. L. Burns; H. J. Ball; D. A. Finlay

1996-01-01

300

Escherichia coli Responses to a Single DNA Adduct  

Microsoft Academic Search

To study the mechanisms by which Escherichia coli modulates the genotoxic effects of DNA damage, a novel system has been developed which permits quantitative measurements of various E. coli pathways involved in mutagenesis and DNA repair. Events measured include fidelity and efficiency of translesion DNA synthesis, excision repair, and recombination repair. Our strategy involves heteroduplex plasmid DNA bearing a single

GAGAN A. PANDYA; IN-YOUNG YANG; ARTHUR P. GROLLMAN; MASAAKI MORIYA

2000-01-01

301

Gene transfer between Escherichia coli and Enterobacter aerogenes  

Microsoft Academic Search

Transfer of chromosomal genes between Escherichia coli K12 and Enterobacter aerogenes was carried out by P1-mediated transduction as well as by transformation of genes cloned in vitro on plasmid vectors. The efficient expression of E. coli genes in E. aerogenes probably reflects the existance of a poor restriction system in the latter, and suggests that this strain might be useful

Shulamit Michaeli; Eliora Z. Ron

1983-01-01

302

Transport of multiple Escherichia coli strains in saturated porous media  

Microsoft Academic Search

The deviation of bacteria transport and deposition patterns on grains in porous media from theory has resulted in the inability to accurately predict transport distances in aquifers, with consequences of polluting drinking water sources (springs, boreholes and wells). Due to the importance of Escherichia coli (E. coli) as an indicator of faecal contamination of drinking water supplies, this thesis research

G. Lutterodt

2012-01-01

303

Phenotypic and genotypic characterization of human and nonhuman escherichia coli  

Microsoft Academic Search

Estuarine waters receive fecal pollution from a variety of sources, including humans and wildlife. Escherichia coli is one of several fecal coliform bacteria that inhabit the intestines of many warm-blooded animals that sometime contaminate water. Its presence does not specifically implicate human fecal input, therefore it is necessary to differentiate contamination sources to accurately assess health risks. E. coli were

Salina Parveen; Nancy C Hodge; Robert E Stall; Samuel R Farrah; Mark L Tamplin

2001-01-01

304

Chicken Ovalbumin is Synthesized and Secreted by Escherichia coli  

Microsoft Academic Search

By recombinant DNA methods, the chicken ovalbumin structural gene has been fused to Escherichia coli lac transcriptional and translational control regions. When a plasmid containing the hybrid gene was introduced into E. coli, a protein identified as ovalbumin by immunoreactivity and sodium dodecyl sulfate\\/polyacrylamide gel electrophoresis was synthesized. The chicken ovalbumin made in bacteria was full length (43,000 daltons) and

Thomas H. Fraser; Barbara J. Bruce

1978-01-01

305

Genetic engineering of ethanol production in Escherichia coli  

Microsoft Academic Search

The genes encoding essential enzymes of the fermentative pathway for ethanol production in Zymomonas mobilis, an obligately ethanologenic bacterium, were inserted into Escherichia coli under the control of a common promoter. Alcohol dehydrogenase II and pyruvate decarboxylase from Z. mobilis were expressed at high levels in E. coli, resulting in increased cell growth and the production of ethanol as the

L. O. Ingram; T. Conway; D. P. Clark; G. W. Sewell; J. F. Preston

1987-01-01

306

Unusual "Flesh-Eating" Strain of Escherichia coli?  

PubMed Central

We report an exceptional case of life-threatening Escherichia coli-induced necrotizing fasciitis. A combined host-pathogen genetic analysis explained the phenotype: the host displayed a susceptibility to intravascular coagulation, and the strain was capable of producing a necrotic toxin (cytotoxic necrotizing factor 1), showing how E. coli can be a dermonecrotic pathogen.

Grimaldi, David; Bonacorsi, Stephane; Roussel, Helene; Zuber, Benjamin; Poupet, Helene; Chiche, Jean-Daniel; Poyart, Claire; Mira, Jean-Paul

2010-01-01

307

Escherichia coli with Resistance Factors in Vegetarians, Babies, and Nonvegetarians  

PubMed Central

The prevalence of Escherichia coli carrying resistance factors (R factors) was examined in meat-consuming individuals and in those not consuming meat (vegetarians and babies below the age of 6 months). Assuming that the transport of resistant E. coli from animals through meat and meat products to the human consumer is most important, with regard to the incidence of resistant E. coli in man, we expected a significant difference in the proportions of people with resistant E. coli between the two groups. However, the percentage with resistant E. coli was larger in the group of vegetarians and babies than in the group of meat-eating individuals.

Guinee, P.; Ugueto, N.; van Leeuwen, N.

1970-01-01

308

First report on class 1 integrons and Trimethoprim-resistance genes from dfrA group in uropathogenic E. coli (UPEC) from the Aleppo area in Syria  

PubMed Central

Horizontal gene transfer (HGT) introduces advantageous genetic elements into pathogenic bacteria using tools such as class1 integrons. This study aimed at investigating the distribution of these integrons among uropathogenic E. coli (UPEC) isolated from patients in Aleppo, Syria. It also set to uncover the frequencies of the clinically relevant DfrA1 and DfrA17,7, as well as various associations leading to reduced susceptibility. This study involved 75 Trimethoprim-resistant E. coli isolates from in- and outpatients with urinary tract infections (UTIs) from 3 major hospitals in Aleppo. Bacterial identification, resistance and extended-spectrum-?-lactamase (ESBL) production testing were performed according to Clinical Laboratory Standards Institute guidelines. Detection of integrons and DfrA genes was done using PCR and statistical significance was inferred through ?2 (Fisher’s) test. Class1 integrons were detected in 54.6% of isolates while DfrA1 and DfrA17,7 were found in 16% and 70.6% of tested samples respectively. Furthermore, only DfrA17,7 were strongly associated with class1 integrons, as were reduced susceptibility to the majority of individual antibiotics, multidrug resistance and ESBL production. This study demonstrated the high prevalence of class1 integrons among UPEC strains in Aleppo, Syria, as well as their significant associations with MDR. This data give information for local healthcare provision using antibiotic chemotherapy.

Al-Assil, Bodour; Mahfoud, Maysa; Hamzeh, Abdul Rezzak

2013-01-01

309

Shiga toxin-producing Escherichia coli  

PubMed Central

Shiga toxin-producing Escherichia coli (STEC) cause hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) in humans. Outbreaks are linked to bovine food sources. STEC O157:H7 has been responsible for the most severe outbreaks worldwide. However, non-O157 serotypes have emerged as important enteric pathogens in several countries. The main virulence factor of STEC is the production of Shiga toxins 1 and 2. Additional virulence markers are a plasmid-encoded enterohemolysin (ehxA), an autoagglutinating adhesin (Saa), a catalase-peroxidase (katP), an extracellular serine protease (espP), a zinc metalloprotease (stcE), a subtilase cytotoxin (subAB), among others. Other virulence factors are intimin and adhesins that had a roll in the adherence of STEC to bovine colon. This review focuses on the virulence traits of STEC and especially on those related to the adhesion to bovine colon. The known of the interaction between STEC and the bovine host is crucial to develop strategies to control cattle colonization.

Etcheverria, Analia Ines; Padola, Nora Lia

2013-01-01

310

Enteroaggregative Escherichia coli: an emerging enteric pathogen.  

PubMed

Enteroaggregative Escherichia coli (EAEC) represents an emerging pathogen that causes enteric and food-borne infectious diseases. Subgroups in many populations throughout the world are susceptible to EAEC infection. EAEC pathogenesis involves adherence to the intestinal mucosa; increased production and deposition of a mucus biofilm; and mucosal toxicity due to inflammation and cytokine release. Due to the heterogeneity of EAEC strains and differing host immune responses, not all EAEC infections are symptomatic. Recent data suggest that individuals with a homozygous genotype -251 AA single nucleotide polymorphism (SNP), in the IL-8 promoter region, are more susceptible to EAEC diarrhea. The HEp-2 cell adherent assay allows identification of EAEC's characteristic aggregative or "stacked brick" adherence pattern. Antimicrobial treatment of individuals who develop EAEC diarrhea should be individually based. Ciprofloxacin and rifaximin, compared to placebo, have been shown to significantly shorten the course of diarrhea in patients who developed EAEC infection. The objective of this review is to increase awareness of this important emerging pathogen and to discuss the epidemiology, pathogenesis, and host-pathogen factors associated with EAEC infection. PMID:15046233

Huang, David B; Okhuysen, Pablo C; Jiang, Zhi-Dong; DuPont, Herbert L

2004-02-01

311

Conformational studies of Escherichia coli pyruvate oxidase.  

PubMed

Pyruvate oxidase (pyruvate:oxygen oxidoreductase (phosphorylating), EC 1.2.3.3) is a peripheral membrane enzyme from Escherichia coli which utilizes the cofactors thiamin pyrophosphate (TPP) and flavin-adenine dinucleotide (FAD) to catalyze the decarboxylation of pyruvate to acetic acid and carbon dioxide. The specific activity of the oxidase is enhanced 25-fold when assayed in the presence of certain lipids and detergents. Previous studies have demonstrated that the affinity of pyruvate oxidase for phospholipids and detergents is substantially increased when the flavin is reduced. In this paper, several techniques are utilized to probe both the nature of the active site and the conformational changes in the protein which are concomitant with flavin reduction and with the binding of lipids to the enzyme. Analysis of the circular dichroism spectrum in the far ultraviolet region indicates that neither the binding of lipid activators to the oxidase nor reduction of the enzyme-bound flavin by pyruvate has a significant effect on the average secondary structure of the enzyme. High-resolution electron microscopy demonstrates that at low enzyme concentrations, i.e., assay conditions, incubation of the reduced flavoprotein in the presence of an amphiphilic activator does not alter the quaternary structure of pyruvate oxidase. The results indicate that the conformational changes in the protein due either to reduction of the flavin or to the binding of lipid activators are localized. PMID:6751398

O'Brien, T A; Shelton, E; Mather, M; Gennis, R B

1982-08-10

312

Mating aggregates in Escherichia coli conjugation.  

PubMed Central

Mating mixtures of Escherichia coli cells were shown to contain mating aggregates of two to 20 cells each rather than only mating pairs of two cells each. The mating aggregate size distribution shows two broad peaks, at two to four cells and at eight to 13 cells. The quantitative mating aggregate size distribution and the proportion of male cells in mating aggregates are dependent on the input ratio of male to female cells. At an input ratio of one to one, the average mating aggregate contains equal proportions of male and female cells and most of the cells involved in mating are in large aggregates of seven or more cells each. The deoxyribonucleic acid (DNA) transfer efficiency per mating aggregate cell was constant regardless of average aggregate size or of the ratio of male to female cells in the aggregate. Under optimal conditions essentially every male cell or every female cell in a mating aggregate can be involved in DNA transfer. A comparison of light microscopy, sucrose gradient centrifugation, and analysis with a modified Coulter counter indicated that the number of cells in mating aggregates is best equantitated using a modified Coulter counter. Images

Achtman, M

1975-01-01

313

Growth rate regulation in Escherichia coli  

PubMed Central

Growth rate regulation in bacteria has been an important issue in bacterial physiology for the past 50 years. This review, using Escherichia coli as a paradigm, summarizes the mechanisms for the regulation of rRNA synthesis in the context of systems biology, particularly, in the context of genome-wide competition for limited RNA polymerase (RNAP) in the cell under different growth conditions including nutrient starvation. The specific location of the seven rrn operons in the chromosome and the unique properties of the rrn promoters contribute to growth rate regulation. The length of the rrn transcripts, coupled with gene dosage effects, influence the distribution of RNAP on the chromosome in response to growth rate. Regulation of rRNA synthesis depends on multiple factors that affect the structure of the nucleoid and the allocation of RNAP for global gene expression. The magic spot ppGpp, which acts with DksA synergistically, is a key effector in both the growth rate regulation and the stringent response induced by nutrient starvation, mainly because the ppGpp level changes in response to environmental cues. It regulates rRNA synthesis via a cascade of events including both transcription initiation and elongation, and can be explained by an RNAP redistribution (allocation) model.

Jin, Ding Jun; Cagliero, Cedric; Zhou, Yan Ning

2012-01-01

314

Isolation of the Escherichia coli nucleoid.  

PubMed

Numerous protocols for the isolation of bacterial nucleoids have been described based on treatment of cells with sucrose-lysozyme-EDTA and subsequent lysis with detergents in the presence of counterions (e.g., NaCl, spermidine). Depending on the lysis conditions both envelope-free and envelope-bound nucleoids could be obtained, often in the same lysate. To investigate the mechanism(s) involved in compacting bacterial DNA in the living cell, we wished to isolate intact nucleoids in the absence of detergents and high concentrations of counterions. Here, we compare the general lysis method using detergents with a procedure involving osmotic shock of Escherichia coli spheroplasts that resulted in nucleoids free of envelope fragments. After staining the DNA with DAPI (4',6-diamidino-2-phenylindole) and cell lysis by either isolation procedure, free-floating nucleoids could be readily visualized in fluorescence microscope preparations. The detergent-salt and the osmotic-shock nucleoids appeared as relatively compact structures under the applied ionic conditions of 1 M and 10 mM, respectively. RNase treatment caused no dramatic changes in the size of either nucleoid. PMID:11278063

Cunha, S; Odijk, T; Süleymanoglu, E; Woldringh, C L

2001-02-01

315

Nucleoside diphosphate kinase from Escherichia coli.  

PubMed Central

Nucleoside diphosphate (NDP) kinase from Escherichia coli was purified to homogeneity and was crystallized. Gel filtration analysis of the purified enzyme indicated that it forms a tetramer. The enzyme was phosphorylated with [gamma-32P]ATP, and the pH stability profile of the phosphoenzyme indicated that two different amino acid residues were phosphorylated. Both a histidine residue and serine residues, including Ser-119 and Ser-121, appear to be phosphorylated. A Ser119Ala/Ser121Ala double mutant (i.e., with a Ser-to-Ala double mutation at positions 119 and 121), as well as Ser119Ala and Ser121Ala mutants, was isolated. All of these retained NDP kinase activity; also, both the Ser119Ala and Ser121Ala mutants could still be autophosphorylated. In the case of the double mutant, a slight autophosphorylation activity, which was resistant to acid treatment, was still detected, indicating that an additional minor autophosphorylation site besides His-117 exists. These results are discussed in light of the recent report of N. J. MacDonald et al. on the autophosphorylation of human NDP kinase (J. Biol. Chem. 268:25780-25789, 1993).

Almaula, N; Lu, Q; Delgado, J; Belkin, S; Inouye, M

1995-01-01

316

Biochemistry of homologous recombination in Escherichia coli.  

PubMed Central

Homologous recombination is a fundamental biological process. Biochemical understanding of this process is most advanced for Escherichia coli. At least 25 gene products are involved in promoting genetic exchange. At present, this includes the RecA, RecBCD (exonuclease V), RecE (exonuclease VIII), RecF, RecG, RecJ, RecN, RecOR, RecQ, RecT, RuvAB, RuvC, SbcCD, and SSB proteins, as well as DNA polymerase I, DNA gyrase, DNA topoisomerase I, DNA ligase, and DNA helicases. The activities displayed by these enzymes include homologous DNA pairing and strand exchange, helicase, branch migration, Holliday junction binding and cleavage, nuclease, ATPase, topoisomerase, DNA binding, ATP binding, polymerase, and ligase, and, collectively, they define biochemical events that are essential for efficient recombination. In addition to these needed proteins, a cis-acting recombination hot spot known as Chi (chi: 5'-GCTGGTGG-3') plays a crucial regulatory function. The biochemical steps that comprise homologous recombination can be formally divided into four parts: (i) processing of DNA molecules into suitable recombination substrates, (ii) homologous pairing of the DNA partners and the exchange of DNA strands, (iii) extension of the nascent DNA heteroduplex; and (iv) resolution of the resulting crossover structure. This review focuses on the biochemical mechanisms underlying these steps, with particular emphases on the activities of the proteins involved and on the integration of these activities into likely biochemical pathways for recombination. Images

Kowalczykowski, S C; Dixon, D A; Eggleston, A K; Lauder, S D; Rehrauer, W M

1994-01-01

317

Mechanisms of Acid Resistance in Escherichia coli.  

PubMed

Adaptation to acid stress is an important factor in the transmission of intestinal microbes. The enterobacterium Escherichia coli uses a range of physiological, metabolic, and proton-consuming acid resistance mechanisms in order to survive acid stresses as low as pH 2.0. The physiological adaptations include membrane modifications and outer membrane porins to reduce proton influx and periplasmic and cytoplasmic chaperones to manage the effects of acid damage. The metabolic acid resistance systems couple proton efflux to energy generation via select components of the electron transport chain, including cytochrome bo oxidase, NADH dehydrogenase I, NADH dehydrogenase II, and succinate dehydrogenase. Under anaerobic conditions the formate hydrogen lyase complex catalyzes conversion of cytoplasmic protons to hydrogen gas. Finally, each major proton-consuming acid resistance system has a pyridoxal-5'-phosphate-dependent amino acid decarboxylase that catalyzes proton-dependent decarboxylation of a substrate amino acid to product and CO2, and an inner membrane antiporter that exchanges external substrate for internal product. PMID:23701194

Kanjee, Usheer; Houry, Walid A

2013-05-20

318

Oligosaccharide Binding in Escherichia coli Glycogen Synthase  

SciTech Connect

Glycogen/starch synthase elongates glucan chains and is the key enzyme in the synthesis of glycogen in bacteria and starch in plants. Cocrystallization of Escherichia coli wild-type glycogen synthase (GS) with substrate ADPGlc and the glucan acceptor mimic HEPPSO produced a closed form of GS and suggests that domain-domain closure accompanies glycogen synthesis. Cocrystallization of the inactive GS mutant E377A with substrate ADPGlc and oligosaccharide results in the first oligosaccharide-bound glycogen synthase structure. Four bound oligosaccharides are observed, one in the interdomain cleft (G6a) and three on the N-terminal domain surface (G6b, G6c, and G6d). Extending from the center of the enzyme to the interdomain cleft opening, G6a mostly interacts with the highly conserved N-terminal domain residues lining the cleft of GS. The surface-bound oligosaccharides G6c and G6d have less interaction with enzyme and exhibit a more curled, helixlike structural arrangement. The observation that oligosaccharides bind only to the N-terminal domain of GS suggests that glycogen in vivo probably binds to only one side of the enzyme to ensure unencumbered interdomain movement, which is required for efficient, continuous glucan-chain synthesis.

Sheng, Fang; Yep, Alejandra; Feng, Lei; Preiss, Jack; Geiger, James H.; (MSU)

2010-11-17

319

Mouse Model of Enteropathogenic Escherichia coli Infection  

PubMed Central

Enteropathogenic Escherichia coli (EPEC) is an important cause of diarrhea in humans. EPEC infection of cultured intestinal epithelial cells induces attaching and effacing (A/E) lesions, alters intestinal ion transport, increases paracellular permeability, and stimulates inflammation. The lack of a small-animal model has restricted in vivo studies examining EPEC-host interactions. The aim of this study was to characterize the C57BL/6J mouse as a model of EPEC infection. We have shown that EPEC can adhere to and colonize the intestinal epithelium of C57BL/6J mice. Animal weight and water intake were not altered during 10 days of EPEC infection. The proximal colon of infected mice contained semisolid stool, with stool pellets forming only in the distal colon. In contrast, the entire colon of control mice contained formed stool. Microvillous effacement and actin rearrangement, characteristic of A/E lesions, were seen in the intestine of infected mice but not control mice. Histological assessment revealed increased numbers of lamina propria neutrophils with occasional crypt abscesses, intraepithelial lymphocytes, and goblet cells in the intestine of EPEC-infected mice. Altogether, these data suggest that the C57BL/6J mouse is susceptible to infection by EPEC and will provide a suitable in vivo model for studying the consequences of EPEC infection.

Savkovic, Suzana D.; Villanueva, Jennilee; Turner, Jerrold R.; Matkowskyj, Kristina A.; Hecht, Gail

2005-01-01

320

Characterization of an Escherichia coli elaC deletion mutant  

Microsoft Academic Search

The elaC gene of Escherichia coli encodes a binuclear zinc phosphodiesterase (ZiPD). ZiPD homologs from various species act as 3? tRNA processing endoribonucleases, and although the homologous gene in Bacillus subtilis is essential for viability [EMBO J. 22 (2003) 4534], the physiological function of E. coli ZiPD has remained enigmatic. In order to investigate the function of E. coli ZiPD

Oliver Schilling; Sabrina Rüggeberg; Andreas Vogel; Nicole Rittner; Sigrid Weichert; Sabine Schmidt; Simon Doig; Thomas Franz; Vladimir Benes; Simon C. Andrews; Michael Baum; Wolfram Meyer-Klaucke

2004-01-01

321

Inactivation of Escherichia coli in orange juice using ozone  

Microsoft Academic Search

\\u000aThis research investigated the efficacy of gaseous ozone for the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in orange juice. Orange juice inoculated with E. coli (106?CFU mL-?1) as a challenge microorganism was treated with ozone at 75-78??g mL-?1 for different time periods (0-18?min). The efficacy of ozone for inactivation of both strains of E. coli was

S. Patil; P. Bourke; J. M. Frias; B. K. Tiwari; P. J. Cullen

2009-01-01

322

Longevity Studies of Escherichia coli on Apples from Tree  

Microsoft Academic Search

The consumption of fresh apple juice and apple cider has been linked to increasing numbers of outbreaks associated with Escherichia coli O157:H7. Apples can become contaminated with E. coli O157:H7 not only during processing but also while still on the tree. This study was undertaken to ascertain if E. coli can survive and grow on apples in an orchard environment

Sun-Young Lee; Dong-Hyun Kang

323

Functional Homology of Chemotaxis Genes Escherichia coli and Salmonella typhimurium  

Microsoft Academic Search

Generally nonchemotactic mutants of Escherichia coli and Salmonella typhi- murium were analyzed by interspecies complementation tests to determine the functional correspondence between the che genes of these two organisms. The E. coli che region was introduced into Salnonella recipients by means of a series of F-prime elements. Wild-type che genes of E. coli F'420 complemented all che mutants of Sabnonella

Anthony L. Defranco; JOHN S. PARKINSON; D. E. KOSHLAND

1979-01-01

324

Inhibition of Escherichia coli-Induced Meningitis by Carboxyfullerence  

Microsoft Academic Search

The effect of a water-soluble malonic acid derivative of carboxyfullerence (C60) against Escherichia coli- induced meningitis was tested. C60 can protect the mice from E. coli-induced death in a dose-dependent manner. C60 administered intraperitoneally as late as 9 h after E. coli injection was still protective. The C60-treated mice had less tumor necrosis factor alpha and interleukin-1b production by staining

NINA TSAO; PUTHUPARAMPIL P. KANAKAMMA; TIEN-YAU LUH; CHEN-KUNG CHOU

1999-01-01

325

Escherichia coli : on-farm contamination of animals  

Microsoft Academic Search

Summary Escherichia coli is one of the main inhabitants of the intestinal tract of most mammalian species, including humans, and birds. Shiga toxin-producing E. coli (STEC), also called verotoxinogenic E. coli, usually do not cause disease in animals but may cause watery diarrhoea, haemorrhagic colitis, and\\/or haemolytic uraemic syndrome in humans. Zoonotic STEC include the O157:H7 strains and, with increasing

J. M. Fairbrother; É. Nadeau

2006-01-01

326

Recombinant Production of Native Proteins from Escherichia coli  

Microsoft Academic Search

\\u000a The production of large quantities of proteins became possible with the advent of recombinant DNA technology, and the subsequent\\u000a expression of recombinant proteins in Escherichia coli (E. coli) (Itakura, 1977). Recombinant proteins are produced in E. coli cytoplasm at high concentrations in a very different environment than that in which they are normally expressed. Their structure,\\u000a stability and solubility are

Tsutomu Arakawa; Tiansheng Li; Linda O. Narhi

327

The Function of OmpA in Escherichia coli  

Microsoft Academic Search

Outer membrane protein A (OmpA) is a major protein in the Escherichia coli outer membrane. In this study, the function of OmpA in E. coli stress survival was examined. An E. coli K1 ompA-deletion mutant was significantly more sensitive than that of its parent strain to sodium dodecyl sulfate (SDS), cholate, acidic environment, high osmolarity, and pooled human serum. A

Ying Wang

2002-01-01

328

Environmental Controls on the Fate of Escherichia coli in Soil  

Microsoft Academic Search

An improved understanding of factors that influence the survival and\\/or growth of Escherichia coli (E. coli) in soil is essential to allow the formation of land management practices to control the spread of the pathogenic strains\\u000a of the bacteria, whose transmission to fresh produce is a threat to food safety. Persistence of E. coli in soils held at different water

M. Habteselassie; M. Bischoff; E. Blume; B. Applegate; B. Reuhs; S. Brouder; R. F. Turco

2008-01-01

329

Antimicrobial resistance of Escherichia coli and therapeutic implications.  

PubMed

Widespread antibiotic resistance has been recognized in Escherichia coli isolates from human, animal and environmental sources. Although prevalence rates for resistant E. coli strains are significantly distinct for various populations and environments, the impact of resistance to antimicrobial drugs is ubiquitous. This article provides information about the epidemiology, mechanisms and molecular principles of resistance, shows consequences for the antiinfective treatment of selected infections and describes measures to control the spread of antibiotic-resistant E. coli. PMID:16238024

von Baum, Heike; Marre, Reinhard

2005-10-01

330

Intrauterine Growth Restriction Is a Direct Consequence of Localized Maternal Uropathogenic Escherichia coli Cystitis  

PubMed Central

Despite the continually increasing rates of adverse perinatal outcomes across the globe, the molecular mechanisms that underlie adverse perinatal outcomes are not completely understood. Clinical studies report that 10% of pregnant women will experience a urinary tract infection (UTI) and there is an association of UTIs with adverse perinatal outcomes. We introduced bacterial cystitis into successfully outbred female mice at gestational day 14 to follow pregnancy outcomes and immunological responses to determine the mechanisms that underlie UTI-mediated adverse outcomes. Outbred fetuses from mothers experiencing localized cystitis displayed intrauterine growth restriction (20–80%) as early as 48 hours post-infection and throughout the remainder of normal gestation. Robust infiltration of cellular innate immune effectors was observed in the uteroplacental tissue following introduction of UTI despite absence of viable bacteria. The magnitude of serum proinflammatory cytokines is elevated in the maternal serum during UTI. This study demonstrates that a localized infection can dramatically impact the immunological status as well as the function of non-infected distal organs and tissues. This model can be used as a platform to determine the mechanism(s) by which proinflammatory changes occur between non-contiguous genitourinary organs

Bolton, Michael; Horvath, Dennis J.; Li, Birong; Cortado, Hanna; Newsom, David; White, Peter; Partida-Sanchez, Santiago; Justice, Sheryl S.

2012-01-01

331

Comparison of Asymptomatic Bacteriuria Escherichia coli Isolates from Healthy Individuals versus Those from Hospital Patients Shows that Long-Term Bladder Colonization Selects for Attenuated Virulence Phenotypes  

PubMed Central

Asymptomatic bacteriuria (ABU) is a condition where bacteria stably colonize the urinary tract, in a manner closely resembling commensalism at other mucosal sites. The patients carry >105 CFU/ml for extended periods of time and rarely develop symptoms. Contrasting the properties of ABU strains to those of uropathogenic isolates causing symptomatic infection is therefore highly relevant to understand mechanisms of bacterial adaptation. The prototype ABU strain Escherichia coli 83972 has a smaller genome than uropathogenic E. coli (UPEC) strains with deletions or point mutations in several virulence genes, suggesting that ABU strains undergo a programmed reductive evolution within human hosts. This study addressed if these observations can be generalized. Strains causing ABU in outpatients or hospitalized patients after catheterization or other invasive procedures were compared to commensal E. coli isolates from the intestinal flora of healthy individuals. Notably, clonal complex 73 (CC73) was a prominent phylogenetic lineage dominated by ABU isolates. ABU isolates from outpatients and hospitalized patients had a similar overall virulence gene repertoire, which distinguished them from many commensals, but typical UPEC virulence genes were less frequently attenuated in hospital strains than in outpatient strains or commensals. The decreased virulence potential of outpatient ABU isolates relative to that of ABU strains from hospitalized patients supports the hypothesis that loss of expression or decay of virulence genes facilitates long-term carriage and adaptation to host environments.

Salvador, Ellaine; Wagenlehner, Florian; Kohler, Christian-Daniel; Mellmann, Alexander; Hacker, Jorg; Svanborg, Catharina

2012-01-01

332

Role of the Vpe Carbohydrate Permease in Escherichia coli Urovirulence and Fitness In Vivo  

PubMed Central

Uropathogenic Escherichia coli (UPEC) strains are a leading cause of infections in humans, but the mechanisms governing host colonization by this bacterium remain poorly understood. Previous studies have identified numerous gene clusters encoding proteins involved in sugar transport, in pathogen-specific islands. We investigated the role in fitness and virulence of the vpe operon encoding an EII complex of the phosphotransferase (PTS) system, which is found more frequently in human strains from infected urine and blood (45%) than in E. coli isolated from healthy humans (15%). We studied the role of this locus in vivo, using the UPEC E. coli strain AL511, mutants, and complemented derivatives in two experimental mouse models of infection. Mutant strains displayed attenuated virulence in a mouse model of sepsis. A role in kidney colonization was also demonstrated by coinfection experiments in a mouse model of pyelonephritis. Electron microscopy examinations showed that the vpeBC mutant produced much smaller amounts of a capsule-like surface material than the wild type, particularly when growing in human urine. Complementation of the vpeBC mutation led to an increase in the amount of exopolysaccharide, resistance to serum killing, and virulence. It was therefore clear that the loss of vpe genes was responsible for all the observed phenotypes. We also demonstrated the involvement of the vpe locus in gut colonization in the streptomycin-treated mouse model of intestinal colonization. These findings confirm that carbohydrate transport and metabolism underlie the ability of UPEC strains to colonize the host intestine and to infect various host sites.

Martinez-Jehanne, Vanessa; Pichon, Christophe; du Merle, Laurence; Poupel, Olivier; Cayet, Nadege; Bouchier, Christiane

2012-01-01

333

Fitness of Escherichia coli during Urinary Tract Infection Requires Gluconeogenesis and the TCA Cycle  

PubMed Central

Microbial pathogenesis studies traditionally encompass dissection of virulence properties such as the bacterium's ability to elaborate toxins, adhere to and invade host cells, cause tissue damage, or otherwise disrupt normal host immune and cellular functions. In contrast, bacterial metabolism during infection has only been recently appreciated to contribute to persistence as much as their virulence properties. In this study, we used comparative proteomics to investigate the expression of uropathogenic Escherichia coli (UPEC) cytoplasmic proteins during growth in the urinary tract environment and systematic disruption of central metabolic pathways to better understand bacterial metabolism during infection. Using two-dimensional fluorescence difference in gel electrophoresis (2D-DIGE) and tandem mass spectrometry, it was found that UPEC differentially expresses 84 cytoplasmic proteins between growth in LB medium and growth in human urine (P<0.005). Proteins induced during growth in urine included those involved in the import of short peptides and enzymes required for the transport and catabolism of sialic acid, gluconate, and the pentose sugars xylose and arabinose. Proteins required for the biosynthesis of arginine and serine along with the enzyme agmatinase that is used to produce the polyamine putrescine were also up-regulated in urine. To complement these data, we constructed mutants in these genes and created mutants defective in each central metabolic pathway and tested the relative fitness of these UPEC mutants in vivo in an infection model. Import of peptides, gluconeogenesis, and the tricarboxylic acid cycle are required for E. coli fitness during urinary tract infection while glycolysis, both the non-oxidative and oxidative branches of the pentose phosphate pathway, and the Entner-Doudoroff pathway were dispensable in vivo. These findings suggest that peptides and amino acids are the primary carbon source for E. coli during infection of the urinary tract. Because anaplerosis, or using central pathways to replenish metabolic intermediates, is required for UPEC fitness in vivo, we propose that central metabolic pathways of bacteria could be considered critical components of virulence for pathogenic microbes.

Alteri, Christopher J.; Smith, Sara N.; Mobley, Harry L. T.

2009-01-01

334

Role of the vpe carbohydrate permease in Escherichia coli urovirulence and fitness in vivo.  

PubMed

Uropathogenic Escherichia coli (UPEC) strains are a leading cause of infections in humans, but the mechanisms governing host colonization by this bacterium remain poorly understood. Previous studies have identified numerous gene clusters encoding proteins involved in sugar transport, in pathogen-specific islands. We investigated the role in fitness and virulence of the vpe operon encoding an EII complex of the phosphotransferase (PTS) system, which is found more frequently in human strains from infected urine and blood (45%) than in E. coli isolated from healthy humans (15%). We studied the role of this locus in vivo, using the UPEC E. coli strain AL511, mutants, and complemented derivatives in two experimental mouse models of infection. Mutant strains displayed attenuated virulence in a mouse model of sepsis. A role in kidney colonization was also demonstrated by coinfection experiments in a mouse model of pyelonephritis. Electron microscopy examinations showed that the vpeBC mutant produced much smaller amounts of a capsule-like surface material than the wild type, particularly when growing in human urine. Complementation of the vpeBC mutation led to an increase in the amount of exopolysaccharide, resistance to serum killing, and virulence. It was therefore clear that the loss of vpe genes was responsible for all the observed phenotypes. We also demonstrated the involvement of the vpe locus in gut colonization in the streptomycin-treated mouse model of intestinal colonization. These findings confirm that carbohydrate transport and metabolism underlie the ability of UPEC strains to colonize the host intestine and to infect various host sites. PMID:22615242

Martinez-Jéhanne, Vanessa; Pichon, Christophe; du Merle, Laurence; Poupel, Olivier; Cayet, Nadčge; Bouchier, Christiane; Le Bouguénec, Chantal

2012-05-21

335

Inhibition of Escherichia coli CFT073 fliC expression and motility by cranberry materials.  

PubMed

In humans, uropathogenic Escherichia coli (UPEC) is the most common etiological agent of uncomplicated urinary tract infections (UTIs). Cranberry extracts have been linked to the prevention of UTIs for over a century; however, a mechanistic understanding of the way in which cranberry derivatives prevent bacterial infection is still lacking. In this study, we used a fliC-lux reporter as well as quantitative reverse transcription-PCR to demonstrate that when UPEC strain CFT073 was grown or exposed to dehydrated, crushed cranberries or to purified cranberry-derived proanthocyanidins (cPACs), expression of the flagellin gene (fliC) was inhibited. In agreement with these results, transmission electron microscopy imaging of bacteria grown in the presence of cranberry materials revealed fewer flagella than those in bacteria grown under control conditions. Furthermore, we showed that swimming and swarming motilities were hindered when bacteria were grown in the presence of the cranberry compounds. Because flagellum-mediated motility has been suggested to enable UPEC to disseminate to the upper urinary tract, we propose that inhibition of flagellum-mediated motility might be a key mechanism by which cPACs prevent UTIs. This is the first report to show that cranberry compounds inhibit UPEC motility via downregulation of the fliC gene. Further studies are required to establish whether these inhibitors play a role in vivo. PMID:21821749

Hidalgo, Gabriela; Chan, Michelle; Tufenkji, Nathalie

2011-08-05

336

Inhibition of Escherichia coli CFT073 fliC Expression and Motility by Cranberry Materials ?  

PubMed Central

In humans, uropathogenic Escherichia coli (UPEC) is the most common etiological agent of uncomplicated urinary tract infections (UTIs). Cranberry extracts have been linked to the prevention of UTIs for over a century; however, a mechanistic understanding of the way in which cranberry derivatives prevent bacterial infection is still lacking. In this study, we used a fliC-lux reporter as well as quantitative reverse transcription-PCR to demonstrate that when UPEC strain CFT073 was grown or exposed to dehydrated, crushed cranberries or to purified cranberry-derived proanthocyanidins (cPACs), expression of the flagellin gene (fliC) was inhibited. In agreement with these results, transmission electron microscopy imaging of bacteria grown in the presence of cranberry materials revealed fewer flagella than those in bacteria grown under control conditions. Furthermore, we showed that swimming and swarming motilities were hindered when bacteria were grown in the presence of the cranberry compounds. Because flagellum-mediated motility has been suggested to enable UPEC to disseminate to the upper urinary tract, we propose that inhibition of flagellum-mediated motility might be a key mechanism by which cPACs prevent UTIs. This is the first report to show that cranberry compounds inhibit UPEC motility via downregulation of the fliC gene. Further studies are required to establish whether these inhibitors play a role in vivo.

Hidalgo, Gabriela; Chan, Michelle; Tufenkji, Nathalie

2011-01-01

337

A sticky chain model of the elongation and unfolding of Escherichia coli P pili under stress.  

PubMed

A model of the elongation of P pili expressed by uropathogenic Escherichia coli exposed to stress is presented. The model is based upon the sticky chain concept, which is based upon Hooke's law for elongation of the layer-to-layer and head-to-tail bonds between neighboring units in the PapA rod and a kinetic description of the opening and closing of bonds, described by rate equations and an energy landscape model. It provides an accurate description of the elongation behavior of P pili under stress and supports a hypothesis that the PapA rod shows all three basic stereotypes of elongation/unfolding: elongation of bonds in parallel, the zipper mode of unfolding, and elongation and unfolding of bonds in series. The two first elongation regions are dominated by a cooperative bond opening, in which each bond is influenced by its neighbor, whereas the third region can be described by individual bond opening, in which the bonds open and close randomly. A methodology for a swift extraction of model parameters from force-versus-elongation measurements performed under equilibrium conditions is derived. Entities such as the free energy, the stiffness, the elastic elongation, the opening length of the various bonds, and the number of PapA units in the rod are determined. PMID:16361334

Andersson, Magnus; Fällman, Erik; Uhlin, Bernt Eric; Axner, Ove

2005-12-16

338

Reproducible gene targeting in recalcitrant Escherichia coli isolates  

PubMed Central

Background A number of allele replacement methods can be used to mutate bacterial genes. For instance, the Red recombinase system of phage Lambda has been used very efficiently to inactivate chromosomal genes in E. coli K-12, through recombination between regions of homology. However, this method does not work reproducibly in some clinical E. coli isolates. Findings The procedure was modified by using longer homologous regions (85 bp and 500-600 bp), to inactivate genes in the uropathogenic E. coli strain UTI89. An lrhA regulator mutant, and deletions of the lac operon as well as the complete type 1 fimbrial gene cluster, were obtained reproducibly. The modified method is also functional in other recalcitrant E. coli, like the avian pathogenic E. coli strain APEC1. The lrhA regulator and lac operon deletion mutants of APEC1 were successfully constructed in the same way as the UTI89 mutants. In other avian pathogenic E. coli strains (APEC3E, APEC11A and APEC16A) it was very difficult or impossible to construct these mutants, with the original Red recombinase-based method, with a Red recombinase-based method using longer (85 bp) homologous regions or with our modified protocol, using 500 - 600 bp homologous regions. Conclusions The method using 500-600 bp homologous regions can be used reliably in some clinical isolates, to delete single genes or entire operons by homologous recombination. However, it does not invariably show a greater efficiency in obtaining mutants, when compared to the original Red-mediated gene targeting method or to the gene targeting method with 85 bp homologous regions. Therefore the length of the homology regions is not the only limiting factor for the construction of mutants in these recalcitrant strains.

2011-01-01

339

Inactivation of Escherichia coli O157:H7 and Escherichia coli 8739 in apple juice by pulsed electric fields.  

PubMed

The effect of high voltage pulsed electric field (PEF) treatment on Escherichia coli O157:H7 and generic E. coli 8739 in apple juice was investigated. Fresh apple juice samples inoculated with E. coli O157:H7 and E. coli 8739 were treated by PEF with selected parameters including electric field strength, treatment time, and treatment temperature. Samples were exposed to bipolar pulses with electric field strengths of 30, 26, 22, and 18 kV/cm and total treatment times of 172, 144, 115, and 86 micros. A 5-log reduction in both cultures was determined by a standard nonselective medium spread plate laboratory procedure. Treatment temperature was kept below 35 degrees C. Results showed no difference in the sensitivities of E. coli O157:H7 and E. coli 8739 against PEF treatment. PEF is a promising technology for the inactivation of E. coli O157:H7 and E. coli 8739 in apple juice. PMID:10419274

Evrendilek, G A; Zhang, Q H; Richter, E R

1999-07-01

340

Very slow growth of Escherichia coli.  

PubMed Central

A recycling fermentor (a chemostat with 100% biomass feedback) was used to study glucose-limited behavior of Escherichia coli B. The expectation from mass transfer analysis that growth would asymptotically approach a limit mass determined by the glucose provision rate (GPR) and the culture's maintenance requirement was not met. Instead, growth proceeded at progressively lower rates through three distinct phases. After the fermentor was seeded, but before glucose became limiting, growth followed the usual, exponential path (phase 1). About 12 h postseeding, residual glucose in the fermentor fell below 1 microgram . ml-1 and the growth rate (dx/dt) became constant and a linear function of GPR (phase 2). The specific growth rate, mu, therefore fell continuously throughout the phase. Biomass yield and glucose assimilation (13%) were near the level for exponential growth, however, and independent of GPR over a broad range. At a critical specific growth rate (0.04 h-1 for this strain), phase 2 ended abruptly and phase 3 commenced. In phase 3, the growth rate was again constant, although lower than in phase 2, so that mu continued to fall, but growth rates and yields were praboloid functions of GPR. They were never zero, however, at any positive value of GPR. By inference, the fraction of metabolic energy used for maintenance functions is constant for a given GPR, although different for phases 2 and 3, and independent of biomass. In both phases 2 and 3, orcinol, diphenylamine, and Lowry reactive materials were secreted at near-constant rates such that over 50% as much biosynthetic mass was secreted as was retained by the cells. Images

Chesbro, W; Evans, T; Eifert, R

1979-01-01

341

Novel mechanism of Escherichia coli porin regulation.  

PubMed

A novel mechanism of Escherichia coli porin regulation was discovered from multicopy suppressors that permitted growth of cells expressing a mutant OmpC protein in the absence of DegP. Analyses of two suppressors showed that both substantially lowered OmpC expression. Suppression activities were confined to a short DNA sequence, which we designated ipeX for inhibition of porin expression, and to DNA containing a 3'-truncated ompR gene. The major effect of ipeX on ompC expression was exerted posttranscriptionally, whereas the truncated OmpR protein reduced ompC transcription. ipeX was localized within an untranslated region of 247 base pairs between the stop codon of nmpC-a remnant porin gene from the cryptic phage qsr' (DLP12) genome-and its predicted Rho-independent transcriptional terminator. Interestingly, another prophage, PA-2, which encodes a porin similar to NmpC, known as Lc, has sequences downstream from lc identical to that of ipeX. PA-2 lysogenization leads to Lc expression and OmpC inhibition. Our data show that the synthesis of the lc transcript, whose 3' end contains the corresponding ipeX sequence, inhibits OmpC expression. Overexpression of ipeX RNA inhibited both OmpC and OmpF expression but not that of OmpA. ompC-phoA chimeric gene constructs revealed a 248-bp untranslated region of ompC required for ipeX-mediated inhibition. However, no sequence complementarity was found between ipeX and this region of ompC, indicating that inhibition may not involve simple base pairing between the two RNA molecules. The effect of ipeX on ompC, but not on ompF, was independent of the RNA chaperone Hfq. PMID:16385048

Castillo-Keller, Maria; Vuong, Phu; Misra, Rajeev

2006-01-01

342

Tobramycin uptake in Escherichia coli membrane vesicles.  

PubMed Central

The uptake of tobramycin was measured in Escherichia coli membrane vesicles prepared in KMES [K(+)-2-(N-morpholino)ethanesulfonic acid] buffer at pH 6.6. Uptake occurred in vesicles energized with ascorbic acid and phenazine methosulfate, in which the electrical potential (delta psi) was -120 mV, but not in vesicles energized with D-lactate (delta psi = -95 mV). The addition of nigericin to vesicles energized with D-lactate did not induce tobramycin uptake despite an increase in delta psi to -110 mV. However, when delta psi was increased or decreased by the addition of nigericin or valinomycin, respectively, uptake in vesicles energized with ascorbic acid and phenazine methosulfate was stimulated or inhibited, respectively, confirming studies with whole cells showing that uptake of aminoglycosides is gated by delta psi rather than by proton motive force (delta microH+) or delta pH. N-ethylmaleimide prevented uptake, suggesting that the aminoglycoside transporter is a cytoplasmic membrane protein with accessible sulfhydryl groups. The observation that uptake is gated in vesicles as well as in whole cells suggested that diffusion occurs through a voltage-gated channel. In vesicles preloaded with tobramycin, no efflux occurred after the addition of the protonophore carbonyl cyanide m-chlorophenylhydrazone. In susceptible cells, aminoglycosides themselves decreased the magnitude of delta psi. We propose a mechanism of aminoglycoside-induced killing in which aminoglycosides themselves close the voltage-gated channel by decreasing the magnitude of delta psi. Channel closure causes aminoglycosides accumulated prior to the fall in delta psi to be trapped, which in turn causes irreversible uptake and subsequent bactericidal effects.

Leviton, I M; Fraimow, H S; Carrasco, N; Dougherty, T J; Miller, M H

1995-01-01

343

The Ascorbate Transporter of Escherichia coli  

PubMed Central

The sgaTBA genes of Escherichia coli encode a putative 12-transmembrane ?-helical segment (12 TMS) transporter, an enzyme IIB-like protein and an enzyme IIA-like protein of the phosphotransferase system (PTS), respectively. We show that all three proteins as well as the energy-coupling PTS proteins, enzyme I and HPr, are required for the anaerobic utilization and uptake of l-ascorbate in vivo and its phosphoenolpyruvate-dependent phosphorylation in vitro. The transporter exhibits an apparent Km for l-ascorbate of 9 ?M and is highly specific. The sgaTBA genes are regulated at the transcriptional level by the yjfQ gene product, as well as by Crp and Fnr. The yjfR gene product is essential for l-ascorbate utilization and probably encodes a cytoplasmic l-ascorbate 6-phosphate lactonase. We conclude that SgaT represents a novel prototypical enzyme IIC that functions with SgaA and SgaB to allow phosphoryl transfer from HPr(his-P) to l-ascorbate via the phosphoryl transfer pathway: PEP???enzyme?I-P???HPr-P???IIA-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{ \\,\\substack{ ^{SgaA} \\\\ P \\\\ }\\, }\\end{equation*}\\end{document}???IIB-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{ \\,\\substack{ ^{SgaB} \\\\ P \\\\ }\\, }\\end{equation*}\\end{document}\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{ \\,\\substack{ ^{IIC} \\\\ {\\rightarrow} \\\\ }\\, }\\end{equation*}\\end{document}SgaTl-ascorbate-6-P.

Zhang, Zhongge; Aboulwafa, Mohammad; Smith, Meghan H.; Saier, Jr., Milton H.

2003-01-01

344

Proteins on Escherichia coli andAgrobacterium tumefaciens Translation Systems  

Microsoft Academic Search

Theeffects of30type1andof2 (ricin andvolkensin) type2ribosome-inactivating proteins (RIPs) on Escherichia coli andAgrobacterium tumefaciens cell-free translation systems were compared withtheeffects on a rabbit reticulocyte translation system. Thedepurinating activity ofRIPson E.coli ribosomes was also evaluated. Onlysixtype1RIPsinhibited endogenous mRNA-directed translational activity ofE.coli lysates, withsubmicromolar 50% inhibitory concentrations. FourRIPshadsimilar activities on poly(U)-directed phenylalanine polymerization byE.coli ribosomes, andthree RIPsinhibited poly(U)-directed polyphenylala- ninesynthesis byA.tumefaciens ribosomes, withsubmicromolar 50%1inhibitory

TOMAS GIRBES; MIGUEL FERRERAS; F. JAVIER ARIAS; M. ANGELES ROJO; ROSARIO IGLESIAS; CARLOS ALEGRE; FIORENZO STIRPE

345

Antimicrobial resistance and prevalence of canine uropathogens at the Western College of Veterinary Medicine Veterinary Teaching Hospital, 2002-2007  

PubMed Central

Between January 2002 and June 2007, uropathogens were isolated from 473 of 1557 canine urine samples submitted to Prairie Diagnostic Services from the Western College of Veterinary Medicine Veterinary Teaching Hospital. Culture and susceptibility results were analyzed, retrospectively, to estimate the prevalence of common bacterial uropathogens in dogs with urinary tract infections and to identify changes in antimicrobial resistance. The most common pathogens identified were Escherichia coli, Staphylococcus intermedius, Enterococcus spp., and Proteus spp. Antimicrobial resistance increased during the study period, particularly among recurrent E. coli isolates. Using the formula to help select rational antimicrobial therapy (FRAT), bacterial isolates were most likely to be susceptible to gentamicin, fluoroquinolones, amoxicillin-clavulanic acid, and groups 4 and 5 (third generation) cephalosporins.

Ball, Katherine R.; Rubin, Joseph E.; Chirino-Trejo, M.; Dowling, Patricia M.

2008-01-01

346

Intestinal Colonization by Enterotoxigenic 'Escherichia coli.'.  

National Technical Information Service (NTIS)

Growth of enterotoxigenic E. coli in porcine small intestine selects for piliated forms which adhere to the intestinal epithelium. Surface antigen K99 on enterotoxigenic E. coli is a pilus. Antigen K99 occurs on porcine enterotoxigenic E. coli strains and...

H. W. Moon

1976-01-01

347

Serological cross-reactions between Escherichia coli O157 and other species of the genus Escherichia.  

PubMed

The antigenic relatedness of Escherichia coli O157 and four sorbitol-negative species of the genus Escherichia was examined. Isolates of Escherichia hermannii, E. fergusonii, E. vulneris, and E. blattae were tested in the tube agglutination assay by using polyclonal antisera and in the slide agglutination assay by using latex reagents. Only four isolates (17%) of E. hermannii exhibited serological cross-reactivity. PMID:1583138

Rice, E W; Sowers, E G; Johnson, C H; Dunnigan, M E; Strockbine, N A; Edberg, S C

1992-05-01

348

Antimicrobial non-susceptibility of cervico-vaginal and rectal Escherichia coli isolates is associated with phylogeny and plasmid carriage.  

PubMed

Uropathogenic Escherichia coli (UPEC) is the primary cause of urinary tract infections (UTIs) in adult women, which are increasingly refractory to antimicrobial treatment. UPEC colonizes the vagina prior to causing a UTI. Our hypothesis was that the vaginal flora would be enriched in UPEC and therefore have a greater prevalence of non-susceptibility relative to the rectal flora. We used disk diffusion to determine the antimicrobial susceptibilities of 100 cervico-vaginal E. coli (CVEC) and 100 rectal E. coli (REC) isolates from 200 different patients. Phylogeny, plasmid replicons, and antimicrobial resistance genes were detected by polymerase chain reaction (PCR). There were no significant differences between CVEC and REC, and the overall levels of non-susceptibility were 39.5% for ampicillin (AM), 11.5% for ampicillin-sulbactam (SAM), 11.5% for trimethoprim-sulfamethoxazole (SXT), 5% for ciprofloxacin (CIP), 2.5% for nitrofurantoin (F/M), 0.5% for ceftazidime (CAZ), 0.5% for cefotaxime (CTX), and 0% for fosfomycin (FOS). SXT non-susceptibility was associated with phylogenetic groups A and D compared with B2. AM and SXT non-susceptibility was associated with plasmid carriage. The vaginal flora is not enriched in antimicrobial non-susceptibility relative to the rectal flora. However, antimicrobial non-susceptibility was associated with phylogeny and plasmid carriage. PMID:19639348

Hilbert, D W; Paulish, T E; Mordechai, E; Adelson, M E; Gygax, S E; Trama, J P

2009-07-29

349

Role of the rapA gene in controlling antibiotic resistance of Escherichia coli biofilms.  

PubMed

By using a high-throughput screening method, a mutant of a uropathogenic Escherichia coli strain affected in the rapA gene was isolated. The mutant formed normal-architecture biofilms but showed decreased penicillin G resistance, although the mutation did not affect planktonic cell resistance. Transcriptome analysis showed that 22 genes were down-regulated in the mutant biofilm. One of these genes was yhcQ, which encodes a putative multidrug resistance pump. Mutants with mutations in this gene also formed biofilms with decreased resistance, although the effect was less pronounced than that of the rapA mutation. Thus, an additional mechanism(s) controlled by a rapA-regulated gene(s) was involved in wild-type biofilm resistance. The search for this mechanism was guided by the fact that another down-regulated gene in rapA biofilms, yeeZ, is suspected to be involved in extra cell wall-related functions. A comparison of the biofilm matrix of the wild-type and rapA strains revealed decreased polysaccharide quantities and coverage in the mutant biofilms. Furthermore, the (fluorescent) functional penicillin G homologue Bocillin FL penetrated the mutant biofilms more readily. The results strongly suggest a dual mechanism for the wild-type biofilm penicillin G resistance, retarded penetration, and effective efflux. The results of studies with an E. coli K-12 strain pointed to the same conclusion. Since efflux and penetration can be general resistance mechanisms, tests were conducted with other antibiotics. The rapA biofilm was also more sensitive to norfloxacin, chloramphenicol, and gentamicin. PMID:17664315

Lynch, S V; Dixon, L; Benoit, M R; Brodie, E L; Keyhan, M; Hu, P; Ackerley, D F; Andersen, G L; Matin, A

2007-07-30

350

Role of the rapA Gene in Controlling Antibiotic Resistance of Escherichia coli Biofilms? †  

PubMed Central

By using a high-throughput screening method, a mutant of a uropathogenic Escherichia coli strain affected in the rapA gene was isolated. The mutant formed normal-architecture biofilms but showed decreased penicillin G resistance, although the mutation did not affect planktonic cell resistance. Transcriptome analysis showed that 22 genes were down-regulated in the mutant biofilm. One of these genes was yhcQ, which encodes a putative multidrug resistance pump. Mutants with mutations in this gene also formed biofilms with decreased resistance, although the effect was less pronounced than that of the rapA mutation. Thus, an additional mechanism(s) controlled by a rapA-regulated gene(s) was involved in wild-type biofilm resistance. The search for this mechanism was guided by the fact that another down-regulated gene in rapA biofilms, yeeZ, is suspected to be involved in extra cell wall-related functions. A comparison of the biofilm matrix of the wild-type and rapA strains revealed decreased polysaccharide quantities and coverage in the mutant biofilms. Furthermore, the (fluorescent) functional penicillin G homologue Bocillin FL penetrated the mutant biofilms more readily. The results strongly suggest a dual mechanism for the wild-type biofilm penicillin G resistance, retarded penetration, and effective efflux. The results of studies with an E. coli K-12 strain pointed to the same conclusion. Since efflux and penetration can be general resistance mechanisms, tests were conducted with other antibiotics. The rapA biofilm was also more sensitive to norfloxacin, chloramphenicol, and gentamicin.

Lynch, S. V.; Dixon, L.; Benoit, M. R.; Brodie, E. L.; Keyhan, M.; Hu, P.; Ackerley, D. F.; Andersen, G. L.; Matin, A.

2007-01-01

351

Escherichia coli Cytochrome c Nitrite Reductase NrfA  

Microsoft Academic Search

The periplasmic cytochrome c nitrite reductase (Nrf) system of Escherichia coli utilizes nitrite as a respiratory electron acceptor by reducing it to ammonium. Nitric oxide (NO) is a proposed intermediate in this six-electron reduction and NrfA can use exogenous NO as a substrate. This chapter describes the method used to assay Nrf-catalyzed NO reduction in whole cells of E. coli

Paul C. Mills; Susie R. Poock; Myles R. Cheesman; Jeffrey A. Cole; Jay C. D. Hinton; Andrew M. Hemmings; k Stephen Spiro; Jessica Van Wonderen; David J. Richardson

352

Detection of radiation effects using recombinant bioluminescent Escherichia coli strains  

Microsoft Academic Search

Effects of ionizing radiation (0.1–500 Gy) on recombinant Escherichia coli cells containing the stress promoters recA, grpE, or katG, fused to luxCDABE, were characterized by monitoring transcriptional responses reflected by the bioluminescent output. The minimum dose of gamma-irradiation\\u000a detected by E. coli DPD2794 (recA::luxCDABE) was about 1.5 Gy, while the maximum response was obtained at 200 Gy. The amount of

Jiho Min; Chang Woo Lee; Seung-Hyeun Moon; Robert A. LaRossa; Man Bock Gu

2000-01-01

353

Mechanisms of Acid Resistance in Enterohemorrhagic Escherichia coli  

Microsoft Academic Search

Enterohemorrhagic strains ofEscherichia colimust pass through the acidic gastric barrier to cause gastro- intestinal disease. Taking into account the apparent low infectious dose of enterohemorrhagic E. coli ,1 1 O157:H7 strains and 4 commensal strains of E. coli were tested for their abilities to survive extreme acid exposures (pH 3). Three previously characterized acid resistance systems were tested. These included

GEORGE N. BENNETT; ANDJOHN W. FOSTER

1996-01-01

354

Genes and proteins of Escherichia coli K-12.  

PubMed

GenProtEC is a database of Escherichia coli genes and their gene products, classified by type of function and physiological role and with citations to the literature for each. Also present are data on sequence similarities among E.coli proteins, representing groups of paralogous genes, with PAM values, percent identity of amino acids, length of alignment and percent aligned. GenProtEC can be accessed at the URL http://www.mbl.edu/html/ecoli.html PMID:9399799

Riley, M

1998-01-01

355

Large surface blebs on Escherichia coli heated to inactivating temperatures.  

PubMed

Large surface blebs were observed with phase-contrast optics on Escherichia coli B/r and B(s-1) heated to temperatures at which colony-forming ability was lost. Characterization of such blebs was consistent with the view that they were formed by a physical process and were bounded by the outer membrane of the cell. A hypothesis for thermal inactivation of E. coli is presented that places membrane damage near the primary lethal event. PMID:4196258

Scheie, P; Ehrenspeck, S

1973-05-01

356

Assembly of a Functional Immunoglobulin Fv Fragment in Escherichia coli  

Microsoft Academic Search

An expression system was developed that allows the production of a completely functional antigen-binding fragment of an antibody in Escherichia coli. The variable domains of the phosphorylcholine-binding antibody McPC603 were secreted together into the periplasmic space, where protein folding as well as heterodimer association occurred correctly. Thus, the assembly pathway for the Fv fragment in E. coli is similar to

Arne Skerra; Andreas Pluckthun

1988-01-01

357

Indole Can Act as an Extracellular Signal in Escherichia coli  

Microsoft Academic Search

Previous work has shown that lacZ fusions to the cysK, astD, tnaB, and gabT genes in Escherichia coli are activated by self-produced extracellular signals. Using a combination of ethyl acetate extraction, reversed- phase C18 chromatography, and thin-layer chromatography, we have purified an extracellular activating signal from E. coli supernatants. Mass spectrometry revealed a molecule with an m\\/z peak of 117,

DANDAN WANG; XUEDONG DING

2001-01-01

358

Use of EC-MUG Media to Confirm Escherichia coli Contamination in Water Samples Protocol  

NSDL National Science Digital Library

Escherichia coli broth and Escherichia coli agar media with 4-methylumbelliferyl-Ă-D-glucuronide are used to confirm the presence of Escherichia coli in water samples. In this protocol, the history, procedure, and interpretation of results of this useful technique are discussed in detail.

American Society For Microbiology;

2010-08-23

359

Microbial uropathogens and their antibiotic resistance profile from hospitalized patients in Central Alabama.  

PubMed

Urinary tract infections remain a common problem in inpatient care. They are highly challenging to provide effective initial therapy without sensitivity data. The purpose of this study was to survey the uropathogens and their sensitivity profile at a hospital in Central Alabama and to guide experiential antibiotic selection. This was the first reported study on bacterial uropathogens and their antibiotic resistance profile at this Central Alabama hospital. The survey period was between July 2009 and June 2010, a total of 473 urine cultures were reviewed and susceptibility testing was determined using the Clinical and Laboratory Standards Institute (CLSI) microdilution method. The results indicated that Escherichia coli (45.5%) was the most common organism, followed by Klebsiella pneumoniae (18.2%), Pseudomonas aeruginosa (10.1%), Proteus mirabilis (7.8%), Enterobacter cloacae (4.2%), methicillin-resistant Staphylococcus aureus (3.0%), Klebsiella oxytoca and Citrobacter freundii (1.5%), Morganella morganii (1.3%), and the other species (7.0%). For the 215 E. coli isolates, imipenem and cephalosporins (except for cefazolin) had the highest sensitivity (99-100%, P < 0.05). In contrast, ampicillin had the highest resistance (57%, P < 0.05) as compared to other antibiotics (about 30%) including ampicillin/ sulbactam, ciprofloxacin, levofloxacin, tetracycline, and trimethoprim/sulfamethoxazole. The major finding of this study was that ciprofloxacin, levofloxacin and trimethoprim/sulfamethoxazole had comparable sensitivity patterns for Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Enterobacter cloacae, the most common uropathogens at this Central Alabama hospital. Additionally, this study found that E. coli had a resistant rate of 31% to ciprofloxacin and levofloxacin compared to the resistance rate of 28.4% and 15.8% in earlier reports (Lee et al. 2010; Rattanaumpawan et al. 2010), likely indicating the continuing evolution of resistance due to antibiotic exposure. It is imperative to monitor the resistance of P. aeruginosa considering their high resistance to imipenem found in this study. PMID:23330509

Qian, Li; Camara, Tracy; Taylor, J Kyle; Jones, Kathy W

2012-01-01

360

Virulence Potential and Genomic Mapping of the Worldwide Clone Escherichia coli ST131  

PubMed Central

Recently, the worldwide propagation of clonal CTX-M-15-producing Escherichia coli isolates, namely ST131 and O25b:H4, has been reported. Like the majority of extra-intestinal pathogenic E. coli isolates, the pandemic clone ST131 belongs to phylogenetic group B2, and has recently been shown to be highly virulent in a mouse model, even though it lacks several genes encoding key virulence factors (Pap, Cnf1 and HlyA). Using two animal models, Caenorhabditis elegans and zebrafish embryos, we assessed the virulence of three E. coli ST131 strains (2 CTX-M-15- producing urine and 1 non-ESBL-producing faecal isolate), comparing them with five non-ST131 B2 and a group A uropathogenic E. coli (UPEC). In C. elegans, the three ST131 strains showed intermediate virulence between the non virulent group A isolate and the virulent non-ST131 B2 strains. In zebrafish, the CTX-M-15-producing ST131 UPEC isolates were also less virulent than the non-ST131 B2 strains, suggesting that the production of CTX-M-15 is not correlated with enhanced virulence. Amongst the non-ST131 B2 group isolates, variation in pathogenic potential in zebrafish embryos was observed ranging from intermediate to highly virulent. Interestingly, the ST131 strains were equally persistent in surviving embryos as the non-ST131-group B2 strains, suggesting similar mechanisms may account for development of persistent infection. Optical maps of the genome of the ST131 strains were compared with those of 24 reference E. coli strains. Although small differences were seen within the ST131 strains, the tree built on the optical maps showed that these strains belonged to a specific cluster (86% similarity) with only 45% similarity with the other group B2 strains and 25% with strains of group A and D. Thus, the ST131 clone has a genetic composition that differs from other group B2 strains, and appears to be less virulent than previously suspected.

Goret, Lucie; Sotto, Albert; Combescure, Christophe; Blanco, Jorge; O'Callaghan, David; Nicolas-Chanoine, Marie-Helene

2012-01-01

361

An integrated database to support research on Escherichia coli  

SciTech Connect

We have used logic programming to design and implement a prototype database of genomic information for the model bacterial organism Escherichia coli. This report presents the fundamental database primitives that can be used to access and manipulate data relating to the E. coli genome. The present system, combined with a tutorial manual, provides immediate access to the integrated knowledge base for E. coli chromosome data. It also serves as the foundation for development of more user-friendly interfaces that have the same retrieval power and high-level tools to analyze complex chromosome organization.

Baehr, A.; Dunham, G.; Matsuda, Hideo; Michaels, G.; Taylor, R.; Overbeek, R.; Rudd, K.E. [National Inst. of Mental Health, Bethesda, MD (United States); Ginsburg, A.; Joerg, D.; Kazic, T. [Washington Univ., St. Louis, MO (United States). Dept. of Genetics; Hagstrom, R.; Zawada, D. [Argonne National Lab., IL (United States); Smith, C.; Yoshida, Kaoru [Lawrence Berkeley Lab., CA (United States)

1992-01-01

362

Naturalized Escherichia coli from New Zealand wetland and stream environments.  

PubMed

This research investigates the presence of a naturalized clade of Escherichia coli in wetland and stream biofilms. Escherichia coli is used as a faecal indicator in water quality monitoring programmes worldwide, with the assumption that this bacterium is exclusively a commensal of the vertebrate gut. However, recent findings indicate growth and multiplication of E. coli in water and soils. This study seeks to clarify the relationships between environmental and commensal E. coli strains retrieved from New Zealand streams by evaluating fundamental genetic differences using the multilocus sequence typing (MLST) method. Environmental and commensal strains showed a high diversity of MLST profiles. Genetic analyses of linkage disequilibrium, index of association and rates of synonymous and nonsynonymous substitutions were used to investigate sequence variability and nature of change. Phylogenetic trees based on the concatenated sequences of the seven MLST housekeeping genes displayed distinct clustering of environmental strains. Comparison of the New Zealand sequences with worldwide E. coli strains retrieved from the Shigatox MLST database online did not allow the identification of a clear environmental genotype. However, some New Zealand aquatic E. coli isolates showed close relationships with strains from human and bovine origins, suggesting that environmental isolates were originally derived from subpopulations of commensal E. coli from these sources. PMID:22974403

Perchec-Merien, Anne-Marie; Lewis, Gillian D

2012-10-08

363

Antimicrobial resistance patterns of uropathogens among children in Istanbul, Turkey.  

PubMed

Urinary tract infections are a common cause of end-stage renal disease in Turkey. This prospective study investigated the antibiotic resistance patterns of uropathogens in order to recommend appropriate therapeutic protocols for children with urinary tract infections in Istanbul, Turkey. Between October 2007 and October 2008, children presenting with a first episode of urinary tract infection to a pediatric outpatient clinic were enrolled in the study. Urine samples were cultured, and antimicrobial susceptibility testing was performed. Children with proven urinary tract infections underwent imaging studies where available. A total of 126 children with a first episode of community-acquired urinary tract infection were enrolled in the study. The median age was 60.6 months; 84.1% of the children were female. Of the 126 urine samples, Escherichia coli was the leading uropathogen (81.7%), followed by Proteus spp (7.1%), Klebsiella spp (4.0%), Enterococcus spp (3.2%), Enterobacter spp (2.4%), and Pseudomonas spp (1.6%). Among the isolated uropathogens, resistance to ampicillin (85.0%), amoxicillin-clavulanate (73.8%), cefazolin (37.3%) and trimethoprim-sulfamethoxazole (42.9%) was remarkable. A large number of Enterococcus species were resistant to all antimicrobial agents except vancomycin. A country-based evaluation of antibiotic susceptibility is needed to modify antibiotic treatment. Resistance to antimicrobial agents commonly used to treat urinary tract infections (nitrofurantoin, cefixime) is less a problem than resistance to other antimicrobials (aminopenicillins, cephalosporins, trimethoprim-sulfamethoxazole) frequently prescribed for other indications. PMID:21710858

Ipek, Ilke Ozahi; Bozaykut, Abdulkadir; Arman, Didem Caktir; Sezer, Rabia Gonul

2011-03-01

364

Homolactate Fermentation by Metabolically Engineered Escherichia coli Strains  

Microsoft Academic Search

We report the homofermentative production of lactate in Escherichia coli strains containing mutations in the aceEF, pfl, poxB, and pps genes, which encode the pyruvate dehydrogenase complex, pyruvate formate lyase, pyruvate oxidase, and phosphoenolpyruvate synthase, respectively. The process uses a defined medium and two distinct fermentation phases: aerobic growth to an optical density of about 30, followed by nongrowth, anaerobic

Y. Zhu; M. A. Eiteman; K. DeWitt; E. Altman

2007-01-01

365

What's for Dinner?: Entner-Doudoroff Metabolism in Escherichia coli  

Microsoft Academic Search

The Entner-Doudoroff (ED) pathway was first discovered in 1952 in Pseudomonas saccharophila (21) and several years later was shown to be present in Escherichia coli (23). Although generally considered to be restricted to gram-negative bacteria, the ED pathway is present in all three phylogenetic domains, including the most deeply rooted Archaea (18). The ubiquity of the ED pathway suggests that

N. PEEKHAUS; T. CONWAY

1998-01-01

366

Conformational pathways in the gating of Escherichia coli mechanosensitive channel  

Microsoft Academic Search

The pathway of the gating conformational transition of Escherichia coli mechanosensitive channel was simulated, using the recently modeled open and closed structures, by targeted molecular dynamics method. The transition can be roughly viewed as a four-stage process. The initial motion under a lower tension load is predominantly elastic deformation. The opening of the inner hydrophobic pore on a higher tension

Yifei Kong; Yufeng Shen; Tiffany E. Warth; Jianpeng Ma

2002-01-01

367

Effective Immunomodulatory Treatment of Escherichia coli Experimental Sepsis with Thalidomide  

Microsoft Academic Search

Thalidomide, an agent which inhibits biosynthesis of tumor necrosis factor alpha (TNF-) and which is used to treat a variety of chronic inflammatory conditions, was investigated as therapy for experimental sepsis. Sepsis was induced by intraperitoneal injection of 107 CFU of Escherichia coli per kg of body weight to 80 Wistar rats divided into four groups. Group A consisted of

Evangelos J. Giamarellos-Bourboulis; Helen Poulaki; Nikolaos Kostomitsopoulos; Ismene Dontas; Despina Perrea; Panayotis E. Karayannacos; Helen Giamarellou

2003-01-01

368

Evolution of Escherichia coli During Growth in a Constant Environment  

Microsoft Academic Search

Populations of Escherichia coli, initiated with a single clone and maintained for long periods in glucose-limited continuous culture, developed extensive polymorphisms. In one population, examined after 765 generations, two majority and two minority types were identified. Stable mixed populations were reestablished from the isolated strains. Factors involved in the development of this polymorphism included differences in the maximum specific growth

Robert B. Helling; Christopher N. Vargas; Julian Adams

1987-01-01

369

Escherichia coli and other Enterobacteriaceae: Food poisoning and health effects  

Technology Transfer Automated Retrieval System (TEKTRAN)

The family Enterobactericeae consists of rod-shaped, Gram-negative, facultatively anaerobic, non-spore forming bacteria and also includes the food-borne pathogens, Cronobacter spp., Escherichia coli, Salmonella enterica, Shigella spp., and Yersinia spp. Illness caused by these pathogens is acquired...

370

Escherichia coli swim on the right-hand side  

Microsoft Academic Search

The motion of peritrichously flagellated bacteria close to surfaces is relevant to understanding the early stages of biofilm formation and of pathogenic infection. This motion differs from the random-walk trajectories of cells in free solution. Individual Escherichia coli cells swim in clockwise, circular trajectories near planar glass surfaces. On a semi-solid agar substrate, cells differentiate into an elongated, hyperflagellated phenotype

Willow R. Diluzio; Linda Turner; Michael Mayer; Piotr Garstecki; Douglas B. Weibel; Howard C. Berg; George M. Whitesides

2005-01-01

371

Enterotoxigenic Escherichia coli Infection in Captive Black-footed Ferrets  

Microsoft Academic Search

Enterotoxigenic Escherichia coli with genes for heat stabile toxins Sta and STb was isolated from the gastrointestinal tract and multiple visceral organs of three adult and three juvenile black-footed ferrets (Mustela ni- gripes) that died in a captive breeding colony between 24 May 1998 and 2 July 1998. Similar isolates were obtained from rectal swabs of one adult and one

Gregory A. Bradley; Kathy Orr; Carlos Reggiardo; Robert D. Glock

372

Persistence of colicinogenic Escherichia coli in the mouse gastrointestinal tract  

Microsoft Academic Search

BACKGROUND: The ability of a bacterial strain to competitively exclude or displace other strains can be attributed to the production of narrow spectrum antimicrobials, the bacteriocins. In an attempt to evaluate the importance of bacteriocin production for Escherichia coli strain residence in the gastrointestinal tract, a murine model experimental evolution study was undertaken. RESULTS: Six colicin-producing, yet otherwise isogenic, E.

Osnat Gillor; Itamar Giladi; Margaret A Riley

2009-01-01

373

Electrooptical analysis of the Escherichia coli–phage interaction  

Microsoft Academic Search

This article describes electrooptical (EO) characterization of biospecific binding between the bacterium Escherichia coli XL-1 and the phage M13K07. The electrooptical analyzer (ELUS EO), which has been developed at the State Research Center for Applied Microbiology, Obolensk, Russia, was used as the basic instrument for EO measurements. The operating principle of the analyzer is based on the polarizability of microorganisms,

Victor D Bunin; Oleg V Ignatov; Olga I Guliy; Irina S Zaitseva; Daniel O’Neil; Dmitri Ivnitski

2004-01-01

374

Prediction of rho-independent transcriptional terminators in Escherichia coli  

Microsoft Academic Search

A new algorithm called RNAMotif containing RNA structure and sequence constraints and a thermo- dynamic scoring system was used to search for intrinsic rho-independent terminators in the Escherichia coli K-12 genome. We identified all 135 reported terminators and 940 putative terminator sequences beginning no more than 60 nt away from the 3'-end of the annotated transcription units (TU). Putative and

Elena A. Lesnik; Rangarajan Sampath; Harold B. Levene; Timothy J. Henderson; John A. McNeil; David J. Ecker

2001-01-01

375

Marine macroalgae as a source for osmoprotection for Escherichia coli  

Microsoft Academic Search

At elevated osmolarity of the mineral medium M63, marine macroalgae constitute important osmoprotectants and nutrients sources for Escherichia coli. Growth of bacterial population (16 strains) was improved by supplementing M63 salts medium with either aqueous or ethanolic algal extracts obtained from Ascophyllum nodosum, Fucus serratus, Enteromorpha ramulosa, Ulva lactuca, and Palmaria palmata. In their presence, growth was still observed even

M. Ghoul; J. Minet; T. Bernard; E. Dupray; M. Cormier

1995-01-01

376

Quorum sensing in Escherichia coli and Salmonella typhimurium  

Microsoft Academic Search

Escherichia coli and Salmonella typhimurium strains grown in Luria-Bertani medium containing glucose secrete a small soluble heat labile organic molecule that is involved in intercellular communication. The factor is not produced when the strains are grown in Luria-Bertani me- dium in the absence of glucose. Maximal secretion of the substance occurs in midexponential phase, and the extracel- lular activity is

MICHAEL G. SURETTE; BONNIE L. BASSLER

1998-01-01

377

A DNA structural atlas for Escherichia coli1  

Microsoft Academic Search

We have performed a computational analysis of DNA structural features in 18 fully sequenced prokaryotic genomes using models for DNA curva- ture, DNA flexibility, and DNA stability. The structural values that are computed for the Escherichia coli chromosome are significantly different from (and generally more extreme than) that expected from the nucleo- tide composition. To aid this analysis, we have

Anders Gorm Pedersen; Lars Juhl Jensen; Sřren Brunak; Hans-Henrik Stćrfeldt; David W. Ussery

2000-01-01

378

Physical map of the Escherichia coli K12 genome  

Microsoft Academic Search

A physical map of a genome is the structure of its DNA. Construction of such a map is a first step in the complete characterization of that DNA. The restriction endonuclease Not I cuts the genome of Escherichia coli K12 into 22 DNA fragments ranging from 20 kilobases (20,000 base pairs) to 1000 kilobases. These can be separated by pulsed

C. L. Smith; J. G. Econome; A. Schutt; S. Klco; C. R. Cantor

1987-01-01

379

Model for Bacteriophage T4 Development in Escherichia coli  

Microsoft Academic Search

Mathematical relations for the number of mature T4 bacteriophages, both inside and after lysis of an Escherichia coli cell, as a function of time after infection by a single phage were obtained, with the following five parameters: delay time until the first T4 is completed inside the bacterium (eclipse period, n) and its standard deviation (s), the rate at which

AVINOAM RABINOVITCH; HILLA HADAS; MONICA EINAV; ZEEV MELAMED

1999-01-01

380

The effects of daunomycin and ethidium bromide on Escherichia coli  

Microsoft Academic Search

The effects of two DNA-intercalating agents daunomycin (DMC) and ethidium bromide (EBR) on transcription, translation and replication in Escherichia coli have been studied. The data are consistent with the notion that low concentrations of these drugs primarily inhibit transcription and replication to equal extents and that translation is halted indirectly as a result of the decay of the messenger RNA

T. Třnnesen; J. D. Friesen

1973-01-01

381

Metabolic Switching in the Sugar Phosphotransferase System of Escherichia coli  

Microsoft Academic Search

Bacteria grown in a mixture of multiple sugars will first metabolize a preferred sugar until it is nearly depleted, only then turning to other carbon sources in the medium. This sharp switching of metabolic preference is characteristic of systems that optimize fitness. Here we consider the mechanism by which switching can occur in the Escherichia coli phosphotransferase system (PTS), which

Mukund Thattai; Boris I. Shraiman

2003-01-01

382

Visualizing multiple constrictions in spheroidal Escherichia coli cells  

Microsoft Academic Search

Abstract — An Escherichia coli cell grows,by elongation and divides in a perpendicular plane. Alternating planes of successive divisions in three dimensions can only be ascertained when multiple constrictions exist simultaneously in large, spheroidal cells (with extended constriction process), if the division signals are enhanced. Large, spheroidal cells are obtained by a brief mecillinam treatment, and more frequent divisions are

A. Zaritsky; Geel van A. B. M; I. Fishov; E. Pas; M. Einav; C. L. Woldringh

1999-01-01

383

Escherichia coli Cellulitis in Children With Idiopathic Nephrotic Syndrome  

Microsoft Academic Search

Although Streptococcus pneumoniae is traditionally considered the preponderant bacterial pathogen in children with nephrotic syndrome, recent data suggest an increase of infections with encapsulated gram-negative organisms. We report two children with idiopathic nephrotic syndrome in relapse who developed spontaneous Escherichia coli cellulitis. The organism was recovered from the cellulitis tissue aspirate of one, and from the blood of the other.

Basim I. Asmar; Bassam N. Bashour; Larry E. Fleischmann

1987-01-01

384

Expression of Thiobacillus ferrooxidans origin of replication in Escherichia coli  

SciTech Connect

A cryptic plasmid from an autotrophically grown arsenic-resistant strain of Thiobacillus ferrooxidans was isolated and cloned into pBR325. The origin of replication of pBR325 was deleted, and the recombinant plasmid was shown to replicate in Escherichia coli, using an origin of replication located on the Thiobacillus plasmid.

Rawlings, D.E.; Pretorius, I.; Woods, D.R.

1984-05-01

385

Serotyping and biotyping of 160 Escherichia coli strains: comparative study.  

PubMed Central

One hundred and sixty Escherichia coli strains were serotyped and biotyped. Serotyping revealed 68 different types, with 25 strains not typable. Biotyping was possible in all strains but revealed 55 different types. One biotype could be subdivided into 35 different serotypes, indicating that for this biotype the series of biochemical and fermentation reactions could be extended for further differentiation.

Van Der Waaij, D; Speltie, T M; Guinee, P A; Agterberg, C

1975-01-01

386

Exploitation of host cells by enteropathogenic Escherichia coli  

Microsoft Academic Search

Microbial pathogens have evolved many ingenious ways to infect their hosts and cause disease, including the subversion and exploitation of target host cells. One such subversive microbe is enteropathogenic Escherichia coli (EPEC). A major cause of infantile diarrhea in developing countries, EPEC poses a significant health threat to children worldwide. Central to EPEC-mediated disease is its colonization of the intestinal

B. A. Vallance; B. B. Finlay

2000-01-01

387

Alteration of Escherichia coli Topoisomerase IV to Novobiocin Resistance  

Microsoft Academic Search

DNA gyrase and topoisomerase IV (topo IV) are the two essential type II topoisomerases of Escherichia coli. Gyrase is responsible for maintaining negative supercoiling of the bacterial chromosome, whereas topo IV's primary role is in disentangling daughter chromosomes following DNA replication. Coumarins, such as novobiocin, are wide-spectrum antimicrobial agents that primarily interfere with DNA gyrase. In this work we designed

Christine D. Hardy; Nicholas R. Cozzarelli

2003-01-01

388

Escherichia coli O104:H4 Infections and International Travel  

PubMed Central

We analyzed travel-associated clinical isolates of Escherichia coli O104:H4, including 1 from the 2011 German outbreak and 1 from a patient who returned from the Philippines in 2010, by genome sequencing and optical mapping. Despite extensive genomic similarity between these strains, key differences included the distribution of toxin and antimicrobial drug–resistance determinants.

Alexander, David C.; Hao, Weilong; Gilmour, Matthew W.; Zittermann, Sandra; Sarabia, Alicia; Melano, Roberto G.; Peralta, Analyn; Lombos, Marina; Warren, Keisha; Amatnieks, Yuri; Virey, Evangeline; Ma, Jennifer H.; Jamieson, Frances B.; Low, Donald E.

2012-01-01

389

The Evolutionary History of Shigella and Enteroinvasive Escherichia coli Revised  

Microsoft Academic Search

In Shigella and enteroinvasive Escherichia coli (EIEC), the etiologic agents of shigellosis in humans, the determinants responsible for entry of bacteria into and dissemination within epithelial cells are encoded by a virulence plasmid. To understand the evolution of the association between the virulence plasmid and the chromosome, we performed a phylogenetic analysis using the sequences of four chromosomal genes (

Patricia Escobar-Páramo; Catherine Giudicelli; Claude Parsot; Erick Denamur

2003-01-01

390

Strategies for efficient production of heterologous proteins in Escherichia coli  

Microsoft Academic Search

In recent years, the number of recombinant proteins used for therapeutic applications has increased dramatically. Production of these proteins has a remarkable demand in the market. Escherichia coli offers a means for the rapid and economical production of recombinant proteins. These advantages, coupled with a wealth of biochemical and genetic knowledge, have enabled the production of such economically therapeutic proteins

S. Jana; J. K. Deb

2005-01-01

391

Modeling hexavalent chromium reduction in Escherichia coli 33456  

Microsoft Academic Search

A model based on the analysis of the mechanism of enzymatic reaction was developed to characterize the rate and extent of microbial reduction of hexavalent chromium in Escherichia coli 33456. A finite reduction capacity (R[sub c]) was proposed and incorporated into the enzymatic model to regulate the toxicity effect on cells due to the oxidizing power of Cr(6). The parameter

Hai Shen; Yi-Tin Wang

1994-01-01

392

DNA degradation in minicells of Escherichia coli K-12  

Microsoft Academic Search

The properties of minicell producing mutants of Escherichia coli deficient in gentic recombination were examined. Experiments were designed to test recombinant formation in conjugal crosses, survival following UV-irradiation in cells, and the state of DNA metabolism in minicells. The REC- phenotypes are unaffected by min+\\/- genotypes in whole cells. In contrast to minicells produced by rec+ parental cells, minicells from

George G. Khachatourians; M. C. Paterson; Ronald J. Sheehy; B. Van Dorp; T. E. Worthy

1975-01-01

393

Growth-rate dependent RNA polyadenylation in Escherichia coli  

Microsoft Academic Search

RNA polyadenylation occurs not only in eukaryotes but also in bacteria. In prokaryotes, polyadenylated RNA molecules are usually degraded more efficiently than non-modified transcripts. Here we demonstrate that two transcripts, which were shown previously to be substrates for poly(A) polymerase I (PAP I), Escherichia coli lpp messenger RNA and bacteriophage ? oop RNA, are polyadenylated more efficiently in slowly growing

Jacek Jasiecki

2003-01-01

394

Global Gene Expression Responses to Cadmium Toxicity in Escherichia coli  

PubMed Central

Genome-wide analysis of temporal gene expression profiles in Escherichia coli following exposure to cadmium revealed a shift to anaerobic metabolism and induction of several stress response systems. Disruption in the transcription of genes encoding ribosomal proteins and zinc-binding proteins may partially explain the molecular mechanisms of cadmium toxicity.

Wang, Anyou; Crowley, David E.

2005-01-01

395

MICROARRAY BASED COMPARISON OF TWO ESCHERICHIA COLI 0157 LINEAGES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Previous research has identified the potential for the existence of two separate lineages of Escherichia coli O157:H7. Clinical isolates tended to cluster with only one of these two lineages. To determine if there are common genes differentially expressed between the two lineages, we chose to utiliz...

396

Antibiotic resistance in Escherichia coli from Nigerian students, 1986 1998.  

PubMed Central

We tested 758 fecal Escherichia coli isolates, recovered from Nigerian students in 1986, 1988, 1990, 1994, and 1998, for susceptibility to seven antimicrobial drugs. The prevalences of strains resistant to tetracycline, ampicillin, chloramphenicol, and streptomycin were 9% to 35% in 1986 and 56% to 100% in 1998. These findings demonstrate that resistance gene reservoirs are increasing in healthy persons.

Okeke, I. N.; Fayinka, S. T.; Lamikanra, A.

2000-01-01

397

In search of the minimal Escherichia coli genome  

Microsoft Academic Search

Recent plans announced for the systematic cataloging of the minimal Escherichia coli gene set, the pheno- types of all mutations, the expression levels of every transcript and gene product, and the interactions of all genetic loci or their gene products point the way towards a new frontier in the biology of model organ- isms. Powerful tools for this endeavor are

Darren J. Smalley; Marvin Whiteley; Tyrrell Conway

2002-01-01

398

Methods for Detecting Enterohaemorrhagic Escherichia Coli in Food  

Microsoft Academic Search

Enterohaemorrhagic Escherichia coli (EHEC) serogroup determines worldwide foodborne illnesses and remains one of the major concerns for the population and for the food industry. These strains, indeed, determine gastrointestinal disease varying from diarrhoea to haemorrhagic colitis, haemolytic uraemic syndrome, and thrombotic thrombocytopaenic purpura. Classic detection methods are based on specific enrichment, often coupled with immunomagnetic separation system, specific media, and

Rossana Sidari; Andrea Caridi

2011-01-01

399

Escherichia coli induces apoptosis and proliferation of mammary cells  

Microsoft Academic Search

Mammary cell apoptosis and proliferation were assessed after injection of Escherichia coli into the left mammary quarters of six cows. Bacteriological analysis of foremilk samples revealed coliform infection in the injected quarters of four cows. Milk somatic cell counts increased in these quarters and peaked at 24 h after bacterial injection. Body temperature also increased, peaking at 12 h postinjection.

E Long; A V Capuco; D L Wood; T Sonstegard; G Tomita; M J Paape; X Zhao

2001-01-01

400

Effects of Hyperoxia on Sulfhydryl Concentration of 'Escherichia coli'.  

National Technical Information Service (NTIS)

The concentration of reduced sulfhydryl (SH) in cell-free extracts of Escherichia coli grown with air as the gas phase was 26.8 plus or minus 1.2 mnoles SH/mg soluble protein. Exposure of bacteria to 1 ata of oxygen where growth continued but at a reduced...

J. L. Stees O. R. Brown

1972-01-01

401

Pressure-Sensitive Ion Channel in Escherichia coli  

Microsoft Academic Search

We have used the patch-clamp electrical recording technique on giant spheroplasts of Escherichia coli and have discovered pressure-activated ion channels. The channels have the following properties: (i) activation by slight positive or negative pressure; (ii) voltage dependence; (iii) large conductance; (iv) selectivity for anions over cations; (v) dependence of activity on the species of permeant ions. We believe that these

Boris Martinac; Matthew Buechner; Anne H. Delcour; Julius Adler; Ching Kung

1987-01-01

402

Method 1103.1: Escherichia coli (E. coli) in Water by Membrane Filtration Using membrane-Thermotolerant Escherichia coli Agar (mTEC), April 2005.  

National Technical Information Service (NTIS)

Method 1103.1 describes a membrane filter (MF) procedure for the detection and enumeration of Escherichia coli bacteria in ambient water. E. coli is a common inhabitant of the intestinal tract of warm-blooded animals, and its presence in water samples is ...

2005-01-01

403

Sex and virulence in Escherichia coli: an evolutionary perspective  

PubMed Central

Pathogenic Escherichia coli cause over 160 million cases of dysentery and one million deaths per year, whereas non-pathogenic E. coli constitute part of the normal intestinal flora of healthy mammals and birds. The evolutionary pathways underlying this dichotomy in bacterial lifestyle were investigated by multilocus sequence typing of a global collection of isolates. Specific pathogen types [enterohaemorrhagic E. coli, enteropathogenic E. coli, enteroinvasive E. coli, K1 and Shigella] have arisen independently and repeatedly in several lineages, whereas other lineages contain only few pathogens. Rates of evolution have accelerated in pathogenic lineages, culminating in highly virulent organisms whose genomic contents are altered frequently by increased rates of homologous recombination; thus, the evolution of virulence is linked to bacterial sex. This long-term pattern of evolution was observed in genes distributed throughout the genome, and thereby is the likely result of episodic selection for strains that can escape the host immune response.

Wirth, Thierry; Falush, Daniel; Lan, Ruiting; Colles, Frances; Mensa, Patience; Wieler, Lothar H; Karch, Helge; Reeves, Peter R; Maiden, Martin CJ; Ochman, Howard; Achtman, Mark

2006-01-01

404

Removal of Escherichia coli in wastewater by activated sludge.  

PubMed Central

Removal of bacteria from wastewater treated with activated sludge was studied by the use of a streptomycin-resistant Escherichia coli strain. The removal appeared to be a biphasic process. A rapid sorption of bacteria to the sludge flocs took place in the first hour after seeding mixed liquor with E. coli. Thereafter, slower elimination of E. coli was observed. The latter process was due to predation on E. coli by ciliated protozoa. This was shown by: (i) appearance of fluorescent food vacuoles of ciliates when fluorescent E. coli cells were added to mixed liquor; (ii) inhibition of predation either in the presence of cycloheximide or under anaerobic conditions; and (iii) absence of predation in bulking and washed sludge. Images

van der Drift, C; van Seggelen, E; Stumm, C; Hol, W; Tuinte, J

1977-01-01

405

A Critical Examination of Escherichia coli Esterase Activity*  

PubMed Central

The ability of Escherichia coli to grow on a series of acetylated and glycosylated compounds has been investigated. It is surmised that E. coli maintains low levels of nonspecific esterase activity. This observation may have ramifications for previous reports that relied on nonspecific esterases from E. coli to genetically encode nonnatural amino acids. It had been reported that nonspecific esterases from E. coli deacetylate tri-acetyl O-linked glycosylated serine and threonine in vivo. The glycosylated amino acids were reported to have been genetically encoded into proteins in response to the amber stop codon. However, it is our contention that such amino acids are not utilized in this manner within E. coli. The current results report in vitro analysis of the original enzyme and an in vivo analysis of a glycosylated amino acid. It is concluded that the amber suppression method with nonnatural amino acids may require a caveat for use in certain instances.

Antonczak, Alicja K.; Simova, Zuzana; Tippmann, Eric M.

2009-01-01

406

A critical examination of Escherichia coli esterase activity.  

PubMed

The ability of Escherichia coli to grow on a series of acetylated and glycosylated compounds has been investigated. It is surmised that E. coli maintains low levels of nonspecific esterase activity. This observation may have ramifications for previous reports that relied on nonspecific esterases from E. coli to genetically encode nonnatural amino acids. It had been reported that nonspecific esterases from E. coli deacetylate tri-acetyl O-linked glycosylated serine and threonine in vivo. The glycosylated amino acids were reported to have been genetically encoded into proteins in response to the amber stop codon. However, it is our contention that such amino acids are not utilized in this manner within E. coli. The current results report in vitro analysis of the original enzyme and an in vivo analysis of a glycosylated amino acid. It is concluded that the amber suppression method with nonnatural amino acids may require a caveat for use in certain instances. PMID:19666472

Antonczak, Alicja K; Simova, Zuzana; Tippmann, Eric M

2009-08-07

407

Injury by heavy metals in Escherichia coli  

SciTech Connect

The aim of the present study on the effects of sublethal concentrations of metals on the growth and recovery of E. coli, is to throw light on some of the aspects of the viability and recovery of E. coli as well as changes in its cell enzymatic activity when exposed to sublethal concentrations of heavy metals. Total dehydrogenase was used since it is a measure of bacterial activity closely related to energetic metabolic systems and ..beta..-galactosidase as a typical inducible enzyme in E. coli. E. coli was chosen as the test organism, both on account of its importance in public health (sanitary indicators) and for the information available (biochemical and genetic properties) on it.

Cenci, G.; Morozzi, G.; Caldini, G.

1985-02-01

408

INHIBITION OF OXIDATIVE PHOSPHORYLATION IN ESCHERICHIA COLI BY DIHYDROSTREPTOMYCIN  

PubMed Central

Bragg, P. D. (University of British Columbia, Vancouver, B.C., Canada), and W. J. Polglase. Inhibition of oxidative phosphorylation in Escherichia coli by dihydrostreptomycin. J. Bacteriol. 86:1236–1240. 1963.—Dihydrostreptomycin inhibited the oxidation of succinate in extracts of antibiotic-sensitive Escherichia coli. The inhibitable reaction required both the particulate and the supernatant fractions from sonic extracts which had been centrifuged at 100,000 × g. Dihydrostreptomycin was found to inhibit phosphorylation coupled with the oxidation of reduced nicotinamide adenine dinucleotide (NADH). The inhibition of oxidative phosphorylation by dihydrostreptomycin appeared to precede the effect of the antibiotic on oxidation. The streptomycin antagonist, 2-heptyl-4-hydroxyquinoline N-oxide, inhibited the oxidation of succinate and of NADH, but showed little effect on oxidative phosphorylation. Oxidative phosphorylation was not affected by dihydrostreptomycin in strains of E. coli which were antibiotic-resistant or -dependent.

Bragg, P. D.; Polglase, W. J.

1963-01-01

409

Kinetics of bacteriophage lambda deoxyribonucleic acid infection of Escherichia coli.  

PubMed

Barnhart, Benjamin J. (Los Alamos Scientific Laboratory, University of California, Los Alamos, N.M.). Kinetics of bacteriophage lambda deoxyribonucleic acid infection of Escherichia coli. J. Bacteriol. 90:1617-1623. 1965.-The kinetics of Escherichia coli K-12 infection by phage lambda deoxyribonucleic acid (DNA) were determined. An initial lag of 55 to 80 sec was found to be the time required for infecting DNA to become deoxyribonuclease-insensitive at 33 C. When cell-DNA interactions were stopped by washing away unbound DNA, the already bound DNA continued to infect the cell at rates described by linear kinetics with no apparent lag. Whereas the lag period was relatively insensitive to DNA and cell concentrations, both the lag and the subsequent linear portions of the rate curves were temperature-sensitive. Cell and DNA dose-response curves prescribed hyperbolic functions. Similarities between lambda DNA infection of E. coli and bacterial transformation systems are discussed. PMID:5322721

Barnhart, B J

1965-12-01

410

Novel phage-based bio-processing of pathogenic Escherichia coli and its biofilms  

Microsoft Academic Search

To explore new approaches of phage-based bio-process of specifically pathogenic Escherichia coli bacteria in food products within a short period. One hundred and forty highly lytic designed coliphages were used. Escherichia coli naturally contaminated and Enterohemorrhagic Escherichia coli experimentally inoculated samples of lettuce, cabbage, meat, and egg were used. In addition, experimentally produced biofilms\\u000a of E. coli were tested. A

S. A. A. Jassim; A. S. Abdulamir; F. Abu Bakar

411

Fate of Escherichia coli during Ensiling of Wheat and Corn†  

PubMed Central

A recombinant Escherichia coli strain carrying a plasmid with an antibiotic resistance marker and expressing the green fluorescent protein was inoculated at a concentration of 3.8 × 108 CFU/g into direct-cut wheat (348 g of dry matter kg?1), wilted wheat (450 g of dry matter kg?1), and corn (375 g of dry matter kg?1). The forages were ensiled in mini-silos. The treatments included control (no E. coli added), application of tagged E. coli, and delayed sealing of the inoculated wheat. Three silos per treatment were sampled on predetermined dates, and the numbers of E. coli were determined on Chromocult TBX medium with or without kanamycin. Colonies presumptively identified as E. coli were also tested for fluorescence activity. Addition of E. coli at the time of ensiling resulted in a more rapid decrease in the pH but had almost no effect on the chemical composition of the final silages or their aerobic stability. E. coli disappeared from the silages when the pH decreased below 5.0. It persisted longer in silages of wilted wheat, in which the pH declined more slowly. Control silages of all crops also contained bacteria, presumptively identified as E. coli, that were resistant to the antibiotic, which suggests that some epiphytic strains are naturally resistant to antibiotics.

Chen, Y.; Sela, S.; Gamburg, M.; Pinto, R.; Weinberg, Z. G.

2005-01-01

412

Engineered synthetic pathway for isopropanol production in Escherichia coli.  

PubMed

A synthetic pathway was engineered in Escherichia coli to produce isopropanol by expressing various combinations of genes from Clostridium acetobutylicum ATCC 824, E. coli K-12 MG1655, Clostridium beijerinckii NRRL B593, and Thermoanaerobacter brockii HTD4. The strain with the combination of C. acetobutylicum thl (acetyl-coenzyme A [CoA] acetyltransferase), E. coli atoAD (acetoacetyl-CoA transferase), C. acetobutylicum adc (acetoacetate decarboxylase), and C. beijerinckii adh (secondary alcohol dehydrogenase) achieved the highest titer. This strain produced 81.6 mM isopropanol in shake flasks with a yield of 43.5% (mol/mol) in the production phase. To our knowledge, this work is the first to produce isopropanol in E. coli, and the titer exceeded that from the native producers. PMID:17933911

Hanai, T; Atsumi, S; Liao, J C

2007-10-12

413

Escherichia coli resistance to quinolones at a comprehensive cancer center.  

PubMed

As part of Meropenem Yearly Susceptibility Test Information Collection/USA Surveillance Programme, we monitored the occurrence of quinolone resistance in Escherichia coli over a 10-year period. A total of 271 E. coli isolates from our institution were tested over a 10-year period. Screening for quinolone resistance (qnr) gene was performed. A decline in susceptibility of E. coli isolates to quinolones and aminoglycosides was noted over the 10-year span (P < 0.0001), which was significantly reduced compared with the average susceptibility of all sites. Introduction of quinolone prophylaxis has led to a significant decline in susceptibility of E. coli to all quinolones. The organisms remain susceptible to carbapenems, cefepime, and piperacillin/tazobactam. Periodic surveillance allows for detection of resistance patterns and adjustment of empiric antibiotic choice in patients at high risk for infection. PMID:20471765

Mihu, Coralia N; Rhomberg, Paul R; Jones, Ronald N; Coyle, Elizabeth; Prince, Randall A; Rolston, Kenneth V

2010-05-15

414

Engineered Synthetic Pathway for Isopropanol Production in Escherichia coli? †  

PubMed Central

A synthetic pathway was engineered in Escherichia coli to produce isopropanol by expressing various combinations of genes from Clostridium acetobutylicum ATCC 824, E. coli K-12 MG1655, Clostridium beijerinckii NRRL B593, and Thermoanaerobacter brockii HTD4. The strain with the combination of C. acetobutylicum thl (acetyl-coenzyme A [CoA] acetyltransferase), E. coli atoAD (acetoacetyl-CoA transferase), C. acetobutylicum adc (acetoacetate decarboxylase), and C. beijerinckii adh (secondary alcohol dehydrogenase) achieved the highest titer. This strain produced 81.6 mM isopropanol in shake flasks with a yield of 43.5% (mol/mol) in the production phase. To our knowledge, this work is the first to produce isopropanol in E. coli, and the titer exceeded that from the native producers.

Hanai, T.; Atsumi, S.; Liao, J. C.

2007-01-01

415

Biosynthesis of bioactive O-methylated flavonoids in Escherichia coli.  

PubMed

Two bioactive O-methylflavonoids, sakuranetin (7-O-methylnaringenin) and ponciretin (7-O-methylnaringenin), were synthesized in Escherichia coli. Sakuranetin inhibits germination of Magnaporthe grisea, and ponciretin is a potential inhibitor of Helicobacter pylori. To achieve this, we reconstructed the naringenin biosynthesis pathway in E. coli. First, the shikimic acid pathway, which leads to the biosynthesis of tyrosine, was engineered in E. coli to increase the amount of available tyrosine. Second, several genes for the biosynthesis of ponciretin and sakuranetin such as tyrosine ammonia lyase (TAL), 4-coumaroyl CoA ligase (4CL), chalcone synthase (CHS), and O-methyltransferase (OMT) were overexpressed. In order to increase the supply the Coenzyme A (CoA), one gene (icdA, isocitrate dehydrogenase) was deleted. Using these strategies, we synthesized ponciretin and sakuranetin from glucose in E. coli at the concentration of 42.5 mg/L and 40.1 mg/L, respectively. PMID:23771780

Kim, Min-Ji; Kim, Bong-Gyu; Ahn, Joong-Hoon

2013-06-15

416

Proton-linked D-xylose transport in Escherichia coli.  

PubMed Central

The addition of xylose to energy-depleted cells of Escherichia coli elicited an alkaline pH change which failed to appear in the presence of uncoupling agents. Accumulation of [14C]xylose by energy-replete cells was also inhibited by uncoupling agents, but not by fluoride or arsenate. Subcellular vesicles of E. coli accumulated [14C]xylose provided that ascorbate plus phenazine methosulfate were present for respiration, and this accumulation was inhibited by uncoupling agents or valinomycin. Therefore, the transport of xylose into E. coli appears to be energized by a proton-motive force, rather than by a phosphotransferase or directly energized mechanism. Its specificity for xylose as inducer and substrate and the genetic location of a xylose-H+ transport-negative mutation near mtl showed that the xylose-H+ system is distinct from other proton-linked sugar transport systems of E. coli.

Lam, V M; Daruwalla, K R; Henderson, P J; Jones-Mortimer, M C

1980-01-01

417

EcoCyc: Enyclopedia of Escherichia coli Genes and Metabolism.  

PubMed Central

The Encyclopedia of Genes and Metabolism (EcoCyc) is a database that combines information about the genome and the intermediary metabolism of Escherichia coli. It describes 2970 genes of E.coli, 547 enzymes encoded by these genes, 702 metabolic reactions that occur in E.coli and the organization of these reactions into 107 metabolic pathways. The EcoCyc graphical user interface allows scientists to query and explore the EcoCyc database using visualization tools such as genomic-map browsers and automatic layouts of metabolic pathways. EcoCyc spans the space from sequence to function to allow scientists to investigate an unusually broad range of questions. EcoCyc can be thought of as both an electronic review article because of its copious references to the primary literature, and as an in silicio model of E.coli metabolism that can be probed and analyzed through computational means.

Karp, P D; Riley, M; Paley, S M; Pellegrini-Toole, A; Krummenacker, M

1997-01-01

418

EcoCyc: Enyclopedia of Escherichia coli Genes and Metabolism.  

PubMed

The Encyclopedia of Genes and Metabolism (EcoCyc) is a database that combines information about the genome and the intermediary metabolism of Escherichia coli. It describes 2970 genes of E.coli, 547 enzymes encoded by these genes, 702 metabolic reactions that occur in E.coli and the organization of these reactions into 107 metabolic pathways. The EcoCyc graphical user interface allows scientists to query and explore the EcoCyc database using visualization tools such as genomic-map browsers and automatic layouts of metabolic pathways. EcoCyc spans the space from sequence to function to allow scientists to investigate an unusually broad range of questions. EcoCyc can be thought of as both an electronic review article because of its copious references to the primary literature, and as an in silicio model of E.coli metabolism that can be probed and analyzed through computational means. PMID:9016502

Karp, P D; Riley, M; Paley, S M; Pellegrini-Toole, A; Krummenacker, M

1997-01-01

419

Purification of penicillin-binding protein 2 of Escherichia coli.  

PubMed Central

Penicillin-binding protein 2 (PBP-2) of Escherichia coli K-12 was purified by covalent affinity chromatography using 6-aminopenicillanic acid covalently coupled to carboxymethyl-Sepharose (6-APA-CM-Sepharose). Purification of PBP-2 was accomplished by prebinding the methoxy cephalosporin, cefoxitin, to the Triton X-100-solubilized PBPs of E. coli and then incubating the PBPs with 6-APA-CM-Sepharose. Cefoxitin readily binds to all the E. coli PBPs except PBP-2 and, thus, in the presence of cefoxitin, only PBP-2 could bind to the 6-APA-CM-Sepharose. The purification of a mixture of all of the PBPs of E. coli by affinity chromatography is also described. Images

Curtis, S J; Strominger, J L

1981-01-01

420

Brief heat treatment causes a structural change and enhances cytotoxicity of the Escherichia coli ?-hemolysin.  

PubMed

?-Hemolysin (HLY) is an important virulence factor for uropathogenic Escherichia coli. HLY is a member of the RTX family of exotoxins secreted by a number of Gram-negative bacteria. Recently, it was reported that a related RTX toxin, the Mannheimia haemolytica leukotoxin, exhibits increased cytotoxicity following brief heat treatment. In this article, we show that brief heat treatment (1?min at 100°C) increases cytotoxicity of HLY for human bladder cells, kidney epithelial cells (A498) and neutrophils. Heat treatment also increased hemolysis of human red blood cells (RBCs). Furthermore, heat treatment of previously inactived HLY restored its cytotoxicity. Heat-activated and native HLY both required glycophorin A to lyse RBCs. Native and heat-activated HLY appeared to bind equally well to the surface of A498 cells; although, Western blot analyses demonstrated binding to different proteins on the surface. Confocal microscopy revealed that heat-activated HLY bound more extensively to internal structures of permeabilized A498 cells than did native HLY. Several lines of spectroscopic evidence demonstrate irreversible changes in the structure of heat activated compared to native HLY. We show changes in secondary structure, increased exposure of tryptophan residues to the aqueous environment, an increase in molecular dimension and an increase in hydrophobic surface area. These properties are among the most common characteristics described for the molten globule state, first identified as an intermediate in protein folding. We hypothesize that brief heat treatment of HLY causes a conformational change leading to significant differences in protein-protein interactions that result in increased cytotoxicity for target cells. PMID:22994841

Aulik, Nicole A; Atapattu, Dhammika N; Czuprynski, Charles J; McCaslin, Darrel R

2012-09-21

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