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Sample records for aerogenes enterobacter cloacae

  1. Comparison of the clinical and microbiologic characteristics of patients with Enterobacter cloacae and Enterobacter aerogenes bacteremia: a prospective observation study.

    PubMed

    Song, Eun Hee; Park, Ki-Ho; Jang, Eun-Young; Lee, Eun Jung; Chong, Yong Pil; Cho, Oh-Hyun; Kim, Sung-Han; Lee, Sang-Oh; Sung, Heungsup; Kim, Mi-Na; Jeong, Jin-Yong; Kim, Yang Soo; Woo, Jun Hee; Choi, Sang-Ho

    2010-04-01

    We compared the characteristics and outcomes of 172 Enterobacter cloacae bacteremia and 67 Enterobacter aerogenes bacteremia (EAB) cases. Antimicrobial resistance rates to E. cloacae were higher than those to E. aerogenes. However, EAB more frequently presented as septic shock and was associated with poorer outcomes.

  2. Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment.

    PubMed

    Davin-Regli, Anne; Pagès, Jean-Marie

    2015-01-01

    Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution.

  3. Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment

    PubMed Central

    Davin-Regli, Anne; Pagès, Jean-Marie

    2015-01-01

    Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution. PMID:26042091

  4. Irreproducible and uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes.

    PubMed

    Landman, David; Salamera, Julius; Quale, John

    2013-12-01

    Carbapenem-resistant Enterobacter species are emerging nosocomial pathogens. As with most multidrug-resistant Gram-negative pathogens, the polymyxins are often the only therapeutic option. In this study involving clinical isolates of E. cloacae and E. aerogenes, susceptibility testing methods with polymyxin B were analyzed. All isolates underwent testing by the broth microdilution (in duplicate) and agar dilution (in duplicate) methods, and select isolates were examined by the Etest method. Selected isolates were also examined for heteroresistance by population analysis profiling. Using a susceptibility breakpoint of ≤2 μg/ml, categorical agreement by all four dilution tests (two broth microdilution and two agar dilution) was achieved in only 76/114 (67%) of E. cloacae isolates (65 susceptible, 11 resistant). Thirty-eight (33%) had either conflicting or uninterpretable results (multiple skip wells, i.e., wells that exhibit no growth although growth does occur at higher concentrations). Of the 11 consistently resistant isolates, five had susceptible MICs as determined by Etest. Heteroresistant subpopulations were detected in eight of eight isolates tested, with greater percentages in isolates with uninterpretable MICs. For E. aerogenes, categorical agreement between the four dilution tests was obtained in 48/56 (86%), with conflicting and/or uninterpretable results in 8/56 (14%). For polymyxin susceptibility testing of Enterobacter species, close attention must be paid to the presence of multiple skip wells, leading to uninterpretable results. Susceptibility also should not be assumed based on the results of a single test. Until the clinical relevance of skip wells is defined, interpretation of polymyxin susceptibility tests for Enterobacter species should be undertaken with extreme caution.

  5. Irreproducible and Uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes

    PubMed Central

    Landman, David; Salamera, Julius

    2013-01-01

    Carbapenem-resistant Enterobacter species are emerging nosocomial pathogens. As with most multidrug-resistant Gram-negative pathogens, the polymyxins are often the only therapeutic option. In this study involving clinical isolates of E. cloacae and E. aerogenes, susceptibility testing methods with polymyxin B were analyzed. All isolates underwent testing by the broth microdilution (in duplicate) and agar dilution (in duplicate) methods, and select isolates were examined by the Etest method. Selected isolates were also examined for heteroresistance by population analysis profiling. Using a susceptibility breakpoint of ≤2 μg/ml, categorical agreement by all four dilution tests (two broth microdilution and two agar dilution) was achieved in only 76/114 (67%) of E. cloacae isolates (65 susceptible, 11 resistant). Thirty-eight (33%) had either conflicting or uninterpretable results (multiple skip wells, i.e., wells that exhibit no growth although growth does occur at higher concentrations). Of the 11 consistently resistant isolates, five had susceptible MICs as determined by Etest. Heteroresistant subpopulations were detected in eight of eight isolates tested, with greater percentages in isolates with uninterpretable MICs. For E. aerogenes, categorical agreement between the four dilution tests was obtained in 48/56 (86%), with conflicting and/or uninterpretable results in 8/56 (14%). For polymyxin susceptibility testing of Enterobacter species, close attention must be paid to the presence of multiple skip wells, leading to uninterpretable results. Susceptibility also should not be assumed based on the results of a single test. Until the clinical relevance of skip wells is defined, interpretation of polymyxin susceptibility tests for Enterobacter species should be undertaken with extreme caution. PMID:24088860

  6. The differential importance of mutations within AmpD in cephalosporin resistance of Enterobacter aerogenes and Enterobacter cloacae.

    PubMed

    Babouee Flury, Baharak; Ellington, Matthew J; Hopkins, Katie L; Turton, Jane F; Doumith, Michel; Woodford, Neil

    2016-11-01

    Mechanisms leading to carbapenem and cephalosporin resistance were sought in Enterobacter aerogenes isolates that were highly resistant to carbapenems but had no known carbapenemase. Results were compared with recent work examining carbapenem-resistant Enterobacter cloacae. Eighteen carbapenem-resistant E. aerogenes were screened for known β-lactamase and carbapenemase genes, and novel carbapenemases were sought in whole-genome sequencing (WGS) data of the three most resistant isolates. For all isolates, ampC, ampR, ampD and the porin genes omp35 and omp36 were investigated by Sanger sequencing or from available WGS data. Expression of ampC and porin genes was measured in comparison with cephalosporin- and carbapenem-susceptible control strains by reverse transcriptase PCR, with porin translation also detected by SDS-PAGE. Loss of Omp35, primarily due to decreased transcription (up to 250×), was observed in ertapenem-resistant isolates (MICs ≥ 2 mg/L), whereas meropenem resistance (MICs ≥ 4 mg/L) was observed in those isolates also showing decreased or no production of Omp36. Loss of Omp36 was due to combinations of premature translation termination or reduced transcription. In contrast to E. cloacae, cephalosporin resistance in E. aerogenes was not associated with lesions in AmpD. High-level cefepime resistance (MIC = 32 mg/L) was caused by a novel modification in the H-10 helix of AmpC in one isolate. The differential importance of AmpD lesions in cephalosporin resistance in E. cloacae and E. aerogenes underlines the differences between these contrasting members of the Enterobacter genus. Porin loss resulted in high-level carbapenem resistance with gradual loss of Omp36, which led to high-level meropenem resistance.

  7. Detection of extended-spectrum beta-lactamases in clinical isolates of Enterobacter cloacae and Enterobacter aerogenes.

    PubMed

    Tzelepi, E; Giakkoupi, P; Sofianou, D; Loukova, V; Kemeroglou, A; Tsakris, A

    2000-02-01

    The aim of the present study was to investigate the frequency of extended-spectrum beta-lactamases (ESBLs) in a consecutive collection of clinical isolates of Enterobacter spp. The abilities of various screening methods to detect ESBLs in enterobacters were simultaneously tested. Among the 68 consecutive isolates (56 Enterobacter cloacae and 12 Enterobacter aerogenes isolates) that were analyzed for beta-lactamase content, 21 (25 and 58%, respectively) possessed transferable ESBLs with pIs of 8.2 and phenotypic characteristics of SHV-type enzymes, 8 (14.3%) of the E. cloacae isolates produced a previously nondescribed, clavulanate-susceptible ESBL that exhibited a pI of 6.9 and that conferred a ceftazidime resistance phenotype on Escherichia coli transconjugants, and 2 E. cloacae isolates produced both of these enzymes. Among the total of 31 isolates that were considered ESBL producers, the Vitek ESBL detection test was positive for 2 (6.5%) strains, and the conventional double-disk synergy test (DDST) with amoxicillin-clavulanate and with expanded-spectrum cephalosporins and aztreonam was positive for 5 (16%) strains. Modifications of the DDST consisting of closer application of the disks (at 20 instead of 30 mm), the use of cefepime, and the use of both modifications increased the sensitivity of this test to 71, 61, and 90%, respectively. Of the 37 isolates for which isoelectric focusing failed to determine ESBLs, the Vitek test was false positive for 1 isolate and the various forms of DDSTs were false-positive for 3 isolates.

  8. Draft Genome Assemblies of Enterobacter aerogenes CDC 6003-71, Enterobacter cloacae CDC 442-68, and Pantoea agglomerans UA 0804-01.

    PubMed

    Minogue, T D; Daligault, H E; Davenport, K W; Bishop-Lilly, K A; Bruce, D C; Chain, P S; Coyne, S R; Chertkov, O; Freitas, T; Frey, K G; Jaissle, J; Koroleva, G I; Ladner, J T; Palacios, G F; Redden, C L; Xu, Y; Johnson, S L

    2014-10-23

    The Enterobacteriaceae are environmental and enteric microbes. We sequenced the genomes of two Enterobacter reference strains, E. aerogenes CDC 6003-71 and E. cloacae CDC 442-68, as well as one near neighbor used as an exclusionary reference for diagnostics, Pantoea agglomerans CDC UA0804-01. The genome sizes range from 4.72 to 5.55 Mbp and have G+C contents from 54.6 to 55.1%.

  9. Draft Genome Assemblies of Enterobacter aerogenes CDC 6003-71, Enterobacter cloacae CDC 442-68, and Pantoea agglomerans UA 0804-01

    PubMed Central

    Minogue, T. D.; Daligault, H. E.; Davenport, K. W.; Bishop-Lilly, K. A.; Bruce, D. C.; Chain, P. S.; Coyne, S. R.; Chertkov, O.; Freitas, T.; Frey, K. G.; Jaissle, J.; Koroleva, G. I.; Ladner, J. T.; Palacios, G. F.; Redden, C. L.; Xu, Y.

    2014-01-01

    The Enterobacteriaceae are environmental and enteric microbes. We sequenced the genomes of two Enterobacter reference strains, E. aerogenes CDC 6003-71 and E. cloacae CDC 442-68, as well as one near neighbor used as an exclusionary reference for diagnostics, Pantoea agglomerans CDC UA0804-01. The genome sizes range from 4.72 to 5.55 Mbp and have G+C contents from 54.6 to 55.1%. PMID:25342683

  10. Characterization of KPC-2-producing Escherichia coli, Citrobacter freundii, Enterobacter cloacae, Enterobacter aerogenes, and Klebsiella oxytoca isolates from a Chinese Hospital.

    PubMed

    Luo, Yanping; Yang, Jiyong; Ye, Liyan; Guo, Lin; Zhao, Qiang; Chen, Rong; Chen, Yong; Han, Xuelin; Zhao, Jingya; Tian, Shuguang; Han, Li

    2014-08-01

    Twelve nonduplicated KPC-2-producing enterobacterial isolates, including three Escherichia coli, two Citrobacter freundii, two Enterobacter cloacae, four Enterobacter aerogenes, and one Klebsiella oxytoca, were collected from various clinical samples within 18 months (March 2011 to September 2012). Two of the 12 patients died from infections caused by KPC-2-producing pathogens, while the rest of the patients with KPC-2-producing pathogens improved or were cured. The majority of the clinical isolates exhibited a high-level of resistance to oxyimino-cephalosporins and carbapenems, and possessed self-transferable bla(KPC-2)-carrying plasmids with sizes ranging from 20 to 120 kb. Most isolates carried bla(CTX-M) and plasmid-mediated quinolone resistance genes, while some isolates produced 16S rRNA methylases (ArmA or RmtB). The genetic environment of bla(KPC-2) of most clinical strains was consistent with the genetic structure surrounding bla(KPC-2) on the plasmid pKP048, which contains an integration structure of a Tn3-based transposon and partial Tn4401 segment. Inserted fragments (truncated bla(TEM)) were detected upstream of the bla(KPC-2) gene for two E. aerogenes strains. In conclusion, the enterobacterial isolates exhibited sporadic emergence and did not arise by clonal spread at our hospital. The outcome of infections caused by KPC-producing enterobacterial isolates and their mortality were closely associated with the baseline condition of patients. The spread of bla(KPC-2) gene between different enterobacterial species in China was mainly mediated by horizontal transfer of the Tn3-based transposons and not the bla(KPC-2)-carrying plasmids.

  11. Clonal spread and accumulation of β-lactam resistance determinants in Enterobacter aerogenes and Enterobacter cloacae complex isolates from infection and colonization in patients at a public hospital in Recife, Pernambuco, Brazil.

    PubMed

    Cabral, Adriane Borges; Maciel, Maria Amélia Vieira; Barros, Josineide Ferreira; Antunes, Marcelo Maranhão; Barbosa de Castro, Célia Maria Machado; Lopes, Ana Catarina Souza

    2017-01-01

    Enterobacter aerogenes and Enterobacter cloacae complex are the two species of this genus most involved in healthcare-associated infections that are ESBL and carbapenemase producers. This study characterized, phenotypically and genotypically, 51 isolates of E. aerogenes and E. cloacae complex originating from infection or colonization in patients admitted to a public hospital in Recife, Pernambuco, Brazil, by antimicrobial susceptibility profile, analysis of β-lactamase genes (blaTEM, blaSHV, blaCTX-M, blaKPC, blaVIM, blaIMP and blaSPM), PCR and DNA sequencing, plasmid profile and ERIC-PCR. In both species, the genes blaTEM, blaCTX-M and blaKPC were detected. The DNA sequencing confirmed the variants blaTEM-1, blaCTX-M-15 and blaKPC-2 in isolates. More than one gene conferring resistance in the isolates, including the detection of the three previously cited genes in strains isolated from infection sites, was observed. The detection of blaCTX-M was more frequent in isolates from infection sites than from colonization. The gene blaKPC predominated in E. cloacae complex isolates obtained from infections; however, in E. aerogenes isolates, it predominated in samples obtained from colonization. A clonal relationship among all of E. aerogenes isolates was detected by ERIC-PCR. The majority of E. cloacae complex isolates presented the same ERIC-PCR pattern. Despite the clonal relation presented by the isolates using ERIC-PCR, different plasmid and resistance profiles and several resistance genes were observed. The clonal dissemination and the accumulation of β-lactam resistance determinants presented by the isolates demonstrated the ability of E. aerogenes and E. cloacae complex, obtained from colonization and infection, to acquire and maintain different resistance genes.

  12. Evaluation of Phoenix Automated Microbiology System for detecting extended-spectrum beta-lactamases among chromosomal AmpC-producing Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii, and Serratia marcescens.

    PubMed

    Park, Yeon-Joon; Yu, Jin Kyung; Lee, Seungok; Park, Jung-Jun; Oh, Eun-Jee

    2007-01-01

    We evaluated the BD Phoenix Extended-Spectrum beta-Lactamase (ESBL) detection test among chromosomal AmpC-producing Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii, and Serratia marcescens. The study was conducted on 72 non-repetitive ESBL producers (33 E. cloacae, 13 E. aerogenes, 14 C. freundii, and 12 S. marcescens) and 77 ESBL non-producers (33 E. cloacae, 9 E. aerogenes, 6 C. freundii, and 29 S. marcescens). The organisms were selected as suspected ESBL-producers based on the double disk synergy test and confirmed by PCR amplification of blaTEM-1, blaSHV-1, blaCTX-M-1, blaCTX-M-2, and blaCTX-M-9. The Phoenix ESBL test, using a 5-well confirmatory test and the BDXpert system, was evaluated. Of the 72 isolates identified as ESBL-producers based on the DDST, 46 isolates harbored CTX-M-type enzymes, 21 harbored TEM type enzymes, and 31 harbored SHV enzymes. The Phoenix system identified ESBL only in 15 isolates. Of the 77 ESBL non-producers, ths Phoenix system identified ESBL in 4 isolates, 3 of which were confirmed to be ESBL-producers. In this study, the Phoenix system was highly specific (76/77, 98.7%), and it identified 3 additional ESBL-producers that were not detected by DDST. However, the Phoenix system's sensitivity was very low (15/72, 20.8%). Considering the increasing prevalence of ESBL production among AmpC-producers, the BD Phoenix system could not be considered a reliable stand-alone ESBL detection method for the strains tested in our study.

  13. Infectious discitis caused by Enterobacter cloacae.

    PubMed Central

    Solans, R; Simeon, P; Cuenca, R; Fonollosa, V; Bago, J; Vilardell, M

    1992-01-01

    The case is reported of a patient who developed a vertebral osteomyelitis caused by Enterobacter cloacae. The organism was isolated in cultures of blood and vertebral puncture biopsy samples. The patient was satisfactorily treated with trimethroprim and sulphamethoxazole. Enterobacter cloacae, a Gram negative organism, has been confirmed as the cause of bacteremia in patients with burns, urinary infections, in adults with pneumonia, and in children with joint infections. Spondylodiscitis caused by Enterobacter cloacae has not previously been described. Images PMID:1632668

  14. Population genetics of the nomenspecies Enterobacter cloacae.

    PubMed

    Hoffmann, Harald; Roggenkamp, Andreas

    2003-09-01

    The genetic heterogeneity of the nomenspecies Enterobacter cloacae is well known. Enterobacter asburiae, Enterobacter cancerogenus, Enterobacter dissolvens, Enterobacter hormaechei, Enterobacter kobei, and Enterobacter nimipressuralis are closely related to it and are subsumed in the so-called E. cloacae complex. DNA-DNA hybridization studies performed previously identified at least five DNA-relatedness groups of this complex. In order to analyze the genetic structure and the phylogenetic relationships between the clusters of the nomenspecies E. cloacae, 206 strains collected from 22 hospitals, a veterinarian, and an agricultural center in 11 countries plus all 13 type strains of the genus and reference strain CDC 1347-71(R) were examined with a combination of sequence and PCR-restriction fragment length polymorphism (PCR-RFLP) analyses of the three housekeeping genes hsp60, rpoB, and hemB as well as ampC, the gene of a class C beta-lactamase. Based on the neighbor-joining tree of the hsp60 sequences, 12 genetic clusters (I to XII) and an unstable sequence crowd (xiii) were identified. The robustness of the genetic clusters was confirmed by analyses of rpoB and hemB sequences and ampC PCR-RFLPs. Sequence crowd xiii split into two groups after rpoB analysis. Only three strains formed a cluster with the type strain of E. cloacae, indicating that the minority of isolates identified as E. cloacae truly belong to the species; 13% of strains grouped with other type strains of the genus, suggesting that the phenotypes of these species seem to be more heterogeneous than so far believed. Three clusters represented 70% of strains, but none of them included a type or reference strain. The genetic clustering presented in this study might serve as a framework for future studies dealing with taxonomic, evolutionary, epidemiological, or pathogenetic characteristics of bacteria belonging to the E. cloacae complex.

  15. Population Genetics of the Nomenspecies Enterobacter cloacae

    PubMed Central

    Hoffmann, Harald; Roggenkamp, Andreas

    2003-01-01

    The genetic heterogeneity of the nomenspecies Enterobacter cloacae is well known. Enterobacter asburiae, Enterobacter cancerogenus, Enterobacter dissolvens, Enterobacter hormaechei, Enterobacter kobei, and Enterobacter nimipressuralis are closely related to it and are subsumed in the so-called E. cloacae complex. DNA-DNA hybridization studies performed previously identified at least five DNA-relatedness groups of this complex. In order to analyze the genetic structure and the phylogenetic relationships between the clusters of the nomenspecies E. cloacae, 206 strains collected from 22 hospitals, a veterinarian, and an agricultural center in 11 countries plus all 13 type strains of the genus and reference strain CDC 1347-71R were examined with a combination of sequence and PCR-restriction fragment length polymorphism (PCR-RFLP) analyses of the three housekeeping genes hsp60, rpoB, and hemB as well as ampC, the gene of a class C β-lactamase. Based on the neighbor-joining tree of the hsp60 sequences, 12 genetic clusters (I to XII) and an unstable sequence crowd (xiii) were identified. The robustness of the genetic clusters was confirmed by analyses of rpoB and hemB sequences and ampC PCR-RFLPs. Sequence crowd xiii split into two groups after rpoB analysis. Only three strains formed a cluster with the type strain of E. cloacae, indicating that the minority of isolates identified as E. cloacae truly belong to the species; 13% of strains grouped with other type strains of the genus, suggesting that the phenotypes of these species seem to be more heterogeneous than so far believed. Three clusters represented 70% of strains, but none of them included a type or reference strain. The genetic clustering presented in this study might serve as a framework for future studies dealing with taxonomic, evolutionary, epidemiological, or pathogenetic characteristics of bacteria belonging to the E. cloacae complex. PMID:12957918

  16. Comparative Genome Analysis of Enterobacter cloacae

    PubMed Central

    Liu, Wing-Yee; Wong, Chi-Fat; Chung, Karl Ming-Kar; Jiang, Jing-Wei; Leung, Frederick Chi-Ching

    2013-01-01

    The Enterobacter cloacae species includes an extremely diverse group of bacteria that are associated with plants, soil and humans. Publication of the complete genome sequence of the plant growth-promoting endophytic E. cloacae subsp. cloacae ENHKU01 provided an opportunity to perform the first comparative genome analysis between strains of this dynamic species. Examination of the pan-genome of E. cloacae showed that the conserved core genome retains the general physiological and survival genes of the species, while genomic factors in plasmids and variable regions determine the virulence of the human pathogenic E. cloacae strain; additionally, the diversity of fimbriae contributes to variation in colonization and host determination of different E. cloacae strains. Comparative genome analysis further illustrated that E. cloacae strains possess multiple mechanisms for antagonistic action against other microorganisms, which involve the production of siderophores and various antimicrobial compounds, such as bacteriocins, chitinases and antibiotic resistance proteins. The presence of Type VI secretion systems is expected to provide further fitness advantages for E. cloacae in microbial competition, thus allowing it to survive in different environments. Competition assays were performed to support our observations in genomic analysis, where E. cloacae subsp. cloacae ENHKU01 demonstrated antagonistic activities against a wide range of plant pathogenic fungal and bacterial species. PMID:24069314

  17. A new oxolane from Enterobacter cloacae.

    PubMed

    Yap, Ann-Chee; Chan, Kok-Gan; Sim, Kae-Shin; Choo, Yeun-Mun

    2016-01-01

    Enterobacter cloacae is a highly pathogenic Gram-negative proteobacterium which is responsible for a wide array of infections. In the present study, the fermentation culture of E. cloacae has yielded one new oxolane compound, Rimboxo (1) in addition to three known compounds, i.e. Maculosine (2), phenylacetic acid (3) and methyl myristate (4). These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods, and were subjected to cytotoxicity evaluations.

  18. A solvent tolerant isolate of Enterobacter aerogenes.

    PubMed

    Gupta, Anshu; Singh, Rajni; Khare, S K; Gupta, M N

    2006-01-01

    A solvent tolerant strain of Enterobacter aerogenes was isolated from soil by cyclohexane enrichment. Presence of cyclohexane (20%) in culture media prolonged the lag phase and caused reduction in biomass. Transmission electron micrographs showed convoluted cell membrane and accumulation of solvent in case of the cells grown in cyclohexane. The Enterobacter isolate was able to grow in the range of organic solvents having log P above 3.2 and also in presence of mercury, thus showing potential for treatment of solvent rich wastes.

  19. Complete Genome Sequence of the Endophytic Enterobacter cloacae subsp. cloacae Strain ENHKU01

    PubMed Central

    Liu, Wing-Yee; Chung, Karl Ming-Kar; Wong, Chi-Fat; Jiang, Jing-Wei; Hui, Raymond Kin-Hi

    2012-01-01

    Enterobacter cloacae subsp. cloacae strain ENHKU01 is a Gram-negative endophyte isolated from a diseased pepper (Capsicum annuum) plant in Hong Kong. This is the first complete genome sequence report of a plant-endophytic strain of E. cloacae subsp. cloacae. PMID:23045485

  20. Bioengineering of the Enterobacter aerogenes strain for biohydrogen production.

    PubMed

    Zhang, Chong; Lv, Feng-Xiang; Xing, Xin-Hui

    2011-09-01

    Enterobacter aerogenes is one of the most widely-studied model strains for fermentative hydrogen production. To improve the hydrogen yield of E. aerogenes, the bioengineering on a biomolecular level and metabolic network level is of importance. In this review, the fermentative technology of E. aerogenes for hydrogen production will be first briefly summarized. And then the bioengineering of E. aerogenes for the improvement of hydrogen yield will be thoroughly reviewed, including the anaerobic metabolic networks for hydrogen evolution in E. aerogenes, metabolic engineering for improving hydrogen production in E. aerogenes and mixed culture of E. aerogenes with other hydrogen-producing bacteria to enhance the overall yield in anaerobic cultivation. Finally, a perspective on E. aerogenes as a hydrogen producer including systems bioengineering approach for improving the hydrogen yield and application of the engineered E. aerogenes in mixed culture will be presented.

  1. [Outbreak of Enterobacter aerogenes in paediatric unit].

    PubMed

    Burnichon, G; Le Floch, M F; Virmaux, M; Baron, R; Tandé, D; Lejeune, B

    2004-04-01

    Within the framework of breast milk control the hygiene laboratory of Brest hospital isolates, on 3 January 1996 a strain of Enterobacter aerogenes secretory of cephalosporinase in the breast milk of a mother whose child was hospitalized in neonatalogy. On 15 April 1996 a new strain of E. aerogenes is isolated from another mother's breast milk. Until 18 August 1997, 21 samples of breast milk were tested positive to this bacteria. During the same period, E. aerogenes was isolated in 26 children under 1 year of age, 11 of which were infected and 15 colonized. The breast milk did not correspond to those of the mothers of the infected or colonized children. All the strains presented the same antibioresistance. The pulsed-field gel electrophoresis showed that the children's strains, those colonized or infected as well as those isolated in breast milk had the same restriction profile. The epidemiological study concerned the biberonnery-lactarium. The biberonnery's staff is the same as the staff of the lactarium. A portage was searched for among the members of the staff of these units, but without success. The search for E. aerogenes in the environment and in baby-food, others than breast milk was negative. Finally, we did not find any source for these contagions. The only hypothesis we have retained is that of a common source from the biberonnery-lactarium, but without being able to bring any proof to it. Following this epidemic, we have revised all the working modalities and practices with the staff of the biberonnery-lactarium.

  2. Phenotypic characterization of ESBL producing Enterobacter cloacae among children

    PubMed Central

    Amin, Hafsa; Zafar, Aizza; Ejaz, Hasan; Jameel, Noor-ul-Ain

    2013-01-01

    Objective: The emergence of ESBL producing Enterobacter cloacae in clinical isolates is posing a serious threat for treating nosocomial infections. The aim of the study was to determine the frequency of extended spectrum β-lactamase (ESBL) producing Enterobacter cloacae and to compare the phenotypic methods used for the characterization of ESBL producing strains. Methodology: This cross sectional observational study was conducted during April 2011 to March 2012 at Microbiology department of The Children’s Hospital and Institute of Child Health, Lahore. A total number of 20,257 various clinical samples were analyzed during the study period. Enterobacter cloacae were identified using API 20E system and ESBL detection was carried out using double-disk synergy test (DDST) and CLSI confirmatory test. Results: Enterobacter cloacae were isolated from 221 samples, out of which 33 (14.93%) were ESBL producers and 188 (85.07%) were non-ESBL producers. The gender distribution of ESBL producing Enterobacter cloacae was 21 (63.6%) in males and 12 (36.4%) in females. Highest frequency (63%) of ESBL producing Enterobacter cloacae was detected in blood samples. Comparison of DDST and CLSI confirmatory test showed that 25 (75.75%) isolates were characterized by DDST and 33 (100%) using CLSI confirmatory test. Conclusion: The present study shows moderately high frequency of ESBL producing Enterobacter cloacae among children. DDST was found to be less efficient in ESBL detection as compared to CLSI confirmatory test. PMID:24353527

  3. Complete genome sequence of Enterobacter aerogenes KCTC 2190.

    PubMed

    Shin, Sang Heum; Kim, Sewhan; Kim, Jae Young; Lee, Soojin; Um, Youngsoon; Oh, Min-Kyu; Kim, Young-Rok; Lee, Jinwon; Yang, Kap-Seok

    2012-05-01

    This is the first complete genome sequence of the Enterobacter aerogenes species. Here we present the genome sequence of E. aerogenes KCTC 2190, which contains 5,280,350 bp with a G + C content of 54.8 mol%, 4,912 protein-coding genes, and 109 structural RNAs.

  4. Transmission of Enterobacter aerogenes septicemia in healthcare workers.

    PubMed

    Jha, Piyush; Kim, Choon-Mee; Kim, Dong-Min; Chung, Jong-Hoon; Yoon, Na-Ra; Jha, Babita; Kim, Seok Won; Jang, Sook Jin; Ahn, Young-Joon; Chung, Jae Keun; Jeon, Doo Young

    2016-01-01

    Enterobacter aerogenes is recognized as an important bacterial pathogen in hospital-acquired infections. This report describes two unusual cases of septicemia caused by E. aerogenes in immunocompetent healthcare workers. E. aerogenes was isolated from blood cultures of the two patients experiencing septicemia. The clinical isolates were initially identified as E. aerogenes using a VITEK II automated system and 16S rRNA sequence analysis, and; both isolates involved in the outbreak shared a common pulse-field gel electrophoresis pattern. The similarities between the two cases included the simultaneous development of gastroenteritis symptoms, severe sepsis and thrombocytopenia after taking intravenous injections of ketorolac tromethamine. A common source of normal saline, a 100 mL bottle, was used for diluting the analgesic in both cases. In addition to the general population, healthcare workers, especially those who are also intravenous drug abusers, should be considered subjects that could cause a transmission of Enterobacter infection.

  5. Draft Genome Sequence of Enterobacter cloacae subsp. cloacae Strain 08XA1, a Fecal Bacterium of Giant Pandas

    PubMed Central

    Yan, Yue; Zhao, Chuan-Wu; Zhang, Yi-Zheng; Zhang, Zhi-He; Pan, Guang-Lin; Liu, Wen-Wang; Ma, Qing-Yi; Hou, Rong

    2012-01-01

    Enterobacter cloacae, a common pathogenic bacterium, is a Gram-negative bacillus. We analyzed the draft genome of Enterobacter cloacae subsp. cloacae strain 08XA1 from the feces of a giant panda in China. Genes encoding a β-lactamase and efflux pumps, as well as other factors, have been found in the genome. PMID:23209197

  6. Clonal distribution of multidrug-resistant Enterobacter cloacae.

    PubMed

    Girlich, Delphine; Poirel, Laurent; Nordmann, Patrice

    2015-04-01

    A multilocus sequence typing (MLST) scheme including 7 housekeeping genes was used to evaluate whether the current spread of multidrug-resistant Enterobacter cloacae isolates worldwide might be associated to specific successful clones. Fifty E. cloacae clinical isolates of worldwide origin, with various β-lactamase content, and recovered at different periods of time were studied. Forty-four sequence types were identified, highlighting a high clonal diversity with 3 main lineages. This study revealed that a precise identification of the isolates by sequencing of the chromosomal ampC gene of E. cloacae would provide a significant added value to improve the reliability of the MLST scheme.

  7. Single-cell protein from methanol with Enterobacter aerogenes

    SciTech Connect

    Gnan, S.O.; Abodreheba, A.O.

    1987-02-20

    An identified Enterobacter aerogenes utilizing methanol as a sole carbon source was studied for the optimization of biomass production and the reduction of its nucleic acid content. Results indicated that the highest yield and conversion were obtained at 0.5% methanol. The addition of seawater as a source of trace elements has an adverse effect. However, the addition of urea as source of nitrogen enhanced the growth of E. aerogenes. Heat shock at 60 degrees C for one minute followed by incubation at 50 degrees C for 2 hours caused 72.6% reduction in the nucleic acid. 12 references.

  8. Draft Genome Sequence of Enterobacter cloacae Strain JD6301

    PubMed Central

    Wilson, Jessica G.; French, William T.; Lipzen, Anna; Martin, Joel; Schackwitz, Wendy; Woyke, Tanja; Shapiro, Nicole; Bullard, James W.; Champlin, Franklin R.

    2014-01-01

    Enterobacter cloacae strain JD6301 was isolated from a mixed culture with wastewater collected from a municipal treatment facility and oleaginous microorganisms. A draft genome sequence of this organism indicates that it has a genome size of 4,772,910 bp, an average G+C content of 53%, and 4,509 protein-coding genes. PMID:24874669

  9. Draft Genome Sequence of Enterobacter cloacae Strain S611

    PubMed Central

    Han, Cliff S.; Dichosa, Armand E. K.; Gleasner, Cheryl D.; Johnson, Shannon L.; Daligault, Hajnalka E.; Davenport, Karen W.; Li, Po-E; Pierson, Elizabeth A.; Pierson, Leland S.

    2014-01-01

    We report draft genomes of Enterobacter cloacae strain S611, an endophytic bacterium isolated from surface-sterilized germinating wheat seeds. We present the assembly and annotation of its genome, which may provide insights into the metabolic pathways involved in adaptation. PMID:25502660

  10. Enterobacter cloacae inhibits human norovirus infectivity in gnotobiotic pigs

    PubMed Central

    Lei, Shaohua; Samuel, Helen; Twitchell, Erica; Bui, Tammy; Ramesh, Ashwin; Wen, Ke; Weiss, Mariah; Li, Guohua; Yang, Xingdong; Jiang, Xi; Yuan, Lijuan

    2016-01-01

    Human noroviruses (HuNoVs) are the leading cause of epidemic gastroenteritis worldwide. Study of HuNoV biology has been hampered by the lack of an efficient cell culture system. Recently, enteric commensal bacteria Enterobacter cloacae has been recognized as a helper in HuNoV infection of B cells in vitro. To test the influences of E. cloacae on HuNoV infectivity and to determine whether HuNoV infects B cells in vivo, we colonized gnotobiotic pigs with E. cloacae and inoculated pigs with 2.74 × 104 genome copies of HuNoV. Compared to control pigs, reduced HuNoV shedding was observed in E. cloacae colonized pigs, characterized by significantly shorter duration of shedding in post-inoculation day 10 subgroup and lower cumulative shedding and peak shedding in individual pigs. Colonization of E. cloacae also reduced HuNoV titers in intestinal tissues and in blood. In both control and E. cloacae colonized pigs, HuNoV infection of enterocytes was confirmed, however infection of B cells was not observed in ileum, and the entire lamina propria in sections of duodenum, jejunum, and ileum were HuNoV-negative. In summary, E. cloacae inhibited HuNoV infectivity, and B cells were not a target cell type for HuNoV in gnotobiotic pigs, with or without E. cloacae colonization. PMID:27113278

  11. Enterobacter cloacae inhibits human norovirus infectivity in gnotobiotic pigs.

    PubMed

    Lei, Shaohua; Samuel, Helen; Twitchell, Erica; Bui, Tammy; Ramesh, Ashwin; Wen, Ke; Weiss, Mariah; Li, Guohua; Yang, Xingdong; Jiang, Xi; Yuan, Lijuan

    2016-04-26

    Human noroviruses (HuNoVs) are the leading cause of epidemic gastroenteritis worldwide. Study of HuNoV biology has been hampered by the lack of an efficient cell culture system. Recently, enteric commensal bacteria Enterobacter cloacae has been recognized as a helper in HuNoV infection of B cells in vitro. To test the influences of E. cloacae on HuNoV infectivity and to determine whether HuNoV infects B cells in vivo, we colonized gnotobiotic pigs with E. cloacae and inoculated pigs with 2.74 × 10(4) genome copies of HuNoV. Compared to control pigs, reduced HuNoV shedding was observed in E. cloacae colonized pigs, characterized by significantly shorter duration of shedding in post-inoculation day 10 subgroup and lower cumulative shedding and peak shedding in individual pigs. Colonization of E. cloacae also reduced HuNoV titers in intestinal tissues and in blood. In both control and E. cloacae colonized pigs, HuNoV infection of enterocytes was confirmed, however infection of B cells was not observed in ileum, and the entire lamina propria in sections of duodenum, jejunum, and ileum were HuNoV-negative. In summary, E. cloacae inhibited HuNoV infectivity, and B cells were not a target cell type for HuNoV in gnotobiotic pigs, with or without E. cloacae colonization.

  12. Enterobacter cloacae pericardial effusion in a frail elderly patient

    PubMed Central

    Blundell, H J; Mason, C A

    2015-01-01

    We report a case of a frail 82-year-old man with seronegative rheumatoid arthritis and a recent pacemaker insertion, admitted with pulmonary oedema and a symptomatic pericardial effusion. He was treated with diuretics and an urgent pericardiocentesis, a sample from which cultured Enterobacter cloacae. A subsequent abdominal CT scan revealed faecal loading, an abnormal anorectal canal and sigmoid colon and a bowel perforation. Endoscopy, biopsies and histopathology confirmed a diagnosis of cytomegalovirus (CMV) colitis with coexistent fungal infection. The E. cloacae infection was successfully treated with 6 weeks of intravenous meropenem, while the CMV and fungal infections were treated with a combination of valganciclovir and fluconazole. We postulate that the bowel perforation resulted from a combination of CMV colitis, faecal loading and steroid therapy and led to bacterial translocation of E. cloacae and the development of the pericardial effusion. This case represents an unusual pathophysiology for the development of an E. cloacae pericardial effusion. PMID:25697299

  13. Bioadsorption and biostabilization of cadmium by Enterobacter cloacae TU.

    PubMed

    Xu, Canran; He, Shengbao; Liu, Yongmin; Zhang, Wei; Lu, Diannan

    2017-04-01

    Biostabilization of cadmium, a hazardous chemical found widely in China, was attempted using Enterobacter cloacae TU (E.cloacae TU). A cadmium (Cd)-tolerant E.cloacae TU was obtained by mutagenesis using an atmosphere pressure glow discharge plasma system, and it displayed regular growth behavior in the presence of 250 mg/L Cd in solution. The maximum stabilization capacity of E.cloacae TU toward Cd reached 67.0 ± 3.5 mg/g dry cell weight at an initial Cd concentration of 200 mg/L. The percentage of Cd removal by E.cloacae TU reached 97.4± 0.3% at an initial Cd concentration of 20 mg/L. A desorption experiment confirmed both extracellular adsorption and intracellular uptake contribute to biostabilization, although Cd was mainly distributed on the surface of E.cloacae TU cells due to over-secretion of extracellular polysaccharides under Cd stimulus. The changes in morphology and functional groups of the E.cloacae TU cell surface in the presence of Cd were analyzed using X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Fourier Transform Infrared Spectoscopy (FT-IR). The feasibility of using E.cloacae TU for this purpose was further confirmed by on site remediation, in which the application of E.cloacae TU reduced the bioavailability and moreover the accumulation of Cd in tobacco plants without affecting the quality of flue-cured tobacco.

  14. Multilocus Sequence Typing (MLST) for Characterization of Enterobacter cloacae

    PubMed Central

    Miyoshi-Akiyama, Tohru; Hayakawa, Kayoko; Ohmagari, Norio; Shimojima, Masahiro; Kirikae, Teruo

    2013-01-01

    Enterobacter cloacae is an important emerging pathogen, which sometime causes respiratory infection, surgical site infection, urinary infection, sepsis, and outbreaks at neonatal units. We have developed a multilocus sequence typing (MLST) scheme utilizing seven housekeeping genes and evaluated the performance in 101 clinical isolates. The MLST scheme yielded 83 sequence types (ST) including 78 novel STs found in the clinical isolates. These findings supported the robustness of the MLST scheme developed in this study. PMID:23776664

  15. Enterobacter cloacae Postsurgical Endophthalmitis: Report of a Positive Outcome

    PubMed Central

    Butikofer, Scott; Dettori, Jason M.; Vemulakonda, G. Atma; Slabaugh, Mark

    2013-01-01

    We report a positive outcome of postcataract endophthalmitis caused by Enterobacter cloacae, which has previously resulted in poor outcomes in endophthalmitis. A 67-year-old man underwent uncomplicated cataract surgery. On the morning of postoperative day (POD) #1, he had significant anterior chamber inflammation without pain, hypopyon, or vitritis but then rapidly developed hypopyon and worsening visual acuity. He underwent a tap and inject with vancomycin and ceftazidime and was prescribed topical steroids and antibiotics as well as oral levofloxacin. On POD #3, cultures of the vitreous and aqueous returned positive for E. cloacae. By POD #6, his hypopyon had resolved with improved vitritis, decreased inflammation, and visual acuity of 20/200. Two weeks after surgery, his best-corrected visual acuity was 20/60. Contrary to prior reports, we demonstrate that it is possible to achieve a good outcome in cases of E. cloacae endophthalmitis treated early with appropriate antibiotics and anti-inflammatory agents. PMID:23626573

  16. Enhanced hydrogen production of Enterobacter aerogenes mutated by nuclear irradiation.

    PubMed

    Cheng, Jun; Liu, Min; Song, Wenlu; Ding, Lingkan; Liu, Jianzhong; Zhang, Li; Cen, Kefa

    2017-03-01

    Nuclear irradiation was used for the first time to generate efficient mutants of hydrogen-producing bacteria Enterobacter aerogenes, which were screened with larger colour circles of more fermentative acid by-products. E. aerogenes cells were mutated by nuclear irradiation of (60)Co γ-rays. The screened E. aerogenes ZJU1 mutant with larger colour circles enhanced the hydrogenase activity from 89.8 of the wild strain to 157.4mLH2/(gDWh). The hereditary stability of the E. aerogenes ZJU1 mutant was certified after over ten generations of cultivation. The hydrogen yield of 301mLH2/gglucose with the mutant was higher by 81.8% than that of 166mL/gglucose with the wild strain. The peak hydrogen production rate of 27.2mL/(L·h) with the mutant was higher by 40.9% compared with that of 19.3mL/(L·h) with the wild strain. The mutant produced more acetate and butyrate but less ethanol compared with the wild strain during hydrogen fermentation.

  17. Chloramphenicol and expression of multidrug efflux pump in Enterobacter aerogenes.

    PubMed

    Ghisalberti, Didier; Masi, Muriel; Pagès, Jean-Marie; Chevalier, Jacqueline

    2005-03-25

    Chloramphenicol has been reported to act as an inducer of the multidrug resistance in Escherichia coli. A resistant variant able to grow on plates containing 64 microg/ml chloramphenicol was obtained from the Enterobacter aerogenes ATCC 13048-type strain. Chloramphenicol resistance was due to an active efflux of this antibiotic and it was associated with resistance to fluoroquinolones and tetracycline, but not to aminoglycoside or beta-lactam antibiotics. MDR in the chloramphenicol-resistant variant is linked to the overexpression of the major AcrAB-TolC efflux system. This overexpression seems unrelated to the global Mar and the local AcrR regulatory pathways.

  18. Antibiotic combinations for controlling colistin-resistant Enterobacter cloacae.

    PubMed

    Lima, Thais Bergamin; Silva, Osmar Nascimento; de Almeida, Keyla Caroline; Ribeiro, Suzana Meira; Motta, Dielle de Oliveira; Maria-Neto, Simone; Lara, Michelle Brizolla; Filho, Carlos Roberto Souza; Ombredane, Alicia Simalie; de Faria Junior, Celio; Parachin, Nadia Skorupa; Magalhães, Beatriz Simas; Franco, Octávio Luiz

    2017-02-01

    Enterobacter cloacae is a Gram-negative bacterium associated with high morbidity and mortality in intensive care patients due to its resistance to multiple antibiotics. Currently, therapy against multi-resistant bacteria consists of using colistin, in spite of its toxic effects at higher concentrations. In this context, colistin-resistant E. cloacae strains were challenged with lower levels of colistin combined with other antibiotics to reduce colistin-associated side effects. Colistin-resistant E. cloacae (ATCC 49141) strains were generated by serial propagation in subinhibitory colistin concentrations. After this, three colistin-resistant and three nonresistant replicates were isolated. The identity of all the strains was confirmed by MALDI-TOF MS, VITEK 2 and MicroScan analysis. Furthermore, cross-resistance to other antibiotics was checked by disk diffusion and automated systems. The synergistic effects of the combined use of colistin and chloramphenicol were observed via the broth microdilution checkerboard method. First, data here reported showed that all strains presented intrinsic resistance to penicillin, cephalosporin (except fourth generation), monobactam, and some associations of penicillin and β-lactamase inhibitors. Moreover, a chloramphenicol and colistin combination was capable of inhibiting the induced colistin-resistant strains as well as two colistin-resistant clinical strains. Furthermore, no cytotoxic effect was observed by using such concentrations. In summary, the data reported here showed for the first time the possible therapeutic use of colistin-chloramphenicol for infections caused by colistin-resistant E. cloacae.

  19. Effects of Selected Hydrazines on the Early Death Rates of Enterobacter cloacae

    DTIC Science & Technology

    1983-01-01

    Early Death Rates of Enterobacter cloacae S. A. London, C. R. Mantel, J. D. Robinson, and S. Luking Toxic Hazards Division, Air Force Aerospace Medical...A. enumerate cell death rate at low culture concentrations. C.3 MATERIALS AID 1ETHODS The organism used in this study - Enterobacter cloacae strain D...response to "transfer shock" than exposed cells. The effects of hydrazines on the duration of the lag phase of growth of E. cloacae str D-31 provide a

  20. Production of diacetyl by metabolically engineered Enterobacter cloacae

    PubMed Central

    Zhang, Lijie; Zhang, Yingxin; Liu, Qiuyuan; Meng, Liying; Hu, Mandong; Lv, Min; Li, Kun; Gao, Chao; Xu, Ping; Ma, Cuiqing

    2015-01-01

    Diacetyl, a high value product that can be extensively used as a food ingredient, could be produced from the non-enzymatic oxidative decarboxylation of α-acetolactate during 2,3-butanediol fermentation. In this study, the 2,3-butanediol biosynthetic pathway in Enterobacter cloacae subsp. dissolvens strain SDM, a good candidate for microbial 2,3-butanediol production, was reconstructed for diacetyl production. To enhance the accumulation of the precursor of diacetyl, the α-acetolactate decarboxylase encoding gene (budA) was knocked out in strain SDM. Subsequently, the two diacetyl reductases DR-I (gdh) and DR-II (budC) encoding genes were inactivated in strain SDM individually or in combination to decrease the reduction of diacetyl. Although the engineered strain E. cloacae SDM (ΔbudAΔbudC) was found to have a good ability for diacetyl production, more α-acetolactate than diacetyl was produced simultaneously. In order to enhance the nonenzymatic oxidative decarboxylation of α-acetolactate to diacetyl, 20 mM Fe3+ was added to the fermentation broth at the optimal time. In the end, by using the metabolically engineered strain E. cloacae SDM (ΔbudAΔbudC), diacetyl at a concentration of 1.45 g/L was obtained with a high productivity (0.13 g/(L·h)). The method developed here may be a promising process for biotechnological production of diacetyl. PMID:25761989

  1. Biological Conversion of Glycerol to Ethanol by Enterobacter aerogenes

    NASA Astrophysics Data System (ADS)

    Nwachukwu, Raymond E. S.

    In a search to turn the economically and environmentally non-valuable "waste" streams of biodiesel production into a profitable byproduct, a mutant strain of Enterobacter aerogenes ATCC 13048 was developed by six-tube subculturing technique. This technique is based on the principle of adaptive evolution, and involved subculturing the bacterium in a tryptic soy broth without dextrose (TSB) containing specific glycerol and ethanol concentration for six consecutive times. Then, the six consecutive subculturing was repeated in a fresh TSB of higher glycerol and ethanol concentrations. A new mutant strain, E. aerogenes S012, which could withstand a combination of 200 g/l glycerol and 30 g/l ethanol concentrations, was developed. The wild and mutant strains were used for the fermentation of pure (P-) and recovered (R-) glycerol. Taguchi and full factorial methods of design of experiments were used to screen and optimize the important process factors that influence the microbial production of ethanol. A statistically sound regression model was used to establish the mathematical relationship between the process variables and ethanol production. Temperature of 38°C, agitation speed of 200 rpm, pH of 6.3-6.6, and microaerobic condition were the optimum process conditions. Different pretreatment methods to recover glycerol from the crude glycerol and the subsequent fermentation method showed that direct acidification using 85% H3PO4 was the best. The R-glycerol contained 51% pure glycerol and 21% methanol. The wild strain, E. aerogenes ATCC 13048, produced only 12 g/l and 12.8 g/l ethanol from 20 g/l P- and R-glycerol respectively, and could not utilize higher glycerol concentrations. The mutant, E. aerogenes S012, produced ethanol amount and yield of 43 g/l and 1.12 mol/mol-glycerol from P-glycerol, respectively within 96 h. It also produced ethanol amount and yield of 26.8 g/l and 1.07 mol/mol-glycerol, respectively, from R-glycerol within the same duration. In a

  2. Vitreoscilla hemoglobin renders Enterobacter aerogenes highly susceptible to heavy metals.

    PubMed

    Geckil, Hikmet; Arman, Ahmet; Gencer, Salih; Ates, Burhan; Yilmaz, H Ramazan

    2004-12-01

    When expressed in heterologous microorganisms Vitreoscilla hemoglobin (VHb) acts as oxygen storage and causes a higher oxygen uptake. In this study, the effect of this protein on growth, sensitivity and antioxidant properties of Enterobacter aerogenes exposed to metal stress was investigated. The strain expressing VHb was more sensitive to mercury and cadmium as the minimal inhibitory concentration (MIC) for these metals was up to 2-fold lower in this strain than the host and the recombinant strain carrying a comparable plasmid. At lower concentrations than MIC, the metals partially limited growth and caused an inhibition proportional to metal concentration applied. The growth pattern of VHb expressing strain was also distinctly different from other two non-hemoglobin strains. The hemoglobin containing strain showed substantially higher superoxide dismuates (SOD) activity than the non-hemoglobin strains, while catalase levels were similar in all strains. All strains exposed to copper, however, showed similar MIC values, growth patterns, and SOD and catalase levels.

  3. Hydrogen production from biodiesel byproduct by immobilized Enterobacter aerogenes.

    PubMed

    Han, Jinmi; Lee, Dohoon; Cho, Jinku; Lee, Jeewon; Kim, Sangyong

    2012-01-01

    The recent rapid growth of the biodiesel industry has generated a significant amount of glycerol as a byproduct. As a result, the price of glycerol is currently relatively low, making it an attractive starting material for the production of chemicals with higher values. Crude glycerol can be directly converted through microbial fermentation into various chemicals such as hydrogen. In this study, we optimized immobilization of a facultative hydrogen producing microorganism, Enterobacter aerogenes, with the goal of developing biocatalysts that was appropriate for the continuous hydrogen production from glycerol. Several carriers were tested and agar was found to be the most effective. In addition, it was clearly shown that variables such as the carrier content and cell loading should be controlled for the immobilization of biocatalysts with high hydrogen productivity, stability, and reusability. After optimization of these variables, we were able to obtain reusable biocatalysts that could directly convert the byproduct stream from biodiesel processes into hydrogen in continuous processes.

  4. Effects of formate on fermentative hydrogen production by Enterobacter aerogenes.

    PubMed

    Kurokawa, Tatsuo; Tanisho, Shigeharu

    2005-01-01

    This paper describes the effects of formate on fermentative hydrogen production by Enterobacter aerogenes by way of batch culture. When 20 mM formate was added to pH 6.3 and pH 5.8 E. aerogenes glucose cultures (formate culture) at the beginning of cultivation, hydrogen evolution through both glucose consumption and decomposition of the extrinsic formate occurred together, while hydrogen evolution occurred only through glucose consumption in the control cultures. The hydrogen evolution rates in the formate cultures were faster than in the control cultures, although cell growth and glucose consumption rates in the formate cultures were slower than the control cultures'. The decomposition rate of the extrinsic formate in the pH 5.8 formate culture was faster than in the pH 6.3 formate culture. The hydrogen yield from glucose in the pH 6.3 formate culture increased due to the increasing amount of the nicotinamide adenine dinucleotide for hydrogen production.

  5. [Characteristics of selected virulence factors of Enterobacter cloacae strains isolated from clinical specimens].

    PubMed

    Nieradko, Józef; Kurlenda, Juliana

    2004-01-01

    We demonstrated that Enterobacter cloacae possesses a selective haemolytic activity on sheep erythrocytes. All the screened strains showed a haemolytic activity on sheep erythrocytes when cultures were preincubated with beta-mercaptoethanol. The investigation circulation of the genes encoding extended spectrum beta-lactamases (ESBL) shows that beta-lactamase producers can be ascribed to specific patterns of plasmids. We also demonstrated that genetic material from E. coli can be transferred and established in selected Enterobacter cloacae strains. In a survival tests we demonstrated that similarly to Salmonella or Vibrio clinical isolates Enterobacter cloacae doesn't demonstrate acid tolerance.

  6. Antibiotic failure mediated by a resistant subpopulation in Enterobacter cloacae.

    PubMed

    Band, Victor I; Crispell, Emily K; Napier, Brooke A; Herrera, Carmen M; Tharp, Greg K; Vavikolanu, Kranthi; Pohl, Jan; Read, Timothy D; Bosinger, Steven E; Trent, M Stephen; Burd, Eileen M; Weiss, David S

    2016-05-09

    Antibiotic resistance is a major public health threat, further complicated by unexplained treatment failures caused by bacteria that appear antibiotic susceptible. We describe an Enterobacter cloacae isolate harbouring a minor subpopulation that is highly resistant to the last-line antibiotic colistin. This subpopulation was distinct from persisters, became predominant in colistin, returned to baseline after colistin removal and was dependent on the histidine kinase PhoQ. During murine infection, but in the absence of colistin, innate immune defences led to an increased frequency of the resistant subpopulation, leading to inefficacy of subsequent colistin therapy. An isolate with a lower-frequency colistin-resistant subpopulation similarly caused treatment failure but was misclassified as susceptible by current diagnostics once cultured outside the host. These data demonstrate the ability of low-frequency bacterial subpopulations to contribute to clinically relevant antibiotic resistance, elucidating an enigmatic cause of antibiotic treatment failure and highlighting the critical need for more sensitive diagnostics.

  7. Eight-Year Surveillance of Antimicrobial Resistance among Enterobacter Cloacae Isolated in the First Bethune Hospital

    NASA Astrophysics Data System (ADS)

    Zhou, Qi; Zhang, Man; Wang, Ailin; Xu, Jiancheng; Yuan, Ye

    This study was to investigate the antimicrobial resistance of Enterobacter cloacae isolated in 8 consecutive years in the First Bethune Hospital. Disk diffusion test was used to study the antimicrobial resistance. The data were analyzed by WHONET 5 software according to Clinical and Laboratory Standards Institute (CLSI). Most of 683 strains of Enterobacter cloacae were collected from sputum 410 (60.0%), secretions and pus 105 (15.4%), urine 69 (10.1%) during the past 8 years. No Enterobacter cloacae was resistant to imipenem and meropenem in the First Bethune Hospital. The antimicrobial resistance of Enterobacter cloacae had increased in recent 8 years. The change of the antimicrobial resistance should be investigated in order to direct rational drug usage in the clinic and prevent bacterial strain of drug resistance from b eing transmitted.

  8. Bioconversion of glycerol to ethanol by a mutant Enterobacter aerogenes.

    PubMed

    Nwachukwu, Res; Shahbazi, A; Wang, L; Ibrahim, S; Worku, M; Schimmel, K

    2012-03-29

    The main objective of this research is to develop, by adaptive evolution, mutant strains of Enterobacter aerogenes ATCC 13048 that are capable of withstanding high glycerol concentration as well as resisting ethanol-inhibition. The mutant will be used for high ethanol fermentation from glycerol feedstock. Ethanol production from pure (P-) and recovered (R-) glycerol using the stock was evaluated. A six-tube-subculture-generations method was used for developing the mutant. This involved subculturing the organism six consecutive times in tubes containing the same glycerol and ethanol concentrations at the same culture conditions. Then, the glycerol and/or ethanol concentration was increased and the six subculture generations were repeated. A strain capable of growing in 200 g/L glycerol and 30 g/L ethanol was obtained. The ability of this mutant, vis-à-vis the original strain, in utilizing glycerol in a high glycerol containing medium, with the concomitant ethanol yield, was assessed. Tryptic soy broth without dextrose (TSB) was used as the fermentation medium. Fermentation products were analyzed using HPLC.In a 20 g/L glycerol TSB, E. aerogenes ATCC 13048 converted 18.5 g/L P-glycerol and 17.8 g/L R-glycerol into 12 and 12.8 g/L ethanol, respectively. In a 50 g/L P-glycerol TSB, it utilized only 15.6 g/L glycerol; but the new strain used up 39 g/L, yielding 20 g/L ethanol after 120 h, an equivalence of 1.02 mol ethanol/mol-glycerol. This is the highest ethanol yield reported from glycerol bioconversion. The result of this P-glycerol fermentation can be duplicated using the R-glycerol from biodiesel production.

  9. Genome Sequence of the Plant Growth-Promoting Bacterium Enterobacter cloacae GS1

    PubMed Central

    Shankar, Manoharan; Ponraj, Paramasivan; Ilakiam, Devaraj; Rajendhran, Jeyaprakash

    2012-01-01

    Here, we present the genome sequence of Enterobacter cloacae GS1. This strain proficiently colonizes rice roots and promotes plant growth by improving plant nutrition. Analyses of the E. cloacae GS1 genome will throw light on the genetic factors involved in root colonization, growth promotion, and ecological success of this rhizobacterium. PMID:22843603

  10. An efficient ribitol-specific dehydrogenase from Enterobacter aerogenes.

    PubMed

    Singh, Ranjitha; Singh, Raushan; Kim, In-Won; Sigdel, Sujan; Kalia, Vipin C; Kang, Yun Chan; Lee, Jung-Kul

    2015-05-01

    An NAD(+)-dependent ribitol dehydrogenase from Enterobacter aerogenes KCTC 2190 (EaRDH) was cloned and successfully expressed in Escherichia coli. The complete 729-bp gene was amplified, cloned, expressed, and subsequently purified in an active soluble form using nickel affinity chromatography. The enzyme had an optimal pH and temperature of 11.0 and 45°C, respectively. Among various polyols, EaRDH exhibited activity only toward ribitol, with Km, Vmax, and kcat/Km values of 10.3mM, 185Umg(-1), and 30.9s(-1)mM(-1), respectively. The enzyme showed strong preference for NAD(+) and displayed no detectable activity with NADP(+). Homology modeling and sequence analysis of EaRDH, along with its biochemical properties, confirmed that EaRDH belongs to the family of NAD(+)-dependent ribitol dehydrogenases, a member of short-chain dehydrogenase/reductase (SCOR) family. EaRDH showed the highest activity and unique substrate specificity among all known RDHs. Homology modeling and docking analysis shed light on the molecular basis of its unusually high activity and substrate specificity.

  11. Complete Genome Sequence of Enterobacter cloacae B2-DHA, a Chromium-Resistant Bacterium

    PubMed Central

    Rahman, Aminur; Nahar, Noor; Olsson, Björn

    2016-01-01

    Previously, we reported a chromium-resistant bacterium, Enterobacter cloacae B2-DHA, isolated from the landfills of tannery industries in Bangladesh. Here, we investigated its genetic composition using massively parallel sequencing and comparative analysis with other known Enterobacter genomes. Assembly of the sequencing reads revealed a genome of ~4.21 Mb in size. PMID:27257201

  12. Complete Genome Sequence of Enterobacter cloacae B2-DHA, a Chromium-Resistant Bacterium.

    PubMed

    Rahman, Aminur; Nahar, Noor; Olsson, Björn; Mandal, Abul

    2016-06-02

    Previously, we reported a chromium-resistant bacterium, Enterobacter cloacae B2-DHA, isolated from the landfills of tannery industries in Bangladesh. Here, we investigated its genetic composition using massively parallel sequencing and comparative analysis with other known Enterobacter genomes. Assembly of the sequencing reads revealed a genome of ~4.21 Mb in size.

  13. Degradation of pentaerythritol tetranitrate by Enterobacter cloacae PB2.

    PubMed Central

    Binks, P R; French, C E; Nicklin, S; Bruce, N C

    1996-01-01

    A mixed microbial culture capable of metabolizing the explosive pentaerythritol tetranitrate (PETN) was obtained from soil enrichments under aerobic and nitrogen-limiting conditions. A strain of Enterobacter cloacae, designated PB2, was isolated from this culture and was found to use PETN as a sole source of nitrogen for growth. Growth yields suggested that 2 to 3 mol of nitrogen was utilized per mol of PETN. The metabolites pentaerythritol dinitrate, 3-hydroxy-2,2-bis-[(nitrooxy)methyl]propanal, and 2,2-bis-[(nitrooxy)methyl]-propanedial were identified by mass spectrometry and 1H-nuclear magnetic resonance. An NADPH-dependent PETN reductase was isolated from cell extracts and shown to liberate nitrite from PETN, producing pentaerythritol tri- and dinitrates which were identified by mass spectrometry. PETN reductase was purified to apparent homogeneity by ion-exchange and affinity chromatography. The purified enzyme was found to be a monomeric flavoprotein with a M(r) of approximately 40,000, binding flavin mononucleotide noncovalently. PMID:8919782

  14. Kinetics and modeling of hexavalent chromium reduction in Enterobacter cloacae

    SciTech Connect

    Yamamoto, Koji; Kato, Junichi; Yano, Takuo; Ohtake, Hisao )

    1993-01-05

    Kinetics of bacterial reduction of toxic hexavalent chromium (chromate: CrO[sub 4][sup [minus]2]) was investigated using batch and fed-batch cultures of Enterobacter cloacae strain HO1. In fed-batch cultures, the CrO[sub 4][sup [minus]2] feed was controlled on the basis of the rate of pH change. This control strategy has proven to be useful for avoiding toxic CrO[sub 3][sup [minus]2] overload. A simple mathematical model was developed to describe the bacterial process of CrO[sub 4][sup [minus]2] reduction. In this model, two types of bacterial cells were considered: induced, CrO[sub 4][sup [minus]2]-resistant cells and uninduced, sensitive ones. Only resistant cells were assumed to be able to reduce CrO[sub 4][sup [minus]2]. These fundamental ideas were supported by the model predictions which well approximated all experimental data. In a simulation study, the model was also used to optimize fed-batch cultures, instead of lengthy and expensive laboratory experiments.

  15. Resistance to imipenem, cefepime, and cefpirome associated with mutation in Omp36 osmoporin of Enterobacter aerogenes.

    PubMed

    Thiolas, Aurélie; Bornet, Charléric; Davin-Régli, Anne; Pagès, Jean-Marie; Bollet, Claude

    2004-05-07

    Enterobacter aerogenes develops increased multidrug resistance via a functional alteration of outer-membrane permeability associated with a decrease in porin function. We have sequenced the gene coding the major porin of Enterobacter aerogenes, omp36. The sequence shows a high similarity with the Klebsiella pneumoniae ompK36 gene and is closely related to the enterobacterial OmpC family. Sequence analysis of several Omp36 issued from clinical strains indicated variability in putative cell-surface exposed domains. Interestingly, substitution Gly112Asp was observed in the conserved eyelet L3 region of the porin produced by two strains, C and 3. This substitution is associated with a high general beta-lactam resistance observed in these isolates and with alteration of pore properties previously described in strain 3 porin [Mol. Microbiol. 41 (2001) 189]. This is the first genetic identification of impermeability-mediated resistance to beta-lactams in various clinical E. aerogenes strains.

  16. Isolation and characterization of a bacteriophage phiEap-2 infecting multidrug resistant Enterobacter aerogenes.

    PubMed

    Li, Erna; Wei, Xiao; Ma, Yanyan; Yin, Zhe; Li, Huan; Lin, Weishi; Wang, Xuesong; Li, Chao; Shen, Zhiqiang; Zhao, Ruixiang; Yang, Huiying; Jiang, Aimin; Yang, Wenhui; Yuan, Jing; Zhao, Xiangna

    2016-06-20

    Enterobacter aerogenes (Enterobacteriaceae) is an important opportunistic pathogen that causes hospital-acquired pneumonia, bacteremia, and urinary tract infections. Recently, multidrug-resistant E. aerogenes have been a public health problem. To develop an effective antimicrobial agent, bacteriophage phiEap-2 was isolated from sewage and its genome was sequenced because of its ability to lyse the multidrug-resistant clinical E. aerogenes strain 3-SP. Morphological observations suggested that the phage belongs to the Siphoviridae family. Comparative genome analysis revealed that phage phiEap-2 is related to the Salmonella phage FSL SP-031 (KC139518). All of the structural gene products (except capsid protein) encoded by phiEap-2 had orthologous gene products in FSL SP-031 and Serratia phage Eta (KC460990). Here, we report the complete genome sequence of phiEap-2 and major findings from the genomic analysis. Knowledge of this phage might be helpful for developing therapeutic strategies against E. aerogenes.

  17. DNA analysis of nosocomial infection by Enterobacter aerogenes in three cases of septicaemia in Japan.

    PubMed

    Goshi, S; Taneike, I; Nakagawa, S; Kojio, S; Tamura, Y; Ohara, T; Ozaki, K; Tsukada, H; Aoki, Y; Asakura, H; Gejyo, F; Itoh, M; Yamamoto, T

    2002-07-01

    Ceftazidime-resistant Enterobacter aerogenes was isolated from blood cultures of three patients with fever. DNA analysis using pulsed-field gel electrophoresis and ribosomal RNA gene restriction digest pattern analysis revealed that the strains were clonally similar to each other with a 79.3-96.0% homology. The same strain of E. aerogenes was isolated from a three-way stopcock connected to the indwelling catheter in one of the patients at a concentration of 45 cfu/mL. A similar strain was also isolated from the urine of one other patient on the same floor. The data suggest that E. aerogenes caused septicaemia via low bacterial contamination of a three-way stopcock in a peripheral drip intravenous infusion system in at least one patient, and that the outbreak of E. aerogenes infections was due to clonally-related strains.

  18. Isolation and characterization of a bacteriophage phiEap-2 infecting multidrug resistant Enterobacter aerogenes

    PubMed Central

    Li, Erna; Wei, Xiao; Ma, Yanyan; Yin, Zhe; Li, Huan; Lin, Weishi; Wang, Xuesong; Li, Chao; Shen, Zhiqiang; Zhao, Ruixiang; Yang, Huiying; Jiang, Aimin; Yang, Wenhui; Yuan, Jing; Zhao, Xiangna

    2016-01-01

    Enterobacter aerogenes (Enterobacteriaceae) is an important opportunistic pathogen that causes hospital-acquired pneumonia, bacteremia, and urinary tract infections. Recently, multidrug-resistant E. aerogenes have been a public health problem. To develop an effective antimicrobial agent, bacteriophage phiEap-2 was isolated from sewage and its genome was sequenced because of its ability to lyse the multidrug-resistant clinical E. aerogenes strain 3-SP. Morphological observations suggested that the phage belongs to the Siphoviridae family. Comparative genome analysis revealed that phage phiEap-2 is related to the Salmonella phage FSL SP-031 (KC139518). All of the structural gene products (except capsid protein) encoded by phiEap-2 had orthologous gene products in FSL SP-031 and Serratia phage Eta (KC460990). Here, we report the complete genome sequence of phiEap-2 and major findings from the genomic analysis. Knowledge of this phage might be helpful for developing therapeutic strategies against E. aerogenes. PMID:27320081

  19. Evaluating Hawaii-Grown Papaya for Resistance to Internal Yellowing Disease Caused by Enterobacter cloacae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Papaya (Carica papaya L.) cultivars and breeding lines were evaluated for resistance to Enterobacter cloacae (Jordan) Hormaeche & Edwards, the bacterial causal agent of internal yellowing disease (IY), using a range of concentrations of the bacterium. Linear regression analysis was performed and IY ...

  20. Treatment of KPC-2 Enterobacter cloacae empyema with cefepime and levofloxacin.

    PubMed

    Cardile, Anthony P; Briggs, Heather; Burguete, S Rodrigo; Herrera, Monica; Wickes, Brian L; Jorgensen, James H

    2014-02-01

    Carbapenem-resistant Enterobacteriaceae infections are becoming more common, are associated with high mortality rates, and are difficult to treat due to multiple mechanisms of resistance. We describe the successful treatment of Klebsiella pneumoniae carbapenemase-expressing Enterobacter cloacae empyema in a lung transplant recipient with cefepime and levofloxacin.

  1. Alterations in the response of pigs to Salmonella typhimurium when provided Enterobacter cloacae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weanling pigs are at risk of succumbing to illness due to an immature immune system and insufficient supply of available energy at the time of weaning. Recent evidence has suggested that providing pigs with Enterobacter cloacae can increase the concentration of circulating triglycerides (TAGs) and t...

  2. Carbapenem resistance via the blaKPC-2 gene in Enterobacter cloacae blood culture isolate.

    PubMed

    Lo, Andy; Verrall, Rosemary; Williams, John; Stratton, Charles; Della-Latta, Phyllis; Tang, Yi-Wei

    2010-05-01

    An Enterobacter cloacae blood culture isolate expressing carbapenem resistance via the Klebsiella pneumoniae carbapenemase KPC-2 gene is reported. To our knowledge, this is the first report of a nosocomial isolate with carbapenemase-mediated resistance causing infection in a patient from Tennessee.

  3. Successive Emergence of Enterobacter aerogenes Strains Resistant to Imipenem and Colistin in a Patient

    PubMed Central

    Thiolas, Aurélie; Bollet, Claude; La Scola, Bernard; Raoult, Didier; Pagès, Jean-Marie

    2005-01-01

    Enterobacter aerogenes is an agent of hospital-acquired infection that exhibits a remarkable resistance to β-lactam antibiotics during therapy. Five successive isolates of E. aerogenes infecting a patient and exhibiting a multiresistance phenotype to β-lactam antibiotics and fluoroquinolones were investigated. Among these clinical strains, four presented resistant phenotypes during successive imipenem and colistin treatments. The involved resistance mechanisms exhibited by the successive isolates were associated with alterations of the outer membrane that caused a porin decrease and lipopolysaccharide modifications. PMID:15793111

  4. Successive emergence of Enterobacter aerogenes strains resistant to imipenem and colistin in a patient.

    PubMed

    Thiolas, Aurélie; Bollet, Claude; La Scola, Bernard; Raoult, Didier; Pagès, Jean-Marie

    2005-04-01

    Enterobacter aerogenes is an agent of hospital-acquired infection that exhibits a remarkable resistance to beta-lactam antibiotics during therapy. Five successive isolates of E. aerogenes infecting a patient and exhibiting a multiresistance phenotype to beta-lactam antibiotics and fluoroquinolones were investigated. Among these clinical strains, four presented resistant phenotypes during successive imipenem and colistin treatments. The involved resistance mechanisms exhibited by the successive isolates were associated with alterations of the outer membrane that caused a porin decrease and lipopolysaccharide modifications.

  5. Chloroquinolines block antibiotic efflux pumps in antibiotic-resistant Enterobacter aerogenes isolates.

    PubMed

    Ghisalberti, Didier; Mahamoud, Abdallah; Chevalier, Jacqueline; Baitiche, Milad; Martino, Michèle; Pagès, Jean-Marie; Barbe, Jacques

    2006-06-01

    Efflux mechanisms protect bacterial cells by pumping out toxic compounds and actively contribute to bacterial multidrug resistance. Agents inhibiting efflux pumps are of interest for the control of multidrug-resistant bacterial infections. Herein we report the effects of new chloroquinoline derivatives that render resistant Enterobacter aerogenes isolates noticeably more susceptible to structurally unrelated antibiotics. In addition, some of these chloroquinolines increase the intracellular concentration of chloramphenicol. Some of the molecules tested in this work are able to inhibit the main efflux pump (AcrAB-TolC), which is involved in E. aerogenes antibiotic resistance.

  6. Association of antibiotic resistance with SHV-12 extended-spectrum β-lactamase in Enterobacter cloacae

    PubMed Central

    LIU, JUN; LI, GUO-MING; LIN, LI-YAO; WU, XIA-LEI; HUANG, SHAO-LONG; ZHOU, YONG; ZHAO, ZU-GUO

    2016-01-01

    The association between antibiotic resistance and SHV-12 extended-spectrum β-lactamase (ESBL) in Enterobacter cloacae remains unknown. The aim of the present study was to investigate the prevalence of both chromosome- and plasmid-borne SHV-12 ESBL genes in Enterobacter cloacae. Transmission of the SHV-12 ESBL gene was explored, and the risk factors for antibiotic resistance in E. cloacae were analyzed. Polymerase chain reaction (PCR) results showed that 58 out of the 100 isolates carried the SHV-12 ESBL gene: 34.48% of them occurred in the chromosome, 48.28% were plasmid-borne and 17.24% appeared in both. Enterobacterial repetitive intergenic consensus-PCR tests detected 82 chromosomal genotypes. Conjugation assays showed that 70.00% of plasmid-borne SHV-12 ESBL genes were successfully transconjugated into E. coli C600 and that the antibiotic resistance phenotype of E. cloacae was partially (84%) or completely (10%) transferred. A significantly higher SHV-12 ESBL detection rate was found in patients with underlying conditions and/or complications compared with those without (P<0.05). The detection of SHV-12 ESBL-producing E. cloacae from vertical transmission varied significantly across clinical departments and age groups (P<0.05), with the highest rates in the intensive care unit and the group of patients aged ≥60 years. The present results indicate that the location and transmission efficiency of SHV-12 ESBL are closely correlated with the antibiotic resistance of E. cloacae. PMID:26889253

  7. Association of antibiotic resistance with SHV-12 extended-spectrum β-lactamase in Enterobacter cloacae.

    PubMed

    Liu, Jun; Li, Guo-Ming; Lin, Li-Yao; Wu, Xia-Lei; Huang, Shao-Long; Zhou, Yong; Zhao, Zu-Guo

    2016-01-01

    The association between antibiotic resistance and SHV-12 extended-spectrum β-lactamase (ESBL) in Enterobacter cloacae remains unknown. The aim of the present study was to investigate the prevalence of both chromosome- and plasmid-borne SHV-12 ESBL genes in Enterobacter cloacae. Transmission of the SHV-12 ESBL gene was explored, and the risk factors for antibiotic resistance in E. cloacae were analyzed. Polymerase chain reaction (PCR) results showed that 58 out of the 100 isolates carried the SHV-12 ESBL gene: 34.48% of them occurred in the chromosome, 48.28% were plasmid-borne and 17.24% appeared in both. Enterobacterial repetitive intergenic consensus-PCR tests detected 82 chromosomal genotypes. Conjugation assays showed that 70.00% of plasmid-borne SHV-12 ESBL genes were successfully transconjugated into E. coli C600 and that the antibiotic resistance phenotype of E. cloacae was partially (84%) or completely (10%) transferred. A significantly higher SHV-12 ESBL detection rate was found in patients with underlying conditions and/or complications compared with those without (P<0.05). The detection of SHV-12 ESBL-producing E. cloacae from vertical transmission varied significantly across clinical departments and age groups (P<0.05), with the highest rates in the intensive care unit and the group of patients aged ≥60 years. The present results indicate that the location and transmission efficiency of SHV-12 ESBL are closely correlated with the antibiotic resistance of E. cloacae.

  8. A Multiple Antibiotic-Resistant Enterobacter cloacae Strain Isolated from a Bioethanol Fermentation Facility

    PubMed Central

    Murphree, Colin A.; Li, Qing; Heist, E. Patrick; Moe, Luke A.

    2014-01-01

    An Enterobacter cloacae strain (E. cloacae F3S3) that was collected as part of a project to assess antibiotic resistance among bacteria isolated from bioethanol fermentation facilities demonstrated high levels of resistance to antibiotics added prophylactically to bioethanol fermentors. PCR assays revealed the presence of canonical genes encoding resistance to penicillin (ampC) and erythromycin (ermG). Assays measuring biofilm formation under antibiotic stress indicated that erythromycin induced biofilm formation in E. cloacae F3S3. Planktonic growth and biofilm formation were observed at a high ethanol content, indicating E. cloacae F3S3 can persist in a bioethanol fermentor under the highly variable environmental conditions found in fermentors. PMID:24941895

  9. The dissemination of multidrug-resistant Enterobacter cloacae throughout the UK and Ireland.

    PubMed

    Moradigaravand, Danesh; Reuter, Sandra; Martin, Veronique; Peacock, Sharon J; Parkhill, Julian

    2016-09-26

    Enterobacter cloacae is a clinically important Gram-negative member of the Enterobacteriaceae, which has increasingly been recognized as a major pathogen in nosocomial infections. Despite this, knowledge about the population structure and the distribution of virulence factors and antibiotic-resistance determinants of this species is scarce. In this study, we analysed a systematic collection of multidrug-resistant E. cloacae isolated between 2001 and 2011 from bloodstream infections across hospitals in the UK and Ireland. We found that the population is characterized by the presence of multiple clones formed at widely different time periods in the past. The clones exhibit a high degree of geographical heterogeneity, which indicates extensive dissemination of these E. cloacae clones across the UK and Ireland. These findings suggest that a diverse, community-based, commensal population underlies multidrug-resistant E. cloacae infections within hospitals.

  10. Abdominal aortitis due to Streptococcus pneumoniae and Enterobacter aerogenes: a case report and review.

    PubMed

    Rondina, Matthew T; Raphael, Kalani; Pendleton, Robert; Sande, Merle A

    2006-07-01

    Endovascular infections are 1 cause of fever of unknown origin. We describe a diagnostically challenging case of cryptogenic abdominal aortitis from Streptococcus pneumoniae and Enterobacter aerogenes. A 72-year-old male presented with epigastric pain, fevers, and chills. A computed tomography scan demonstrated enlargement and ulceration of the distal abdominal aorta, prompting urgent vascular surgery. Intraoperative tissue cultures grew S. pneumoniae and E. aerogenes and gatifloxacin was administered for 6 weeks. Spontaneous abdominal aortitis is uncommon and usually due to a single pathogen. This is the second reported case of polymicrobial infectious aortitis and to date, Enterobacter has only been reported in infected aortic grafts. Clinicians should maintain a high index of suspicion for infectious aortitis as the mortality, if only treated medically, approaches 100%.

  11. Induction of nucleoside phosphorylase in Enterobacter aerogenes and enzymatic synthesis of adenine arabinoside.

    PubMed

    Wei, Xiao-Kun; Ding, Qing-Bao; Zhang, Lu; Guo, Yong-Li; Ou, Lin; Wang, Chang-Lu

    2008-07-01

    Nucleoside phosphorylases (NPases) were found to be induced in Enterobacter aerogenes DGO-04, and cytidine and cytidine 5'-monophosphate (CMP) were the best inducers. Five mmol/L to fifteen mmol/L cytidine or CMP could distinctly increase the activities of purine nucleoside phosphorylase (PNPase), uridine phosphorylase (UPase) and thymidine phosphorylase (TPase) when they were added into medium from 0 to 8 h. In the process of enzymatic synthesis of adenine arabinoside from adenine and uracil arabinoside with wet cells of Enterobacter aerogenes DGO-04 induced by cytidine or CMP, the reaction time could be shortened from 36 to 6 h. After enzymatic reaction the activity of NPase in the cells induced remained higher than that in the cells uninduced.

  12. Rapid detection of a gfp-marked Enterobacter aerogenes under anaerobic conditions by aerobic fluorescence recovery.

    PubMed

    Zhang, Chong; Xing, Xin-Hui; Lou, Kai

    2005-08-15

    A gfp- and kanamycin-resistance gene-containing plasmid pUCGK was successfully constructed and transformed into Enterobacter aerogenes to develop a rapid GFP-based method for quantifying the bacterial concentration under anaerobic conditions for production of biohydrogen. Since the use of GFP as a molecular reporter is restricted by its requirement for oxygen in the development of the fluorophore, fluorescence detection for the fluorescent E. aerogenes grown anaerobically for hydrogen production was performed by developing a method of aerobic fluorescence recovery (AFR) of the anaerobically expressed GFP. By using this AFR method, rapid and non-disruptive cell quantification of E. aerogenes by fluorescence density was achieved for analyzing the hydrogen production process.

  13. The melatonin-sensitive circadian clock of the enteric bacterium Enterobacter aerogenes.

    PubMed

    Paulose, Jiffin K; Cassone, Vincent M

    2016-09-02

    Circadian clocks are fundamental properties of all eukaryotic organisms and at least some prokaryotic organisms. Recent studies in our laboratory have shown that the gastrointestinal system contains a circadian clock that controls many, if not all, aspects of gastrointestinal function. We now report that at least one species of intestinal bacteria, Enterobacter aerogenes, responds to the pineal and gastrointestinal hormone melatonin by an increase in swarming activity. This swarming behavior is expressed rhythmically, with a period of approximately 24 hrs. Transformation of E. aerogenes to express luciferase with a MotA promoter reveals circadian patterns of bioluminescence that are synchronized by melatonin and whose periods are temperature compensated from 26°C to 40°C. Bioinformatics suggest similarities between the E. aerogenes and cyanobacterial clocks, suggesting the circadian clock may have evolved very early in the evolution of life. They also point to a coordination of host circadian clocks with those residing in the microbiota themselves.

  14. Enterobacter aerogenes OmpX, a cation-selective channel mar- and osmo-regulated.

    PubMed

    Dupont, Myrielle; Dé, Emmanuelle; Chollet, Renaud; Chevalier, Jacqueline; Pagès, Jean-Marie

    2004-07-02

    The ompX gene of Enterobacter aerogenes was cloned. Its overexpression induced a decrease in the major porin Omp36 production and consequently a beta-lactam resistance was noted. Purified outer membrane protein X (OmpX) was reconstituted into artificial membranes and formed ion channels with a conductance of 20 pS in 1 M NaCl and a cationic selectivity. Both MarA expression and high osmolarity induced a noticeable increase of the OmpX synthesis in the E. aerogenes ATCC 13048 strain. In addition, OmpX synthesis increased under conditions in which the expression of the E. aerogenes major non-specific porins, Omp36 and Omp35, decreased.

  15. Enterobacter aerogenes Needle Stick Leads to Improved Biological Management System

    SciTech Connect

    Johanson, Richard E.

    2004-08-01

    A laboratory worker who received a needle stick from a contaminated needle while working with a culture containing Enterobactor aerogenes developed a laboratory acquired infection. Although this organism has been shown to cause community and nosocomial infections, there have been no documented cases of a laboratory acquired infections. Lessons learned from the event led to corrective actions which included modification of lab procedures, development of a biological inventory tracking and risk identification system and the establishment of an effective biological safety program.

  16. Characterization of a novel qepA3 variant in Enterobacter aerogenes.

    PubMed

    Wang, Dongguo; Huang, Xitian; Chen, Jiayu; Mou, Yonghua; Qi, Yongxiao

    2016-02-10

    Five isolates harboring qepA were studied by polymerase chain reaction (PCR) amplification and relevant methods. One was determined to be a novel qepA3 from Enterobacter aerogenes, and four involved three qepA1 and one qepA2 determinants from Escherichia coli; the qepA3 changed five amino acids. These results characterized genetic structures A, B, C, D, and E.

  17. Genome analysis and identification of gelatinase encoded gene in Enterobacter aerogenes

    NASA Astrophysics Data System (ADS)

    Shahimi, Safiyyah; Mutalib, Sahilah Abdul; Khalid, Rozida Abdul; Repin, Rul Aisyah Mat; Lamri, Mohd Fadly; Bakar, Mohd Faizal Abu; Isa, Mohd Noor Mat

    2016-11-01

    In this study, bioinformatic analysis towards genome sequence of E. aerogenes was done to determine gene encoded for gelatinase. Enterobacter aerogenes was isolated from hot spring water and gelatinase species-specific bacterium to porcine and fish gelatin. This bacterium offers the possibility of enzymes production which is specific to both species gelatine, respectively. Enterobacter aerogenes was partially genome sequenced resulting in 5.0 mega basepair (Mbp) total size of sequence. From pre-process pipeline, 87.6 Mbp of total reads, 68.8 Mbp of total high quality reads and 78.58 percent of high quality percentage was determined. Genome assembly produced 120 contigs with 67.5% of contigs over 1 kilo base pair (kbp), 124856 bp of N50 contig length and 55.17 % of GC base content percentage. About 4705 protein gene was identified from protein prediction analysis. Two candidate genes selected have highest similarity identity percentage against gelatinase enzyme available in Swiss-Prot and NCBI online database. They were NODE_9_length_26866_cov_148.013245_12 containing 1029 base pair (bp) sequence with 342 amino acid sequence and NODE_24_length_155103_cov_177.082458_62 which containing 717 bp sequence with 238 amino acid sequence, respectively. Thus, two paired of primers (forward and reverse) were designed, based on the open reading frame (ORF) of selected genes. Genome analysis of E. aerogenes resulting genes encoded gelatinase were identified.

  18. Infective endocarditis due to Enterobacter cloacae resistant to third- and fourth-generation cephalosporins.

    PubMed

    Yoshino, Yusuke; Okugawa, Shu; Kimura, Satoshi; Makita, Eiko; Seo, Kazunori; Koga, Ichiro; Matsunaga, Naohisa; Kitazawa, Takatoshi; Ota, Yasuo

    2015-04-01

    We report the case of using a long-term combination of meropenem and amikacin to treat infective endocarditis caused by Enterobacter cloacae resistant to third- and fourth-generation cephalosporins. Multi-drug resistant Gram-negative bacilli, such as the E. cloacae in our study, may become possible pathogens of infective endocarditis. Our experience with this case indicates that long-term use of a combination of β-lactam and aminoglycosides might represent a suitable management option for future infective endocarditis cases due to non-Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella spp. (HACEK group) Gram-negative bacilli such as ours.

  19. Effect of cefoxitin and clindamycin on selection of derepressed mutants in Enterobacter cloacae.

    PubMed

    Saverino, D; Milintenda-Floriani, F; Medeiros, A A

    2004-07-01

    The characteristics of an antibiotic that favor its ability to select for resistant bacteria are not completely understood. Otherwise, by the common use of broad-spectrum cephalosporins, resistant strains of several gram-negative species, especially Enterobacter cloacae, have been more frequently isolated. During our studies on beta-lactam resistance in E. cloacae, we observed that the addition of an inhibitor (clindamycin) to a potent inducer (cefoxitin) leads to an enhanced selection of resistant mutants. This could explain the emergence of beta-lactam resistant strains during antibiotic therapy.

  20. Production of Internal Yellowing Symptoms on Resistant and Susceptible Papaya Cultivars by Enterobacter cloacae at Varying Inoculum Concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Internal yellowing (IY) is a bacterial disease of ripening papaya flesh caused by Enterobacter cloacae and characterized by yellow softening tissue. IY restricts food safety of value-added products like fresh or frozen papaya cubes. The incidence of E. cloacae presumably differs in resistant (R) a...

  1. Extreme furfural tolerance of a soil bacterium Enterobacter cloacae GGT036.

    PubMed

    Choi, Sun Young; Gong, Gyeongtaek; Park, Hong-Sil; Um, Youngsoon; Sim, Sang Jun; Woo, Han Min

    2015-01-10

    Detoxification process of cellular inhibitors including furfural is essential for production of bio-based chemicals from lignocellulosic biomass. Here we isolated an extreme furfural-tolerant bacterium Enterobacter cloacae GGT036 from soil sample collected in Mt. Gwanak, Republic of Korea. Among isolated bacteria, only E. cloacae GGT036 showed cell growth with 35 mM furfural under aerobic culture. Compared to the maximal half inhibitory concentration (IC50) of well-known industrial strains Escherichia coli (24.9 mM furfural) and Corynebacterium glutamicum (10 mM furfural) based on the cell density, IC50 of E. cloacae GGT036 (47.7 mM) was significantly higher after 24 h, compared to E. coli and C. glutamicum. Since bacterial cell growth was exponentially inhibited depending on linearly increased furfural concentrations in the medium, we concluded that E. cloacae GGT036 is an extreme furfural-tolerant bacterium. Recently, the complete genome sequence of E. cloacae GGT036 was announced and this could provide an insight for engineering of E. cloacae GGT036 itself or other industrially relevant bacteria.

  2. Colistin heteroresistance in Enterobacter cloacae is associated with cross-resistance to the host antimicrobial lysozyme.

    PubMed

    Napier, Brooke A; Band, Victor; Burd, Eileen M; Weiss, David S

    2014-09-01

    Here, we describe the first identification of colistin-heteroresistant Enterobacter cloacae in the United States. Treatment of this isolate with colistin increased the frequency of the resistant subpopulation and induced cross-resistance to the host antimicrobial lysozyme. This is the first description of heteroresistance conferring cross-resistance to a host antimicrobial and suggests that clinical treatment with colistin may inadvertently select for bacteria that are resistant to components of the host innate immune system.

  3. Colistin Heteroresistance in Enterobacter cloacae Is Associated with Cross-Resistance to the Host Antimicrobial Lysozyme

    PubMed Central

    Napier, Brooke A.; Band, Victor

    2014-01-01

    Here, we describe the first identification of colistin-heteroresistant Enterobacter cloacae in the United States. Treatment of this isolate with colistin increased the frequency of the resistant subpopulation and induced cross-resistance to the host antimicrobial lysozyme. This is the first description of heteroresistance conferring cross-resistance to a host antimicrobial and suggests that clinical treatment with colistin may inadvertently select for bacteria that are resistant to components of the host innate immune system. PMID:24982068

  4. Enterobacter cloacae, an obligatory endophyte of pollen grains of Mediterranean pines.

    PubMed

    Madmony, A; Chernin, L; Pleban, S; Peleg, E; Riov, J

    2005-01-01

    Enterobacter cloacae was found to be associated with the pollen of several Mediterranean pines. The bacterium was detected only in mature pollen of Pinus halepensis, P. brutia, and P. pinea. E. cloacae is considered to be an obligatory endophyte based on its occurrence in disinfected male cones and the successful inoculation of seedlings of the above 3 species with E. cloacae AS1 isolated from pollen of P. halepensis used as a model strain. Strain AS1 was able to produce indolyl-3-acetic acid (IAA) from L-tryptophan in culture, and this was probably the source of the increased IAA content in the germination medium of pollen. In addition, strain AS1 promoted adventitious root formation in mung bean (Vigna radiata) cuttings. However, it was not possible to obtain bacterium-free pollen to elucidate its role in pollen germination.

  5. Risk factors and outcome of extended-spectrum β-lactamase-producing Enterobacter cloacae bloodstream infections.

    PubMed

    Qureshi, Zubair A; Paterson, David L; Pakstis, Diana L; Adams-Haduch, Jennifer M; Sandkovsky, Gabriel; Sordillo, Emilia; Polsky, Bruce; Peleg, Anton Y; Bhussar, Manveen K; Doi, Yohei

    2011-01-01

    Enterobacter cloacae is a major nosocomial pathogen that causes serious infections, including bloodstream infections (BSIs). The clinical significance of extended-spectrum β-lactamase (ESBL) production in E. cloacae is not well established. A multicentre, retrospective, cohort study was conducted to identify clinical characteristics of patients with E. cloacae BSI. ESBL production was confirmed by genotypic methods. A total of 159 patients with E. cloacae BSI were identified at three medical centres in north-eastern USA. Amongst them, 16 patients (10.1%) harboured ESBL-producing E. cloacae. Independent risk factors for ESBL production included admission from a nursing home, the presence of a gastrostomy tube and history of transplant. For the outcome analysis, 15 consecutive patients who had ESBL-producing E. cloacae BSI prior to the study were included. Amongst the 31 patients with ESBL-producing E. cloacae, 8, 9, 4 and 2 patients received a carbapenem, cefepime, piperacillin/tazobactam and ciprofloxacin, respectively, as initial therapy. All patients who received a carbapenem (n=8) were alive at 28 days, whereas 7 (38.9%) of 18 patients who received a non-carbapenem antibiotic did not survive (P=0.06). Clinical failure at 96 h was observed in 2 (25.0%) of 8 patients who received a carbapenem and in 14 (77.8%) of 18 patients who received a non-carbapenem antibiotic (P=0.03). Pulsed-field gel electrophoresis showed little clonality amongst the study isolates. The majority of isolates produced SHV-type ESBL, whereas two isolates produced CTX-M-type ESBL. Initial therapy with a carbapenem appears to be associated with improved clinical outcome in BSI due to ESBL-producing E. cloacae.

  6. Reduction of selenite to elemental selenium by Enterobacter cloacae SLD1a-1

    SciTech Connect

    Dungan, R.S.; Frankenberger, W.T. Jr.

    1998-11-01

    The facultative anaerobic bacterium Enterobacter cloacae strain SLD1a-1 was studied in washed cell suspensions to assess optimal conditions required for the reduction of selenite (SeO{sub 3}{sup 2{minus}}) to elemental selenium (Se{sup 0}). Enterobacter cloacae using glucose (1.4 mM) as an electron donor removed 79% of the added SeO{sub 3}{sup 2{minus}} from solution in 2.5 h. Optimal SeO{sub 3}{sup 2{minus}} reduction occurred at a pH of 6.5 and a temperature of 40 C. Carbohydrate sources arabinose, xylose, and sorbose were found to significantly enhance SeO{sub 3}{sup 2{minus}} reduction over that of glucose. The reduction of SeO{sub 3}{sup 2{minus}} at 7.9 {micro}M was inhibited by nitrate of levels 1 to 100 times greater, nitrite at levels 5 and 10 times greater, while sulfite at levels of two to four times greater was found to stimulate the reduction of SeO{sub 3}{sup 2{minus}}. Enterobacter cloacae grows on anaerobically incubated plates containing NO{sub 3}{sup {minus}} as the sole terminal electron acceptor and acetate as the electron donor. Use of SeO{sub 3}{sup 2{minus}} as the terminal electron acceptor during anaerobic respiration did not support growth and could only be reduced to Se{sup 0} when NO{sub 3}{sup {minus}} was present.

  7. RamA is an alternate activator of the multidrug resistance cascade in Enterobacter aerogenes.

    PubMed

    Chollet, Renaud; Chevalier, Jacqueline; Bollet, Claude; Pages, Jean-Marie; Davin-Regli, Anne

    2004-07-01

    Multidrug resistance (MDR) in Enterobacter aerogenes can be mediated by induction of MarA, which is triggered by certain antibiotics and phenolic compounds. In this study, we identified the gene encoding RamA, a 113-amino-acid regulatory protein belonging to the AraC-XylS transcriptional activator family, in the Enterobacter aerogenes ATCC 13048 type strain and in a clinical multiresistant isolate. Overexpression of RamA induced an MDR phenotype in drug-susceptible Escherichia coli JM109 and E. aerogenes ATCC 13048, as demonstrated by 2- to 16-fold-increased resistance to beta-lactams, tetracycline, chloramphenicol, and quinolones, a decrease in porin production, and increased production of AcrA, a component of the AcrAB-TolC drug efflux pump. We show that RamA enhances the transcription of the marRAB operon but is also able to induce an MDR phenotype in a mar-deleted strain. We demonstrate here that RamA is a transcriptional activator of the Mar regulon and is also a self-governing activator of the MDR cascade.

  8. Partial purification and characterization of a novel histidine decarboxylase from Enterobacter aerogenes DL-1.

    PubMed

    Zou, Yu; Hu, Wenzhong; Jiang, Aili; Tian, Mixia

    2015-08-18

    Histidine decarboxylase (HDC) from Enterobacter aerogenes DL-1 was purified in a three-step procedure involving ammonium sulfate precipitation, Sephadex G-100, and DEAE-Sepharose column chromatography. The partially purified enzyme showed a single protein band of 52.4 kD on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH for HDC activity was 6.5, and the enzyme was stable between pH 4 and 8. Enterobacter aerogenes HDC had optimal activity at 40°C and retained most of its activity between 4 and 50°C. HDC activity was reduced in the presence of numerous tested compounds. Particularly with SDS, it significantly (p < 0.01) inhibited enzyme activity. Conversely, Ca(2+) and Mn(2+) showed prominent activation effects (p < 0.01) with activity increasing to 117.20% and 123.42%, respectively. The Lineweaver-Burk plot showed that K m and V max values of the enzyme for L-histidine were 0.21 mM and 71.39 µmol/min, respectively. In comparison with most HDCs from other microorganisms and animals, HDC from E. aerogenes DL-1 displayed higher affinity and greater reaction velocity toward L-histidine.

  9. Use of flow cytometry for analysis of phage-mediated killing of Enterobacter aerogenes.

    PubMed

    Verthé, Kristof; Verstraete, Willy

    2006-09-01

    In this study, the use of flow cytometry to analyze phage-mediated killing of Enterobacter aerogenes under varying conditions of temperature and nutrient availability was assessed. Bacteriophage UZ1, specific for an E. aerogenes strain, was applied at a multiplicity of infection (MOI) of 1 and 1000 to a Teflon surface, artificially infected with its host at a level of 4.5 log cells. After incubation for 20 h, bacteriophages were quantified using the soft agar layer method. For the quantification of bacterial cells, plate counting and flow cytometric analysis of live/dead stained cells were performed in parallel. At an MOI of 1, phage treatment was successful only after incubation under nutrient-rich conditions at 37 degrees C: E. aerogenes cells were not detected and a tenfold increase in phage UZ1 was observed. At a MOI of 1000, no E. aerogenes cells could be cultured after incubation at 37 and 4 degrees C. However, flow cytometric analysis revealed that lysis did not occur at 4 degrees C but was achieved during subsequent plate culture. In conclusion, the use of flow cytometry enabled identification of culture-based bias during plate culture. The flow cytometric assay used in this study proved to be rapid, as this culture-independent method does not require lengthy incubation periods post-sampling. The bacteriophage-mediated killing of E. aerogenes cells on Teflon surfaces indicated that disinfection of E. aerogenes with bacteriophage UZ1 can be successful when high MOIs are achieved, while at low multiplicities of infection conditions favorable for phage replication are required.

  10. National epidemiologic surveys of Enterobacter aerogenes in Belgian hospitals from 1996 to 1998.

    PubMed

    De Gheldre, Y; Struelens, M J; Glupczynski, Y; De Mol, P; Maes, N; Nonhoff, C; Chetoui, H; Sion, C; Ronveaux, O; Vaneechoutte, M

    2001-03-01

    Two national surveys were conducted to describe the incidence and prevalence of Enterobacter aerogenes in 21 Belgian hospitals in 1996 and 1997 and to characterize the genotypic diversity and the antimicrobial resistance profiles of clinical strains of E. aerogenes isolated from hospitalized patients in Belgium in 1997 and 1998. Twenty-nine hospitals collected 10 isolates of E. aerogenes, which were typed by arbitrarily primed PCR (AP-PCR) using two primers and pulsed-field gel electrophoresis. MICs of 10 antimicrobial agents were determined by the agar dilution method. Beta-lactamases were detected by the double-disk diffusion test and characterized by isoelectric point. The median incidence of E. aerogenes colonization or infection increased from 3.3 per 1,000 admissions in 1996 to 4.2 per 1000 admissions in the first half of 1997 (P < 0.01). E. aerogenes strains (n = 260) clustered in 25 AP-PCR types. Two major types, BE1 and BE2, included 36 and 38% of strains and were found in 21 and 25 hospitals, respectively. The BE1 type was indistinguishable from a previously described epidemic strain in France. Half of the strains produced an extended-spectrum beta-lactamase, either TEM-24 (in 86% of the strains) or TEM-3 (in 14% of the strains). Over 75% of the isolates were resistant to ceftazidime, piperacillin-tazobactam, and ciprofloxacin. Over 90% of the strains were susceptible to cefepime, carbapenems, and aminoglycosides. In conclusion, these data suggest a nationwide dissemination of two epidemic multiresistant E. aerogenes strains in Belgian hospitals. TEM-24 beta-lactamase was frequently harbored by one of these epidemic strains, which appeared to be genotypically related to a TEM-24-producing epidemic strain from France, suggesting international dissemination.

  11. An adaptive response of Enterobacter aerogenes to imipenem: regulation of porin balance in clinical isolates.

    PubMed

    Lavigne, Jean-Philippe; Sotto, Albert; Nicolas-Chanoine, Marie-Hélène; Bouziges, Nicole; Pagès, Jean-Marie; Davin-Regli, Anne

    2013-02-01

    Imipenem (IPM) is a carbapenem antibiotic frequently used in severe hospital infections. Several reports have mentioned the emergence of resistant isolates exhibiting membrane modifications. A study was conducted between September 2005 and August 2007 to survey infections due to Enterobacter aerogenes in patients hospitalised in a French university hospital. Resistant E. aerogenes clinical isolates obtained from patients treated with IPM and collected during the 3 months following initiation of treatment were phenotypically and molecularly characterised for β-lactamases, efflux pumps activity and outer membrane proteins. Among the 339 patients infected with E. aerogenes during the study period, 41 isolates (12.1%) were resistant to extended-spectrum cephalosporins and 17 patients (5.0%) were treated with IPM. The isolates from these 17 patients presented TEM-24 and basal efflux expression. Following IPM treatment, an IPM-intermediate-susceptible (IPM-I) isolate emerged in 11 patients and an IPM-resistant (IPM-R) isolate in 6 patients. A change in the porin balance (Omp35/Omp36) was observed in IPM-I isolates exhibiting ertapenem resistance. Finally, a porin deficiency (Omp35 and Omp36 absence) was detected in IPM-R isolates associated with efflux pump expression. This study indicates that the alteration in porin expression, including the shift of porin expression and lack of porins, contribute to the E. aerogenes adaptive response to IPM treatment.

  12. Development of Enterobacter aerogenes fuel cells: from in situ biohydrogen oxidization to direct electroactive biofilm.

    PubMed

    Zhuang, Li; Zhou, Shungui; Yuan, Yong; Liu, Tinglin; Wu, Zhifeng; Cheng, Jiong

    2011-01-01

    This study described an Enterobacter aerogenes-catalyzed microbial fuel cell (MFC) with a carbon-based anode that exhibited a maximum power density of 2.51 W/m(3) in the absence of artificial electron mediators. The MFC was started up rapidly, within hours, and the current generation in the early stage was demonstrated to result from in situ oxidation of biohydrogen produced by E. aerogenes during glucose fermentation. Over periodic replacement of substrate, both planktonic biomass in the culture liquid and hydrogen productivity decreased, while increased power density and coulombic efficiency and decreased internal resistance were unexpectedly observed. Using scanning electron microscopy and cyclic voltammetry, it was found that the enhanced MFC performance was associated with the development of electroactive biofilm on the anodic surface, proposed to involve an acclimation and selection process of E. aerogenes cells under electrochemical tension. The significant advantage of rapid start-up and the ability to develop an electroactive biofilm identifies E. aerogenes as a suitable biocatalyst for MFC applications.

  13. Effect of Some nitrosative agents on the growth of vgb-bearing Enterobacter aerogenes strains.

    PubMed

    Khleifat, Khaled M; Al-Mustafa, Ahmed H

    2007-07-01

    The effect of transnitrosation intermediate between S-nitroso-N-acetylcysteine (NACysNO) and cysteine on the growth of vgb-bearing Enterobacter aerogenes was investigated using three parameters: the ratio of the specific growth rates, the inhibition zone, and alpha-amylase synthesis for the culture exposed to stressors to that of the same stressor-free cultures. The effect of NACysNO/cysteine on the growth of Enterobacter strains was distinctive as compared with the CysNO, NACysNO, and their combination. At a higher concentration (2 mM), the extents of inhibition based on the mu(NACysNO/cysteine)/mu(no stress) ratio for these cultures were 57%, 62%, and 68% for VHb-expressing, parental, and pUC9-harboring cells, respectively. The inhibition caused by 2 mM: NACysNO in the presence of 1 mM cysteine in all bacterial strains was almost twofold that achieved by NACysNO alone. Based on the diameter of the inhibition zone and alpha-amylase productivity, the four compounds (NACysNO/Cysteine, CysNO, NACysNO, and their combinations) affected the E. aerogenes strains in a concentration-dependent and negative manner. This negative effect was lower in vgb-bearing than vgb-lacking strains. Thus, sulfur-to-sulfur transnitrosation was an efficient NO release and significantly (P < 0.05) affects the growth of Enterobacter strains, to a lesser extent in vgb-bearing strains.

  14. Outbreak of TEM-24-producing Enterobacter aerogenes in a Spanish hospital.

    PubMed

    Salso, S; Culebras, E; Andrade, R; Picazo, J J

    2003-01-01

    Organisms encoding multidrug resistance genes are becoming increasingly prevalent. During a 2-month period (December, 2000, to January, 2001), 83 consecutive isolates of Enterobacter spp. were collected in our microbiology department. Antibiotic susceptibility was determined using the Vitek II automatic system. We selected strains with decreased susceptibility to extended-spectrum cephalosporins. The double-disk potentiation test was positive in 10 of these strains, indicating the presence of extended-spectrum beta-lactamases (ESBLs). Polymerase chain reaction (PCR), isoelectric focusing (IEF), and sequencing identified TEM 24 beta-lactamase in the 10 selected E. aerogenes. Random amplification of polymorphic DNA (RAPD-PCR) revealed the same clonal origin for all the strains tested and strongly suggest an outbreak of multidrug-resistant E. aerogenes. To follow up the trends in ESBLs-producing Enterobacter infections in the hospital over time, we repeated the study 1 year later (December, 2001, to February, 2002). Only three ESBLs-producing Enterobacter were found. All of them corresponded to the previously characterized clone.

  15. Molecular Characteristics of Carbapenem-Resistant Enterobacter cloacae in Ningxia Province, China

    PubMed Central

    Shi, Zhiyun; Zhao, Huizheng; Li, Gang; Jia, Wei

    2017-01-01

    The emergence of carbapenem-resistant Enterobacteriaceae (CRE) has become a major public health concern worldwide and a new challenge in the treatment of infectious diseases. The molecular characteristics of Enterobacter cloacae in Ningxia China are unknown. In this study, we reported 10 carbapenem-resistant E. cloacae isolates from the General Hospital of Ningxia Medical University, the largest university hospital in Ningxia between January 2012 and December 2013. Bacteria isolates were identified by Vitek2 compact and the identity of non-duplicate E. cloacae isolates was further confirmed by PCR and sequencing. The drug susceptibility and phenotype identification of these isolates were analyzed by agar dilution method, modified Hodge test (MHT), and EDTA synergy test. Beta-lactamase (bla) genes blaNDM−1 was found in 8 out of 10 isolates. Most isolates harbored multiple resistance genes including blaESBL, blaAmpC, quinolones, aminoglycosides, and disinfectant resistance genes. Pulsed field gel electrophoresis (PFGE) showed that these E. cloacae isolates were grouped into 6 clusters based on a cutoff of 80% genetic similarity. In conjugative assay, 9 out of 10 isolates transferred carbapenem-resistant genes to Escherichia coli. Our study has revealed that NDM-1-producing isolates are the most prevalent carbapenem-resistant E. cloacae in Ningxia. These isolates also carry several other carbapenem-resistant genes and can transfer these genes to other bacteria through conjugation. These findings highlight an urgent need to monitor these isolates to prevent their further spread in this region. PMID:28197140

  16. Particular Distribution of Enterobacter cloacae Strains Isolated from Urinary Tract Infection within Clonal Complexes

    PubMed Central

    Akbari, Majid; Bakhshi, Bita; Najar Peerayeh, Shahin

    2016-01-01

    Background: Based on biochemical properties, Enterobacter cloacae represents a large complex of at least 13 variant species, subspecies, and genotypes that progressively identified as the most species causing hospital-acquired infections. The aim of this study was to determine the relevance between phylogenetically related strains within the E. cloacae complex and the frequency of urinary tract infection caused by them. Methods: A 268-bp fragment was obtained from hsp60 gene for 50 clinical E. cloacae isolates from urine cultures of inpatients that admitted to six hospitals in Tehran, Iran during December 2012 to November 2013. The 107 nucleotide sequences were analyzed and the evolutionary distances of sequences were computed and neighbor-joining tree was calculated. Results: It showed that all of the genetic clusters have not an equal involvement in pathogenesis of urinary tract infections. Three superior clusters were found, together representing more than two third (80%) of the isolates (cluster VI with 25 members; clusters III and VIII with 9 and 6 members, respectively) and some genetic clusters were absent (IV, X, XII, and xiii), some of which are supposed to be associated with plants and no human infection has been reported. Conclusions: This study, for the first time, reports the unequal contribution of E. cloacae complex subspecies and clusters in urinary tract infections in Iran and together with studies from other countries suggest that the subspecies of E.hormaechei subsp. Oharae is the most prevalent E. cloacae complex subspecies regardless of country under study. PMID:26498349

  17. Molecular mechanisms of carbapenem resistance in Enterobacter cloacae clinical isolates from Korea and clinical outcome.

    PubMed

    Lee, Yangsoon; Choi, Heekyeong; Yum, Jong Hwa; Kang, Girung; Bae, Il Kwon; Jeong, Seok Hoon; Lee, Kyungwon

    2012-01-01

    We investigated the molecular mechanisms of carbapenem resistance in clinical isolates of Enterobacter cloacae and their clinical characteristics. Nonreplicable E. cloacae isolates were recovered from six cancer patients and one patient with liver cirrhosis at a tertiary-care hospital in Korea between 2002 and 2009. Two patients who were considered to have a true infection caused by these microorganisms have died. All isolates produced AmpC β-lactamases, including ACT-1, ACT-2, MIR-3 and DHA-1, and CTX-M- or SHV-type extended-spectrum β-lactamase. Two isolates produced plasmid-borne VIM-2 carbapenemase. All probes specific for bla(AmpC) genes hybridized with I-CeuI chromosomal fragments were also recognized by a probe specific for 16S rDNA, suggesting a chromosomal location. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that a major outer membrane protein, OmpF, was absent in all isolates. PFGE of XbaI-digested DNA were considered to be unrelated. The results of our study suggest that the chromosomal AmpC β-lactamase with impermeability in E. cloacae clinical isolates implicated in reduced carbapenem susceptibility. Although carbapenem-resistant E. cloacae isolates were isolated in a few patients in our study, the clinical outcomes were grave. Therefore, the patients colonized or infected by carbapenem-resistant E. cloacae isolates should gain attention of antibiotic therapy.

  18. Molecular Characteristics of Carbapenem-Resistant Enterobacter cloacae in Ningxia Province, China.

    PubMed

    Shi, Zhiyun; Zhao, Huizheng; Li, Gang; Jia, Wei

    2017-01-01

    The emergence of carbapenem-resistant Enterobacteriaceae (CRE) has become a major public health concern worldwide and a new challenge in the treatment of infectious diseases. The molecular characteristics of Enterobacter cloacae in Ningxia China are unknown. In this study, we reported 10 carbapenem-resistant E. cloacae isolates from the General Hospital of Ningxia Medical University, the largest university hospital in Ningxia between January 2012 and December 2013. Bacteria isolates were identified by Vitek2 compact and the identity of non-duplicate E. cloacae isolates was further confirmed by PCR and sequencing. The drug susceptibility and phenotype identification of these isolates were analyzed by agar dilution method, modified Hodge test (MHT), and EDTA synergy test. Beta-lactamase (bla) genes blaNDM-1 was found in 8 out of 10 isolates. Most isolates harbored multiple resistance genes including blaESBL, blaAmpC, quinolones, aminoglycosides, and disinfectant resistance genes. Pulsed field gel electrophoresis (PFGE) showed that these E. cloacae isolates were grouped into 6 clusters based on a cutoff of 80% genetic similarity. In conjugative assay, 9 out of 10 isolates transferred carbapenem-resistant genes to Escherichia coli. Our study has revealed that NDM-1-producing isolates are the most prevalent carbapenem-resistant E. cloacae in Ningxia. These isolates also carry several other carbapenem-resistant genes and can transfer these genes to other bacteria through conjugation. These findings highlight an urgent need to monitor these isolates to prevent their further spread in this region.

  19. Isolation and Characterization of an Enterobacter cloacae Strain That Reduces Hexavalent Chromium under Anaerobic Conditions

    PubMed Central

    Wang, Pi-Chao; Mori, Tsukasa; Komori, Kohya; Sasatsu, Masanori; Toda, Kiyoshi; Ohtake, Hisao

    1989-01-01

    An Enterobacter cloacae strain (HO1) capable of reducing hexavalent chromium (chromate) was isolated from activated sludge. This bacterium was resistant to chromate under both aerobic and anaerobic conditions. Only the anaerobic culture of the E. cloacae isolate showed chromate reduction. In the anaerobic culture, yellow turned white with chromate and the turbidity increased as the reduction proceeded, suggesting that insoluble chromium hydroxide was formed. E. cloacae is likely to utilize toxic chromate as an electron acceptor anaerobically because (i) the anaerobic growth of E. cloacae HO1 accompanied the decrease of toxic chromate in culture medium, (ii) the chromate-reducing activity was rapidly inhibited by oxygen, and (iii) the reduction occurred more rapidly in glycerol- or acetate-grown cells than in glucose-grown cells. The chromate reduction in E. cloacae HO1 was observed at pH 6.0 to 8.5 (optimum pH, 7.0) and at 10 to 40°C (optimum, 30°C). PMID:16347962

  20. Efficacy of metal ions and isothiazolones in inhibiting Enterobacter cloacae BF-17 biofilm formation.

    PubMed

    Zhou, Gang; Li, Long-Jie; Shi, Qing-Shan; Ouyang, You-Sheng; Chen, Yi-Ben; Hu, Wen-Feng

    2014-01-01

    Enterobacter cloacae is a nosocomial pathogen. The E. cloacae strain BF-17, with a high capacity for biofilm formation, was screened and identified from industrially contaminated samples, carried out in our laboratory. To develop an efficient strategy to deal with biofilms, we investigated the effects of metal ions, including Na⁺, K⁺, Ca⁺, Mg⁺, Cu⁺, and Mn⁺, and 3 isothiazolones, on elimination of E. cloacae BF-17 biofilm formation by using a 0.1% crystal violet staining method. The results revealed that higher concentrations of Na⁺ or K⁺ significantly inhibited E. cloacae BF-17 biofilm development. Meanwhile, Ca²⁺ and Mn²⁺ stimulated biofilm formation at low concentration but exhibited a negative effect at high concentration. Moreover, biofilm formation decreased with increasing concentration of Mg²⁺ and Cu²⁺. The isothiazolones Kathon (14%), 1,2-benzisothiazolin-3-one (11%), and 2-methyl-4-isothiazolin-3-one (10%) stimulated initial biofilm formation but not planktonic growth at low concentrations and displayed inhibitory effects on both biofilm formation and planktonic growth at higher concentrations. Unfortunately, the 3 isothiazolones exerted negligible effects on preformed or fully mature biofilms. Our findings suggest that Na⁺, K⁺, Mg²⁺, and isothiazolones could be used to prevent and eliminate E. cloacae BF-17 biofilms.

  1. Purification and antibiofilm activity of AHL-lactonase from endophytic Enterobacter aerogenes VT66.

    PubMed

    Rajesh, P S; Rai, V Ravishankar

    2015-11-01

    The opportunistic pathogen Pseudomonas aeruginosa uses biofilm lifestyle to resist antibiotic treatment. In our study, endophytic bacterium Enterobacter aerogenes VT66 quenched the N-acyl homoserine lactone (AHL) molecules produced by P. aeruginosa PAO1. The quorum quenching activity was attributed to the presence of AHL-lactonase. The AHL-lactonase was purified using column chromatography and purified AHL-lactonase was applied for the control of biofilm formation in P. aeruginosa PAO1. The results showed that purified AHL-lactonase obtained with a molecular weight about 30kDa was able to inhibit more than 70% of biofilm in P. aeruginosa PAO1 (P<0.001). Antibiofilm activity of AHL-lactonase was correlated well with results from staining technique used to determine inhibition of biomass and viable cell activity. Therefore, results unambiguously confirm that the AHL-lactonase from E. aerogenes VT66 could be used as antibiofilm therapeutics in P. aeruginosa associated biomedical applications.

  2. Optimization of key process variables for enhanced hydrogen production by Enterobacter aerogenes using statistical methods.

    PubMed

    Jo, Ji Hye; Lee, Dae Sung; Park, Donghee; Choe, Woo-Seok; Park, Jong Moon

    2008-04-01

    The individual and mutual effects of glucose concentration, temperature and pH on the hydrogen production by Enterobacter aerogenes were investigated in a batch system. A Box-Behnken design and response surface methodology (RSM) were employed to determine the optimum condition for enhanced hydrogen production. The hydrogen production rate was investigated by simultaneously changing the three independent variables, which all had significant influences on the hydrogen production rate. The maximum hydrogen production rate of 425.8 ml H(2)(g dry cell h)(-1) was obtained under the optimum condition of glucose concentration 118.06 mM, temperature 38 degrees C and pH 6.13. The experimental results showed that the RSM with the Box-Behnken design was a useful tool for achieving high rate of hydrogen production by E. aerogenes.

  3. Engineered Enterobacter aerogenes for efficient utilization of sugarcane molasses in 2,3-butanediol production.

    PubMed

    Jung, Moo-Young; Park, Bu-Soo; Lee, Jinwon; Oh, Min-Kyu

    2013-07-01

    Sugarcane molasses is considered to be a good carbon source for biorefinery due to its high sugar content and low price. Sucrose occupies more than half of the sugar in the molasses. Enterobacter aerogenes is a good host strain for 2,3-butanediol production, but its utilization of sucrose is not very efficient. To improve sucrose utilization in E. aerogenes, a sucrose regulator (ScrR) was disrupted from the genomic DNA. The deletion mutation increased the sucrose consumption rate significantly when sucrose or sugarcane molasses was used as a carbon source. The 2,3-butanediol production from sugarcane molasses by the mutant was enhanced by 60% in batch fermentation compared to that by the wild type strain. In fed-batch fermentation, 98.69 g/L of 2,3-butanediol production was achieved at 36 h.

  4. Enhanced dark hydrogen fermentation by addition of ferric oxide nanoparticles using Enterobacter aerogenes.

    PubMed

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Liu, Min; Zhou, Junhu; Cen, Kefa

    2016-05-01

    Ferric oxide nanoparticles (FONPs) were used to facilitate dark hydrogen fermentation using Enterobacter aerogenes. The hydrogen yield of glucose increased from 164.5±2.29 to 192.4±1.14mL/g when FONPs concentration increased from 0 to 200mg/L. SEM images of E. aerogenes demonstrated the existence of bacterial nanowire among cells, suggesting FONPs served as electron conduits to enhance electron transfer. TEM showed cellular internalization of FONPs, indicating hydrogenase synthesis and activity was potentially promoted due to the released iron element. When further increasing FONPs concentration to 400mg/L, the hydrogen yield of glucose decreased to 147.2±2.54mL/g. Soluble metabolic products revealed FONPs enhanced acetate pathway of hydrogen production, but weakened ethanol pathway. This shift of metabolic pathways allowed more nicotinamide adenine dinucleotide for reducing proton to hydrogen.

  5. Direct production of L-tagatose from L-psicose by Enterobacter aerogenes 230S.

    PubMed

    Rao, Devendar; Gullapalli, Pushpakiran; Yoshihara, Akihide; Jenkinson, Sarah F; Morimoto, Kenji; Takata, Goro; Akimitsu, Kazuya; Tajima, Shigeyuki; Fleet, George W J; Izumori, Ken

    2008-11-01

    L-tagatose was produced directly from L-psicose by subjecting the same biomass suspension to microbial reduction followed by oxidation using a newly isolated bacteria Enterobacter aerogenes 230S. After various optimizations, it was observed that cells grown on xylitol have the best conversion potential. Moreover, E. aerogenes 230S converted L-psicose to L-tagatose at a faster rate in the presence of polyols such as glycerol, D-sorbitol, ribitol, L-arabitol, D-mannitol and xylitol. At 5% substrate concentration, the conversion ratio of L-psicose to L-tagatose was above 60% in the presence of glycerol. Identity of crystalline L-tagatose was confirmed by HPLC analysis, (13)C-NMR spectra, and optical rotation.

  6. Biotransformation of ferulic acid to 4-vinylguaiacol by Enterobacter soli and E. aerogenes.

    PubMed

    Hunter, William J; Manter, Daniel K; van der Lelie, Daniel

    2012-12-01

    We investigated the conversion of ferulic acid to 4-vinylguaiacol (4-VG), vanillin, vanillyl alcohol, and vanillic acid by five Enterobacter strains. These high-value chemicals are usually synthesized by chemical methods but biological synthesis adds market value. Ferulic acid, a relatively inexpensive component of agricultural crops, is plentiful in corn hulls, cereal bran, and sugar-beet pulp. Two Enterobacter strains, E. soli, and E. aerogenes, accumulated 550-600 ppm amounts of 4-VG when grown in media containing 1,000 ppm ferulic acid; no accumulations were observed with the other strains. Decreasing the amount of ferulic acid present in the media increased the conversion efficiency. When ferulic acid was supplied in 500, 250, or 125 ppm amounts E. aerogenes converted ~72 % of the ferulic acid present to 4-VG while E. soli converted ~100 % of the ferulic acid to 4-VG when supplied with 250 or 125 ppm amounts of ferulic acid. Also, lowering the pH improved the conversion efficiency. At pH 5.0 E. aerogenes converted ~84 % and E. soli converted ~100 % of 1,000 ppm ferulic acid to 4-VG. Only small, 1-5 ppm, accumulations of vanillin, vanillyl alcohol, and vanillic acid were observed. E. soli has a putative phenolic acid decarboxylase (PAD) that is 168 amino acids long and is similar to PADs in other enterobacteriales; this protein is likely involved in the bioconversion of ferulic acid to 4-VG. E. soli or E. aerogenes might be useful as a means of biotransforming ferulic acid to 4-VG.

  7. Isolation of KPC 3-producing Enterobacter aerogenes in a patient colonized by MDR Klebsiella pneumoniae.

    PubMed

    Venditti, Carolina; Villa, Laura; Capone, Alessandro; Fortini, Daniela; D'Arezzo, Silvia; Nisii, Carla; Bordi, Eugenio; Puro, Vincenzo; Antonini, Mario; Carattoli, Alessandra; Cataldo, Maria Adriana; Petrosillo, Nicola; Di Caro, Antonino

    2016-10-01

    We describe the interspecies transmission of the plasmid-mediated blaKPC-3 gene, which confers carbapenem resistance, between clinically relevant gram-negative bacteria in a single patient. A KPC-3 producing Enterobacter aerogenes was isolated from a hospitalized patient previously colonized and then infected by a Klebsiella pneumoniae ST101 carrying the blaKPC-3 gene. The strains showed identical plasmids. Since intense horizontal exchanges among bacteria can occur in the gut, clinicians should be aware that patients colonized by carbapenem-resistant K. pneumoniae could become carriers of other carbapenem-resistant Enterobacteriaceae.

  8. The eefABC multidrug efflux pump operon is repressed by H-NS in Enterobacter aerogenes.

    PubMed

    Masi, Muriel; Pagès, Jean-Marie; Villard, Claude; Pradel, Elizabeth

    2005-06-01

    The Enterobacter aerogenes eefABC locus, which encodes a tripartite efflux pump, was cloned by complementation of an Escherichia coli tolC mutant. E. aerogenes deltaacrA expressing EefABC became less susceptible to a wide range of antibiotics. Data from eef::lacZ fusions showed that eefABC was not transcribed in the various laboratory conditions tested. However, increased transcription from Peef was observed in an E. coli hns mutant. In addition, EefA was detected in E. aerogenes expressing a dominant negative E. coli hns allele.

  9. Plant growth promoting bacteria Enterobacter asburiae JAS5 and Enterobacter cloacae JAS7 in mineralization of endosulfan.

    PubMed

    Abraham, Jayanthi; Silambarasan, Sivagnanam

    2015-04-01

    Endosulfan and their metabolites can be detected in soils with a history of endosulfan application. Microbial degradation offers an effective approach to remove toxicants, and in this study, Enterobacter asburiae JAS5 and Enterobacter cloacae JAS7 were isolated through enrichment technique. The biodegradation of endosulfan and its metabolites rate constant (k) and DT50 were determined through first-order kinetic models. E. asburiae JAS5 degraded the endosulfan, and its metabolites in liquid medium was characterized by the k which was 0.382 day(-1) (α-endosulfan), 0.284 day(-1) (β-endosulfan) and 0.228 day(-1) (endosulfan sulphate), and DT50 was 1.8 day (α-endosulfan), 2.4 days (β-endosulfan) and 3.0 days (endosulfan sulphate). The α-endosulfan, β-endosulfan and endosulfan sulphate metabolites were present in the liquid medium that was degraded by E. cloacae JAS7 which was characterized by the k of 0.391, 0.297 day(-1) and 0.273 day(-1), and DT50 was 1.7, 2.3 and 2.5 days, respectively. The infrared spectrum of endosulfan degraded sample in the aqueous medium by E. asburiae JAS5 and E. cloacae JAS7 showed a band at 1402 cm(-1) which is the characteristics of COOH group. E. asburiae JAS5 and E. cloacae JAS7 strains also showed the ability of plant growth promoting traits such as indole-3-acetic acid (IAA) production, organic acids production and solubilization of various inorganic phosphates. E. asburiae JAS5 solubilized 324 ± 2 μg ml(-1) of tricalcium phosphate, 296 ± 6 μg ml(-1) of dicalcium phosphate and 248 ± 5 μg ml(-1) of zinc phosphate, whereas E. cloacae JAS7 solubilized 338 ± 5, 306 ± 4 and 268 ± 3 μg ml(-1) of tricalcium phosphate, dicalcium phosphate and zinc phosphate, respectively. The IAA production by JAS5 and JAS7 strains were estimated to be 38.6 ± 0.3 and 46.6 ± 0.5 μg ml(-1), respectively. These bacterial strains form a potential candidate for bioremediation of pesticide-contaminated agricultural

  10. Subtractive Hybridization Yields a Silver Resistance Determinant Unique to Nosocomial Pathogens in the Enterobacter cloacae Complex

    PubMed Central

    Hoffmann, Harald

    2012-01-01

    The heterogeneity and the increasing clinical importance of the Enterobacter cloacae complex have often been discussed. However, little is known about molecular factors causing pathogenicity within this nomenspecies. Here, we analyzed the genetic differences between an avirulent plant isolate and a pathogenic strain causing an outbreak with septicemia in three patients. We identified an IncHI-2 plasmid as a major difference between these two strains. Besides resistance to several antibiotics, this plasmid encoded a silver resistance determinant. We further showed that this sil determinant was present not only in the analyzed outbreak strain but also in the vast majority of clinical isolates of the E. cloacae complex, predominantly in (sub)species that frequently cause nosocomial infections. The identified sil determinant was highly conserved within the E. cloacae complex and mediated resistance to up to 600 μM silver nitrate. As silver is often used as a disinfectant and treatment for burn wounds, we present here an important fitness factor within the clinically most prevalent subspecies of the E. cloacae complex. This provides a possible explanation for their unequal involvement in nosocomial and especially burn wound infections. PMID:22837330

  11. Drug Resistance of Pseudomonas aeruginosa and Enterobacter cloacae Isolated from ICU, Babol, Northern Iran

    PubMed Central

    Bayani, Masoomeh; Siadati, Sepideh; Rajabnia, Ramzan; Taher, Ali Asghar

    2013-01-01

    Multidrug resistant (MDR) bacteria are spread throughout the world which causes nosocomial infections, especially in Intensive Care Unit (ICU). This study aimed to investigate the resistance pattern of Pseudomonas aeruginosa and Enterobacter cloacae isolated from patients in the ICU. During 2011-2012, 30 isolates for each P. aeruginosa and E. cloacae were collected from the patients who acquired nosocomial infection after admition to the ICU at the hospitals affiliated to Babol University of Medical Sciences, Babol, northern Iran. Antimicrobial susceptibility test was performed for five category antibiotics by microdilution method. The data were analyzed by SPSS version 20 and p<0.05 was considered statistically significant. The highest resistance rate of P. aeruginosa was seen to amikacin (53.3%) followed by ceftazidime (43.3%). Also, 16.7% of E. cloacae was resistant to ceftazidime. Among P. aeruginosa isolates,18 (60%) were MDR while no E. cloacae isolates were MDR. The significant correlation was only demonstrated between MDR P. aeruginosa and the reason of hospitalization (P=0.004). In conclusion, there was alarming amount of P. aeruginosa MDR in patients in the ICU which could lead to a hazardous outcome for the patients. Therefore, new prevention policies regarding to hospital infection should be established. Also, the periodical assessment of bacterial resistance pattern particularly in ICUs should be performed. PMID:24551814

  12. Anti-biofilm effects of honey against wound pathogens Proteus mirabilis and Enterobacter cloacae.

    PubMed

    Majtan, Juraj; Bohova, Jana; Horniackova, Miroslava; Klaudiny, Jaroslav; Majtan, Viktor

    2014-01-01

    Biofilm growth and its persistence within wounds have recently been suggested as contributing factors to impaired healing. The goal of this study was to investigate the anti-biofilm effects of several honey samples of different botanical origin, including manuka honey against Proteus mirabilis and Enterobacter cloacae wound isolates. Quantification of biofilm formation was carried out using a microtiter plate assay. All honeys at a sub-inhibitory concentration of 10% (w/v) significantly reduced the biofilm development of both isolates. Similarly, at a concentration of 50% (w/v), each of the honeys caused significant partial detachment of Pr. mirabilis biofilm after 24 h. On the other hand, no honey was able to significantly detach Ent. cloacae biofilm. In addition, treatment of Ent. cloacae and Pr. mirabilis biofilms with all honeys resulted in a significant decrease in colony-forming units per well values in a range of 0.35-1.16 and 1.2-7.5 log units, respectively. Of the tested honeys, manuka honey possessed the most potent anti-biofilm properties. Furthermore, methylglyoxal, an antibacterial compound of manuka honey, was shown to be responsible for killing biofilm-embedded wound bacteria. These findings suggest that manuka honey could be used as a potential therapy for the treatment of wounds containing Pr. mirabilis or Ent. cloacae.

  13. [Isolation and identification of degradation bacteria Enterobacter aerogenes for pyrethriods pesticide residues and its degradation characteristics].

    PubMed

    Liao, Min; Zhang, Hai-jun; Xie, Xiao-mei

    2009-08-15

    By incubation experiment, the bacterial strain labeled as M6R9 was isolated from the tame sludge in water course of Pesticide Factory of Hangzhou, and was identified as Enterobacter aerogenes, which had highly efficient degradation for Bifenthrin, Fenpropathrin and Cypermethrin. By investigating the physiological characteristics of the strain, the results show that the bacterium is a gram-negative aerobe bacilli, size is (0.8-1.9) microm x (0.5-1.0) microm, and is capable of utilizing Bifenthrin, Fenpropathrin and Cypermethrin as sole carbon source. Under the condition of ventilation, (25-30) degrees C, inoculated amount at D(415 nm) 0.2, pH 7.0, pesticide concentration 100 mg x L(-1) and vibrational speed 180 r x min(-1), the degradation efficiencies to Bifenthrin, Fenpropathrin and Cypermethrin are the highest by strain M6R9. Under such condition, in the mixture culture medium with 100 mg x L(-1) Bifenthrin, Fenpropathrin and Cypermethrin, the degradation ratios are 55.74%, 55.11% and 55.96% after culturing 3 d, respectively, the degradation processes are fitted for first-order kinetic equation and the half lives (t(1/2)) are 65.4,70.7 and 68.6 h respectively. The degradation ability of Enterobacter aerogenes M6R9 on Bifenthrin, Fenpropathrin and Cypermethrin is positively correlated to inoculated amount,vibrational speed and ventilation.

  14. Sulphation can enhance the antioxidant activity of polysaccharides produced by Enterobacter cloacae Z0206.

    PubMed

    Jin, Mingliang; Wang, Youming; Huang, Ming; Lu, Zeqing; Wang, Yizhen

    2014-01-01

    The protective effects of sulfated polysaccharide derivatives produced by Enterobacter cloacae Z0206 against H₂O₂-induced oxidative damage in RAW264.7 murine macrophages as well as the possible mechanisms governing the protective effects were studied. Sulfated polysaccharides protected RAW264.7 cells from oxidative damage and apoptosis induced by H₂O₂ by protecting the cellular structure; improving the activity of antioxidant enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px); and inhibiting caspase-3 activation and DNA fragmentation. In addition, the sulfated polysaccharides conferred higher levels of protection from H₂O₂-induced oxidative damage in RAW264.7 murine macrophages compared to the native polysaccharide lacking sulfation. These results indicated that sulfated modifications might be an effective approach to enhance the antioxidant activity of polysaccharides produced by E. cloacae Z0206, and the sulfated derivatives of these polysaccharides may act as potent antioxidant agents.

  15. Structure and gene cluster of the O-antigen of Enterobacter cloacae G3421.

    PubMed

    Perepelov, Andrei V; Filatov, Andrei V; Wang, Min; Shashkov, Alexander S; Wang, Lei; Knirel, Yuriy A

    2016-06-02

    The O-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide of Enterobacter cloacae G3421 and studied by sugar analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy. In addition, partial solvolysis with anhydrous trifluoroacetic acid was applied, which cleaved selectively the α-l-rhamnopyranosidic linkages. The following structure of the branched hexasaccharide repeating unit was established. The O-polysaccharide studied shares the β-l-Rhap-(1→4)-α-l-Rhap-(1→2)-α-l-Rhap trisaccharide fragment with the O-polysaccharide of Shigella boydii type 18. The O-antigen gene cluster of E. cloacae G3421 was sequenced. Functions of genes in the cluster, including those for glycosyltransferases, were tentatively assigned by a comparison with sequences in the available databases and found to be consistent with the O-polysaccharide structure.

  16. Most Enterobacter aerogenes strains in France belong to a prevalent clone.

    PubMed

    Bosi, C; Davin-Regli, A; Bornet, C; Mallea, M; Pages, J M; Bollet, C

    1999-07-01

    The aim of this study was to determine the distribution in France of the Enterobacter aerogenes prevalent clone isolated in the hospitals of the Marseille area (A. Davin-Regli, D. Monnet, P. Saux, C. Bosi, R. Charrel, A. Barthelemy, and C. Bollet, J. Clin. Microbiol. 34:1474-1480, 1996). A total of 123 E. aerogenes isolates were collected from 23 hospital laboratories and analyzed by random amplification of polymorphic DNA and enterobacterial repetitive intergenic consensus-PCR to determine their epidemiological relatedness. Molecular typing revealed that 21 of the 23 laboratories had isolated this prevalent clone harboring the plasmid encoding for extended-spectrum beta-lactamase of the TEM-24 type. Most isolates were susceptible only to imipenem and gentamicin. Their dissemination seems to be clonal and was probably the result of the general use of broad-spectrum cephalosporins and quinolones. Four isolates showed an alteration of their outer membrane proteins, causing decrease of susceptibility to third-generation cephalosporins and imipenem and leading to the critical situation of having no alternative therapeutic. The large dissemination of the E. aerogenes prevalent clone probably results from its good adaptation to the antibiotics administered in France and the hospital environment, particularly in intensive care units.

  17. Deletion of lactate dehydrogenase in Enterobacter aerogenes to enhance 2,3-butanediol production.

    PubMed

    Jung, Moo-Young; Ng, Chiam Yu; Song, Hyohak; Lee, Jinwon; Oh, Min-Kyu

    2012-07-01

    2,3-Butanediol is an important bio-based chemical product, because it can be converted into several C4 industrial chemicals. In this study, a lactate dehydrogenase-deleted mutant was constructed to improve 2,3-butanediol productivity in Enterobacter aerogenes. To delete the gene encoding lactate dehydrogenase, λ Red recombination method was successfully adapted for E. aerogenes. The resulting strain produced a very small amount of lactate and 16.7% more 2,3-butanediol than that of the wild-type strain in batch fermentation. The mutant and its parental strain were then cultured with six different carbon sources, and the mutant showed higher carbon source consumption and microbial growth rates in all media. The 2,3-butanediol titer reached 69.5 g/l in 54 h during fed-batch fermentation with the mutant,which was 27.4% higher than that with the parental strain.With further optimization of the medium and aeration conditions,118.05 g/l 2,3-butanediol was produced in 54 h during fed-batch fermentation with the mutant. This is by far the highest titer of 2,3-butanediol with E. aerogenes achieved by metabolic pathway engineering.

  18. Regulation of glycerol metabolism in Enterobacter aerogenes NBRC12010 under electrochemical conditions.

    PubMed

    Hatayama, Kouta; Yagishita, Tatsuo

    2009-06-01

    Enterobacter aerogenes NBRC12010 was able to ferment glycerol to ethanol and hydrogen gas. Fermentation of glycerol ceased in the stationary phase of growth, and it was activated by electrochemical reactions using thionine as an electron transfer mediator from bacterial cells to an electrode. Using resting cells of E. aerogenes NBRC12010 in only citrate buffer solution, the cells did not consume glycerol at all, but they could metabolize glucose. These results suggest that the regulation of glycerol metabolism occurred at enzymatic steps before glycolysis. In E. aerogenes NBRC12010, glycerol was metabolized via glycerol dehydrogenase (GDH) and then dehydroxyacetone kinase. The GDH-catalyzed reaction mainly depended on the ratio of NAD(+)/NADH. At a NAD(+)/NADH ratio of nearly 1 or less, it was substantially suppressed and glycerol metabolism stopped. When the ratio was higher than 1, GDH was activated and glycerol was metabolized. Thus, the reaction of glycerol metabolism depended on the balance of cellular NAD(+)/NADH. Exogenous NADH was oxidized to NAD(+) by electrochemical reactions with thionine. We proposed the activation mechanism of glycerol metabolism under electrochemical conditions.

  19. Inactivation of Enterobacter aerogenes in reconstituted skim milk by high- and low-frequency ultrasound.

    PubMed

    Gao, Shengpu; Hemar, Yacine; Lewis, Gillian D; Ashokkumar, Muthupandian

    2014-11-01

    The inactivation of Enterobacter aerogenes in skim milk using low-frequency (20kHz) and high-frequency (850kHz) ultrasonication was investigated. It was found that low-frequency acoustic cavitation resulted in lethal damage to E. aerogenes. The bacteria were more sensitive to ultrasound in water than in reconstituted skim milk having different protein concentrations. However, high-frequency ultrasound was not able to inactivate E. aerogenes in milk even when powers as high as 50W for 60min were used. This study also showed that high-frequency ultrasonication had no influence on the viscosity and particle size of skim milk, whereas low-frequency ultrasonication resulted in the decrease in viscosity and particle size of milk. The decrease in particle size is believed to be due to the breakup of the fat globules, and possibly to the cleavage of the κ-casein present at the surface of the casein micelles. Whey proteins were also found to be slightly affected by low-frequency ultrasound, with the amounts of α-lactalbumin and β-lactoglobulin slightly decreasing.

  20. Characteristics of the melibiose transporter and its primary structure in Enterobacter aerogenes.

    PubMed

    Okazaki, N; Kuroda, M; Shimamoto, T; Shimamoto, T; Tsuchiya, T

    1997-05-22

    Cells of Enterobacter aerogenes can grow on melibiose as a sole source of carbon. This suggests the presence of melibiose operon in this organism. We found that E. aerogenes cells possess both alpha-galactosidase activity and melibiose transport activity, which were induced by melibiose. Neither Na+ nor Li+ stimulated the melibiose transport. However, transport of methyl-beta-thiogalactoside (TMG) was stimulated by Li+ but not by Na+. These findings suggest that the major coupling cation for the melibiose transporter in E. aerogenes is H+. In fact, we observed H+ entry into cells caused by an influx of melibiose and some of its analogs. We cloned the melB gene which encodes the melibiose transporter, and sequenced it. Deduced amino acid sequence of the transporter revealed that the melibiose transporter consists of 471 amino acid residues and the molecular weight was calculated to be 52214 Da. The sequence showed high homology with the sequences of the melibiose transporters of Escherichia coli, Salmonella typhimurium and Klebsiella pneumoniae. Higher homology was found with the melibiose transporter of K. pneumoniae than with that of E. coli and S. typhimurium.

  1. Cloning, Nucleotide Sequencing, and Analysis of the AcrAB-TolC Efflux Pump of Enterobacter cloacae and Determination of Its Involvement in Antibiotic Resistance in a Clinical Isolate▿

    PubMed Central

    Pérez, Astrid; Canle, Delia; Latasa, Cristina; Poza, Margarita; Beceiro, Alejandro; del Mar Tomás, María; Fernández, Ana; Mallo, Susana; Pérez, Sonia; Molina, Francisca; Villanueva, Rosa; Lasa, Iñigo; Bou, Germán

    2007-01-01

    Enterobacter cloacae is an emerging clinical pathogen that may be responsible for nosocomial infections. Management of these infections is often difficult, owing to the high frequency of strains that are resistant to disinfectants and antimicrobial agents in the clinical setting. Multidrug efflux pumps, especially those belonging to the resistance-nodulation-division family, play a major role as a mechanism of antimicrobial resistance in gram-negative pathogens. In the present study, we cloned and sequenced the genes encoding an AcrAcB-TolC-like efflux pump from an E. cloacae clinical isolate (isolate EcDC64) showing a broad antibiotic resistance profile. Sequence analysis showed that the acrR, acrA, acrB, and tolC genes encode proteins that display 79.8%, 84%, 88%, and 82% amino acid identities with the respective homologues of Enterobacter aerogenes and are arranged in a similar pattern. Deletion of the acrA gene to yield an AcrA-deficient EcDC64 mutant (EcΔacrA) showed the involvement of AcrAB-TolC in multidrug resistance in E. cloacae. However, experiments with an efflux pump inhibitor suggested that additional efflux systems also play a role in antibiotic resistance. Investigation of several unrelated isolates of E. cloacae by PCR analysis revealed that the AcrAB system is apparently ubiquitous in this species. PMID:17638702

  2. Aerobic and heterotrophic nitrogen removal by Enterobacter cloacae CF-S27 with efficient utilization of hydroxylamine.

    PubMed

    Padhi, Soumesh Kumar; Tripathy, Swetaleena; Mohanty, Sriprakash; Maiti, Nikhil Kumar

    2017-05-01

    Heterotrophic bacterium, Enterobacter cloacae CF-S27 exhibited simultaneous nitrification and aerobic denitrification in presence of high concentration of hydroxylamine. With the initial nitrogen concentration of 100mgL(-1)h(-1), ammonium, nitrate and nitrite removal efficiencies were 81%, 99.9% and 92.8%, while the corresponding maximum removal rates reached as high as 11.6, 15.1 and 11.2mgL(-1)h(-1) respectively. Quantitative amplification by real time PCR and enzyme assay demonstrated that hydroxylamine reductase gene (hao) is actively involved in hetrotrophic nitrification and aerobic denitrification process of Enterobacter cloacae CF-S27. PCR primers were designed targeting amplification of hao gene from diversified environmental soil DNA. The strain Enterobacter cloacae CF-S27 significantly maintained the undetectable amount of dissolved nitrogen throughout 60days of zero water exchange fish culture experiment in domestic wastewater.

  3. Carbapenem- and Colistin-Resistant Enterobacter cloacae from Delta, Colorado, in 2015

    PubMed Central

    Norgan, Andrew P.; Freese, Jarred M.; Tuin, Patricia M.; Cunningham, Scott A.

    2016-01-01

    Resistance to carbapenems in Enterobacteriaceae is a clinical problem of growing significance. Difficulty in treating multidrug-resistant Gram-negative organisms with conventional antibiotics has led to a renewed and increasing use of polymyxin compounds, such as colistin. Here, we report the isolation of carbapenem- and colistin-resistant Enterobacter cloacae from a polymicrobial lower extremity wound in an ambulatory patient. Whole-genome sequencing demonstrated the presence of chromosomal blaIMI-1 and blaAmpC, as well as numerous efflux pump genes. PMID:26883705

  4. Carbapenem- and Colistin-Resistant Enterobacter cloacae from Delta, Colorado, in 2015.

    PubMed

    Norgan, Andrew P; Freese, Jarred M; Tuin, Patricia M; Cunningham, Scott A; Jeraldo, Patricio R; Patel, Robin

    2016-05-01

    Resistance to carbapenems in Enterobacteriaceae is a clinical problem of growing significance. Difficulty in treating multidrug-resistant Gram-negative organisms with conventional antibiotics has led to a renewed and increasing use of polymyxin compounds, such as colistin. Here, we report the isolation of carbapenem- and colistin-resistant Enterobacter cloacae from a polymicrobial lower extremity wound in an ambulatory patient. Whole-genome sequencing demonstrated the presence of chromosomal blaIMI-1 and blaAmpC, as well as numerous efflux pump genes.

  5. Genomic Characterization of Enterobacter cloacae Isolates from China That Coproduce KPC-3 and NDM-1 Carbapenemases

    PubMed Central

    Chen, Liang; Chavda, Kalyan D.; Pandey, Ruchi; Zhang, Haifang; Xie, Xiaofang

    2016-01-01

    Here, we report two Enterobacter cloacae sequence type 231 isolates coproducing KPC-3 and NDM-1 that have caused lethal infections in a tertiary hospital in China. The blaNDM-1-harboring plasmids carry IncA/C2 and IncR replicons, showing a mosaic plasmid structure, and the blaNDM-1 is harbored on a novel class I integron-like element. blaKPC-3 is located on a Tn3-ΔblaTEM-1-blaKPC-3-ΔTn1722 element, flanked by two 9-bp direct-repeat sequences and harbored on an IncX6 plasmid. PMID:26787700

  6. KPC and VIM producing Enterobacter cloacae strain from a hospital in northeastern Venezuela.

    PubMed

    Martínez, Dianny; Marcano, Daniel; Rodulfo, Hectorina; Salgado, Nurys; Cuaical, Nirvia; Rodriguez, Lucy; Caña, Luisa; Medina, Belkis; Guzman, Militza; De Donato, Marcos

    2015-06-01

    An 83-year-old male patient is admitted to the central hospital in Cumana, Venezuela with severe urinary infection, history of hospitalizaions and prolonged antimicrobial treatments. A strain of Enterobacter cloacae was isolated showing resistance to multiple types of antibiotics (only sensitive to gentamicin), with phenotype of serine- and metallo-carbapenemases. Both, bla(VIM-2) and bla(KPC) genes were detected in the isolate. This is the first report of an Enterobacteriaceae species producing both KPC carbapenemase and VIM metallo carbapenemase in Venezuela. This finding has a great clinical and epidemiological impact in the region, because of the feasibility of transferring these genes, through mobile elements to other strains of Enterobacter and to other infection-causing species of bacteria.

  7. Biodegradation of 2-methylquinoline by Enterobacter aerogenes TJ-D isolated from activated sludge.

    PubMed

    Wang, Lin; Li, Yongmei; Duan, Jingyuan

    2013-07-01

    Bacterial strain Enterobacter aerogenes TJ-D capable of utilizing 2-methylquinoline as the sole carbon and energy source was isolated from acclimated activated sludge under denitrifying conditions. The ability to degrade 2-methylquinoline by E. aerogenes TJ-D was investigated under denitrifying conditions. Under optimal conditions of temperature (35 degrees C) and initial pH 7, 2-methylquinoline of 100 mg/L was degraded within 176 hr. The degradation of 2-methylquinoline by E. aerogenes TJ-D could be well described by the Haldane model (R2 > 0.91). During the degradation period of 2-methylquinoline (initial concentration 100 mg/L), nitrate was almost completely consumed (the removal efficiency was 98.5%), while nitrite remained at low concentration (< 0.62 mg/L) during the whole denitrification period. 1,2,3,4-Tetrahydro-2-methylquinoline, 4-ethyl-benzenamine, N-butyl-benzenamine, N-ethyl-benzenamine and 2,6-diethyl-benzenamine were metabolites produced during the degradation. The degradation pathway of 2-methylquinoline by E. aerogenes TJ-D was proposed. 2-Methylquinoline is initially hydroxylated at C-4 to form 2-methyl-4-hydroxy-quinoline, and then forms 2-methyl-4-quinolinol as a result of tautomerism. Hydrogenation of the heterocyclic ring at positions 2 and 3 produces 2,3-dihydro-2-methyl-4-quinolinol. The carbon-carbon bond at position 2 and 3 in the heterocyclic ring may cleave and form 2-ethyl-N-ethyl-benzenamine. Tautomerism may result in the formation of 2,6-diethyl-benzenamine and N-butyl-benzenamine. 4-Ethyl-benzenamine and N-ethyl-benzenamine were produced as a result of losing one ethyl group from the above molecules.

  8. Stability and activity of an Enterobacter aerogenes-specific bacteriophage under simulated gastro-intestinal conditions.

    PubMed

    Verthé, K; Possemiers, S; Boon, N; Vaneechoutte, M; Verstraete, W

    2004-09-01

    A bacteriophage, designated UZ1 and showing lytic activity against a clinically important strain (BE1) of Enterobacter aerogenes was isolated from hospital sewage. The stability and lytic activity against this strain under simulated gastro-intestinal conditions was evaluated. After addition of bacteriophage UZ1 to a liquid feed at gastric pH 2, the phage was immediately inactivated and could not be recovered. However, by use of an antacid to neutralize stomach acidity, no significant changes in phage titer were observed after 2 h incubation at 37 degrees C. After supplementing pancreatic juice and further incubation for 4 h, the phage titer remained stable. The persistence of UZ1 in a mixed microbial ecosystem that was representative for the large intestine was monitored using an in vitro simulation of the human intestinal microbial ecosystem. A pulse administration of bacteriophage UZ1 at a concentration of 10(5) plaque-forming units (PFU)/ml to reactor 3 (which simulates the ascending colon) showed that, in the absence of the host, bacteriophage UZ1 persisted for 13 days in the simulated colon, while the theoretical washout was calculated at 16 days. To assess its lytic activity in an intestinal microbial ecosystem, a green fluorescent protein (gfp)-labeled E. aerogenes BE1 strain was constructed and gfp-specific primers were designed in order to quantify the host strain using real-time PCR. It was observed that bacteriophage UZ1 was able to replicate and showed lytic activity against E. aerogenes BE1/ gfp in an intestinal microbial ecosystem. Indeed, after 17 h a 2 log unit reduction of E. aerogenes BE1/ gfp was measured as compared with the assay without bacteriophage UZ1, while the phage titer increased by 2 log units at an initial multiplicity of infection of 0.07 PFU/colony-forming unit. This is the first report of an in vitro model to study bacteriophage activity in the complex intestinal microbial community.

  9. Plant growth promoting potential and phylogenetic characteristics of a lichenized nitrogen fixing bacterium, Enterobacter cloacae.

    PubMed

    Swamy, Chidanandamurthy Thippeswamy; Gayathri, Devaraja; Devaraja, Thimmalapura Neelakantaiah; Bandekar, Mandar; D'Souza, Stecy Elvira; Meena, Ram Murti; Ramaiah, Nagappa

    2016-12-01

    Lichens are complex symbiotic association of mycobionts, photobionts, and bacteriobionts, including chemolithotropic bacteria. In the present study, 46 lichenized bacteria were isolated by conventional and enrichment culture methods on nitrogen-free bromothymol blue (NFb) medium. Only 11 of the 46 isolates fixed nitrogen on NFb and had reduced acetylene. All these 11 isolates had also produced siderophore and 10 of them the IAA. Further, ammonia production was recorded from nine of these nitrogen fixers (NF). On molecular characterization, 16 S rRNA sequencing recorded that, nine NF belonged to Proteobacteria, within Gammaproteobacteria, and were closely related to Enterobacter sp. with a maximum similarity to Enterobacter cloacae. Each one of our NF isolates was aligned closely to Enterobacter pulveris strain E443, Cronobacter sakazakii strain PNP8 and Providencia rettgeri strain ALK058. Notably, a few strains we examined found to possess plant growth promoting properties. This is the first report of Enterobacter sp. from lichens which may be inhabit lichen thalli extrinsically or intrinsically.

  10. SugE, a new member of the SMR family of transporters, contributes to antimicrobial resistance in Enterobacter cloacae.

    PubMed

    He, Gui-Xin; Zhang, Chu; Crow, Robert R; Thorpe, Conner; Chen, Huizhong; Kumar, Sanath; Tsuchiya, Tomofusa; Varela, Manuel F

    2011-08-01

    We cloned a gene, sugE, from the chromosome of Enterobacter cloacae ATCC 13047. Analysis of the susceptibilities of the sugE-containing strain (Escherichia coli KAM32/pSUGE28) and sugE-deficient E. cloacae (EcΔsugE) showed that SugE confers resistance to cetyltrimethylammonium bromide, cetylpyridinium chloride, tetraphenylphosphonium, benzalkonium chloride, ethidium bromide, and sodium dodecyl sulfate. We also investigated expression of sugE. We confirm here that SugE from E. cloacae is an SMR family transporter as determined by observing its energy-dependent drug efflux activity.

  11. Enterobacter cloacae Sacroiliitis with Acute Respiratory Distress Syndrome in an Adolescent.

    PubMed

    Kim, Jin Soo; Ko, Jeong Hee; Lee, Seunghun; Jeon, Seok Chol; Oh, Sung Hee

    2015-06-01

    Enterobacter cloacae has emerged as an important nosocomial pathogen, but is rarely a cause of sacroiliitis. Herein, we present the first reported case of Enterobacter cloacae sacroiliitis associated with sepsis and acute respiratory distress syndrome (ARDS). A previously healthy 14-year-old boy presented with low-grade fever and pain in the left side of the hip that was aggravated by walking. Pelvic computed tomography (CT) showed normal findings, and the patient received supportive care for transient synovitis with no antibiotics. However, there was no clinical improvement. On the third day of hospitalization, magnetic resonance imaging of the hip revealed findings compatible with sacroiliitis, for which vancomycin and ceftriaxone were administered. The patient suddenly developed high fever with dyspnea. Chest radiography and CT findings and a PaO2/FiO2 ratio <200 mmHg were suggestive of ARDS; the patient subsequently received ventilatory support and low-dose methylprednisolone infusions. Within one week, defervescence occurred, and the patient was able to breathe on his own. Following the timely recognition of, and therapeutic challenge to, ARDS, and after 6 weeks of parenteral antimicrobial therapy, the patient was discharged in good health with no complications.

  12. Identification of sdiA-regulated genes in a mouse commensal strain of Enterobacter cloacae

    PubMed Central

    Sabag-Daigle, Anice; Dyszel, Jessica L.; Gonzalez, Juan F.; Ali, Mohamed M.; Ahmer, Brian M. M.

    2015-01-01

    Many bacteria determine their population density using quorum sensing. The most intensively studied mechanism of quorum sensing utilizes proteins of the LuxI family to synthesize a signaling molecule of the acylhomoserine lactone (AHL) type, and a protein of the LuxR family to bind AHL and regulate transcription. Genes regulated by quorum sensing often encode functions that are most effective when a group of bacteria are working cooperatively (e.g., luminescence, biofilm formation, host interactions). Bacteria in the Escherichia, Salmonella, Klebsiella, and Enterobacter genera do not encode an AHL synthase but they do encode an AHL receptor of the LuxR family, SdiA. Instead of detecting their own AHL synthesis, these organisms use SdiA to detect the AHLs synthesized by other bacterial species. In this study, we used a genetic screen to identify AHL-responsive genes in a commensal Enterobacter cloacae strain that was isolated from a laboratory mouse. The genes include a putative type VI secretion system, copA (a copper transporter), and fepE (extends O-antigen chain length). A new transposon mutagenesis strategy and suicide vectors were used to construct an sdiA mutant of E. cloacae. The AHL-responsiveness of all fusions was entirely sdiA-dependent, although some genes were regulated by sdiA in the absence of AHL. PMID:26075189

  13. Identification of sdiA-regulated genes in a mouse commensal strain of Enterobacter cloacae.

    PubMed

    Sabag-Daigle, Anice; Dyszel, Jessica L; Gonzalez, Juan F; Ali, Mohamed M; Ahmer, Brian M M

    2015-01-01

    Many bacteria determine their population density using quorum sensing. The most intensively studied mechanism of quorum sensing utilizes proteins of the LuxI family to synthesize a signaling molecule of the acylhomoserine lactone (AHL) type, and a protein of the LuxR family to bind AHL and regulate transcription. Genes regulated by quorum sensing often encode functions that are most effective when a group of bacteria are working cooperatively (e.g., luminescence, biofilm formation, host interactions). Bacteria in the Escherichia, Salmonella, Klebsiella, and Enterobacter genera do not encode an AHL synthase but they do encode an AHL receptor of the LuxR family, SdiA. Instead of detecting their own AHL synthesis, these organisms use SdiA to detect the AHLs synthesized by other bacterial species. In this study, we used a genetic screen to identify AHL-responsive genes in a commensal Enterobacter cloacae strain that was isolated from a laboratory mouse. The genes include a putative type VI secretion system, copA (a copper transporter), and fepE (extends O-antigen chain length). A new transposon mutagenesis strategy and suicide vectors were used to construct an sdiA mutant of E. cloacae. The AHL-responsiveness of all fusions was entirely sdiA-dependent, although some genes were regulated by sdiA in the absence of AHL.

  14. Enterobacter cloacae Sacroiliitis with Acute Respiratory Distress Syndrome in an Adolescent

    PubMed Central

    Kim, Jin Soo; Ko, Jeong Hee; Lee, Seunghun; Jeon, Seok Chol

    2015-01-01

    Enterobacter cloacae has emerged as an important nosocomial pathogen, but is rarely a cause of sacroiliitis. Herein, we present the first reported case of Enterobacter cloacae sacroiliitis associated with sepsis and acute respiratory distress syndrome (ARDS). A previously healthy 14-year-old boy presented with low-grade fever and pain in the left side of the hip that was aggravated by walking. Pelvic computed tomography (CT) showed normal findings, and the patient received supportive care for transient synovitis with no antibiotics. However, there was no clinical improvement. On the third day of hospitalization, magnetic resonance imaging of the hip revealed findings compatible with sacroiliitis, for which vancomycin and ceftriaxone were administered. The patient suddenly developed high fever with dyspnea. Chest radiography and CT findings and a PaO2/FiO2 ratio <200 mmHg were suggestive of ARDS; the patient subsequently received ventilatory support and low-dose methylprednisolone infusions. Within one week, defervescence occurred, and the patient was able to breathe on his own. Following the timely recognition of, and therapeutic challenge to, ARDS, and after 6 weeks of parenteral antimicrobial therapy, the patient was discharged in good health with no complications. PMID:26157593

  15. Multidrug efflux systems in Escherichia coli and Enterobacter cloacae obtained from wholesome broiler carcasses

    PubMed Central

    Moreira, Maria Aparecida S.; Rodrigues, Patrícia P.C.F.; Tomaz, Rafael S.; de Moraes, Célia A.

    2009-01-01

    Members of the Enterobacteriaceae family are present in the intestines of man and animals as commensals or are important disease causing agents. Bacteria bearing multidrug efflux systems (MDR) are able to survive adverse ecological niches. Multiresistant Escherichia coli and Enterobacter cloacae isolates from wholesome broiler carcasses were investigated for the presence of MDR. Lowering of Minimal Inhibitory Concentration for antimicrobials in the presence of a proton-motive force (PMF) uncoupler was tested as a potential display of the MDR phenotype. PCR amplification of the genes encoding AcrA and AcrB, components of a MDR system was performed. Diversity of each species was ascertained by Pulsed-Field Gel Electrophoresis (PFGE) of DNA digested with endonuclease XbaI. For all the isolates, except E. coli 1 and E. cloacae 9, lowering of MIC or of the growth rate in the presence of antimicrobials was observed, indicating a PMF dependent resistance mechanism. Expected products of DNA amplification with acrAB derived primers was obtained with all E. coli strains and with two of the five E. cloacae strains. Dendrogram generated shows diverse pulsetypes, confirming the genetic diversity among the strains. An important issue and related public health is the fact that different models and mechanisms of antimicrobial resistance are present in a small number of non-pathogenic strains and isolated from the same origin. These may be sources of resistance genes to others microorganisms, among them, pathogenic strains. PMID:24031352

  16. A Snapshot of Co-Resistance to Carbapenems and Tigecycline in Clinical Isolates of Enterobacter cloacae.

    PubMed

    Huang, Ling-Fu; Lee, Chao-Tai; Su, Lin-Hui; Chang, Chin-Lu

    2017-01-01

    Enterobacter cloacae is one of the most common carbapenem-resistant Enterobacteriaceae (CRE) global wide. Resistance to tigecycline, one of the few therapeutic options for CRE infections, in carbapenem-resistant E. cloacae is of clinical significance. Fourteen E. cloacae clinical isolates (EC1-EC14) co-resistant to tigecycline and carbapenems were studied. Two tigecycline-susceptible/carbapenem-resistant isolates (TS1-TS2) were used for comparison. Genotyping by pulsed-field gel electrophoresis and multilocus sequence typing identified seven pulsotypes and three sequence types (STs). All three STs belonged to the published international clones. Polymerase chain reaction (PCR) and sequence analysis revealed the coexistence of blaSHV-12 and blaIMP-8 in 11 EC isolates from five pulsotypes/two STs. Reverse transcription PCR demonstrated overexpression of the chromosomal AmpC-like β-lactamase in seven EC isolates (four pulsotypes/two STs) and TS1 (pulsotype F/ST78). Reduced expression of outer membrane protein C (OmpC) was found in three EC isolates (all pulsotype C/ST204), whereas reduced expression of OmpF was found in nine EC isolates (three pulsotypes/two STs) and TS2 (pulsotype G/ST114). Overexpression of the efflux pump AcrB was found in all EC isolates although three showed borderline significance. Multiple mechanisms jointly contributed to the observed co-resistance to tigecycline and carbapenems. Some international clones have infiltrated into Taiwan and acquired various resistance traits independently.

  17. Optimization of Enterobacter cloacae (KU923381) for diesel oil degradation using response surface methodology (RSM).

    PubMed

    Ramasamy, Sugumar; Arumugam, Arumugam; Chandran, Preethy

    2017-02-01

    Efficiency of Enterobacter cloacae KU923381 isolated from petroleum hydrocarbon contaminated soil was evaluated in batch culture and bioreactor mode. The isolate were screened for biofilm formation using qualitative and quantitative assays. Response surface methodology (RSM) was used to study the effect of pH, temperature, glucose concentration, and sodium chloride on diesel degradation. The predicted values for diesel oil degradation efficiency by the statistical designs are in a close agreement with experimental data (R (2) = 99.66%). Degradation efficiency is increased by 36.78% at pH = 7, temperature = 35°C, glucose = 5%, and sodium chloride concentration = 5%. Under the optimized conditions, the experiments were performed for diesel oil degradation by gas chromatographic mass spectrometric analysis (GC-MS). GC-MS analysis confirmed that E. cloacae had highly degrade hexadecane, heptadecane, tridecane, and docosane by 99.71%, 99.23%, 99.66%, and 98.34% respectively. This study shows that rapid bioremoval of hydrocarbons in diesel oil is acheived by E. cloacae with abet of biofilm formation. The potential use of the biofilms for preparing trickling filters (gravel particles) for the degradation of hydrocarbons from petroleum wastes before their disposal in the open environment is highly suggested. This is the first successful attempt for artificially establishing petroleum hydrocarbon degrading bacterial biofilm on solid substrates in bioreactor.

  18. Characterization of IS26-composite transposons and multidrug resistance in conjugative plasmids from Enterobacter cloacae.

    PubMed

    Chen, Chih-Ming; Yu, Wen-Liang; Huang, Mei; Liu, Jau-Jin; Chen, I-Chien; Chen, Huei-Fen; Wu, Lii-Tzu

    2015-09-01

    SHV-12 is the most widespread resistance determinant of Enterobacter cloacae in Taiwan; however, blaSHV-12 has rarely been mobilized. Six multidrug-resistant E. cloacae isolates were collected. After conjugal transfer, plasmid profiling and analysis of incompatibility groups was performed to characterize the genetic context of blaSHV-12 -containing fragments. The presence of mobile genetic elements was demonstrated by PCR, cloning, sequencing and bioinformatics analyses. Four different β-lactamase genes (blaTEM-1 , blaSHV-12 , blaCTX-M-3 and/or blaCTX-M-14 ) were observed in the conjugative plasmids belonging to the IncHI2 (n = 4), IncI1 or IncP incompatibility groups. The IS26-blaSHV-12 -IS26 locus was located in five different genetic environments. A novel structural organization of a class 1 integron with the aac(6')-IIc cassette truncated by IS26 was identified in one isolate. Thus, blaSHV-12 was obtained from different plasmids through IS26-mediated homologous recombination. IS26 plays a vital role in the distribution of mobile resistance elements between different plasmids found in multidrug-resistant E. cloacae isolates.

  19. Surface-mediated chromate-resistant mechanism of Enterobacter cloacae bacteria investigated by atomic force microscopy.

    PubMed

    Yang, Chunpeng; Cheng, Yangjian; Ma, Xiaoyan; Zhu, Ying; Holman, Hoi-Ying; Lin, Zhang; Wang, Chen

    2007-04-10

    The Enterobacter cloacae CYS-25 strain isolated from a chromate plant shows a strong capability for chromate resistance instead of chromate reduction in aerobic conditions. In this study, atomic force microscopy (AFM) was used for studying the morphology characteristics of bacterial properties during the chromate resistance process. The average length of E. cloacae bacteria in the stationary phase is about 2.3 +/- 0.6 microm, while under the stimulation of 400 mg/L CrO42-, the length of bacteria increases to 3.2 +/- 0.7 microm. Height and phase images showed that, with the addition of CrO42-, the smooth surface of bacteria changed into one with discontinuous features with characteristic dimension of 40-200 nm. Analysis reveals that these compact convex patches are organic components stimulated by CrO42-. A chromate resistance mechanism relating to the overexpression of extracellular biologic components for preventing the permeability of CrO42- into the cell is proposed as the survival strategy of E. cloacae in chromate situation.

  20. Simultaneous cellulose degradation and electricity production by Enterobacter cloacae in a microbial fuel cell.

    PubMed

    Rezaei, Farzaneh; Xing, Defeng; Wagner, Rachel; Regan, John M; Richard, Tom L; Logan, Bruce E

    2009-06-01

    Electricity can be directly generated by bacteria in microbial fuel cells (MFCs) from many different biodegradable substrates. When cellulose is used as the substrate, electricity generation requires a microbial community with both cellulolytic and exoelectrogenic activities. Cellulose degradation with electricity production by a pure culture has not been previously demonstrated without addition of an exogenous mediator. Using a specially designed U-tube MFC, we enriched a consortium of exoelectrogenic bacteria capable of using cellulose as the sole electron donor. After 19 dilution-to-extinction serial transfers of the consortium, 16S rRNA gene-based community analysis using denaturing gradient gel electrophoresis and band sequencing revealed that the dominant bacterium was Enterobacter cloacae. An isolate designated E. cloacae FR from the enrichment was found to be 100% identical to E. cloacae ATCC 13047(T) based on a partial 16S rRNA sequence. In polarization tests using the U-tube MFC and cellulose as a substrate, strain FR produced 4.9 +/- 0.01 mW/m(2), compared to 5.4 +/- 0.3 mW/m(2) for strain ATCC 13047(T). These results demonstrate for the first time that it is possible to generate electricity from cellulose using a single bacterial strain without exogenous mediators.

  1. The effects of cyanide on the growth and respiration of Enterobacter aerogenes in continuous culture.

    PubMed

    Porter, N; Drozd, J W; Linton, J D

    1983-01-01

    The effect of cyanide on the physiology of lactate- and oxygen-limited Enterobacter aerogenes NCTC 10336 was studied in chemostat culture (D = 0.1 h-1). In the absence of cyanide, the molar growth yield from oxygen (YO2) under oxygen limitation was 60% of the carbon-limited value. A similar decrease in yield was observed in a lactate-limited culture (excess oxygen) which was continuously fed low concentrations of potassium cyanide. The cultures with the lower growth yields possessed respiratory systems less sensitive to inhibition by cyanide. This was particularly marked in cultures grown in the presence of cyanide. Increased cyanide resistance was associated with an increase in the concentration of a cytochrome oxidase tentatively identified as a d-type and the appearance of additional cytochromes tentatively identified as b-type.

  2. Blood infection with Enterobacter aerogenes--an unusual cause of portal vein gas.

    PubMed

    Fayyaz, Afshan

    2011-01-01

    Portal vein gas was once thought of as an invariably fatal condition. Now, with the availability of better equipment and expertise, the condition is more frequently diagnosed. A case of fever with rigors is presented and on ultrasound and CT examination was found to have portal venous gas which resolved with adequate antibiotic treatment. Blood culture revealed growth of gram negative bacillus; Enterobacter aerogenes. Patient was investigated further for portal vein gas, and although no other cause for the development of portal vein gas was found, she was treated with antibiotics and showed an immediate response. The aim of this case report is to highlight the benign causes of portal vein gas as well as to discuss the causes which warrant immediate surgery. Portal vein gas may herald a more ominous condition, which if intercepted in its course may result in complete cure.

  3. Pathological fracture of the right distal radius caused by Enterobacter aerogenes osteomyelitis in an adult.

    PubMed

    Lin, Te-Yu; Chi, Hung-Wei; Wang, Ning-Chi

    2010-05-01

    A pathological fracture is a break in a diseased bone caused by weakening of the bone structure by a pathological process with no identifiable trauma. Acute bacterial osteomyelitis that results in pathological fractures in the extremities is rare in adults. To our knowledge, we report the first case of Enterobacter aerogenes osteomyelitis of the right distal radius, complicated with a pathological fracture, in a 79-year-old man with diabetes, which was diagnosed by radiological, microbiological, and histopathological examinations. He recovered well after an 8-week course of antibiotics and surgical debridement. This highlights the fact that radial osteomyelitis should be included in the differential diagnosis when an elderly diabetic patient with no history of trauma presents with pain in the forearm.

  4. Polygalacturonase production by calcium alginate immobilized Enterobacter aerogenes NBO2 cells.

    PubMed

    Darah, I; Nisha, M; Lim, Sheh-Hong

    2015-03-01

    Bacterial cells of Enterobacter aerogenes NBO2 were entrapped in calcium alginate beads in order to enhance polygalacturonase production compared to free cells. The optimized condition of 5 % (w/v) sodium alginate concentration, agitation speed of 250 rpm, and 15 beads of calcium alginate with inoculum size of 4 % (v/v; 5.4 × 10(7) cells/ml) produced 23.48 U/mL of polygalacturonase compared to free cells of 18.54 U/ml. There was about 26.6 % increment in polygalaturonase production. However, in this study, there was 296.6 % of increment in polygalacturonase production after improvement parameters compared to before improvement parameters of calcium alginate bead immobilization cells (5.92 U/ml). This research has indicated that optimized physical parameters of calcium alginate bead immobilization cells have significantly enhanced the production of polygalacturonase.

  5. Clonal Dissemination of Enterobacter cloacae Harboring blaKPC-3 in the Upper Midwestern United States

    PubMed Central

    Hargreaves, Melissa L.; Shaw, Kristin M.; Dobbins, Ginette; Snippes Vagnone, Paula M.; Harper, Jane E.; Boxrud, Dave; Lynfield, Ruth; Aziz, Maliha; Price, Lance B.; Silverstein, Kevin A. T.; Danzeisen, Jessica L.; Youmans, Bonnie; Case, Kyle; Sreevatsan, Srinand

    2015-01-01

    Carbapenemase-producing, carbapenem-resistant Enterobacteriaceae, or CP-CRE, are an emerging threat to human and animal health, because they are resistant to many of the last-line antimicrobials available for disease treatment. Carbapenemase-producing Enterobacter cloacae harboring blaKPC-3 recently was reported in the upper midwestern United States and implicated in a hospital outbreak in Fargo, North Dakota (L. M. Kiedrowski, D. M. Guerrero, F. Perez, R. A. Viau, L. J. Rojas, M. F. Mojica, S. D. Rudin, A. M. Hujer, S. H. Marshall, and R. A. Bonomo, Emerg Infect Dis 20:1583–1585, 2014, http://dx.doi.org/10.3201/eid2009.140344). In early 2009, the Minnesota Department of Health began collecting and screening CP-CRE from patients throughout Minnesota. Here, we analyzed a retrospective group of CP-E. cloacae isolates (n = 34) collected between 2009 and 2013. Whole-genome sequencing and analysis revealed that 32 of the strains were clonal, belonging to the ST171 clonal complex and differing collectively by 211 single-nucleotide polymorphisms, and it revealed a dynamic clone under positive selection. The phylogeography of these strains suggests that this clone existed in eastern North Dakota and western Minnesota prior to 2009 and subsequently was identified in the Minneapolis and St. Paul metropolitan area. All strains harbored identical IncFIA-like plasmids conferring a CP-CRE phenotype and an additional IncX3 plasmid. In a single patient with multiple isolates submitted over several months, we found evidence that these plasmids had transferred from the E. cloacae clone to an Escherichia coli ST131 bacterium, rendering it as a CP-CRE. The spread of this clone throughout the upper midwestern United States is unprecedented for E. cloacae and highlights the importance of continued surveillance to identify such threats to human health. PMID:26438492

  6. Altered Outer Membrane Transcriptome Balance with AmpC Overexpression in Carbapenem-Resistant Enterobacter cloacae.

    PubMed

    Majewski, Piotr; Wieczorek, Piotr; Ojdana, Dominika; Sieńko, Anna; Kowalczuk, Oksana; Sacha, Paweł; Nikliński, Jacek; Tryniszewska, Elżbieta

    2016-01-01

    The growing incidence of multidrug-resistant (MDR) bacteria is an emerging challenge in modern medicine. The utility of carbapenems, considered "last-line" agents in therapy of infections caused by MDR pathogens, is being diminished by the growing incidence of various resistance mechanisms. Enterobacter cloacae have lately begun to emerge as an important pathogen prone to exhibiting multiple drug resistance. We aimed to investigate the molecular basis of carbapenem-resistance in 44 E. cloacae clinical strains resistant to at least one carbapenem, and 21 susceptible strains. Molecular investigation of 65 E. cloacae clinical strains was based on quantitative polymerase chain reaction (qPCR) allowing for amplification of ampC, ompF, and ompC transcripts, and analysis of nucleotide sequences of alleles included in MLST scheme. Co-operation of three distinct carbapenem resistance mechanisms has been reported-production of OXA-48 (5%), AmpC overproduction (97.7%), and alterations in outer membrane (OM) transcriptome balance. Carbapenem-resistant E. cloacae were characterized by (1.) downregulation of ompF gene (53.4%), which encodes protein with extensive transmembrane channels, and (2.) the polarization of OM transcriptome-balance (79.1%), which was sloped toward ompC gene, encoding proteins recently reported to possess restrictive transmembrane channels. Subpopulations of carbapenem-susceptible strains showed relatively high degrees of sequence diversity without predominant types. ST-89 clearly dominates among carbapenem-resistant strains (88.6%) suggesting clonal spread of resistant strains. The growing prevalence of pathogens resistant to all currently available antimicrobial agents heralds the potential risk of a future "post-antibiotic era." Great efforts need to be taken to explore the background of resistance to "last resort" antimicrobials.

  7. Altered Outer Membrane Transcriptome Balance with AmpC Overexpression in Carbapenem-Resistant Enterobacter cloacae

    PubMed Central

    Majewski, Piotr; Wieczorek, Piotr; Ojdana, Dominika; Sieńko, Anna; Kowalczuk, Oksana; Sacha, Paweł; Nikliński, Jacek; Tryniszewska, Elżbieta

    2016-01-01

    The growing incidence of multidrug-resistant (MDR) bacteria is an emerging challenge in modern medicine. The utility of carbapenems, considered “last-line” agents in therapy of infections caused by MDR pathogens, is being diminished by the growing incidence of various resistance mechanisms. Enterobacter cloacae have lately begun to emerge as an important pathogen prone to exhibiting multiple drug resistance. We aimed to investigate the molecular basis of carbapenem-resistance in 44 E. cloacae clinical strains resistant to at least one carbapenem, and 21 susceptible strains. Molecular investigation of 65 E. cloacae clinical strains was based on quantitative polymerase chain reaction (qPCR) allowing for amplification of ampC, ompF, and ompC transcripts, and analysis of nucleotide sequences of alleles included in MLST scheme. Co-operation of three distinct carbapenem resistance mechanisms has been reported—production of OXA-48 (5%), AmpC overproduction (97.7%), and alterations in outer membrane (OM) transcriptome balance. Carbapenem-resistant E. cloacae were characterized by (1.) downregulation of ompF gene (53.4%), which encodes protein with extensive transmembrane channels, and (2.) the polarization of OM transcriptome-balance (79.1%), which was sloped toward ompC gene, encoding proteins recently reported to possess restrictive transmembrane channels. Subpopulations of carbapenem-susceptible strains showed relatively high degrees of sequence diversity without predominant types. ST-89 clearly dominates among carbapenem-resistant strains (88.6%) suggesting clonal spread of resistant strains. The growing prevalence of pathogens resistant to all currently available antimicrobial agents heralds the potential risk of a future “post-antibiotic era.” Great efforts need to be taken to explore the background of resistance to “last resort” antimicrobials. PMID:28066375

  8. Effects of Enterobacter cloacae on boar sperm quality during liquid storage at 17°C.

    PubMed

    Prieto-Martínez, Noelia; Bussalleu, Eva; Garcia-Bonavila, Estela; Bonet, Sergi; Yeste, Marc

    2014-07-01

    Contamination of fresh and extended boar sperm often occurs in farms and artificial insemination (AI) centres during semen collection, processing and storage. The presence of bacteria produces detrimental effects on boar sperm quality, which may cause economic losses in reproductive centres. The present study has evaluated for the first time how the presence of Enterobacter cloacae affects the preservation of boar spermatozoa in liquid storage at 15-17 °C for an 11-day period. With this purpose, extended semen samples from seven healthy post-pubertal boars were artificially contaminated with different sperm:bacterium ratios (2:1; 1:1; 1:5 and 1:10) of E. cloacae. The 1:0 ratio (non-inoculated) served as a negative control. The most infective ratios (i.e. 1:5 and 1:10) significantly damaged sperm motility and membrane integrity, increased sperm agglutination, and decreased the osmotic resistance of spermatozoa. In contrast, the negative impact that the lowest bacterial concentration (2:1) had on boar sperm quality was clearly lower. In addition, other parameters such as pH were also more affected at the highest infective ratios (i.e. 1:5 and 1:10), despite no damage being observed on sperm morphology. In conclusion, the present work shows that damage inflicted by the presence of E. cloacae in boar sperm during liquid storage at 15-17 °C compromises the longevity and fertilising ability of seminal doses when bacterial concentration is higher than a 1:1 ratio. Further research is warranted to address by which mechanism E. cloacae impairs boar sperm quality.

  9. Isolation and characterization of a glyphosate-degrading rhizosphere strain, Enterobacter cloacae K7.

    PubMed

    Kryuchkova, Yelena V; Burygin, Gennady L; Gogoleva, Natalia E; Gogolev, Yuri V; Chernyshova, Marina P; Makarov, Oleg E; Fedorov, Evgenii E; Turkovskaya, Olga V

    2014-01-20

    Plant-growth-promoting rhizobacteria exert beneficial effects on plants through their capacity for nitrogen fixation, phytohormone production, phosphate solubilization, and improvement of the water and mineral status of plants. We suggested that these bacteria may also have the potential to express degradative activity toward glyphosate, a commonly used organophosphorus herbicide. In this study, 10 strains resistant to a 10 mM concentration of glyphosate were isolated from the rhizoplane of various plants. Five of these strains--Alcaligenes sp. K1, Comamonas sp. K4, Azomonas sp. K5, Pseudomonas sp. K3, and Enterobacter cloacae K7--possessed a number of associative traits, including fixation of atmospheric nitrogen, solubilization of phosphates, and synthesis of the phytohormone indole-3-acetic acid. One strain, E. cloacae K7, could utilize glyphosate as a source of P. Gas-liquid chromatography showed that E. cloacae growth correlated with a decline in herbicide content in the culture medium (40% of the initial 5mM content), with no glyphosate accumulating inside the cells. Thin-layer chromatography analysis of the intermediate metabolites of glyphosate degradation found that E. cloacae K7 had a C-P lyase activity and degraded glyphosate to give sarcosine, which was then oxidized to glycine. In addition, strain K7 colonized the roots of common sunflower (Helianthus annuus L.) and sugar sorghum (Sorghum saccharatum Pers.), promoting the growth and development of sunflower seedlings. Our findings extend current knowledge of glyphosate-degrading rhizosphere bacteria and may be useful for developing a biotechnology for the cleanup and restoration of glyphosate-polluted soils.

  10. Clonal Dissemination of Enterobacter cloacae Harboring blaKPC-3 in the Upper Midwestern United States.

    PubMed

    Hargreaves, Melissa L; Shaw, Kristin M; Dobbins, Ginette; Snippes Vagnone, Paula M; Harper, Jane E; Boxrud, Dave; Lynfield, Ruth; Aziz, Maliha; Price, Lance B; Silverstein, Kevin A T; Danzeisen, Jessica L; Youmans, Bonnie; Case, Kyle; Sreevatsan, Srinand; Johnson, Timothy J

    2015-12-01

    Carbapenemase-producing, carbapenem-resistant Enterobacteriaceae, or CP-CRE, are an emerging threat to human and animal health, because they are resistant to many of the last-line antimicrobials available for disease treatment. Carbapenemase-producing Enterobacter cloacae harboring blaKPC-3 recently was reported in the upper midwestern United States and implicated in a hospital outbreak in Fargo, North Dakota (L. M. Kiedrowski, D. M. Guerrero, F. Perez, R. A. Viau, L. J. Rojas, M. F. Mojica, S. D. Rudin, A. M. Hujer, S. H. Marshall, and R. A. Bonomo, Emerg Infect Dis 20:1583-1585, 2014, http://dx.doi.org/10.3201/eid2009.140344). In early 2009, the Minnesota Department of Health began collecting and screening CP-CRE from patients throughout Minnesota. Here, we analyzed a retrospective group of CP-E. cloacae isolates (n = 34) collected between 2009 and 2013. Whole-genome sequencing and analysis revealed that 32 of the strains were clonal, belonging to the ST171 clonal complex and differing collectively by 211 single-nucleotide polymorphisms, and it revealed a dynamic clone under positive selection. The phylogeography of these strains suggests that this clone existed in eastern North Dakota and western Minnesota prior to 2009 and subsequently was identified in the Minneapolis and St. Paul metropolitan area. All strains harbored identical IncFIA-like plasmids conferring a CP-CRE phenotype and an additional IncX3 plasmid. In a single patient with multiple isolates submitted over several months, we found evidence that these plasmids had transferred from the E. cloacae clone to an Escherichia coli ST131 bacterium, rendering it as a CP-CRE. The spread of this clone throughout the upper midwestern United States is unprecedented for E. cloacae and highlights the importance of continued surveillance to identify such threats to human health.

  11. Complete Genome Sequence of Enterobacter cloacae UW5, a Rhizobacterium Capable of High Levels of Indole-3-Acetic Acid Production.

    PubMed

    Coulson, Thomas J D; Patten, Cheryl L

    2015-08-06

    We report the complete genome sequence of Enterobacter cloacae UW5, an indole-3-acetic acid-producing rhizobacterium originally isolated from the rhizosphere of grass. The 4.9-Mbp genome has a G+C content of 54% and contains 4,496 protein-coding sequences.

  12. Complete Genome Sequence of Enterobacter cloacae UW5, a Rhizobacterium Capable of High Levels of Indole-3-Acetic Acid Production

    PubMed Central

    Coulson, Thomas J. D.

    2015-01-01

    We report the complete genome sequence of Enterobacter cloacae UW5, an indole-3-acetic acid-producing rhizobacterium originally isolated from the rhizosphere of grass. The 4.9-Mbp genome has a G+C content of 54% and contains 4,496 protein-coding sequences. PMID:26251488

  13. Association of Enterobacter cloacae and other bacteria with onion bulb rot in the Columbia Basin of Washington and Oregon, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Approximately 1.6 million metric tons of onion bulbs are produced annually in the Pacific Northwest USA. Bulb decay can be a major problem and is caused by a variety of plant pathogens. Onion bulbs exhibiting symptoms of bacterial rot were sampled to determine the causal agents. Enterobacter cloacae...

  14. The blaSHV-5 gene is encoded in a compound transposon duplicated in tandem in Enterobacter cloacae.

    PubMed

    Garza-Ramos, U; Davila, G; Gonzalez, V; Alpuche-Aranda, C; López-Collada, V R; Alcantar-Curiel, D; Newton, O; Silva-Sanchez, J

    2009-09-01

    The presence of bla(SHV-5) is described in a compound transposon, duplicated in tandem and flanked by IS26 copies on a 70-kb conjugative plasmid (pHNM1), in an Enterobacter cloacae strain associated with a nosocomial outbreak that occurred in Mexico.

  15. Hospital clonal dissemination of Enterobacter aerogenes producing carbapenemase KPC-2 in a Chinese teaching hospital.

    PubMed

    Qin, Xiaohua; Yang, Yang; Hu, Fupin; Zhu, Demei

    2014-02-01

    Carbapenems are first-line agents for the treatment of serious nosocomial infections caused by multidrug-resistant Enterobacteriaceae. However, resistance to carbapenems has increased dramatically among Enterobacteriaceae in our hospital. In this study, we report clonal dissemination caused by carbapenem-resistant Enterobacter aerogenes (CREA). In 2011, CREA was identified from 12 patients admitted to the neurosurgical ward. All 12 clinical isolates were non-susceptible to cefotaxime, ceftazidime, cefoxitin, ertapenem, imipenem or meropenem. All isolates carried the gene encoding Klebsiella pneumoniae carbapenemase-2 (KPC-2), except for the isolate E4. However, a remarkably lower expression level of the porin OmpF was detected in the non-KPC-2-producing isolate E4 on SDS-PAGE compared with the carbapenem-susceptible isolate. Epidemiological and molecular investigations showed that a single E. aerogenes strain (PFGE type A), including seven KPC-2-producing clinical isolates, was primarily responsible for the first isolation and subsequent dissemination. In a case-control study, we identified risk factors for infection/colonization with CREA. Mechanical ventilation, the changing of sickbeds and previous use of broad-spectrum antibiotics were identified as potential risk factors. Our findings suggest that further studies should focus on judicious use of available antibiotics, implementation of active antibiotic resistance surveillance and strict implementation of infection-control measures to avoid the rapid spread or clonal dissemination caused by carbapenem-resistant Enterobacteriaceae in healthcare facilities.

  16. Study of the role of anaerobic metabolism in succinate production by Enterobacter aerogenes.

    PubMed

    Tajima, Yoshinori; Kaida, Kenichi; Hayakawa, Atsushi; Fukui, Keita; Nishio, Yousuke; Hashiguchi, Kenichi; Fudou, Ryosuke; Matsui, Kazuhiko; Usuda, Yoshihiro; Sode, Koji

    2014-09-01

    Succinate is a core biochemical building block; optimizing succinate production from biomass by microbial fermentation is a focus of basic and applied biotechnology research. Lowering pH in anaerobic succinate fermentation culture is a cost-effective and environmentally friendly approach to reducing the use of sub-raw materials such as alkali, which are needed for neutralization. To evaluate the potential of bacteria-based succinate fermentation under weak acidic (pH <6.2) and anaerobic conditions, we characterized the anaerobic metabolism of Enterobacter aerogenes AJ110637, which rapidly assimilates glucose at pH 5.0. Based on the profile of anaerobic products, we constructed single-gene knockout mutants to eliminate the main anaerobic metabolic pathways involved in NADH re-oxidation. These single-gene knockout studies showed that the ethanol synthesis pathway serves as the dominant NADH re-oxidation pathway in this organism. To generate a metabolically engineered strain for succinate production, we eliminated ethanol formation and introduced a heterogeneous carboxylation enzyme, yielding E. aerogenes strain ΔadhE/PCK. The strain produced succinate from glucose with a 60.5% yield (grams of succinate produced per gram of glucose consumed) at pH <6.2 and anaerobic conditions. Thus, we showed the potential of bacteria-based succinate fermentation under weak acidic conditions.

  17. Enhancing hydrogen production of Enterobacter aerogenes by heterologous expression of hydrogenase genes originated from Synechocystis sp.

    PubMed

    Song, Wenlu; Cheng, Jun; Zhao, Jinfang; Zhang, Chuanxi; Zhou, Junhu; Cen, Kefa

    2016-09-01

    The hydrogenase genes (hoxEFUYH) of Synechocystis sp. PCC 6803 were cloned and heterologously expressed in Enterobacter aerogenes ATCC13408 for the first time in this study, and the hydrogen yield was significantly enhanced using the recombinant strain. A recombinant plasmid containing the gene in-frame with Glutathione-S-Transferase (GST) gene was transformed into E. aerogenes ATCC13408 to produce a GST-fusion protein. SDS-PAGE and western blot analysis confirm the successful expression of the hox genes. The hydrogenase activity of the recombinant strain is 237.6±9.3ml/(g-DW·h), which is 152% higher than the wild strain. The hydrogen yield of the recombinant strain is 298.3ml/g-glucose, which is 88% higher than the wild strain. During hydrogen fermentation, the recombinant strain produces more acetate and butyrate, but less ethanol. This is corresponding to the NADH metabolism in the cell due to the higher hydrogenase activity with the heterologous expression of hox genes.

  18. Histamine production by Enterobacter aerogenes in sailfish and milkfish at various storage temperatures.

    PubMed

    Tsai, Yung-Hsiang; Chang, Shiou-Chung; Kung, Hsien-Feng; Wei, Cheng-I; Hwang, Deng-Fwu

    2005-08-01

    Enterobacter aerogenes was studied for its growth and ability to promote the formation of total volatile base nitrogen (TVBN) and histamine in sailfish (Istiophorus platypterus) and milkfish (Chanos chanos) stored at various temperatures from -20 to 37 degrees C. The optimal temperature for bacterial growth in both fish species was 25 degrees C, whereas the optimal temperature for histamine formation was 37 degrees C. The two fish species inoculated with E. aerogenes, when not properly stored at low temperatures such as 15 degrees C for 36 h, formed histamine at above the U.S. Food and Drug Administration hazardous guideline level of 50 mg/100 g. Milkfish was a better substrate than sailfish for histamine formation by bacterial histidine decarboxylation at elevated temperatures (> 15 degrees C). Although higher contents of TVBN were detected in the spiked sailfish than milkfish during the same storage time at temperatures above 15 degrees C, the use of the 30-mg/100 g level of TVBN as a determination index for fish quality and decomposition was not a good criterion for assessing potential histamine hazard for both fish species. Bacterial growth was controlled by cold storage of the fish at 4 degrees C or below, but histamine formation was stopped only by frozen storage. Once the frozen fish samples were thawed and stored at 25 degrees C, histamine started to accumulate rapidly and reached levels greater than the hazardous action level in 36 h.

  19. Thanatin activity on multidrug resistant clinical isolates of Enterobacter aerogenes and Klebsiella pneumoniae.

    PubMed

    Pagès, Jean-Marie; Dimarcq, Jean-Luc; Quenin, Solange; Hetru, Charles

    2003-09-01

    Efflux pumps protect bacterial cells by ejecting intracellular toxic molecules such as antibiotics, detergents and defensins that have penetrated the cell envelope. Some of these efflux pumps recognise structurally unrelated compounds (mdr pump) and account for the resistance of some organisms to two or more agents. It would be of interest to identify molecules that are able to circumvent the problems created by multidrug resistance phenotypes during antibiotic therapy. We have studied the activity of thanatin, a 21-residue cationic antimicrobial peptide produced by an insect, against three bacterial species. The antibacterial effect depended on the size of lipopolysaccharide side chains. In clinically resistant isolates of Enterobacter aerogenes and Klebsiella pneumoniae, the biological activity of thanatin is independent of the membrane permeability, possibly controlled by one or more porins, and/or the expression of drug efflux pumps, two mechanisms which confer high level antibiotic resistance. In addition, thanatin was able to improve the activity of structurally unrelated antibiotics (norfloxacin, chloramphenicol, tetracycline) on a multidrug- resistant E. aerogenes clinical isolate.

  20. Effect of nanocomposite packaging containing ZnO on growth of Bacillus subtilis and Enterobacter aerogenes.

    PubMed

    Esmailzadeh, Hakimeh; Sangpour, Parvaneh; Shahraz, Farzaneh; Hejazi, Jalal; Khaksar, Ramin

    2016-01-01

    Recent advances in nanotechnology have opened new windows in active food packaging. Nano-sized ZnO is an inexpensive material with potential antimicrobial properties. The aim of the present study is to evaluate the antibacterial effect of low density Polyethylene (LDPE) containing ZnO nanoparticles on Bacillus subtilis and Enterobacter aerogenes. ZnO nanoparticles have been synthesized by facil molten salt method and have been characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). Nanocomposite films containing 2 and 4 wt.% ZnO nanoparticles were prepared by melt mixing in a twin-screw extruder. The growth of both microorganisms has decreased in the presence of ZnO containing nanocomposites compared with controls. Nanocomposites with 4 wt.% ZnO nanoparticles had stronger antibacterial effect against both bacteria in comparison with the 2 wt.% ZnO containing nanocomposites. B. subtilis as Gram-positive bacteria were more sensitive to ZnO containing nanocomposite films compared with E. aerogenes as Gram-negative bacteria. There were no significant differences between the migration of Zn ions from 2 and 4 wt.% ZnO containing nanocomposites and the released Zn ions were not significantly increased in both groups after 14 days compared with the first. Regarding the considerable antibacterial effects of ZnO nanoparticles, their application in active food packaging can be a suitable solution for extending the shelf life of food.

  1. The purification, crystallization and preliminary diffraction of a glycerophosphodiesterase from Enterobacter aerogenes

    SciTech Connect

    Jackson, Colin J.; Carr, Paul D.; Kim, Hye-Kyung; Liu, Jian-Wei; Ollis, David L.

    2006-07-01

    The metallo-glycerophosphodiesterase from E. aerogenes (GpdQ) has been cloned, expressed in E. coli and purified. Initial screening of crystallization conditions for this enzyme resulted in the identification of needles from one condition in a sodium malonate grid screen. Removal of the metals from the enzyme and subsequent optimization of these conditions led to crystals. The metallo-glycerophosphodiesterase from Enterobacter aerogenes (GpdQ) has been cloned, expressed in Escherichia coli and purified. Initial screening of crystallization conditions for this enzyme resulted in the identification of needles from one condition in a sodium malonate grid screen. Removal of the metals from the enzyme and subsequent optimization of these conditions led to crystals that diffracted to 2.9 Å and belonged to space group P2{sub 1}3, with unit-cell parameter a = 164.1 Å. Self-rotation function analysis and V{sub M} calculations indicated that the asymmetric unit contains two copies of the monomeric enzyme, corresponding to a solvent content of 79%. It is intended to determine the structure of this protein utilizing SAD phasing from transition metals or molecular replacement.

  2. Isolation and characterization of a bacteriophage F20 virulent to Enterobacter aerogenes.

    PubMed

    Mishra, Charitra Kumar; Choi, Tae Jin; Kang, Sun Chul

    2012-10-01

    An aquatic phage, designated F20, was characterized and its physico-chemical characteristics studied. F20 was specifically virulent to only two strains of Enterobacter aerogenes (ATCC 13048 and the multi-drug-resistant strain K113) among other species tested (n = 15). It was classified in the family Siphoviridae of T1-like viruses and contained a linear dsDNA genome estimated to be 51.5 kbp enclosed by an isometric capsid of 50±2 nm in diameter and a tail of 150±3 nm in length. F20 was able to survive in a broad pH range between 4 and 11, showed potential for future animal trials using oral solution and resisted chloroform and ethanol. It exhibited remarkable stability between room temperature and 70 °C for up to 150 min, and even up to 6 months at room temperature. Knowledge of this phage belonging to the widespread T1-like viruses might be helpful for adopting therapeutic strategies against E. aerogenes.

  3. A toxaphene-degrading bacterium related to Enterobacter cloacae, strain D1 isolated from aged contaminated soil in Nicaragua.

    PubMed

    Lacayo-Romero, Martha; Quillaguamán, Jorge; van Bavel, Bert; Mattiasson, Bo

    2005-09-01

    Enterobacter sp. strain D1 is a facultative anaerobic, Gram-negative heterotrophic bacterium isolated from toxaphene-contaminated soil. This organism was identified and characterized through phylogenetic and taxonomic studies. Based on 16S rDNA analysis, the strain D1 was clustered closely with the species Enterobacter cloacae subsp. dissolvens (LMG 2683) and E. cloacae (ATCC 13047T). Strain D1 resembled these E. cloacae strains with respect to various biochemical and nutritional characteristics, but also exhibited differences. Moreover, strain D1 is able to grow and survive with toxaphene supplied in the medium in the range 3-96 mg/L. Amongst the chemical components of toxaphene, octachlorocamphenes, nonachlorobornanes and decachlorobornanes were seen to be rapidly metabolized, although levels of hexachlorocamphenes and heptachlorobornanes were found to be slowly degraded, and subsequently accumulated during the last stage of the cultivation.

  4. The AcrAB-TolC pump is involved in macrolide resistance but not in telithromycin efflux in Enterobacter aerogenes and Escherichia coli.

    PubMed

    Chollet, Renaud; Chevalier, Jacqueline; Bryskier, André; Pagès, Jean-Marie

    2004-09-01

    The role of the AcrAB-TolC pump in macrolide and ketolide susceptibility in Escherichia coli and Enterobacter aerogenes was studied. Efflux pump inhibitor restored erythromycin, clarithromycin, and telithromycin susceptibilities to multidrug-resistant isolates. No modification of telithromycin accumulation was detected in E. aerogenes acrAB or tolC derivatives compared to that in the parental strain. Two independent efflux pumps, inhibited by phenylalanine arginine beta-naphthylamide, expel macrolides and telithromycin in E. aerogenes.

  5. Bacteremia due to extended-spectrum-beta-lactamase-producing Enterobacter cloacae: role of carbapenem therapy.

    PubMed

    Lee, Ching-Chi; Lee, Nan-Yao; Yan, Jing-Jou; Lee, Hsin-Chun; Chen, Po-Lin; Chang, Chia-Ming; Wu, Chi-Jung; Ko, Nai-Ying; Wang, Li-Rong; Chi, Chih-Hsien; Ko, Wen-Chien

    2010-09-01

    Enterobacter cloacae is an important nosocomial pathogen. However, few studies specifically dealing with the clinical characteristics and outcome of extended-spectrum beta-lactamase (ESBL)-producing E. cloacae infections have been published. During an 8-year period in a medical center, of 610 E. cloacae bacteremic isolates, 138 (22.6%) with ESBL genes were designated the ESBL group, and 120 (19.6%) cefotaxime-nonsusceptible isolates without the ESBL phenotype and genes were designated the control group. Of the former group of isolates, 133 (96.3%) carried the bla(SHV-12) gene, 3 (2.1%) had bla(CTX-M3), and 2 (1.4%) had both the bla(SHV-12) and bla(CTX-M3) genes. After patients under the age of 18 years were excluded, there were 206 adults with E. cloacae bacteremia, and these consisted of 121 patients in the ESBL group and 85 in the control group. More episodes of hospital-onset and polymicrobial bacteremia, increased severity of illness, more cases of bacteremia onset in intensive care units (ICUs), and longer stays in the hospital and ICU after bacteremia onset were noted in the ESBL group. However, the crude and sepsis-related mortality rates in two groups were similar. Of the ESBL group, the in-hospital sepsis-related mortality rate of patients definitively treated by a carbapenem was lower than that of those treated by noncarbapenem beta-lactams (5/53, or 9.4%, versus 13/44, or 29.5%; P = 0.01) though the difference was not significant in the hierarchical multivariate analysis (P = 0.46). Among 62 patients with follow-up blood cultures within 14 days of bacteremia onset, breakthrough bacteremia was more common in those treated by a noncarbapenem beta-lactam agent than in those treated by a carbapenem (18/31, or 58.0%, versus 3/31, or 9.6%; P < 0.001). Thus, carbapenem therapy for ESBL-producing E. cloacae that cause bacteremia may provide therapeutic benefits.

  6. An unusual cause of necrosis and nasal septum perforation after septoplasty: Enterobacter cloacae.

    PubMed

    Binar, M; Arslan, F; Tasli, H; Karakoc, O; Kilic, A; Aydin, U

    2015-11-01

    A 20-year-old man with nasal obstruction underwent septoplasty due to nasal septal deviation. Nasal packs were inserted at the end of surgery and removed 48 hours after surgery. Twenty-four hours after removal of nasal packs, there was necrosis in both sides of septal mucosa and in bilateral inferior turbinates. Nasal swab culture was performed from both nasal cavities. Enterobacter cloacae was isolated from samples. Two weeks after surgery, nasal septum perforation was unavoidable. To our knowledge, this is the first case in literature describing septal mucosal necrosis caused by this pathogen after septoplasty. Mucosal necrosis and perforation as septoplasty complications should be kept in mind, the result of causes both common and, as in the present case, unusual.

  7. Structure characterization of a fucose-containing exopolysaccharide produced by Enterobacter cloacae Z0206.

    PubMed

    Wang, Fengqin; Yang, Hangxian; Wang, Yizhen

    2013-01-30

    A novel high molecular weight (1.1 × 10(6)Da) exopolysaccharide (EPS) produced by Enterobacter cloacae Z0206 strain was isolated by column chromatography. Complete hydrolysis of the EPS followed by gas chromatography mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC) analyses showed that the EPS is composed of L-fucose, D-glucose, D-galactose, D-glucuronic acid and pyruvic acid in the approximate molar ratio of 2:1:3:1:1. Partial acid hydrolysis of the purified EPS followed by gel permeation chromatography (GPC) yielded a hexasaccharide. A combination of chemical analysis coupled with mass spectrometry and 1D and 2D NMR spectroscopy applied to the oligosaccharide showed that the EPS comprises a heptasaccharide repeating unit.

  8. VIM-4 carbapenemase-producing Enterobacter cloacae in the United Arab Emirates.

    PubMed

    Sonnevend, Á; Ghazawi, A; Yahfoufi, N; Al-Baloushi, A; Hashmey, R; Mathew, M; Tariq, W Z; Pál, T

    2012-12-01

    Screening 34 carbapenem non-susceptible Enterobacteriaceae recovered in Abu Dhabi hospitals identified an Enterobacter cloacae strain carrying bla(VIM-4) , bla(CMY-4) and bla(CTX-M-15) . It was isolated from the urine of an Egyptian patient repeatedly hospitalized and treated with broad-spectrum antibiotics, including carbapenems, in the United Arab Emirates. The bla(VIM-4) coding class I integron, highly similar to In416, was carried on a 175-kilobase non-conjugative incA/C type plasmid also hybridizing with the bla(CMY-4) probe. This is the first detailed report on the isolation of a Verona integron-encoded metallo-β-lactamase (VIM) -producing enteric bacterium in the Arabian Peninsula with characteristics suggestive of spreading from the Mediterranean region.

  9. Exopolysaccharide production by a genetically engineered Enterobacter cloacae strain for microbial enhanced oil recovery.

    PubMed

    Sun, Shanshan; Zhang, Zhongzhi; Luo, Yijing; Zhong, Weizhang; Xiao, Meng; Yi, Wenjing; Yu, Li; Fu, Pengcheng

    2011-05-01

    Microbial enhanced oil recovery (MEOR) is a petroleum biotechnology for manipulating function and/or structure of microbial environments existing in oil reservoirs for prolonged exploitation of the largest source of energy. In this study, an Enterobacter cloacae which is capable of producing water-insoluble biopolymers at 37°C and a thermophilic Geobacillus strain were used to construct an engineered strain for exopolysaccharide production at higher temperature. The resultant transformants, GW3-3.0, could produce exopolysaccharide up to 8.83 g l(-1) in molasses medium at 54°C. This elevated temperature was within the same temperature range as that for many oil reservoirs. The transformants had stable genetic phenotype which was genetically fingerprinted by RAPD analysis. Core flooding experiments were carried out to ensure effective controlled profile for the simulation of oil recovery. The results have demonstrated that this approach has a promising application potential in MEOR.

  10. KPC-2 carbapenemase and DHA-1 AmpC determinants carried on the same plasmid in Enterobacter aerogenes.

    PubMed

    Kuai, Shougang; Shao, Haifeng; Huang, Lihua; Pei, Hao; Lu, Zhonghua; Wang, Weiping; Liu, Jun

    2014-03-01

    This study was conducted to analyse the presence of a plasmid-mediated carbapenem resistance mechanism in a clinical Enterobacter aerogenes isolate from a patient from Jiangsu province, People's Republic of China. PCR and sequencing confirmed that the isolate harboured Klebsiella pneumoniae carbapenemase (KPC)-2, DHA-1 and TEM-1 β-lactamase genes. Both the KPC-2 and DHA-1 genes were transferred to Escherichia coli C600 by transconjugation, and Southern blotting confirmed that these two genes were located on the same plasmid, which was of approximately 56 kb in size. The Enterobacter aerogenes isolate was resistant to carbapenems and other tested antimicrobial agents. The Escherichia coli transconjugant showed reduced susceptibility but not resistance to carbapenems and other β-lactams, indicating the presence of another, possibly permeability-related, resistance mechanism in the clinical isolate.

  11. Genetically engineered termite gut bacteria (Enterobacter cloacae) deliver and spread foreign genes in termite colonies.

    PubMed

    Husseneder, Claudia; Grace, J Kenneth

    2005-08-01

    Indigenous gut bacteria of the Formosan subterranean termite (Coptotermes formosanus Shiraki, Isoptera: Rhinotermitidae) were used as shuttle systems to deliver, express and spread foreign genes in termite colonies. The gut bacterium Enterobacter cloacae was transformed with a recombinant plasmid (pEGFP) containing genes encoding ampicillin resistance and green fluorescent protein (GFP). In laboratory experiments, termite workers and soldiers from three colonies were fed with filter paper inoculated with transformed bacteria. Transformed bacteria were detected in termite guts by growing the entire gut flora under selective conditions and checking the cultures visually for fluorescence. We demonstrated that (1) transformed bacteria were ingested within a few hours and the GFP gene was expressed in the termite gut; (2) transformed bacteria established a persistent population in the termite gut for up to 11 weeks; (3) transformed bacteria were efficiently transferred throughout a laboratory colony, even when the donor (termites initially fed with transformed bacteria) to recipient (not fed) ratio was low; (4) transformed E. cloacae were transferred into soil; however, they did not accumulate over time and the GFP plasmid was not transferred to other soil bacteria. In the future, transgenic bacteria may be used to shuttle detrimental genes into termite colonies for improved pest control.

  12. Proteomic response of β-lactamases-producing Enterobacter cloacae complex strain to cefotaxime-induced stress.

    PubMed

    Maravić, Ana; Cvjetan, Svjetlana; Konta, Marina; Ladouce, Romain; Martín, Fernando A

    2016-07-01

    Bacteria of the Enterobacter cloacae complex are among the ten most common pathogens causing nosocomial infections in the USA. Consequently, increased resistance to β-lactam antibiotics, particularly expanded-spectrum cephalosporins like cefotaxime (CTX), poses a serious threat. Differential In-Gel Electrophoresis (DIGE), followed by LC-MS/MS analysis and bioinformatics tools, was employed to investigate the survival mechanisms of a multidrug-resistant E. hormaechei subsp. steigerwaltii 51 carrying several β-lactamase-encoding genes, including the 'pandemic' blaCTX-M-15 After exposing the strain with sub-minimal inhibitory concentration (MIC) of CTX, a total of 1072 spots from the whole-cell proteome were detected, out of which 35 were differentially expressed (P ≤ 0.05, fold change ≥1.5). Almost 50% of these proteins were involved in cell metabolism and energy production, and then cell wall organization/virulence, stress response and transport. This is the first study investigating the whole-cell proteomic response related to the survival of β-lactamases-producing strain, belonging to the E. cloacae complex when exposed to β-lactam antibiotic. Our data support the theory of a multifactorial synergistic effect of diverse proteomic changes occurring in bacterial cells during antibiotic exposure, depicting the complexity of β-lactam resistance and giving us an insight in the key pathways mediating the antibiotic resistance in this emerging opportunistic pathogen.

  13. Determination for Enterobacter cloacae based on a europium ternary complex labeled DNA probe

    NASA Astrophysics Data System (ADS)

    He, Hui; Niu, Cheng-Gang; Zeng, Guang-Ming; Ruan, Min; Qin, Pin-Zhu; Liu, Jing

    2011-11-01

    The fast detection and accurate diagnosis of the prevalent pathogenic bacteria is very important for the treatment of disease. Nowadays, fluorescence techniques are important tools for diagnosis. A two-probe tandem DNA hybridization assay was designed for the detection of Enterobacter cloacae based on time-resolved fluorescence. In this work, the authors synthesized a novel europium ternary complex Eu(TTA) 3(5-NH 2-phen) with intense luminescence, high fluorescence quantum yield and long lifetime before. We developed a method based on this europium complex for the specific detection of original extracted DNA from E. cloacae. In the hybridization assay format, the reporter probe was labeled with Eu(TTA) 3(5-NH 2-phen) on the 5'-terminus, and the capture probe capture probe was covalent immobilized on the surface of the glutaraldehyde treated glass slides. The original extracted DNA of samples was directly used without any DNA purification and amplification. The detection was conducted by monitoring the fluorescence intensity from the glass surface after DNA hybridization. The detection limit of the DNA was 5 × 10 -10 mol L -1. The results of the present work proved that this new approach was easy to operate with high sensitivity and specificity. It could be conducted as a powerful tool for the detection of pathogen microorganisms in the environment.

  14. Characteristics of a Novel Aerobic Denitrifying Bacterium, Enterobacter cloacae Strain HNR.

    PubMed

    Guo, Long-Jie; Zhao, Bin; An, Qiang; Tian, Meng

    2016-03-01

    A novel aerobic denitrifier strain HNR, isolated from activated sludge, was identified as Enterobacter cloacae by16S rRNA sequencing analysis. Glucose was considered as the most favorable C-source for strain HNR. The logistic equation well described the bacterial growth, yielding a maximum growth rate (μmax) of 0.283 h(-1) with an initial NO3 (-)-N concentration of 110 mg/L. Almost all NO3 (-)-N was removed aerobically within 30 h with an average removal rate of 4.58 mg N L(-1) h(-1). Nitrogen balance analysis revealed that proximately 70.8 % of NO3 (-)-N was removed as gas products and only 20.7 % was transformed into biomass. GC-MS result indicates that N2 was the end product of aerobic denitrification. The enzyme activities of nitrate reductase and nitrite reductase, which are related to the process of aerobic denitrification, were 0.0688 and 0.0054 U/mg protein, respectively. Thus, the aerobic denitrification of reducing NO3 (-) to N2 by strain HNR was demonstrated. The optimal conditions for nitrate removal were C/N ratio 13, pH value 8, shaking speed 127 rpm and temperature 30 °C. These findings show that E. cloacae strain HNR has a potential application on wastewater treatment to achieve nitrate removal under aerobic conditions.

  15. New aerobactin-mediated iron uptake system in a septicemia-causing strain of Enterobacter cloacae.

    PubMed Central

    Crosa, L M; Wolf, M K; Actis, L A; Sanders-Loehr, J; Crosa, J H

    1988-01-01

    Unlike the great majority of the aerobactin-producing enteric bacteria documented in the literature, Enterobacter cloacae EK33, isolated from a case of human neonatal meningitis, did not show any homology at the DNA level with the prototype aerobactin system encoded by the ColV-K30 plasmid. However, both the nuclear magnetic resonance spectrum and fast-atom bombardment mass spectrometry of the siderophore purified from EK33 confirmed its identity with aerobactin. Bioassay screening of a gene library of total DNA of EK33 led to the isolation of several aerobactin-positive clones. Under conditions of iron limitation, these clones expressed in Escherichia coli a protein of 72 kilodaltons that reacted with antiserum raised against the pColV-K30 74-kilodalton aerobactin receptor, while the original E. cloacae strain synthesized an 85-kilodalton protein which also cross-reacted with the antiserum. Restriction endonuclease analysis of the cloned DNA confirmed the structural differences between the two aerobactin genetic systems. Images PMID:3192510

  16. Landscape of Resistance-Nodulation-Cell Division (RND)-Type Efflux Pumps in Enterobacter cloacae Complex

    PubMed Central

    Guérin, François; Lallement, Claire; Isnard, Christophe; Dhalluin, Anne; Giard, Jean-Christophe

    2016-01-01

    In Gram-negative bacteria, the active efflux is an important mechanism of antimicrobial resistance, but little is known about the Enterobacter cloacae complex (ECC). It is mediated primarily by pumps belonging to the RND (resistance-nodulation-cell division) family, and only AcrB, part of the AcrAB-TolC tripartite system, was characterized in ECC. However, detailed genome sequence analysis of the strain E. cloacae subsp. cloacae ATCC 13047 revealed to us that 10 other genes putatively coded for RND-type transporters. We then characterized the role of all of these candidates by construction of corresponding deletion mutants, which were tested for their antimicrobial susceptibility to 36 compounds, their virulence in the invertebrate Galleria mellonella model of infection, and their ability to form biofilm. Only the ΔacrB mutant displayed significantly different phenotypes compared to that of the wild-type strain: 4- to 32-fold decrease of MICs of several antibiotics, antiseptics, and dyes, increased production of biofilm, and attenuated virulence in G. mellonella. In order to identify specific substrates of each pump, we individually expressed in trans all operons containing an RND pump-encoding gene into the ΔacrB hypersusceptible strain. We showed that three other RND-type efflux systems (ECL_00053-00055, ECL_01758-01759, and ECL_02124-02125) were able to partially restore the wild-type phenotype and to superadd to and even enlarge the broad range of antimicrobial resistance. This is the first global study assessing the role of all RND efflux pumps chromosomally encoded by the ECC, which confirms the major role of AcrB in both pathogenicity and resistance and the potential involvement of other RND-type members in acquired resistance. PMID:26856831

  17. Occurrence of efflux mechanism and cephalosporinase variant in a population of Enterobacter aerogenes and Klebsiella pneumoniae isolates producing extended-spectrum beta-lactamases.

    PubMed

    Tran, Que-Tien; Dupont, Myrielle; Lavigne, Jean-Philippe; Chevalier, Jacqueline; Pagès, Jean-Marie; Sotto, Albert; Davin-Regli, Anne

    2009-04-01

    We investigated the occurrence of multidrug resistance in 44 Enterobacter aerogenes and Klebsiella pneumoniae clinical isolates. Efflux was involved in resistance in E. aerogenes isolates more frequently than in K. pneumoniae isolates (100 versus 38% of isolates) and was associated with the expression of phenylalanine arginine beta-naphthylamide-susceptible active efflux. AcrA-TolC overproduction in E. aerogenes isolates was noted. An analysis of four E. aerogenes isolates for which cefepime MICs were high revealed no modification in porin expression but a new specific mutation in the AmpC beta-lactamase.

  18. Biosensing and bioremediation of Cr(VI) by cell free extract of Enterobacter aerogenes T2.

    PubMed

    Panda, Jigisha; Sarkar, Priyabrata

    2014-01-01

    Hexavalent chromium or Cr(VI) enters the environment through several anthropogenic activities and it is highly toxic and carcinogenic. Hence it is required to be detected and remediated from the environment. In this study, low-cost and environment-friendly methods of biosensing and bioremediation of Cr(VI) have been proposed. Crude cell free extract (CFE) of previously isolated Enterobacter aerogenes T2 (GU265554; NII 1111) was prepared and exploited to develop a stable biosensor for direct estimation of Cr(VI) in waste water, by using three electrodes via cyclic voltammetry. For bioremediation studies, a homogeneous solution of commercially available sodium alginate and CFE was added dropwise in a continuously stirred calcium chloride solution. Biologically modified calcium alginate beads were produced and these were further utilized for bioremediation studies. The proposed sensor showed linear response in the range of 10-40 μg L(-1) Cr(VI) and the limit of detection was found to be 6.6 μg L(-1) Cr(VI). No interference was observed in presence of metal ions, e.g., lead, cadmium, arsenic, tin etc., except for insignificant interference with molybdenum and manganese. In bioremediation studies, modified calcium alginate beads showed encouraging removal rate 900 mg Cr(VI)/m(3) water per day with a removal efficiency of 90%, much above than reported in literature. The proposed sensing system could be a viable alternative to costly measurement procedures. Calcium alginate beads, modified with CFE of E. aerogenes, could be used in bioremediation of Cr(VI) since it could work in real conditions with extraordinarily high capacity.

  19. Mutation of a degS homologue in Enterobacter cloacae decreases colonization and biological control of damping-off caused by Pythium ultimum on cucumber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have been using a mutational approach to determine how plant-beneficial bacteria, such as Enterobacter cloacae, deal with complex nutritional environments found in association with subterranean plant parts during colonization and disease suppression. E. cloacae C10, a mini-Tn5 Km mutant of E. cl...

  20. Polyclonal Outbreak of KPC-3-Producing Enterobacter cloacae at a Single Hospital in Montréal, Québec, Canada

    PubMed Central

    Lévesque, Simon; Lefebvre, Brigitte; Blanchette, Ruth; Tomkinson, Melissa; Mataseje, Laura; Mulvey, Michael R.; Miller, Mark A.

    2013-01-01

    From September 2010 to December 2011, 26 KPC-3-producing Enterobacter cloacae isolates were identified from 16 patients at a single hospital. Analyses revealed the blaKPC gene to be localized on multiple plasmids in a diverse nonclonal E. cloacae genetic background. These findings highlight the potential complexity of a KPC outbreak at a single hospital. PMID:23637289

  1. SHV-Type Extended-Spectrum Beta-Lactamase Production Is Associated with Reduced Cefepime Susceptibility in Enterobacter cloacae

    PubMed Central

    Szabó, Dóra; Bonomo, Robert A.; Silveira, Fernanda; Pasculle, A. William; Baxter, Carla; Linden, Peter K.; Hujer, Andrea M.; Hujer, Kristine M.; Deeley, Kathleen; Paterson, David L.

    2005-01-01

    Cefepime is a potentially useful antibiotic for treatment of infections with Enterobacter cloacae. However, in our institution the MIC90 for E. cloacae bloodstream isolates is 16 μg/ml. PCR amplification of bla genes revealed that one-third (15/45) of E. cloacae bloodstream isolates produced SHV-type extended-spectrum beta-lactamases (ESBLs) in addition to hyperproduction of AmpC-type beta-lactamases. The majority (11/15) of ESBL producers also produced the TEM-1 beta-lactamase. The SHV types included SHV-2, -5, -7, -12, -14, and -30. All but two of the ESBL-producing E. cloacae isolates, but none of the non-ESBL-producing strains, had MICs of cefepime of ≥2 μg/ml. The MIC90 for cefepime for ESBL-producing strains was 64 μg/ml, while for non-ESBL producers it was 0.5 μg/ml. Using current Clinical and Laboratory Standards Institute breakpoints for cefepime, two thirds (10/15) of ESBL-producing isolates would have been regarded as susceptible to cefepime. Phenotypic ESBL detection methods were generally unreliable with these E. cloacae isolates. Based on these results, pharmacokinetic, pharmacodynamic, and clinical reevaluation of cefepime breakpoints for E. cloacae may be prudent. PMID:16207962

  2. Effect of crude glycerol-derived inhibitors on ethanol production by Enterobacter aerogenes.

    PubMed

    Lee, Sang Jun; Kim, Sung Bong; Kang, Seong Woo; Han, Sung Ok; Park, Chulhwan; Kim, Seung Wook

    2012-01-01

    In this study, ethanol production from pure and crude glycerol using Enterobacter aerogenes ATCC 29007 was evaluated under anaerobic culture conditions. Inhibitory effects of substrate concentrations, pH, and salt concentrations were investigated based on crude glycerol components. Ethanol production was performed with pure glycerol concentrations ranging from 5 to 30 g/L to evaluate the effects of substrate concentration and osmotic pressure. The consumed glycerol was 5-14.33 g/L, and the yield of ethanol was higher than 0.75 mol ethanol/mol glycerol after 24 h of cultivation. To evaluate the inhibitory effects of salts (NaCl and KCl), experiments were performed with 0-20 g/L of each salt. Inhibitory effects of salts were strongest at high salt concentrations. The inhibitory effect of pH was performed in the pH range 4-10, and cell growth and ethanol production were highest at pH 5-6. Also, ethanol production was slightly inhibited at low concentration of crude glycerol comparison with pure glycerol. However, significant inhibitory effects were not observed at 1.5 and 2% crude glycerol which showed higher ethanol production compared to pure glycerol.

  3. Nucleotide sequence and expression of the Enterobacter aerogenes alpha-acetolactate decarboxylase gene in brewer's yeast.

    PubMed Central

    Sone, H; Fujii, T; Kondo, K; Shimizu, F; Tanaka, J; Inoue, T

    1988-01-01

    The nucleotide sequence of a 1.4-kilobase DNA fragment containing the alpha-acetolactate decarboxylase gene of Enterobacter aerogenes was determined. The sequence contains an entire protein-coding region of 780 nucleotides which encodes an alpha-acetolactate decarboxylase of 260 amino acids. The DNA sequence coding for alpha-acetolactate decarboxylase was placed under the control of the alcohol dehydrogenase I promoter of the yeast Saccharomyces cerevisiae in a plasmid capable of autonomous replication in both S. cerevisiae and Escherichia coli. Brewer's yeast cells transformed by this plasmid showed alpha-acetolactate decarboxylase activity and were used in laboratory-scale fermentation experiments. These experiments revealed that the diacetyl concentration in wort fermented by the plasmid-containing yeast strain was significantly lower than that in wort fermented by the parental strain. These results indicated that the alpha-acetolactate decarboxylase activity produced by brewer's yeast cells degraded alpha-acetolactate and that this degradation caused a decrease in diacetyl production. PMID:3278689

  4. Biodegradation of acrylamide by Enterobacter aerogenes isolated from wastewater in Thailand.

    PubMed

    Buranasilp, Kanokhathai; Charoenpanich, Jittima

    2011-01-01

    A widespread use of acrylamide, probably a neurotoxicant and carcinogen, in various industrial processes has led to environmental contamination. Fortunately, some microorganisms are able to derive energy from acrylamide. In the present work, we reported the isolation and characterization of a novel acrylamide-degrading bacterium from domestic wastewater in Chonburi, Thailand. The strain grew well in the presence of acrylamide as 0.5% (W/V), at pH 6.0 to 9.0 and 25 degrees C. Identification based on biochemical characteristics and 16S rRNA gene sequence identified the strain as Enterobacter aerogenes. Degradation of acrylamide to acrylic acid started in the late logarithmic growth phase as a biomass-dependent pattern. Specificity of cell-free supernatant towards amides completely degraded butyramide and urea and 86% of lactamide. Moderate degradation took place in other amides with that by formamide > benzamide > acetamide > cyanoacetamide > propionamide. No degradation was detected in the reactions of N,N-methylene bisacrylamide, sodium azide, thioacetamide, and iodoacetamide. These results highlighted the potential of this bacterium in the cleanup of acrylamide/amide in the environment.

  5. Optimization of organosolv pretreatment of rice straw for enhanced biohydrogen production using Enterobacter aerogenes.

    PubMed

    Asadi, Nooshin; Zilouei, Hamid

    2017-03-01

    Ethanol organosolv pretreated rice straw was used to produce biohydrogen using Enterobacter aerogenes. The effect of temperature (120-180°C), residence time (30-90min), and ethanol concentration (45-75%v/v) on the hydrogen yield, residual biomass, and lignin recovery was investigated using RSM. In contrast to the residual solid and lignin recovery, no considerable trend could be observed for the changes in the hydrogen yield at different treatment severities. The maximum hydrogen yield of 19.73mlg(-1) straw was obtained at the ethanol concentration of 45%v/v and 180°C for 30min. Furthermore, the potential amount of biohydrogen was estimated in the top ten rice producing nations using the experimental results. Approximately 355.8kt of hydrogen and 11.3Mt of lignin could globally be produced. Based on a Monte Carlo analysis, the production of biohydrogen from rice straw has the lowest risk in China and the highest in Japan.

  6. Optimization of cultural conditions for conversion of glycerol to ethanol by Enterobacter aerogenes S012

    PubMed Central

    2013-01-01

    The aim of this research is to optimize the cultural conditions for the conversion of glycerol to ethanol by Enterobacter aerogenes S012. Taguchi method was used to screen the cultural conditions based on their signal to noise ratio (SN). Temperature (°C), agitation speed (rpm) and time (h) were found to have the highest influence on both glycerol utilization and ethanol production by the organism while pH had the lowest. Full factorial design, statistical analysis, and regression model equation were used to optimize the selected cultural parameters for maximum ethanol production. The result showed that fermentation at 38°C and 200 rpm for 48 h would be ideal for the bacteria to produce maximum amount of ethanol from glycerol. At these optimum conditions, ethanol production, yield and productivity were 25.4 g/l, 0.53 g/l/h, and 1.12 mol/mol-glycerol, repectively. Ethanol production increased to 26.5 g/l while yield and productivity decreased to 1.04 mol/mol-glycerol and 0.37 g/l/h, respectively, after 72 h. Analysis of the fermentation products was performed using HPLC, while anaerobic condition was created by purging the fermentation vessel with nitrogen gas. PMID:23388539

  7. Improved hydrogen production under microaerophilic conditions by overexpression of polyphosphate kinase in Enterobacter aerogenes.

    PubMed

    Lu, Yuan; Zhang, Chong; Lai, Qiheng; Zhao, Hongxin; Xing, Xin-Hui

    2011-02-08

    Effects of different microaerophilic conditions on cell growth, glucose consumption, hydrogen production and cellular metabolism of wild Enterobacter aerogenes strain and polyphosphate kinase (PPK) overexpressing strain were systematically studied in this paper, using NaH(2)PO(4) as the phosphate sources. Under different microaerophilic conditions, PPK-overexpressing strain showed better cell growth, glucose consumption and hydrogen production than the wild strain. In the presence of limited oxygen (2.1%) and by PPK overexpression, the hydrogen production per liter of culture, the hydrogen production per cell and the hydrogen yield per mol of glucose increased by 20.1%, 12.3% and 10.8%, respectively, compared with the wild strain under strict anaerobic conditions. Metabolic analysis showed that the increase of the total hydrogen yield was attributed to the improvement of NADH pathway. The result of more reductive cellular oxidation state balance also further demonstrated that, under proper initial microaerophilic conditions and by PPK overexpression, the cell could adjust the cellular redox states and make more energy flow into hydrogen production pathways.

  8. [Mechanisms of bioelectricity generation in Enterobacter aerogenes-based microbial fuel cells].

    PubMed

    Zhang, Jin-Tao; Zhou, Shun-Gui; Zhang, Li-Xia; Lu, Na; Deng, Li-Fang; Ni, Jin-Ren

    2009-04-15

    Microbial fuel cells (MFCs) using hydrogen-producing bacteria (HPB) could utilize a large number of substrates to generate power. However, the coulombic efficiency is limited by the fact that only suspended cells are used as biocatalyst in anodic medium. MFCs using Fe (III)-reducing bacteria have high energy recovery efficiency, but can only utilize some simple organic matters. In this study, Enterobacter aerogenes XM02, a hydrogen-producing strain with Fe(III)-reducing activity, was selected as biocatalyst for MFCs, which could produce electricity by digesting lots of carbohydrates even starch. Graphite felt, a material with high specific surface area and hydrogen catalysis, instead of carbon paper supported platinum, was used as anode material. The coulombic efficiency had been substantially improved from 1.68% to 42.49%, higher than other HPB-based MFCs previously reported. The SEM image proved the ability of XM02 strain to colonize on the anode surface. Power generation of MFCs could restore quickly when anodic medium was completely replaced with non-growth medium containing glucose. This suggested that the attached cells contributed to electricity production because planktonic cells had been removed during the medium replacement. This study proposed the mechanism of power generated from in situ oxidation of hydrogen produced by the XM02 strain biofilm.

  9. Draft Genome Sequence of a High-Level Colistin-Resistant Clinical Strain of the Enterobacter cloacae Complex

    PubMed Central

    Lin, Ji; Zhao, Feifei; Feng, Yu

    2017-01-01

    ABSTRACT Strain WCHECl-C4 of the Enterobacter cloacae complex, recovered from the blood of a patient with peritonitis, was high-level resistant to colistin. Here, we report its 5.1-Mb draft genome sequence, comprising 92 contigs with an average 55.74% G+C content. The genome contained 4,783 coding sequences and 68 tRNA genes. PMID:28385849

  10. Draft Whole-Genome Sequence of VIM-1-Producing Multidrug-Resistant Enterobacter cloacae EC_38VIM1

    PubMed Central

    Villa, Jennifer; Viedma, Esther; Otero, Joaquín R.

    2013-01-01

    The VIM-1-producing multidrug-resistant strain Enterobacter cloacae was isolated from blood culture. The strain showed multiple resistances to clinically used antibiotics, including all β-lactams, fluoroquinolones, aminoglycosides, and sulfonamides. Sequence analysis showed the presence of 14 genes associated with resistance to antibiotics, including the metallo-β-lactamase VIM-1 gene, which was located in a class 1 integron. PMID:24009122

  11. Complete Sequence of a blaOXA-48-Harboring IncL Plasmid from an Enterobacter cloacae Clinical Isolate.

    PubMed

    Manageiro, Vera; Pinto, Margarida; Caniça, Manuela

    2015-09-17

    We report a 63,584-bp conjugative IncL plasmid (pUR17313-1) from an Enterobacter cloacae clinical isolate, containing a blaOXA-48 gene. The plasmid sequence also carried important mobile genetic elements involved in the spread of antibiotic resistance, namely, the Tn1999.2 composite transposon, which enclosed blaOXA-48-, integrase-, and transposase-encoding genes.

  12. Complete Sequence of a blaOXA-48-Harboring IncL Plasmid from an Enterobacter cloacae Clinical Isolate

    PubMed Central

    Pinto, Margarida

    2015-01-01

    We report a 63,584-bp conjugative IncL plasmid (pUR17313-1) from an Enterobacter cloacae clinical isolate, containing a blaOXA-48 gene. The plasmid sequence also carried important mobile genetic elements involved in the spread of antibiotic resistance, namely, the Tn1999.2 composite transposon, which enclosed blaOXA-48-, integrase-, and transposase-encoding genes. PMID:26383652

  13. Metal Accumulation and Vanadium-Induced Multidrug Resistance by Environmental Isolates of Escherichia hermannii and Enterobacter cloacae

    PubMed Central

    Hernández, Alicia; Mellado, Rafael P.; Martínez, José L.

    1998-01-01

    Contaminated soils from an oil refinery were screened for the presence of microorganisms capable of accumulating either nickel, vanadium, or both metals. Three strains of bacteria that belonged to the family Enterobacteriaceae were selected. Two of them were Escherichia hermannii strains, and outer membrane profile (OMP) analysis showed that they were similar to a strain of clinical origin; the other one was an Enterobacter cloacae strain that differed from clinical isolates. The selected bacteria accumulated both nickel and vanadium. Growth in the presence of vanadium induced multidrug resistance phenotypes in E. hermannii and E. cloacae. Incubation with this metal changed the OMP profile of E. hermannii but did not produce variations in the expression of the major OMPs of E. cloacae. PMID:9797283

  14. Genome Sequence of Enterobacter cloacae Strain SENG-6, a Bacterium Producing Histo-Blood Group Antigen-Like Substances That Can Bind with Human Noroviruses

    PubMed Central

    Amarasiri, Mohan; Hashiba, Satoshi; Yang, Peiyi; Okabe, Satoshi

    2016-01-01

    Enterobacter sp. strain SENG-6, isolated from healthy human feces, produces histo-blood group antigen (HBGA)-like substances that can bind with human noroviruses. Based on the genome sequence analysis, strain SENG-6 belongs to the species Enterobacter cloacae. The genome sequence of this strain should help identify genes associated with the production of HBGA-like substances. PMID:27563051

  15. Genome Sequence of Enterobacter cloacae Strain SENG-6, a Bacterium Producing Histo-Blood Group Antigen-Like Substances That Can Bind with Human Noroviruses.

    PubMed

    Ishii, Satoshi; Amarasiri, Mohan; Hashiba, Satoshi; Yang, Peiyi; Okabe, Satoshi; Sano, Daisuke

    2016-08-25

    Enterobacter sp. strain SENG-6, isolated from healthy human feces, produces histo-blood group antigen (HBGA)-like substances that can bind with human noroviruses. Based on the genome sequence analysis, strain SENG-6 belongs to the species Enterobacter cloacae The genome sequence of this strain should help identify genes associated with the production of HBGA-like substances.

  16. Dominance of IMP-4-Producing Enterobacter cloacae among Carbapenemase-Producing Enterobacteriaceae in Australia

    PubMed Central

    Townell, Nicola; Nimmo, Graeme R.; George, Narelle M.; Robson, Jennifer; Vohra, Renu; Davis, Louise; Heney, Claire; Paterson, David L.

    2015-01-01

    The prevalence of carbapenemase-producing Enterobacteriaceae (CPE) has been increasing worldwide. blaIMP has been reported to be the predominant carbapenemase-encoding gene within Enterobacteriaceae in Australia. However, there are limited data currently available on CPE from Queensland, Australia. A total of 58 CPE isolates were isolated between July 2009 and March 2014 from Queensland hospitals. The clonality of isolates was determined by Diversilab repetitive sequence-based PCR. The isolates were investigated for the resistance mechanisms carbapenemase, extended-spectrum β-lactamase, and AmpC β-lactamase and for aminoglycoside resistance and plasmid-mediated quinolone resistance genes by PCR. The plasmid types associated with carbapenemase-encoding genes were characterized. The majority of the CPE were Enterobacter cloacae (n = 29). The majority of Queensland CPE isolates were IMP producers and comprised 11 species (n = 48). Nine NDM-producing Enterobacteriaceae were identified. One NDM-producing Klebsiella pneumoniae isolate coproduced OXA-48. One K. pneumoniae isolate was an OXA-181 producer. The incidence of IMP producers increased significantly in 2013. blaIMP-4 was found in all IMP-producing isolates. blaTEM, qnrB, and aacA4 were common among IMP-4 producers. The HI2 (67%) and L/M (21%) replicons were associated with blaIMP-4. All HI2 plasmids were of sequence type 1 (ST1). All but one of the NDM producers possessed blaCTX-M-15. The 16S rRNA methylase genes found among NDM producers were armA, rmtB, rmtC, and rmtF. The substantial increase in the prevalence of CPE in Queensland has been associated mainly with the emergence E. cloacae strains possessing HI2 plasmids carrying blaIMP-4 over the past 2 years. The importation of NDM producers and/or OXA-48-like producers in patients also contributed to the increased emergence of CPE. PMID:25918153

  17. Dominance of IMP-4-producing enterobacter cloacae among carbapenemase-producing Enterobacteriaceae in Australia.

    PubMed

    Sidjabat, Hanna E; Townell, Nicola; Nimmo, Graeme R; George, Narelle M; Robson, Jennifer; Vohra, Renu; Davis, Louise; Heney, Claire; Paterson, David L

    2015-07-01

    The prevalence of carbapenemase-producing Enterobacteriaceae (CPE) has been increasing worldwide. blaIMP has been reported to be the predominant carbapenemase-encoding gene within Enterobacteriaceae in Australia. However, there are limited data currently available on CPE from Queensland, Australia. A total of 58 CPE isolates were isolated between July 2009 and March 2014 from Queensland hospitals. The clonality of isolates was determined by Diversilab repetitive sequence-based PCR. The isolates were investigated for the resistance mechanisms carbapenemase, extended-spectrum β-lactamase, and AmpC β-lactamase and for aminoglycoside resistance and plasmid-mediated quinolone resistance genes by PCR. The plasmid types associated with carbapenemase-encoding genes were characterized. The majority of the CPE were Enterobacter cloacae (n = 29). The majority of Queensland CPE isolates were IMP producers and comprised 11 species (n = 48). Nine NDM-producing Enterobacteriaceae were identified. One NDM-producing Klebsiella pneumoniae isolate coproduced OXA-48. One K. pneumoniae isolate was an OXA-181 producer. The incidence of IMP producers increased significantly in 2013. blaIMP-4 was found in all IMP-producing isolates. blaTEM, qnrB, and aacA4 were common among IMP-4 producers. The HI2 (67%) and L/M (21%) replicons were associated with blaIMP-4. All HI2 plasmids were of sequence type 1 (ST1). All but one of the NDM producers possessed blaCTX-M-15. The 16S rRNA methylase genes found among NDM producers were armA, rmtB, rmtC, and rmtF. The substantial increase in the prevalence of CPE in Queensland has been associated mainly with the emergence E. cloacae strains possessing HI2 plasmids carrying blaIMP-4 over the past 2 years. The importation of NDM producers and/or OXA-48-like producers in patients also contributed to the increased emergence of CPE.

  18. Importance of pfkA for rapid growth of Enterobacter cloacae during colonization of crop seeds.

    PubMed

    Roberts, D P; Dery, P D; Yucel, I; Buyer, J S

    2000-01-01

    Enterobacter cloacae A-11 is a prototrophic, glycolytic mutant of strain 501R3 with a single transposon insertion in pfkA. The populations of strain A-11 on cucumber and radish seeds were smaller than the populations of strain 501R3 in natural soil, but the populations of these two strains on pea, soybean, sunflower, and sweet corn seeds were similar (D. P. Roberts, P. D. Dery, I. Yucel, J. Buyer, M. A. Holtman, and D. Y. Kobayashi, Appl. Environ. Microbiol. 65:2513-2519, 1999). The net effect of the mutation in pfkA in vitro was a shift from rapid growth on certain carbohydrates detected in seed exudates to much slower growth on other carbohydrates, amino acids, and organic acids. The impact of the mutation in pfkA was greatest on the growth rate of E. cloacae on the seeds that released the smallest quantities of fructose, other carbohydrates, and amino acids. Corn, pea, soybean, and sunflower seeds released total amounts of carbohydrates and amino acids at rates that were approximately 10- to 100-fold greater than the rates observed with cucumber and radish seeds for the first 24 h after inhibition began. The growth rate of strain A-11 was significantly less (50% less) than the growth rate of strain 501R3 on radish seeds, and the growth rate of strain A-11 was too low to estimate on cucumber seeds in sterile sand for the first 24 h after inhibition began. The growth rate of strain A-11 was also significantly lower on soybean seeds, but it was only 17% lower than the growth rate of strain 501R3. The growth rates of strains 501R3 and A-11 were similar on pea, sunflower, and corn seeds in sterile sand for the first 30 h after imbibition began. Large reductions in the growth rates of strain A-11 on seeds were correlated with subsequent decreased levels of colonization of seeds compared to the levels of colonization of strain 501R3. The strain A-11 populations were significantly smaller than the strain 501R3 populations only on radish and cucumber seeds. The mutation

  19. Infections with VIM-1 Metallo-β-Lactamase-Producing Enterobacter cloacae and Their Correlation with Clinical Outcome▿

    PubMed Central

    Falcone, Marco; Mezzatesta, Maria Lina; Perilli, Mariagrazia; Forcella, Chiara; Giordano, Alessandra; Cafiso, Viviana; Amicosante, Gianfranco; Stefani, Stefania; Venditti, Mario

    2009-01-01

    The aim of this study was to ascertain the incidence and clinical significance of metallo-β-lactamases among Enterobacter strains isolated from patients with nosocomial infections. We prospectively collected data on patients with Enterobacter infection during a 13-month period. All of the strains were investigated for antibiotic susceptibility, the presence and expression of metallo-β-lactamases, and clonality. Of 29 infections (11 involving the urinary tract, 7 pneumonias, 3 skin/soft tissue infections, 3 intra-abdominal infections, 3 bacteremias, and 2 other infections), 7 (24%) were caused by Enterobacter cloacae strains harboring a blaVIM-1 gene associated or not with a blaSHV12 gene. Infections caused by VIM-1-producing strains were more frequently associated with a recent prior hospitalization (P = 0.006), cirrhosis (P = 0.03), relapse of infection (P < 0.001), and more prolonged duration of antibiotic therapy (P = 0.01) than were other infections. All of the isolates were susceptible to imipenem and meropenem and had blaVIM-1 preceded by a weak P1 promoter and inactivated P2 promoters. Most VIM-1-producing Enterobacter isolates belonged to a main clone, but four different clones were found. Multiclonal VIM-1-producing E. cloacae infections are difficult to diagnose due to an apparent susceptibility to various beta-lactams, including carbapenems, and are associated with a high relapse rate and a more prolonged duration of antibiotic therapy. PMID:19741074

  20. Detecting the form of selection in the outer membrane protein C of Enterobacter aerogenes strains and Salmonella species.

    PubMed

    Padhi, Abinash; Verghese, Bindhu; Otta, Subhendu K

    2009-01-01

    The types of selective pressure operating on the outer membrane protein C (ompC) of Enterobacter aerogenes strains, the causative agent for nosocomial infections, and Salmonella sp., the hazardous pathogen are investigated using the maximum likelihood-based codon substitution models. Although the rate of amino acid replacement to the silent substitution (omega) across the entire codon sites of ompC of E. aerogenes (omega=0.3194) and Salmonella sp. (omega=0.2047) indicate that the gene is subjected to purifying selection (i.e. omega<1), approximately 3.7% of ompC codon sites in E. aerogenes (omega=21.52) are under the influence of positive Darwinian selection (i.e. omega>1). Such contrast in the intensity of selective pressures in both pathogens could be associated with the differential response to the adverse environmental changes. In E. aerogenes, majority of the positively selected sites are located in the hypervariable cell-surface-exposed domains whereas the trans-membrane domains are functionally highly constrained.

  1. Fluoroquinolone Resistance Mechanisms and population structure of Enterobacter cloacae non-susceptible to Ertapenem in North-Eastern France

    PubMed Central

    Guillard, Thomas; Cholley, Pascal; Limelette, Anne; Hocquet, Didier; Matton, Lucie; Guyeux, Christophe; Lebreil, Anne-Laure; Bajolet, Odile; Brasme, Lucien; Madoux, Janick; Vernet-Garnier, Véronique; Barbe, Coralie; Bertrand, Xavier; de Champs on behalf of CarbaFrEst Group, Christophe

    2015-01-01

    Fluoroquinolone (FQ) agents are a potential resort to treat infection due to Enterobacteriaceae producing extended spectrum β-lactamase and susceptible to FQ. In a context of increase of non-susceptibility to carbapenems among Enterobacteriaceae, we characterized FQ resistance mechanisms in 75 Enterobacter cloacae isolates non-susceptible to ertapenem in North-Eastern France in 2012 and describe the population structure by pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Among them, 14.7% (12/75) carried a carbapenemase-encoding gene. Except one isolate producing VIM-1, the carbapenemase-producing isolates carried the well-known IncL/M pOXA48a plasmid. Most of the isolates (59/75) harbored at least a FQ-R determinant. qnr genes were predominant (40%, 30/75). The MLST study revealed that E. cloacae isolates’ clonality was wide [24 different sequence types (STs)]. The more widespread STs were ST74, ST101, ST110, ST114, and ST133. Carbapenem MICs were higher for E. cloacae ST74 than for other E. cloacae isolates. Plasmid-mediated quinolone resistance determinants were more often observed in E. cloacae ST74 isolates. These findings showed that (i) pOXA-48a is spreading in North-Eastern France, (ii) qnr is preponderant in E. cloacae, (iii) E. cloacae comprised a large amount of lineages spreading in North-Eastern France, and (iv) FQ as an alternative to β-lactams to treat ertapenem non-susceptible Enterobacteriaceae are compromised. PMID:26557115

  2. Fluoroquinolone Resistance Mechanisms and population structure of Enterobacter cloacae non-susceptible to Ertapenem in North-Eastern France.

    PubMed

    Guillard, Thomas; Cholley, Pascal; Limelette, Anne; Hocquet, Didier; Matton, Lucie; Guyeux, Christophe; Lebreil, Anne-Laure; Bajolet, Odile; Brasme, Lucien; Madoux, Janick; Vernet-Garnier, Véronique; Barbe, Coralie; Bertrand, Xavier; de Champs On Behalf Of CarbaFrEst Group, Christophe

    2015-01-01

    Fluoroquinolone (FQ) agents are a potential resort to treat infection due to Enterobacteriaceae producing extended spectrum β-lactamase and susceptible to FQ. In a context of increase of non-susceptibility to carbapenems among Enterobacteriaceae, we characterized FQ resistance mechanisms in 75 Enterobacter cloacae isolates non-susceptible to ertapenem in North-Eastern France in 2012 and describe the population structure by pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Among them, 14.7% (12/75) carried a carbapenemase-encoding gene. Except one isolate producing VIM-1, the carbapenemase-producing isolates carried the well-known IncL/M pOXA48a plasmid. Most of the isolates (59/75) harbored at least a FQ-R determinant. qnr genes were predominant (40%, 30/75). The MLST study revealed that E. cloacae isolates' clonality was wide [24 different sequence types (STs)]. The more widespread STs were ST74, ST101, ST110, ST114, and ST133. Carbapenem MICs were higher for E. cloacae ST74 than for other E. cloacae isolates. Plasmid-mediated quinolone resistance determinants were more often observed in E. cloacae ST74 isolates. These findings showed that (i) pOXA-48a is spreading in North-Eastern France, (ii) qnr is preponderant in E. cloacae, (iii) E. cloacae comprised a large amount of lineages spreading in North-Eastern France, and (iv) FQ as an alternative to β-lactams to treat ertapenem non-susceptible Enterobacteriaceae are compromised.

  3. Bioremediation of hexavalent chromium (VI) by a soil-borne bacterium, Enterobacter cloacae B2-DHA.

    PubMed

    Rahman, Aminur; Nahar, Noor; Nawani, Neelu N; Jass, Jana; Hossain, Khaled; Saud, Zahangir Alam; Saha, Ananda K; Ghosh, Sibdas; Olsson, Björn; Mandal, Abul

    2015-01-01

    Chromium and chromium containing compounds are discharged into the nature as waste from anthropogenic activities, such as industries, agriculture, forest farming, mining and metallurgy. Continued disposal of these compounds to the environment leads to development of various lethal diseases in both humans and animals. In this paper, we report a soil borne bacterium, B2-DHA that can be used as a vehicle to effectively remove chromium from the contaminated sources. B2-DHA is resistant to chromium with a MIC value of 1000 µg mL(-1) potassium chromate. The bacterium has been identified as a Gram negative, Enterobacter cloacae based on biochemical characteristics and 16S rRNA gene analysis. TOF-SIMS and ICP-MS analyses confirmed intracellular accumulation of chromium and thus its removal from the contaminated liquid medium. Chromium accumulation in cells was 320 µg/g of cells dry biomass after 120-h exposure, and thus it reduced the chromium concentration in the liquid medium by as much as 81%. Environmental scanning electron micrograph revealed the effect of metals on cellular morphology of the isolates. Altogether, our results indicate that B2-DHA has the potential to reduce chromium significantly to safe levels from the contaminated environments and suggest the potential use of this bacterium in reducing human exposure to chromium, hence avoiding poisoning.

  4. Long-term arsenic monitoring with an Enterobacter cloacae microbial fuel cell.

    PubMed

    Rasmussen, Michelle; Minteer, Shelley D

    2015-12-01

    A microbial fuel cell was constructed with biofilms of Enterobacter cloacae grown on the anode. Bioelectrocatalysis was observed when the biofilm was grown in media containing sucrose as the carbon source and methylene blue as the mediator. The presence of arsenic caused a decrease in bioelectrocatalytic current. Biofilm growth in the presence of arsenic resulted in lower power outputs whereas addition of arsenic showed no immediate result in power output due to the short term arsenic resistance of the bacteria and slow transport of arsenic across cellular membranes to metabolic enzymes. Calibration curves plotted from the maximum current and maximum power of power curves after growth show that this system is able to quantify both arsenate and arsenate with low detection limits (46 μM for arsenate and 4.4 μM for arsenite). This system could be implemented as a method for long-term monitoring of arsenic concentration in environments where arsenic contamination could occur and alter the metabolism of the organisms resulting in a decrease in power output of the self-powered sensor.

  5. CdiA from Enterobacter cloacae delivers a toxic ribosomal RNase into target bacteria

    PubMed Central

    Beck, Christina M.; Morse, Robert P.; Cunningham, David A.; Iniguez, Angelina; Low, David A.; Goulding, Celia W.; Hayes, Christopher S.

    2014-01-01

    Summary Contact-dependent growth inhibition (CDI) is one mechanism of inter-bacterial competition. CDI+ cells export large CdiA effector proteins, which carry a variety of C-terminal toxin domains (CdiA-CT). CdiA-CT toxins are specifically neutralized by cognate CdiI immunity proteins to protect toxin-producing cells from auto-inhibition. Here, we use structure determination to elucidate the activity of a unique CDI toxin from Enterobacter cloacae (ECL). The structure of CdiA-CTECL resembles the C-terminal nuclease domain of colicin E3, which cleaves 16S ribosomal RNA to disrupt protein synthesis. In accord with this structural homology, we show that CdiA-CTECL uses the same nuclease activity to inhibit bacterial growth. Surprisingly, although colicin E3 and CdiAECL carry equivalent toxin domains, the corresponding immunity proteins are unrelated in sequence, structure and toxin-binding site. Together, these findings reveal unexpected diversity amongst 16S rRNases and suggest that these nucleases are robust and versatile payloads for a variety of toxin-delivery platforms. PMID:24657090

  6. Longer Contact Times Increase Cross-Contamination of Enterobacter aerogenes from Surfaces to Food.

    PubMed

    Miranda, Robyn C; Schaffner, Donald W

    2016-11-01

    Bacterial cross-contamination from surfaces to food can contribute to foodborne disease. The cross-contamination rate of Enterobacter aerogenes on household surfaces was evaluated by using scenarios that differed by surface type, food type, contact time (<1, 5, 30, and 300 s), and inoculum matrix (tryptic soy broth or peptone buffer). The surfaces used were stainless steel, tile, wood, and carpet. The food types were watermelon, bread, bread with butter, and gummy candy. Surfaces (25 cm(2)) were spot inoculated with 1 ml of inoculum and allowed to dry for 5 h, yielding an approximate concentration of 10(7) CFU/surface. Foods (with a 16-cm(2) contact area) were dropped onto the surfaces from a height of 12.5 cm and left to rest as appropriate. Posttransfer, surfaces and foods were placed in sterile filter bags and homogenized or massaged, diluted, and plated on tryptic soy agar. The transfer rate was quantified as the log percent transfer from the surface to the food. Contact time, food, and surface type all had highly significant effects (P < 0.000001) on the log percent transfer of bacteria. The inoculum matrix (tryptic soy broth or peptone buffer) also had a significant effect on transfer (P = 0.013), and most interaction terms were significant. More bacteria transferred to watermelon (∼0.2 to 97%) than to any other food, while the least bacteria transferred to gummy candy (∼0.1 to 62%). Transfer of bacteria to bread (∼0.02 to 94%) was similar to transfer of bacteria to bread with butter (∼0.02 to 82%), and these transfer rates under a given set of conditions were more variable than with watermelon and gummy candy.

  7. Bioproduction of D-psicose from allitol with Enterobacter aerogenes IK7: a new frontier in rare ketose production.

    PubMed

    Gullapalli, Pushpakiran; Takata, Goro; Poonperm, Wayoon; Rao, Devendar; Morimoto, Kenji; Akimitsu, Kazuya; Tajima, Shigeyuki; Izumori, Ken

    2007-12-01

    D-psicose, a new alternative sweetener, was produced from allitol by microbial oxidation of the newly isolated strain Enterobacter aerogenes IK7. Cells grown in tryptic soy broth medium (TSB) supplemented with D-mannitol at 37 degrees C were found to have the best oxidation potential. The cells, owing to broad substrate specificity, oxidized various polyols (tetritol, pentitol, and hexitol) to corresponding rare ketoses. By a resting cell reaction, 10% of allitol was completely transformed to the product D-psicose, which thus becomes economically feasible for the mass production of D-psicose. Finally, the product was crystallized and confirmed to be D-psicose by analytical methods.

  8. Expression of NAD+-dependent formate dehydrogenase in Enterobacter aerogenes and its involvement in anaerobic metabolism and H2 production.

    PubMed

    Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Lai, Qiheng; Wu, Xi; Xing, Xin-Hui

    2009-10-01

    An expression system for NAD(+)-dependent formate dehydrogenase gene (fdh1), from Candida boidinii, was constructed and cloned into Enterobacter aerogenes IAM1183. With the fdh1 expression, the total H(2) yield was attributed to a decrease in activity of the lactate pathway and an increase of the formate pathway flux due to the NADH regeneration. Analysis of the redox state balance and ethanol-to-acetate ratio in the fdhl-expressed strain showed that increased reducing power arose from the reconstruction of NADH regeneration pathway from formate thereby contributing to the improved H(2) production.

  9. Investigation and control of an outbreak of Enterobacter aerogenes bloodstream infection in a neonatal intensive care unit in Fiji.

    PubMed

    Narayan, Swastika A; Kool, Jacob L; Vakololoma, Miriama; Steer, Andrew C; Mejia, Amelita; Drake, Anne; Jenney, Adam; Turton, Jane F; Kado, Joseph; Tikoduadua, Lisi

    2009-08-01

    Ten neonates developed blood stream infection with extended-spectrum beta-lactamase-producing Enterobacter aerogenes in a neonatal intensive care unit in Fiji. The source of the outbreak was traced to a bag of contaminated normal saline in the ward, which was used for multiple patients. All isolates recovered from patients were indistinguishable from the bacteria recovered from the normal saline by pulsed-field gel electrophoresis. The outbreak was controlled using simple infection control practices such as reinforcement of strict hand hygiene policy, provision of single use vials of normal saline, and strict aseptic technique for injections.

  10. Nosocomial outbreak due to extended-spectrum-beta-lactamase- producing Enterobacter cloacae in a cardiothoracic intensive care unit.

    PubMed

    Manzur, Adriana; Tubau, Fe; Pujol, Miquel; Calatayud, Laura; Dominguez, Maria Angeles; Peña, Carmen; Sora, Mercedes; Gudiol, Francesc; Ariza, Javier

    2007-08-01

    Enterobacter cloacae has been associated with several outbreaks, usually involving strains that overproduce chromosomal beta-lactamase or, uncommonly, strains expressing extended-spectrum beta-lactamases (ESBL). Only sporadic cases of ESBL-producing E. cloacae have been identified in our hospital in recent years. We describe the epidemiology and clinical and microbiological characteristics of an outbreak caused by ESBL-producing E. cloacae in a cardiothoracic intensive care unit (CT-ICU). Prospective surveillance of patients with infection or colonization by ESBL-producing E. cloacae among patients admitted to the CT-ICU was performed during the outbreak. Production of ESBL was determined by decreased susceptibility to expanded-spectrum cephalosporins and a positive double-disk test result. Clone relatedness was determined by pulsed-field gel electrophoresis (PFGE). From July to September 2005, seven patients in the CT-ICU with ESBL-producing E. cloacae were identified (four males; median age, 73 years; range, 45 to 76 years); six patients had cardiac surgery. Four patients developed infections; three had primary bacteremia, one had ventilator-associated pneumonia, and one had tracheobronchitis. ESBL-producing E. cloacae showed resistance to quinolones and aminoglycosides. PFGE revealed two patterns. Five isolates belonged to clone A; two carried a single ESBL (pI 8.2 and a positive PCR result for the SHV type), and three carried two ESBLs (pIs 8.1 and 8.2 and positive PCR results for the SHV and CTX-M-9 types). Isolates belonging to clone B carried a single ESBL (pI 5.4 and a positive PCR result for the TEM type). Review of antibiotic consumption showed increased use of cefepime and quinolones during June and July 2005. The outbreak was stopped by the implementation of barrier measures and cephalosporin restriction. ESBL production could be increasingly common in nosocomial pathogens other than Escherichia coli or Klebsiella pneumoniae.

  11. Characterization of the plant growth promoting bacterium, Enterobacter cloacae MSR1, isolated from roots of non-nodulating Medicago sativa.

    PubMed

    Khalifa, Ashraf Y Z; Alsyeeh, Abdel-Moneium; Almalki, Mohammed A; Saleh, Farag A

    2016-01-01

    The aim of the present study was to characterize the endophytic bacterial strain designated MSR1 that was isolated from inside the non-nodulating roots of Medicago sativa after surface-sterilization. MSR1 was identified as Enterobacter cloacae using both 16S rDNA gene sequence analysis and API20E biochemical identification system (Biomerieux, France). Furthermore, this bacterium was characterized using API50CH kit (Biomerieux, France) and tested for antibacterial activities against some food borne pathogens. The results showed that E. cloacae consumed certain carbohydrates such as glycerol, d-xylose, d-maltose and esculin melibiose as a sole carbon source and certain amino acids such as arginine, tryptophan ornithine as nitrogen source. Furthermore, MSR1 possessed multiple plant-growth promoting characteristics; phosphate solubility, production of phytohormones acetoin and bioactive compounds. Inoculation of Pisum sativum with MSR1 significantly improved the growth parameters (the length and dry weight) of this economically important grain legume compared to the non-treated plants. To our knowledge, this is the first report addressing E. cloacae which exist in roots of alfalfa growing in Al-Ahsaa region. The results confirmed that E. cloacae exhibited traits for plant growth promoting and could be developed as an eco-friendly biofertilizer for P. sativum and probably for other important plant species in future.

  12. EmmdR, a new member of the MATE family of multidrug transporters, extrudes quinolones from Enterobacter cloacae.

    PubMed

    He, Gui-Xin; Thorpe, Conner; Walsh, Dennis; Crow, Robert; Chen, Huizhong; Kumar, Sanath; Varela, Manuel F

    2011-10-01

    We cloned a gene, ECL_03329, from the chromosome of Enterobacter cloacae ATCC13047, using a drug-hypersensitive Escherichia coli KAM32 cell as the host. We show here that this gene, designated as emmdR, is responsible for multidrug resistance in E. cloacae. E. coli KAM32 host cells containing the cloned emmdR gene (KAM32/pEMMDR28) showed decreased susceptibilities to benzalkonium chloride, norfloxacin, ciprofloxacin, levofloxacin, ethidium bromide, acriflavine, rhodamine6G, and trimethoprim. emmdR-deficient E. cloacae cells (EcΔemmdR) showed increased susceptibilities to several of the antimicrobial agents tested. EmmdR has twelve predicted transmembrane segments and some shared identity with members of the multidrug and toxic compound extrusion (MATE) family of transporters. Study of the antimicrobial agent efflux activities revealed that EmmdR is an H+-drug antiporter but not a Na+ driven efflux pump. These results indicate that EmmdR is responsible for multidrug resistance and pumps out quinolones from E. cloacae.

  13. Characterization of the plant growth promoting bacterium, Enterobacter cloacae MSR1, isolated from roots of non-nodulating Medicago sativa

    PubMed Central

    Khalifa, Ashraf Y.Z.; Alsyeeh, Abdel-Moneium; Almalki, Mohammed A.; Saleh, Farag A.

    2015-01-01

    The aim of the present study was to characterize the endophytic bacterial strain designated MSR1 that was isolated from inside the non-nodulating roots of Medicago sativa after surface-sterilization. MSR1 was identified as Enterobacter cloacae using both 16S rDNA gene sequence analysis and API20E biochemical identification system (Biomerieux, France). Furthermore, this bacterium was characterized using API50CH kit (Biomerieux, France) and tested for antibacterial activities against some food borne pathogens. The results showed that E. cloacae consumed certain carbohydrates such as glycerol, d-xylose, d-maltose and esculin melibiose as a sole carbon source and certain amino acids such as arginine, tryptophan ornithine as nitrogen source. Furthermore, MSR1 possessed multiple plant-growth promoting characteristics; phosphate solubility, production of phytohormones acetoin and bioactive compounds. Inoculation of Pisum sativum with MSR1 significantly improved the growth parameters (the length and dry weight) of this economically important grain legume compared to the non-treated plants. To our knowledge, this is the first report addressing E. cloacae which exist in roots of alfalfa growing in Al-Ahsaa region. The results confirmed that E. cloacae exhibited traits for plant growth promoting and could be developed as an eco-friendly biofertilizer for P. sativum and probably for other important plant species in future. PMID:26858542

  14. Aerobic Degradation of 2,4,6-Trinitrotoluene by Enterobacter cloacae PB2 and by Pentaerythritol Tetranitrate Reductase

    PubMed Central

    French, Christopher E.; Nicklin, Stephen; Bruce, Neil C.

    1998-01-01

    Enterobacter cloacae PB2 was originally isolated on the basis of its ability to utilize nitrate esters, such as pentaerythritol tetranitrate (PETN) and glycerol trinitrate, as the sole nitrogen source for growth. The enzyme responsible is an NADPH-dependent reductase designated PETN reductase. E. cloacae PB2 was found to be capable of slow aerobic growth with 2,4,6-trinitrotoluene (TNT) as the sole nitrogen source. Dinitrotoluenes were not produced and could not be used as nitrogen sources. Purified PETN reductase was found to reduce TNT to its hydride-Meisenheimer complex, which was further reduced to the dihydride-Meisenheimer complex. Purified PETN reductase and recombinant Escherichia coli expressing PETN reductase were able to liberate nitrogen as nitrite from TNT. The ability to remove nitrogen from TNT suggests that PB2 or recombinant organisms expressing PETN reductase may be useful for bioremediation of TNT-contaminated soil and water. PMID:9687442

  15. Structure and genetics of the O-antigen of Enterobacter cloacae G3054 containing di-N-acetylpseudaminic acid.

    PubMed

    Perepelov, Andrei V; Wang, Min; Filatov, Andrei V; Guo, Xi; Shashkov, Alexander S; Wang, Lei; Knirel, Yuriy A

    2015-04-30

    Mild acid degradation of the lipopolysaccharide of Enterobacter cloacae G3054 resulted in the cleavage of the O-polysaccharide at the linkage of residues of 5,7-diacetamido-3,5,7,9-tetradeoxy-L-glycero-L-manno-non-2-ulosonic acid (di-N-acetylpseudaminic acid, Pse5Ac7Ac) in the main chain. The resultant oligosaccharide and an alkali-treated lipopolysaccharide were studied by sugar analysis along with (1)H and (13)C NMR spectroscopy, and the following structure of the branched pentasaccharide O-unit of the O-polysaccharide was established: [structure: see text] The O-antigen gene cluster of E. cloacae G3054 between conserved genes galF and gnd was sequenced. Most genes necessary for the O-antigen synthesis were found in the cluster and their functions were tentatively assigned by comparison with sequences in the available databases.

  16. Aerobic degradation of 2,4,6-trinitrotoluene by Enterobacter cloacae PB2 and by pentaerythritol tetranitrate reductase

    SciTech Connect

    French, C.E.; Bruce, N.C.; Nicklin, S.

    1998-08-01

    Enterobacter cloacae PB2 was originally isolated on the basis of its ability to utilize nitrate esters, such as pentaerythritol tetranitrate (PETN) and glycerol trinitrate, as the sole nitrogen source for growth. The enzyme responsible is an NADPH-dependent reductase designated PETN reductase. E. cloacae PB2 was found to be capable of slow aerobic growth with 2,4,6-trinitrotoluene (TNT) as the sole nitrogen source. Dinitrotoluenes were not produced and could not be used as nitrogen sources. Purified PETN reductase was found to reduce TNT to its hydride-Meisenheimer complex, which was further reduced to the dihydride-Meisenheimer complex. Purified PETN reductase and recombinant Escherichia coli expressing PETN reductase were able to liberate nitrogen as nitrite from TNT. The ability to remove nitrogen from TNT suggests that PB2 or recombinant organisms expressing PETN reductase may be useful for bioremediation of TNT-contaminated soil and water.

  17. Landscape of Resistance-Nodulation-Cell Division (RND)-Type Efflux Pumps in Enterobacter cloacae Complex.

    PubMed

    Guérin, François; Lallement, Claire; Isnard, Christophe; Dhalluin, Anne; Cattoir, Vincent; Giard, Jean-Christophe

    2016-04-01

    In Gram-negative bacteria, the active efflux is an important mechanism of antimicrobial resistance, but little is known about theEnterobacter cloacaecomplex (ECC). It is mediated primarily by pumps belonging to the RND (resistance-nodulation-cell division) family, and only AcrB, part of the AcrAB-TolC tripartite system, was characterized in ECC. However, detailed genome sequence analysis of the strainE. cloacaesubsp.cloacaeATCC 13047 revealed to us that 10 other genes putatively coded for RND-type transporters. We then characterized the role of all of these candidates by construction of corresponding deletion mutants, which were tested for their antimicrobial susceptibility to 36 compounds, their virulence in the invertebrateGalleria mellonellamodel of infection, and their ability to form biofilm. Only the ΔacrBmutant displayed significantly different phenotypes compared to that of the wild-type strain: 4- to 32-fold decrease of MICs of several antibiotics, antiseptics, and dyes, increased production of biofilm, and attenuated virulence inG. mellonella In order to identify specific substrates of each pump, we individually expressed intransall operons containing an RND pump-encoding gene into the ΔacrBhypersusceptible strain. We showed that three other RND-type efflux systems (ECL_00053-00055, ECL_01758-01759, and ECL_02124-02125) were able to partially restore the wild-type phenotype and to superadd to and even enlarge the broad range of antimicrobial resistance. This is the first global study assessing the role of all RND efflux pumps chromosomally encoded by the ECC, which confirms the major role of AcrB in both pathogenicity and resistance and the potential involvement of other RND-type members in acquired resistance.

  18. Complex Regulation Pathways of AmpC-Mediated β-Lactam Resistance in Enterobacter cloacae Complex.

    PubMed

    Guérin, François; Isnard, Christophe; Cattoir, Vincent; Giard, Jean Christophe

    2015-12-01

    Enterobacter cloacae complex (ECC), an opportunistic pathogen causing numerous infections in hospitalized patients worldwide, is able to resist β-lactams mainly by producing the AmpC β-lactamase enzyme. AmpC expression is highly inducible in the presence of some β-lactams, but the underlying genetic regulation, which is intricately linked to peptidoglycan recycling, is still poorly understood. In this study, we constructed different mutant strains that were affected in genes encoding enzymes suspected to be involved in this pathway. As expected, the inactivation of ampC, ampR (which encodes the regulator protein of ampC), and ampG (encoding a permease) abolished β-lactam resistance. Reverse transcription-quantitative PCR (qRT-PCR) experiments combined with phenotypic studies showed that cefotaxime (at high concentrations) and cefoxitin induced the expression of ampC in different ways: one involving NagZ (a N-acetyl-β-D-glucosaminidase) and another independent of NagZ. Unlike the model established for Pseudomonas aeruginosa, inactivation of DacB (also known as PBP4) was not responsible for a constitutive ampC overexpression in ECC, whereas it caused AmpC-mediated high-level β-lactam resistance, suggesting a post-transcriptional regulation mechanism. Global transcriptomic analysis by transcriptome sequencing (RNA-seq) of a dacB deletion mutant confirmed these results. Lastly, analysis of 37 ECC clinical isolates showed that amino acid changes in the AmpD sequence were likely the most crucial event involved in the development of high-level β-lactam resistance in vivo as opposed to P. aeruginosa where dacB mutations have been commonly found. These findings bring new elements for a better understanding of β-lactam resistance in ECC, which is essential for the identification of novel potential drug targets.

  19. Complex Regulation Pathways of AmpC-Mediated β-Lactam Resistance in Enterobacter cloacae Complex

    PubMed Central

    Guérin, François; Isnard, Christophe; Giard, Jean Christophe

    2015-01-01

    Enterobacter cloacae complex (ECC), an opportunistic pathogen causing numerous infections in hospitalized patients worldwide, is able to resist β-lactams mainly by producing the AmpC β-lactamase enzyme. AmpC expression is highly inducible in the presence of some β-lactams, but the underlying genetic regulation, which is intricately linked to peptidoglycan recycling, is still poorly understood. In this study, we constructed different mutant strains that were affected in genes encoding enzymes suspected to be involved in this pathway. As expected, the inactivation of ampC, ampR (which encodes the regulator protein of ampC), and ampG (encoding a permease) abolished β-lactam resistance. Reverse transcription-quantitative PCR (qRT-PCR) experiments combined with phenotypic studies showed that cefotaxime (at high concentrations) and cefoxitin induced the expression of ampC in different ways: one involving NagZ (a N-acetyl-β-d-glucosaminidase) and another independent of NagZ. Unlike the model established for Pseudomonas aeruginosa, inactivation of DacB (also known as PBP4) was not responsible for a constitutive ampC overexpression in ECC, whereas it caused AmpC-mediated high-level β-lactam resistance, suggesting a post-transcriptional regulation mechanism. Global transcriptomic analysis by transcriptome sequencing (RNA-seq) of a dacB deletion mutant confirmed these results. Lastly, analysis of 37 ECC clinical isolates showed that amino acid changes in the AmpD sequence were likely the most crucial event involved in the development of high-level β-lactam resistance in vivo as opposed to P. aeruginosa where dacB mutations have been commonly found. These findings bring new elements for a better understanding of β-lactam resistance in ECC, which is essential for the identification of novel potential drug targets. PMID:26438498

  20. Efficient synthesis of tyrosol galactosides by the β-galactosidase from Enterobacter cloacae B5.

    PubMed

    Qi, Tingting; Gu, Guofeng; Xu, Li; Xiao, Min; Lu, Lili

    2017-03-30

    In this work, the β-galactosidase from Enterobacter cloacae B5 (BgaB5) exhibited excellent transglycosylation activity toward tyrosol (p-hydroxyphenethyl alcohol) when using lactose as the glycosyl donor, generating a series of tyrosol glycosides with potential pharmacological properties. The effects of substrate concentration, temperature, pH, and reaction time on the transglycosylation reaction catalyzed by the enzyme BgaB5 were studied in detail. Three tyrosol derivatives were produced in a total high yield of 50.0% when incubating the enzyme with 250 mM tyrosol and 1000 mM lactose (pH 7.5) at 50 °C for 5 min. These derivatives were subsequently purified by column chromatography and preparative thin-layer chromatography. MS analysis of the purified compounds suggested one monogalactoside (M r 300) and two digalactoside derivatives (M r 462). The following NMR analysis further identified them to be p-hydroxyphenethyl β-D-galactopyranoside, p-hydroxyphenethyl β-D- galactopyranosyl-(1 → 3')-β-D-galactopyranoside, and p-hydroxyphenethyl β-D- galactopyranosyl-(1 → 6')-β-D-galactopyranoside, respectively. The yield of the tyrosol monogalactoside which was known to possess potent bioactivities reached 39.4%, higher than other enzymatic yields reported so far. The two digalactosides, which were expected to have potential applications for novel drug screening and discovery, were artificially obtained with 10.6% yield for the first time.

  1. Substrate selectivity of the melibiose permease (MelY) from Enterobacter cloacae.

    PubMed

    Tavoulari, Sotiria; Frillingos, Stathis

    2008-02-22

    We have examined the substrate selectivity of the melibiose permease (MelY) from Enterobacter cloacae in comparison with that of the lactose permease (LacY) from Escherichia coli. Both proteins catalyze active transport of lactose or melibiose with comparable affinity and capacity. However, MelY does not transport the analogue methyl-1-thio-beta,d-galactopyranoside (TMG), which is a very efficient substrate in LacY. We show that MelY binds TMG and conserves Cys148 (helix V) as a TMG binding residue but fails to transport this ligand. Based on homology modeling, organization of the putative MelY sugar binding site is the same as that in LacY and residues irreplaceable for the symport mechanism are conserved. Moreover, only 15% of the residues where a single-Cys mutant is inactivated by site-directed alkylation differ in MelY. Using site-directed mutagenesis at these positions and engineered cross-homolog chimeras, we show that Val367, at the periplasmic end of transmembrane helix XI, contributes in defining the substrate selectivity profile. Replacement of Val367 with the MelY residue (Ala) leads to impairment of TMG uptake. Exchanging domains N6 and C6 between LacY and MelY also leads to impairment of TMG uptake. TMG uptake activity is restored by the re-introduction of a Val367 in the background of chimera N6(LacY)-C6(MelY). Much less prominent effects are found with the same mutants and chimeras for the transport of lactose or melibiose.

  2. Effects of carbon source and Vitreoscilla hemoglobin (VHb) on the production of beta-galactosidase in Enterobacter aerogenes.

    PubMed

    Khleifat, Khaled M; Abboud, Muayad M; Al-Mustafa, Ahmed H; Al-Sharafa, Khalid Y

    2006-10-01

    At fixed concentration (0.5%), lactose and galactose acted as inducers while glucose and other tested carbon sugars showed repression effects on beta-galactosidase production in Enterobacter aerogenes strain. The expression of Vitreoscilla hemoglobin gene (vgb) in this bacterial strain managed to overcome the repression effects as well as improving the induction of beta-galactosidase formation by carbon sources. In parallel, the bacterial O(2) consumption was increased correspondingly to the vgb induction of beta-galactosidase synthesis. When Enterobacter aerogenes strains were grown at the incubation temperature 42 degrees C, about 5-fold higher enzyme productivity was obtained than with a similar incubation at 37 degrees C. The bacterial growth expressed as biomass yield had a different optimum temperature and was not influenced to the same extent by variations in the carbon sources. These data are discussed in terms of proposed enhancement in beta-galactosidase productivity by vgb expression as well as its significance to improve the technology of whey processing.

  3. 4-alkoxy and 4-thioalkoxyquinoline derivatives as chemosensitizers for the chloramphenicol-resistant clinical Enterobacter aerogenes 27 strain.

    PubMed

    Gallo, Sandrine; Chevalier, Jacqueline; Mahamoud, Abdallah; Eyraud, Annie; Pagès, Jean-Marie; Barbe, Jacques

    2003-09-01

    Enterobacter aerogenes is a Gram-negative bacteria frequently responsible for nosocomial respiratory tract infections. Strains resistant to chloramphenicol are frequently isolated. Alkoxy and thio-alkoxyquinolines have a potential to act as chemosensitizers that would render multi-drug-resistant (MDR) bacterial infections susceptible to antibiotics to which they were originally resistant. Several new quinoline derivatives have been prepared, characterized and studied for their ability to increase chloramphenicol sensitivity of E. aerogenes 27, a clinical strain that exhibits the MDR phenotype. Drugs investigated were either quinoline ethers or quinoline thio-ethers. Thio-ethers are much more efficient in increasing chloramphenicol sensitivity than other corresponding ethers. In particular, 4-piperidinoethylthio-quinoline increases the strain sensitivity to chloramphenicol by about 20 times at 2 mM concentration. Similarly, sensitivity to quinolone antibiotics dramatically increases. Because these quinoline derivatives act as inhibitors of the drug efflux pump responsible for bacterial resistance to chloramphenicol, they may serve as adjunct to conventional therapy of E. aerogenes infections.

  4. Quantitative analysis of the growth of Salmonella stanley during alfalfa sprouting and evaluation of Enterobacter aerogenes as its surrogate.

    PubMed

    Liu, Bin; Schaffner, Donald W

    2007-02-01

    Raw seed sprouts have been implicated in several food poisoning outbreaks in the last 10 years. Few studies have included investigations of factors influencing the effectiveness of testing spent irrigation water, and in no studies to date has a nonpathogenic surrogate been identified as suitable for large-scale irrigation water testing trials. Alfalfa seeds were inoculated with Salmonella Stanley or its presumptive surrogate (nalidixic acid-resistant Enterobacter aerogenes) at three concentrations (-3, -30, and -300 CFU/g) and were then transferred into either flasks or a bench top-scale sprouting chamber. Microbial concentrations were determined in seeds, sprouts, and irrigation water at various times during a 4-day sprouting process. Data were fit to logistic regression models, and growth rates and maximum concentrations were compared using the generalized linear model procedure of SAS. No significant differences in growth rates were observed among samples taken from flasks or the chamber. Microbial concentrations in irrigation water were not significantly different from concentrations in sprout samples obtaihed at the same time. E. aerogenes concentrations were similar to those of Salmonella Stanley at corresponding time points for all three inoculum concentrations. Growth rates were also constant regardless of inoculum concentration or strain, except that lower inoculum concentrations resulted in lower final concentrations proportional to their initial concentrations. This research demonstrated that a nonpathogenic easy-to-isolate surrogate (nalidixic acid-resistant E. aerogenes) provides results similar to those obtained with Salmonella Stanley, supporting the use of this surrogate in future large-scale experiments.

  5. Characterization of an Enterobacter cloacae Strain Producing both KPC and NDM Carbapenemases by Whole-Genome Sequencing.

    PubMed

    Wu, Wenjing; Feng, Yu; Carattoli, Alessandra; Zong, Zhiyong

    2015-10-01

    A carbapenem-resistant Enterobacter cloacae strain, WCHECl-14653, causing a fatal bloodstream infection, was characterized by genome sequencing and conjugation experiments. The strain carried two carbapenemase genes, blaNDM-1 and blaKPC-2, on separate IncF plasmids. The coexistence of blaNDM-1 and blaKPC-2 conferred slightly higher-level carbapenem resistance compared with that of blaNDM-1 or blaKPC-2 alone, and the coexistence of two IncF plasmids may generate new platforms for spreading carbapenemase genes.

  6. Characterization of an Enterobacter cloacae Strain Producing both KPC and NDM Carbapenemases by Whole-Genome Sequencing

    PubMed Central

    Wu, Wenjing; Feng, Yu; Carattoli, Alessandra

    2015-01-01

    A carbapenem-resistant Enterobacter cloacae strain, WCHECl-14653, causing a fatal bloodstream infection, was characterized by genome sequencing and conjugation experiments. The strain carried two carbapenemase genes, blaNDM-1 and blaKPC-2, on separate IncF plasmids. The coexistence of blaNDM-1 and blaKPC-2 conferred slightly higher-level carbapenem resistance compared with that of blaNDM-1 or blaKPC-2 alone, and the coexistence of two IncF plasmids may generate new platforms for spreading carbapenemase genes. PMID:26248381

  7. Failure of the MicroScan WalkAway system to detect heteroresistance to carbapenems in a patient with Enterobacter aerogenes bacteremia.

    PubMed

    Gordon, N C; Wareham, D W

    2009-09-01

    We report the failure of the automated MicroScan WalkAway system to detect carbapenem heteroresistance in Enterobacter aerogenes. Carbapenem resistance has become an increasing concern in recent years, and robust surveillance is required to prevent dissemination of resistant strains. Reliance on automated systems may delay the detection of emerging resistance.

  8. Co-fermentation of carbon sources by Enterobacter aerogenes ATCC 29007 to enhance the production of bioethanol.

    PubMed

    Thapa, Laxmi Prasad; Lee, Sang Jun; Yang, Xiao Guang; Yoo, Hah Young; Kim, Sung Bong; Park, Chulhwan; Kim, Seung Wook

    2014-06-01

    We investigated the enhancement of bioethanol production in Enterobacter aerogenes ATCC 29007 by co-fermentation of carbon sources such as glycerol, glucose, galactose, sucrose, fructose, xylose, starch, mannitol and citric acid. Biofuel production increases with increasing growth rate of microorganisms; that is why we investigated the optimal growth rate of E. aerogenes ATCC 29007, using mixtures of different carbon sources with glycerol. E. aerogenes ATCC 29007 was incubated in media containing each carbon source and glycerol; growth rate and bioethanol production improved in all cases compared to those in medium containing glycerol alone. The growth rate and bioethanol production were highest with mannitol. Fermentation was carried out at 37 °C for 18 h, pH 7, using 50 mL defined production medium in 100 mL serum bottles at 200 rpm. Bioethanol production under optimized conditions in medium containing 16 g/L mannitol and 20 g/L glycerol increased sixfold (32.10 g/L) than that containing glycerol alone (5.23 g/L) as the carbon source in anaerobic conditions. Similarly, bioethanol production using free cells in continuous co-fermentation also improved (27.28 g/L) when 90.37 % of 16 g/L mannitol and 67.15 % of 20 g/L glycerol were used. Although naturally existing or engineered microorganisms can ferment mixed sugars sequentially, the preferential utilization of glucose to non-glucose sugars often results in lower overall yield and productivity of ethanol. Here, we present new findings in E. aerogenes ATCC 29007 that can be used to improve bioethanol production by simultaneous co-fermentation of glycerol and mannitol.

  9. The curli biogenesis genes expression level is unassociated with Enterobacter cloacae hsp60 clusters and PFGE genotypes.

    PubMed

    Akbari, Majid; Bakhshi, Bita; Najar-Peerayeh, Shahin; Behmanesh, Mehrdad

    2016-09-01

    The objective of this study was to determine the correlation between Enterobacter cloacae complex subspecies and clusters involved in UTI infections and specific pulsotypes, and to assess the contribution of major curli biogenesis genes (csgD, csgA) expression level to pathogenesis of clusters and genotypes. Based on the PFGE analysis, 37 different profiles were observed among which 8 profiles were common types. Real time PCR of csgD and csgA genes of 50 E. cloacae complex in relation to PFGE and hsp60 genotypes showed that all the genetic clusters are not equally involved in pathogenesis of urinary tract infections. It was elucidated in this study that isolates with common PFGE genotypes belonged to identical hsp60 clusters, and the foremost clusters (VI, III, and V) mainly comprised within PFGE common types. In our study, no significant correlation was detected between the specific hsp60 clusters or PFGE genotypes and the expression level of csgD and csgA genes (P-value > 0.05). This is the first study describing that unequivalent contribution of E. cloacae genotypes and clusters in pathogenesis of UTI, is not owing to varied curli biogenesis expression potential. The PFGE genotyping showed more discriminatory power than hsp60 genotyping for epidemiological studies and source tracking purpose.

  10. Cefepime Therapy for Monomicrobial Enterobacter cloacae Bacteremia: Unfavorable Outcomes in Patients Infected by Cefepime-Susceptible Dose-Dependent Isolates.

    PubMed

    Lee, Nan-Yao; Lee, Ching-Chi; Li, Chia-Wen; Li, Ming-Chi; Chen, Po-Lin; Chang, Chia-Ming; Ko, Wen-Chien

    2015-12-01

    A new category of cefepime susceptibility, susceptible dose dependent (SDD), for Enterobacteriaceae, has been suggested to maximize its clinical use. However, clinical evidence supporting such a therapeutic strategy is limited. A retrospective study of 305 adults with monomicrobial Enterobacter cloacae bacteremia at a medical center from 2008 to 2012 was conducted. The patients definitively treated with in vitro active cefepime (cases) were compared with those treated with a carbapenem (controls) to assess therapeutic effectiveness. The 30-day crude mortality rate is the primary endpoint, and clinical prognostic factors are assessed. Of 144 patients receiving definitive cefepime or carbapenem therapy, there were no significant differences in terms of age, sex, comorbidity, source of bacteremia, disease severity, or 30-day mortality (26.4% versus 22.2%; P = 0.7) among those treated with cefepime (n = 72) or a carbapenem (n = 72). In the multivariate analysis, the presence of critical illness, rapidly fatal underlying disease, extended-spectrum beta-lactamase (ESBL) producers, and cefepime-SDD (cefepime MIC, 4 to 8 μg/ml) isolates was independently associated with 30-day mortality. Moreover, those infected by cefepime-SDD isolates with definitive cefepime therapy had a higher mortality rate than those treated with a carbapenem (5/7 [71.4%], versus 2/11 [18.2%]; P = 0.045). Cefepime is one of the therapeutic alternatives for cefepime-susceptible E. cloacae bacteremia but is inefficient for cases of cefepime-SDD E. cloacae bacteremia compared with carbapenem therapy.

  11. Cefepime Therapy for Monomicrobial Enterobacter cloacae Bacteremia: Unfavorable Outcomes in Patients Infected by Cefepime-Susceptible Dose-Dependent Isolates

    PubMed Central

    Lee, Nan-Yao; Lee, Ching-Chi; Li, Chia-Wen; Li, Ming-Chi; Chen, Po-Lin; Chang, Chia-Ming

    2015-01-01

    A new category of cefepime susceptibility, susceptible dose dependent (SDD), for Enterobacteriaceae, has been suggested to maximize its clinical use. However, clinical evidence supporting such a therapeutic strategy is limited. A retrospective study of 305 adults with monomicrobial Enterobacter cloacae bacteremia at a medical center from 2008 to 2012 was conducted. The patients definitively treated with in vitro active cefepime (cases) were compared with those treated with a carbapenem (controls) to assess therapeutic effectiveness. The 30-day crude mortality rate is the primary endpoint, and clinical prognostic factors are assessed. Of 144 patients receiving definitive cefepime or carbapenem therapy, there were no significant differences in terms of age, sex, comorbidity, source of bacteremia, disease severity, or 30-day mortality (26.4% versus 22.2%; P = 0.7) among those treated with cefepime (n = 72) or a carbapenem (n = 72). In the multivariate analysis, the presence of critical illness, rapidly fatal underlying disease, extended-spectrum beta-lactamase (ESBL) producers, and cefepime-SDD (cefepime MIC, 4 to 8 μg/ml) isolates was independently associated with 30-day mortality. Moreover, those infected by cefepime-SDD isolates with definitive cefepime therapy had a higher mortality rate than those treated with a carbapenem (5/7 [71.4%], versus 2/11 [18.2%]; P = 0.045). Cefepime is one of the therapeutic alternatives for cefepime-susceptible E. cloacae bacteremia but is inefficient for cases of cefepime-SDD E. cloacae bacteremia compared with carbapenem therapy. PMID:26416853

  12. Physicochemical, nutritional, and microbial quality of fresh-cut and frozen papaya prepared from cultivars with varying resistance to internal yellowing disease (Enterobacter cloacae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quality, nutritional, and microbial analyses were completed for fresh-cut and frozen papaya cubes prepared from cultivars with varying resistance to internal yellowing disease, caused by the bacterium Enterobacter cloacae. In general, fresh-cut and frozen papaya retained nutritional and microbial qu...

  13. Involvement of the AcrAB-TolC Efflux Pump in the Resistance, Fitness, and Virulence of Enterobacter cloacae

    PubMed Central

    Pérez, Astrid; Poza, Margarita; Fernández, Ana; del Carmen Fernández, Maria; Mallo, Susana; Merino, María; Rumbo-Feal, Soraya; Cabral, María P.

    2012-01-01

    Multidrug efflux pumps have emerged as important mechanisms of antimicrobial resistance in bacterial pathogens. In order to cause infection, pathogenic bacteria require mechanisms to avoid the effects of host-produced compounds, and express efflux pumps may accomplish this task. In this study, we evaluated the effect of the inactivation of AcrAB-TolC on antimicrobial resistance, fitness, and virulence in Enterobacter cloacae, an opportunistic pathogen usually involved in nosocomial infections. Two different clinical isolates of E. cloacae were used, EcDC64 (multidrug resistance overexpressing the AcrAB-TolC efflux pump) and Jc194 (basal AcrAB-TolC expression). The acrA and tolC genes were deleted in strains EcDC64 and Jc194 to produce, respectively, EcΔacrA and EcΔtolC and JcΔacrA and JcΔtolC knockout (KO) derivatives. Antibiotic susceptibility testing was performed with all isolates, and we discovered that these mechanisms are involved in the resistance of E. cloacae to several antibiotics. Competition experiments were also performed with wild-type and isogenic KO strains. The competition index (CI), defined as the mutant/wild-type ratio, revealed that the acrA and tolC genes both affect the fitness of E. cloacae, as fitness was clearly reduced in the acrA and tolC KO strains. The median CI values obtained in vitro and in vivo were, respectively, 0.42 and 0.3 for EcDC64/EcΔacrA, 0.24 and 0.38 for EcDC64/EcΔtolC, 0.15 and 0.11 for Jc194/JcΔacrA, and 0.38 and 0.39 for Jc194/JcΔtolC. Use of an intraperitoneal mouse model of systemic infection revealed reduced virulence in both E. cloacae clinical strains when either the acrA or tolC gene was inactivated. In conclusion, the structural components of the AcrAB-TolC efflux pump appear to play a role in antibiotic resistance as well as environmental adaptation and host virulence in clinical isolates of E. cloacae. PMID:22290971

  14. Involvement of the AcrAB-TolC efflux pump in the resistance, fitness, and virulence of Enterobacter cloacae.

    PubMed

    Pérez, Astrid; Poza, Margarita; Fernández, Ana; Fernández, Maria del Carmen; Mallo, Susana; Merino, María; Rumbo-Feal, Soraya; Cabral, María P; Bou, Germán

    2012-04-01

    Multidrug efflux pumps have emerged as important mechanisms of antimicrobial resistance in bacterial pathogens. In order to cause infection, pathogenic bacteria require mechanisms to avoid the effects of host-produced compounds, and express efflux pumps may accomplish this task. In this study, we evaluated the effect of the inactivation of AcrAB-TolC on antimicrobial resistance, fitness, and virulence in Enterobacter cloacae, an opportunistic pathogen usually involved in nosocomial infections. Two different clinical isolates of E. cloacae were used, EcDC64 (multidrug resistance overexpressing the AcrAB-TolC efflux pump) and Jc194 (basal AcrAB-TolC expression). The acrA and tolC genes were deleted in strains EcDC64 and Jc194 to produce, respectively, EcΔacrA and EcΔtolC and JcΔacrA and JcΔtolC knockout (KO) derivatives. Antibiotic susceptibility testing was performed with all isolates, and we discovered that these mechanisms are involved in the resistance of E. cloacae to several antibiotics. Competition experiments were also performed with wild-type and isogenic KO strains. The competition index (CI), defined as the mutant/wild-type ratio, revealed that the acrA and tolC genes both affect the fitness of E. cloacae, as fitness was clearly reduced in the acrA and tolC KO strains. The median CI values obtained in vitro and in vivo were, respectively, 0.42 and 0.3 for EcDC64/EcΔacrA, 0.24 and 0.38 for EcDC64/EcΔtolC, 0.15 and 0.11 for Jc194/JcΔacrA, and 0.38 and 0.39 for Jc194/JcΔtolC. Use of an intraperitoneal mouse model of systemic infection revealed reduced virulence in both E. cloacae clinical strains when either the acrA or tolC gene was inactivated. In conclusion, the structural components of the AcrAB-TolC efflux pump appear to play a role in antibiotic resistance as well as environmental adaptation and host virulence in clinical isolates of E. cloacae.

  15. Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor.

    PubMed

    Jitrwung, Rujira; Yargeau, Viviane

    2015-05-11

    Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR). Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol) and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol.

  16. Physiological characterisation of the efflux pump system of antibiotic-susceptible and multidrug-resistant Enterobacter aerogenes.

    PubMed

    Martins, A; Spengler, G; Martins, M; Rodrigues, L; Viveiros, M; Davin-Regli, A; Chevalier, J; Couto, I; Pagès, J M; Amaral, L

    2010-10-01

    Enterobacter aerogenes predominates amongst Enterobacteriaceae species that are increasingly reported as producers of extended-spectrum beta-lactamases. Although this mechanism of resistance to beta-lactams is important, other mechanisms bestowing a multidrug-resistant (MDR) phenotype in this species are now well documented. Amongst these mechanisms is the overexpression of efflux pumps that extrude structurally unrelated antibiotics prior to their reaching their targets. Interestingly, although knowledge of the genetic background behind efflux pumps is rapidly advancing, few studies assess the physiological nature of the overall efflux pump system of this, or for that matter any other, bacterium. The study reported here evaluates physiologically the efflux pump system of an E. aerogenes ATCC reference as well as two strains whose MDR phenotypes are mediated by overexpressed efflux pumps. The activities of the efflux pumps in these strains are modulated by pH and glucose, although the effects of the latter are essentially restricted to pH 8, suggesting the presence of two general efflux pump systems, i.e. proton-motive force-dependent and ABC transporter types, respectively.

  17. Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor

    PubMed Central

    Jitrwung, Rujira; Yargeau, Viviane

    2015-01-01

    Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR). Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol) and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol. PMID:25970750

  18. Biohydrogen and polyhydroxyalkanoate co-production by Enterobacter aerogenes and Rhodobacter sphaeroides from Calophyllum inophyllum oil cake.

    PubMed

    Arumugam, A; Sandhya, M; Ponnusami, V

    2014-07-01

    The feasibility of coupled biohydrogen and polyhydroxyalkanoate production by Enterobacter aerogenes and Rhodobacter sphaeroides using Calophyllum inophyllum oil cake was studied under dark and photo fermentation conditions. The utilization of a non-edible acidic oil cake (C. inophyllum), and exploitation of a modified minimal salt media led to reduction in the cost of media. Cost of fermentation is reduced by implementation of alternate dark-photo fermentative periods and through the use of a co-culture consisting of a dark fermentative (E. aerogenes) and a photo fermentative (R. sphaeroides) bacterium. The biohydrogen and polyhydroxyalkanoate produced were 7.95 L H2/L media and 10.73 g/L media, respectively, under alternate dark and photo fermentation and were 3.23 L H2/L media and 5.6g/L media, respectively under complete dark fermentation. The characteristics of the oil cake and alternate dark (16 h) and photo (8h) fermentative conditions were found to be supportive in producing high biohydrogen and polyhydroxyalkanoate (PHA) yield.

  19. Selection during cefepime treatment of a new cephalosporinase variant with extended-spectrum resistance to cefepime in an Enterobacter aerogenes clinical isolate.

    PubMed

    Barnaud, G; Benzerara, Y; Gravisse, J; Raskine, L; Sanson-Le Pors, M J; Labia, R; Arlet, G

    2004-03-01

    Enterobacter aerogenes resistant to cefepime (MIC, 32 microg/ml) was isolated from a patient treated with cefepime for an infection caused by a strain of E. aerogenes overproducing its AmpC beta-lactamase (MIC of cefepime, 0.5 microg/ml). The AmpC beta-lactamase of the resistant strain had an L-293-P amino acid substitution and a high k(cat)/K(m) ratio for cefepime. Both of these modifications were necessary for resistance to cefepime.

  20. Prevalence of Plasmid-Mediated Quinolone Resistance and Aminoglycoside Resistance Determinants among Carbapeneme Non-Susceptible Enterobacter cloacae

    PubMed Central

    Sun, Shan; Zhang, Xiaojiao; Zhang, Liping

    2012-01-01

    Background Simultaneous resistance to aminoglycosides and fluoroquinolones in carbapeneme non-susceptible (CNS) isolates will inevitably create problems. The present study was performed to characterize the prevalence of the plasmid-mediated quinolone resistance determinants (QRDs) and aminoglycoside resistance determinants (ARDs) among the CNS Enterobacter cloacae (E. cloacae) isolates in a Chinese teaching hospital, and to acquire their molecular epidemiological characteristics. Methods The β-lactamases genes (including class A carbapenemase genes blaKPC and blaSME, metallo-β-lactamase genes (MBLs) blaIMP, blaVIM and blaNDM, and extended spectrum β-lactamases (ESBLs),blaCTX-M, blaTEM and blaSHV), QRDs (including qnrA, qnrB, qnrS and aac(6′)-Ib-cr) and ARDs (including aac(6′)-Ib, armA and rmtB) of these 35 isolates were determined by PCR and sequenced bidirectionally. The clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE). Results Of the 35 isolates, 9 (25.7%) harbored a carbapenemase gene; 23 (65.7%) carried ESBLs; 24 (68.6%) were QRD positive; and 27 (77.1%) were ARD positive. Among the 5 blaIMP-8 positive strains, 4 (80%) contained both ESBL and QRD genes, and all the 5 (100%) harbored ARD genes. Of the 23 ESBLs positive isolates, 6 (26.1%) were carbapenemase positive, 14 (60.9%) were QRD positive, and 18 (78.3%) were ARD positive. PFGE revealed genetic diversity among the 35 isolates, indicating that the high prevalence of CNS E. cloacae isolates was not caused by clonal dissemination. Conclusion QRD and ARD genes were highly prevalent among the CNS E. cloacae isolates. Multiple resistant genes were co-expressed in the same isolates. The CNS E. cloacae isolate co-expressing blaNDM-1, blaIMP-26, qnrA1 and qnrS1 was first reported. PMID:23110085

  1. The β-lactamase inhibitor avibactam (NXL104) does not induce ampC β-lactamase in Enterobacter cloacae

    PubMed Central

    Miossec, Christine; Claudon, Monique; Levasseur, Premavathy; Black, Michael T

    2013-01-01

    Induction of ampC β-lactamase expression can often compromise antibiotic treatment and is triggered by several β-lactams (such as cefoxitin and imipenem) and by the β-lactamase inhibitor clavulanic acid. The novel β-lactamase inhibitor avibactam (NXL104) is a potent inhibitor of both class A and class C enzymes. The potential of avibactam for induction of ampC expression in Enterobacter cloacae was investigated by ampC messenger ribonucleic acid quantitation. Cefoxitin and clavulanic acid were confirmed as ampC inducers, whereas avibactam was found to exert no effect on ampC expression. Thus, avibactam is unlikely to diminish the activity of any partner β-lactam antibiotic against AmpC-producing organisms. PMID:24348054

  2. Regulation of indole-3-acetic acid biosynthesis by branched-chain amino acids in Enterobacter cloacae UW5.

    PubMed

    Parsons, Cassandra V; Harris, Danielle M M; Patten, Cheryl L

    2015-09-01

    The soil bacterium Enterobacter cloacae UW5 produces the rhizosphere signaling molecule indole-3-acetic acid (IAA) via the indolepyruvate pathway. Expression of indolepyruvate decarboxylase, a key pathway enzyme encoded by ipdC, is upregulated by the transcription factor TyrR in response to aromatic amino acids. Some members of the TyrR regulon may also be controlled by branched-chain amino acids and here we show that expression from the ipdC promoter and production of IAA are downregulated by valine, leucine and isoleucine. Regulation of the IAA synthesis pathway by both aromatic and branched-chain amino acids suggests a broader role for this pathway in bacterial physiology, beyond plant interactions.

  3. The locus of heat resistance (LHR) mediates heat resistance in Salmonella enterica, Escherichia coli and Enterobacter cloacae.

    PubMed

    Mercer, Ryan G; Walker, Brian D; Yang, Xianqin; McMullen, Lynn M; Gänzle, Michael G

    2017-06-01

    Enterobacteriaceae comprise food spoilage organisms as well as food-borne pathogens including Escherichia coli. Heat resistance in E. coli was attributed to a genomic island called the locus of heat resistance (LHR). This genomic island is also present in several other genera of Enterobacteriaceae, but its function in the enteric pathogens Salmonella enterica and Enterobacter cloacae is unknown. This study aimed to determine the frequency of the LHR in food isolates of E. coli, and its influence on heat resistance in S. enterica and Enterobacter spp. Cell counts of LHR-positive strains of E. coli, S. enterica and E. cloacae were reduced by less than 1, 1, and 4 log (cfu/mL), respectively, after exposure to 60 °C for 5 min, while cell counts of LHR-negative strains of the same species were reduced by more than 7 log (cfu/mL). Introducing an exogenous copy of the LHR into heat-sensitive enteropathogenic E. coli and S. enterica increased heat resistance to a level that was comparable to LHR-positive wild type strains. Cell counts of LHR-positive S. enterica were reduced by less than 1 log(cfu/mL) after heating to 60 °C for 5 min. Survival of LHR-positive strains was improved by increasing the NaCl concentration from 0 to 4%. Cell counts of LHR-positive strains of E. coli and S. enterica were reduced by less than 2 log (cfu/g) in ground beef patties cooked to an internal core temperature of 71 °C. This study indicates that LHR-positive Enterobacteriaceae pose a risk to food safety.

  4. Membrane permeability, a pivotal function involved in antibiotic resistance and virulence in Enterobacter aerogenes clinical isolates.

    PubMed

    Lavigne, J-P; Sotto, A; Nicolas-Chanoine, M-H; Bouziges, N; Bourg, G; Davin-Regli, A; Pagès, J-M

    2012-06-01

    Imipenem-susceptible E. aerogenes isolates exhibiting extended spectrum β-lactamases, target mutations and a basal efflux expression, were identified in five patients. After imipenem treatment, imipenem-intermediate susceptible (IMI-I) or resistant (IMI-R) isolates emerged in these patients. Alteration in porin synthesis and increase in efflux expression were observed in the IMI-I isolates whereas complete loss of the porins, LPS alteration and efflux overexpression were observed in the IMI-R isolates. Bacterial virulence of the strains was investigated by the Caenorhabditis elegans model. The IMI-R isolates were shown to be significantly less virulent than the IMI-susceptible or IMI-I isolates. The pleiotropic membrane alteration and its associated fitness burden exhibited by E. aerogenes isolates influence their antibiotic resistance and their virulence behaviour. These findings highlight the balance between the low permeability-related resistance and virulence and their relationships with the treatment of resistant pathogens.

  5. Dissemination of multiresistant Enterobacter cloacae isolates producing OXA-48 and CTX-M-15 in a Spanish hospital.

    PubMed

    Fernández, Javier; Montero, Ignacio; Martínez, Óscar; Fleites, Ana; Poirel, Laurent; Nordmann, Patrice; Rodicio, M Rosario

    2015-10-01

    Twenty-one multiresistant Enterobacter cloacae isolates producing OXA-48 (n=10), CTX-M-15 (n=7) or both (n=4) β-lactamases were detected in a Spanish hospital during a 1-year period (June 2013 to June 2014). The isolates were also resistant to non-β-lactam antimicrobials, further complicating the therapeutic options. Genotyping of the isolates identified two major clones (ST74 and ST66) that caused prolonged outbreaks in different buildings of the hospital as well as some sporadic isolates (ST78, ST45 and ST295). Isolates belonging to clone 1 (n=7) were carbapenem-resistant and carried the bla(OXA-48) gene on a conjugative IncL/M plasmid of ca. 65 kb. Clone 2 isolates (n=11) were resistant to cefepime and harboured the bla(CTX-M-15) gene on an ca. 150-kb, non-conjugative plasmid of the IncF group, co-harbouring the qnrB and aac(6')-Ib-cr genes encoding quinolone resistance. Four clone 2 isolates were also resistant to carbapenems owing to the co-production of OXA-48. Most of the isolates were recovered from critically ill patients and were admitted to intensive care units; a single patient was transferred from another Spanish hospital. Intrahospital and interhospital dissemination of multiresistant E. cloacae isolates is of major clinical concern as it could lead to endemic nosocomial situations.

  6. Isolation and Identification of an Enterobacter cloacae Strain Producing a Novel Subtype of Shiga Toxin Type 1

    PubMed Central

    McQuaid, Cassandra; Schrader, Kimmi

    2014-01-01

    We describe here the isolation and identification of a Shiga toxin 1 (Stx1)-producing Enterobacter cloacae strain, M12X01451, from a human clinical specimen. The bacterial isolate was identified as E. cloacae using a polyphasic approach that included phenotypic, genetic, and proteomic analyses. The M12X01451 stx1 was sequenced, and the holotoxin was found to share only 87% amino acid sequence identity with the nearest Stx1 subtype reference sequence. Sequence analysis of the regions immediately flanking stx1 displayed similarities with bacteriophage-related sequences, suggesting a prophage origin. The stx1 gene was a stable element within the M12X01451 genome, as demonstrated by real-time PCR detection following successive subculturing of the bacterial isolate. Culture supernatant from M12X01451 was cytotoxic to Vero cells but was not neutralized by an anti-Stx1 monoclonal antibody. In addition, Stx1 from M12X01451 demonstrated limited antigenicity with two commercially available lateral flow immunoassays. The M12X01451 Stx represents a new Stx1 subtype based on the degree of sequence dissimilarity with Stx1 subtype reference sequences and its limited reactivity with anti-Stx1 antibodies. PMID:24759708

  7. Transgenic ice nucleation-active Enterobacter cloacae reduces cold hardiness of corn borer and cotton bollworm larvae.

    PubMed

    Tang, Chaorong; Sun, Fuzai; Zhang, Xinjian; Zhao, Tingchang; Qi, Jiyan

    2004-12-27

    The ice nucleation (IN) gene iceA of Erwinia ananas 110 was integrated into the chromosomes of two Enterobacter cloacae strains (Enc1.2022 and Enc1.181). These two newly derived transgenic strains, designated Enc2022-I and Enc181-I, respectively, possessed ice nucleation activity at -2.5 degrees C, significantly higher than their parent strains (active at approx -10 degrees C or lower). After ingesting these transgenic bacteria, the mean supercooling points (SCPs) of corn borer and cotton bollworm larvae were -3 to -4 degrees C, significantly higher than those of untreated controls. The SCPs remained significantly elevated over the 9-day period after ingestion, which matched well with the efficient gut colonization of the bacteria during this period. All treated larvae froze and eventually died after exposure for 6 h to a temperature of -7 degrees C, and more than 95% died after 12 h at -5 degrees C. In contrast, few or none of the untreated control larvae froze and died under the same conditions. Furthermore, the growth ability of these transgenic ice nucleation-active (INA) En. cloacae strains on corn leaves was reduced, compared to that of wild-type epiphytic E. ananas, as revealed by pot tests conducted in both greenhouse and outdoor conditions. The stable colonization in insect guts and their lower affinity to plants would make these transgenic INA bacteria useful as a novel tool for biological control of insect pests in agricultural fields.

  8. Changes in ciprofloxacin resistance levels in Enterobacter aerogenes isolates associated with variable expression of the aac(6')-Ib-cr gene.

    PubMed

    Ruiz, Elena; Ocampo-Sosa, Alain A; Alcoba-Flórez, Julia; Román, Elena; Arlet, Guillaume; Torres, Carmen; Martínez-Martínez, Luis

    2012-02-01

    Two closely related Enterobacter aerogenes isolates presented a new identical aac(6')-Ib-cr genetic environment, including IS26. One isolate showed lower MICs of ciprofloxacin, norfloxacin, tobramycin, and amikacin and decreased expression of aac(6')-Ib-cr, which might be related to a 12-bp deletion causing a displacement of the -10 box upstream of the aac(6')-Ib-cr gene.

  9. Molecular and Epidemiological Characterization of IMP-Type Metallo-β-Lactamase-Producing Enterobacter cloacae in a Large Tertiary Care Hospital in Japan

    PubMed Central

    Miyoshi-Akiyama, Tohru; Kirikae, Teruo; Nagamatsu, Maki; Shimada, Kayo; Mezaki, Kazuhisa; Sugiki, Yuko; Kuroda, Emi; Kubota, Shiho; Takeshita, Nozomi; Kutsuna, Satoshi; Tojo, Masayoshi; Ohmagari, Norio

    2014-01-01

    IMP-type metallo-β-lactamase enzymes have been reported in different geographical areas and in various Gram-negative bacteria. However, the risk factors and epidemiology pertaining to IMP-type metallo-β-lactamase-producing Enterobacter cloacae (IMP-producing E. cloacae) have not been systematically evaluated. We conducted a retrospective, matched case-control study of patients from whom IMP-producing E. cloacae isolates were obtained, in addition to performing thorough molecular analyses of the clinically obtained IMP-producing E. cloacae isolates. Unique cases with IMP-producing E. cloacae isolation were included. Patients with IMP-producing E. cloacae were matched to uninfected controls at a ratio of 1 to 3. Fifteen IMP-producing E. cloacae cases were identified, with five of the isolates being obtained from blood, and they were matched to 45 uninfected controls. All (100%) patients from whom IMP-producing E. cloacae isolates were obtained had indwelling devices at the time of isolation, compared with one (2.2%) uninfected control. Independent predictors for isolation of IMP-producing E. cloacae were identified as cephalosporin exposure and invasive procedures within 3 months. Although in-hospital mortality rates were similar between cases and controls (14.3% versus 13.3%), the in-hospital mortality of patients with IMP-producing E. cloacae-caused bacteremia was significantly higher (40%) than the rate in controls. IMP-producing E. cloacae isolates were frequently positive for other resistance determinants. The MICs of meropenem and imipenem were not elevated; 10 (67%) and 12 (80%) of the 15 IMP-producing E. cloacae isolates had a MIC of ≤1 μg/ml. A phylogenetic tree showed a close relationship among the IMP-producing E. cloacae samples. Indwelling devices, exposure to cephalosporin, and a history of invasive procedures were associated with isolation of IMP-producing E. cloacae. Screening for carbapenemase production is important in order to apply

  10. Enterobacter cloacae complex isolates harboring blaNMC-A or blaIMI-type class A carbapenemase genes on novel chromosomal integrative elements and plasmids.

    PubMed

    Boyd, David A; Mataseje, Laura F; Davidson, Ross; Delport, Johannes A; Fuller, Jeff; Hoang, Linda; Lefebvre, Brigitte; Levett, Paul; Roscoe, Diane L; Willey, Barbara M; Mulvey, Michael R

    2017-02-21

    Carbapenem-resistant Enterobacter cloacae complex isolates submitted to a reference laboratory from 2010 to 2015 were screened by PCR for seven common carbapenemase gene groups, namely, KPC, NDM, OXA-48, VIM, IMP, GES, and NMC-A/IMI. Nineteen of the submitted isolates (1.7%) were found to harbor Ambler class A blaNMC-A or blaIMI-type carbapenemases. All 19 isolates were resistant to at least one carbapenem but susceptible to aminoglycosides, trimethoprim-sulfamethoxazole, tigecycline, and ciprofloxacin. Most isolates (17/19) gave positive results with the Carba-NP test for phenotypic carbapenemase detection. Isolates were genetically diverse by pulsed-field gel electrophoresis macrorestriction analysis, multilocus sequence typing, and hsp60 gene analysis. The genes were found in various Enterobacter cloacae complex species, however blaNMC-A was highly associated with Enterobacter ludwiggii Whole genome sequencing and bioinformatics analysis revealed that all NMC-A (n=10), IMI-1 (n=5), and IMI-9 (n=2) producers harbored the carbapenemase gene on EludIMEX-1-like integrative mobile elements, EcloIMEXs, located in the identical chromosomal locus. Two novel genes, blaIMI-5 and blaIMI-6, were harbored on different IncFII-type plasmids. Enterobacter cloacae complex isolates harboring blaNMC-A/IMI-type carbapenemases are relatively rare in Canada. Though mostly found integrated into the chromosome, some variants are located on plasmids that may enhance their mobility potential.

  11. Reduced carbon utilization, competitive colonization of the spermosphere, and disease suppression by Enterobacter cloacae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    De Wit Replacement series and disease suppression experiments with a collection of nutritional mutants of E. cloacae 501R3 are being used to determine the role of reduced carbon compounds found in seed exudate during beneficial activities by this bacterium. Mutants A-11, M2, and M43 contain single ...

  12. Enterobacter cloacae infection after anterior cervical decompression and fusion: case study and literature review

    PubMed Central

    Wang, Hongli; Wang, Lixun; Yang, Yong; Lu, Feizhou; Ma, Xiaosheng; Xia, Xinlei; Jiang, Jianyuan

    2015-01-01

    Wound infection after anterior cervical decompression and fusion can lead to disastrous consequences despite a low incidence rate. Although Gram-positive bacteria such as Staphylococcus aureus are the most common pathogenic bacteria, some rare bacteria such as conditional pathogenic bacteria may also result in such a condition. To the best of our knowledge, E. cloacae-caused acute infection after anterior cervical decompression and fusion has not been reported. Here, we report an E. cloacae-caused acute infection after anterior vertical decompression and fusion. This infection was eventually controlled by virtue of an early diagnosis and the correspondingly-adopted anti-infection, internal fixation removal, and drainage treatments. Exploring the reasons underlying acute infection after anterior cervical decompression and fusion caused by rare bacteria, particularly E. cloacae, by analyzing this case was the basic therapeutic principle in this study. We believe that the therapeutic principle for E. cloacae-caused wound infection after anterior cervical internal fixation is basically consistent with that for other bacterium-caused wound infections after spinal internal fixation. Sufficient drainage, the adoption of sensitive antibacterials, and internal fixation removal as early as possible when necessary are the essential measures in infection control. PMID:26064234

  13. Tuberculose de l’épaule masquée par une infection concomitante à enterobacter cloacae: à propos d'un cas

    PubMed Central

    Gbané-Koné, Mariam; Koné, Samba; Ouali, Boubacar; Djaha, Kouassi Jean-Mermoz; Diomandé, Mohamed; Eti, Edmond; Touré, Stanislas André; Kouakou, N'zué Marcel

    2015-01-01

    La tuberculose de l’épaule est une localisation rare de même que l'arthrite septique à Enterobacter cloacae, les auteurs rapportent un cas d'ostéoarthrite de l’épaule à Bacille de Koch et à E. Cloacae chez une patiente de 36 ans avec un terrain particulier (drépanocytose SC et infection à VIH). Le diagnostic a été possible grâce aux prélèvements chirurgicaux effectués lors de l'arthrotomie PMID:26401203

  14. Probable Interspecies Transfer of the bla(VIM-4) Gene between Enterobacter cloacae and Klebsiella pneumoniae in a Single Infant Patient.

    PubMed

    Piekarska, Katarzyna; Zacharczuk, Katarzyna; Rzeczkowska, Magdalena; Wołkowicz, Tomasz; Januszkiewicz, Aleksandra; Podsiadły, Edyta; Demkow, Urszula; Gierczyński, Rafał

    2015-01-01

    We report the interspecies transfer of the bla(VLM-4) gene in MBL-producing Enterobacter cloacae and Klebsiella pneumoniae isolates from a newborn patient who had received meropenem therapy. We show evidence that gene bla(VIM-4) was transmitted as a part of the class-1 integron on a ca. -90 kb conjugative plasmid. High homology of nucleotide sequence was observed between the integron found in VIM-4 producing E. cloacae and K. pneumoniae strains tested and class-1 integrons previously reporteded in Pseudomonas aeruginosa from Hungary and Poland. This finding may suggest P. aeruginosa as a potential source of acquired VIM-4 in Enterobacteriaceae.

  15. Efficacies of Imipenem, Meropenem, Cefepime, and Ceftazidime in Rats with Experimental Pneumonia Due to a Carbapenem-Hydrolyzing β-Lactamase-Producing Strain of Enterobacter cloacae

    PubMed Central

    Mimoz, Olivier; Leotard, Sophie; Jacolot, Anne; Padoin, Christophe; Louchahi, Kamel; Petitjean, Olivier; Nordmann, Patrice

    2000-01-01

    The antibacterial activities of imipenem-cilastatin, meropenem-cilastatin, cefepime and ceftazidime against Enterobacter cloacae NOR-1, which produces the carbapenem-hydrolyzing β-lactamase NmcA and a cephalosporinase, and against one of its in vitro-obtained ceftazidime-resistant mutant were compared by using an experimental model of pneumonia with immunocompetent rats. The MICs of the β-lactams with an inoculum of 5 log10 CFU/ml were as follows for E. cloacae NOR-1 and its ceftazidime-resistant mutant, respectively: imipenem, 16 and 128 μg/ml, meropenem, 4 and 32 μg/ml, cefepime, <0.03 and 1 μg/ml, and ceftazidime, 1 and 512 μg/ml. The chromosomally located cephalosporinase and carbapenem-hydrolyzing β-lactamase NmcA were inducible by cefoxitin and meropenem in E. cloacae NOR-1, and both were stably overproduced in the ceftazidime-resistant mutant. Renal impairment was induced (uranyl nitrate, 1 mg/kg of body weight) in rats to simulate the human pharmacokinetic parameters for the β-lactams studied. Animals were intratracheally inoculated with 8.5 log10 CFU of E. cloacae, and therapy was initiated 3 h later. At that time, animal lungs showed bilateral pneumonia containing more than 6 log10 CFU of E. cloacae per g of tissue. Despite the relative low MIC of meropenem for E. cloacae NOR-1, the carbapenem-treated rats had no decrease in bacterial counts in their lungs 60 h after therapy onset compared to the counts for the controls, regardless of whether E. cloacae NOR-1 or its ceftazidime-resistant mutant was inoculated. A significant decrease in bacterial titers was observed for the ceftazidime-treated rats infected with E. cloacae NOR-1 only. Cefepime was the only β-lactam tested effective as treatment against infections due to E. cloacae NOR-1 or its ceftazidime-resistant mutant. PMID:10722486

  16. Biotransformation of Ferulic acid to 4-Vinylguaiacol by Enterobacter soli and E. aerogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated the conversion of ferulic acid to 4-vinylguaiacol (4-VG), vanillin, vanillyl alcohol and vanillic acid by five Enterobacter strains. These high-value chemicals are usually synthesized using chemical methods but biological synthesis adds value. Ferulic acid, a relatively inexpensive...

  17. Enterobacter cloacae with a novel variant of ACT AmpC beta-lactamase originating from glaucous gull (Larus hyperboreus) in Svalbard.

    PubMed

    Literak, Ivan; Manga, Ivan; Wojczulanis-Jakubas, Katarzyna; Chroma, Magdalena; Jamborova, Ivana; Dobiasova, Hana; Sedlakova, Miroslava Htoutou; Cizek, Alois

    2014-07-16

    We aimed at Escherichia coli and Enterobacter cloacae isolates resistant to cephalosporins and fluoroquinolones and Salmonella isolates in wild birds in Arctic Svalbard, Norway. Cloacal swabs of little auks (Alle alle, n=215) and samples of faeces of glaucous gulls (Larus hyperboreus, n=15) were examined. Inducible production of AmpC enzyme was detected in E. cloacae KW218 isolate. Sequence analysis of the 1146 bp PCR product of the ampC gene from this isolate revealed 99% sequence homology with the blaACT-14 and blaACT-5 AmpC beta-lactamase genes. Four, respectively six of the identified single nucleotide polymorphisms generated amino acid substitutions in the amino acid chain. As the ampC sequence polymorphism in the investigated E. cloacae strain was identified as unique, we revealed a novel variant of the ampC beta-lactamase gene blaACT-23.

  18. Mutational analysis of the hyc-operon determining the relationship between hydrogenase-3 and NADH pathway in Enterobacter aerogenes.

    PubMed

    Pi, Jian; Jawed, Muhammad; Wang, Jun; Xu, Li; Yan, Yunjun

    2016-01-01

    In this study, the hydrogenase-3 gene cluster (hycDEFGH) was isolated and identified from Enterobacter aerogenes CCTCC AB91102. All gene products were highly homologous to the reported bacterial hydrogenase-3 (Hyd-3) proteins. The genes hycE, hycF, hycG encoding the subunits of hydrogenase-3 were targeted for genetic knockout to inhibit the FHL hydrogen production pathway via the Red recombination system, generating three mutant strains AB91102-E (ΔhycE), AB91102-F (ΔhycF) and AB91102-G (ΔhycG). Deletion of the three genes affected the integrity of hydrogenase-3. The hydrogen production experiments with the mutant strains showed that no hydrogen was detected compared with the wild type (0.886 mol/mol glucose), demonstrating that knocking out any of the three genes could inhibit NADH hydrogen production pathway. Meanwhile, the metabolites of the mutant strains were significantly changed in comparison with the wild type, indicating corresponding changes in metabolic flux by mutation. Additionally, the activity of NADH-mediated hydrogenase was found to be nil in the mutant strains. The chemostat experiments showed that the NADH/NAD(+) ratio of the mutant strains increased nearly 1.4-fold compared with the wild type. The NADH-mediated hydrogenase activity and NADH/NAD(+) ratio analysis both suggested that NADH pathway required the involvement of the electron transport chain of hydrogenase-3.

  19. Substrate-promoted formation of a catalytically competent binuclear center and regulation of reactivity in a glycerophosphodiesterase from Enterobacter aerogenes.

    PubMed

    Hadler, Kieran S; Tanifum, Eric A; Yip, Sylvia Hsu-Chen; Mitić, Natasa; Guddat, Luke W; Jackson, Colin J; Gahan, Lawrence R; Nguyen, Kelly; Carr, Paul D; Ollis, David L; Hengge, Alvan C; Larrabee, James A; Schenk, Gerhard

    2008-10-29

    The glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a promiscuous binuclear metallohydrolase that catalyzes the hydrolysis of mono-, di-, and triester substrates, including some organophosphate pesticides and products of the degradation of nerve agents. GpdQ has attracted recent attention as a promising enzymatic bioremediator. Here, we have investigated the catalytic mechanism of this versatile enzyme using a range of techniques. An improved crystal structure (1.9 A resolution) illustrates the presence of (i) an extended hydrogen bond network in the active site, and (ii) two possible nucleophiles, i.e., water/hydroxide ligands, coordinated to one or both metal ions. While it is at present not possible to unambiguously distinguish between these two possibilities, a reaction mechanism is proposed whereby the terminally bound H2O/OH(-) acts as the nucleophile, activated via hydrogen bonding by the bridging water molecule. Furthermore, the presence of substrate promotes the formation of a catalytically competent binuclear center by significantly enhancing the binding affinity of one of the metal ions in the active site. Asn80 appears to display coordination flexibility that may modulate enzyme activity. Kinetic data suggest that the rate-limiting step occurs after hydrolysis, i.e., the release of the phosphate moiety and the concomitant dissociation of one of the metal ions and/or associated conformational changes. Thus, it is proposed that GpdQ employs an intricate regulatory mechanism for catalysis, where coordination flexibility in one of the two metal binding sites is essential for optimal activity.

  20. Characterization of the genes of the 2,3-butanediol operons from Klebsiella terrigena and Enterobacter aerogenes.

    PubMed Central

    Blomqvist, K; Nikkola, M; Lehtovaara, P; Suihko, M L; Airaksinen, U; Stråby, K B; Knowles, J K; Penttilä, M E

    1993-01-01

    The genes involved in the 2,3-butanediol pathway coding for alpha-acetolactate decarboxylase, alpha-acetolactate synthase (alpha-ALS), and acetoin (diacetyl) reductase were isolated from Klebsiella terrigena and shown to be located in one operon. This operon was also shown to exist in Enterobacter aerogenes. The budA gene, coding for alpha-acetolactate decarboxylase, gives in both organisms a protein of 259 amino acids. The amino acid similarity between these proteins is 87%. The K. terrigena genes budB and budC, coding for alpha-ALS and acetoin reductase, respectively, were sequenced. The 559-amino-acid-long alpha-ALS enzyme shows similarities to the large subunits of the Escherichia coli anabolic alpha-ALS enzymes encoded by the genes ilvB, ilvG, and ilvI. The K. terrigena alpha-ALS is also shown to complement an anabolic alpha-ALS-deficient E. coli strain for valine synthesis. The 243-amino-acid-long acetoin reductase has the consensus amino acid sequence for the insect-type alcohol dehydrogenase/ribitol dehydrogenase family and has extensive similarities with the N-terminal and internal regions of three known dehydrogenases and one oxidoreductase. Images PMID:8444801

  1. Disruption of lactate dehydrogenase and alcohol dehydrogenase for increased hydrogen production and its effect on metabolic flux in Enterobacter aerogenes.

    PubMed

    Zhao, Hongxin; Lu, Yuan; Wang, Liyan; Zhang, Chong; Yang, Cheng; Xing, Xinhui

    2015-10-01

    Hydrogen production by Enterobacter aerogenes from glucose was enhanced by deleting the targeted ldhA and adh genes responsible for two NADH-consuming pathways which consume most NADH generated from glycolysis. Compared with the wild-type, the hydrogen yield of IAM1183-ΔldhA increased 1.5 fold. Metabolic flux analysis showed both IAM1183-ΔldhA and IAM1183-Δadh exhibited significant changes in flux, including enhanced flux towards the hydrogen generation. The lactate production of IAM1183-ΔldhA significantly decreased by 91.42%, while the alcohol yield of IAM1183-Δadh decreased to 30%. The mutant IAM1183-ΔldhA with better hydrogen-producing performance was selected for further investigation in a 5-L fermentor. The hydrogen production of IAM1183-ΔldhA was 2.3 times higher than the wild-type. Further results from the fermentation process showed that the pH decreased to 5.39 levels, then gradually increased to 5.96, indicating that some acidic metabolites might be degraded or uptaken by cells.

  2. Phenolic compounds: Strong inhibitors derived from lignocellulosic hydrolysate for 2,3-butanediol production by Enterobacter aerogenes.

    PubMed

    Lee, Sang Jun; Lee, Ju Hun; Yang, Xiaoguang; Kim, Sung Bong; Lee, Ja Hyun; Yoo, Hah Young; Park, Chulhwan; Kim, Seung Wook

    2015-12-01

    Lignocellulosic biomass are attractive feedstocks for 2,3-butanediol production due to their abundant supply and low price. During the hydrolysis of lignocellulosic biomass, various byproducts are formed and their effects on 2,3-butanediol production were not sufficiently studied compared to ethanol production. Therefore, the effects of compounds derived from lignocellulosic biomass (weak acids, furan derivatives and phenolics) on the cell growth, the 2,3-butanediol production and the enzymes activity involved in 2,3-butanediol production were evaluated using Enterobacter aerogenes ATCC 29007. The phenolic compounds showed the most toxic effects on cell growth, 2,3-butanediol production and enzyme activity, followed by furan derivatives and weak acids. The significant effects were not observed in the presence of acetic acid and formic acid. Also, feasibility of 2,3-butanediol production from lignocellulosic biomass was evaluated using Miscanthus as a feedstock. In the fermentation of Miscanthus hydrolysate, 11.00 g/L of 2,3-butanediol was obtained from 34.62 g/L of reducing sugar. However, 2,3-butanediol was not produced when the concentration of total phenolic compounds in the hydrolysate increased to more than 1.5 g/L. The present study provides useful information to develop strategies for biological production of 2,3-butanediol and to establish biorefinery for biochemicals from lignocellulosic biomass.

  3. Alteration of hydrogen metabolism of ldh-deleted Enterobacter aerogenes by overexpression of NAD+-dependent formate dehydrogenase.

    PubMed

    Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Lai, Qiheng; Wu, Xi; Xing, Xin-Hui

    2010-03-01

    The NAD+-dependent formate dehydrogenase FDH1 gene (fdh1), cloned from Candida boidinii, was expressed in the ldh-deleted mutant of Enterobacter aerogenes IAM1183 strain. The plasmid of pCom10 driven by the PalkB promoter was used to construct the fdh1 expression system and thus introduce a new dihydronicotinamide adenine dinucleotide (NADH) regeneration pathway from formate in the ldh-deleted mutant. The knockout of NADH-consuming lactate pathway affected the whole cellular metabolism, and the hydrogen yield increased by 11.4% compared with the wild strain. Expression of fdh1 in the ldh-deleted mutant caused lower final cell concentration and final pH after 16 h cultivation, and finally resulted in 86.8% of increase in hydrogen yield per mole consumed glucose. The analysis of cellular metabolites and estimated redox state balance in the fdhl-expressed strain showed that more excess of reducing power was formed by the rewired NADH regeneration pathway, changing the metabolic distribution and promoting the hydrogen production.

  4. Risk factor analysis for extended-spectrum β-lactamase-producing Enterobacter cloacae bloodstream infections in central Taiwan

    PubMed Central

    2013-01-01

    Background Enterobacter cloacae (E.cloacae) bloodstream infection (EcBSI) is an important cause of morbidity and mortality, with an increasing incidence in our hospital. We wanted to elucidate the risk factors of mortality among patients with ESBL-positive EcBSI in central Taiwan. Methods We ordered the clinical and microbiological data of cases with diagnosis of EcBSI, and analyzed the isolates by using antibiotyping, detection of ESBL, detection of class 1 integron and genomic fingerprinting by pulsed-field gel electrophoresis (PFGE). Results Seventy episodes of EcBSI from 70 patients (56 hospital-acquired infections) were enrolled. Significant differences were found between ESBL-positive and ESBL-negative isolates with regard to risk factors, including the diseases severity (p = 0.03), category of health care-associated infection (p = 0.04), prior use of antibiotics (p = 0.023), and prior use of a ventilator (p = 0.037). A significant difference in mortality between two groups (p = 0.004) was determined using the chi-square test, and a trend in mortality between two groups (p = 0.006, OR = 4.750, 95% C.I.=1.573-14.344) was determined using univariate logistic regression analysis. The predominant clone in ESBL-positive strains was associated with a higher mortality rate but not with the presence of the integron. Conclusions The study disclosed four types of clinical characteristics to obtain ESBL-positive EcBSI, and there was a trend in mortality too. We suggested the need to review antibiotic prescription practices, and the possible need to consider ESBL-positive strains in empirical treatment of bloodstream infection. PMID:24010678

  5. Bacillus subtilis and Enterobacter cloacae endophytes from healthy Theobroma cacao L. trees can systemically colonize seedlings and promote growth.

    PubMed

    Leite, Hianna Almeida Câmara; Silva, Anderson Barbosa; Gomes, Fábio Pinto; Gramacho, Karina Peres; Faria, José Cláudio; de Souza, Jorge Teodoro; Loguercio, Leandro Lopes

    2013-03-01

    Clonal genotypes resistant to fungal diseases are an important component of the cocoa production system in southeastern Bahia state (Brazil), so that technologies for faster production of stronger and healthier plantlets are highly desirable. In this study, the effects of inoculated bacterial endophytes isolated from healthy adult cacao plants on seedlings, and aspects related to inoculation methods, colonization patterns, and photosynthesis were investigated. Sequencing of 16S rRNA, hsp-60, and rpo-B genes placed the wild-type isolates within the species Enterobacter cloacae (isolates 341 and 344) and Bacillus subtilis (isolate 629). Spontaneous rifampicin-resistant (rif(R)) variants for 344 were also produced and tested. Endophytic application was either by immersion of surface sterilized seeds in bacterial suspensions or direct inoculation into soil, 20 days after planting non-inoculated seeds into pots. Results from in vitro recovery of inoculated isolates showed that the wild-type endophytes and rif(R) variants systemically colonized the entire cacao seedlings in 15-20 days, regardless of the inoculation method. Some endophytic treatments showed significant increases in seedlings' height, number of leaves, and dry matter. Inoculation methods affected the combined application of endophytes, which maintained the growth-promotion effects, but not in the same manner as in single applications. Interestingly, the 344-3.2 rif(R) variant showed improved performance in relation to both the wild type and another related variant. Photosynthetic rates and stomatal conductance increased significantly for some endophytic treatments, being partially associated with effects on growth and affected by the inoculation method. The results suggest that E. cloacae and B. subtilis endophytes from healthy adult plants (not transmitted by seeds) were able to promote vegetative growth on cacao seedlings. The development of products for large-scale use in seedlings

  6. Isolation of Enterobacter aerogenes carrying blaTEM-1 and blaKPC-3 genes recovered from a hospital Intensive Care Unit.

    PubMed

    Pulcrano, Giovanna; Pignanelli, Salvatore; Vollaro, Adriana; Esposito, Matilde; Iula, Vita Dora; Roscetto, Emanuela; Soriano, Amata Amy; Catania, Maria Rosaria

    2016-06-01

    Enterobacter aerogenes has recently emerged as an important hospital pathogen. In this study, we showed the emergence of E. aerogenes isolates carrying the blaKPC gene in patients colonized by carbapenem-resistant Klebsiella pneumoniae strains. Two multiresistant E. aerogenes isolates were recovered from bronchial aspirates of two patients hospitalized in the Intensive Care Unit at the "Santa Maria della Scaletta" Hospital, Imola. The antimicrobial susceptibility test showed the high resistance to carbapenems and double-disk synergy test confirmed the phenotype of KPC and AmpC production. Other investigation revealed that ESBL and blaKPC genes were carried on the conjugative pKpQIL plasmid. This is a relevant report in Italy that describes a nosocomial infection due to the production of KPC beta-lactamases by an E. aerogenes isolate in patients previously colonized by K. pneumoniae carbapenem-resistant. In conclusion, it's necessary a continuous monitoring of multidrug-resistant strains for the detection of any KPC-producing bacteria that could expand the circulation of carbapenem-resistant pathogens.

  7. Inactivation of the Transcriptional Regulator-Encoding Gene sdiA Enhances Rice Root Colonization and Biofilm Formation in Enterobacter cloacae GS1

    PubMed Central

    Shankar, Manoharan; Ponraj, Paramasivan; Illakkiam, Devaraj; Rajendhran, Jeyaprakash

    2013-01-01

    Enterobacter cloacae GS1 is a plant growth-promoting bacterium which colonizes rice roots. In the rhizosphere environment, N-acyl homoserine lactone (NAHL)-like quorum-sensing signals are known to be produced by host plants and other microbial inhabitants. E. cloacae GS1 was unable to synthesize NAHL quorum-sensing signals but had the NAHL-dependent transcriptional regulator-encoding gene sdiA. This study was aimed at understanding the effects of SdiA and NAHL-dependent cross talk in rice root colonization by E. cloacae GS1. Pleiotropic effects of sdiA inactivation included substantial increases in root colonization and biofilm formation, suggesting a negative role for SdiA in bacterial adhesion. We provide evidence that sdiA inactivation leads to elevated levels of biosynthesis of curli, which is involved in cellular adhesion. Extraneous addition of NAHLs had a negative effect on root colonization and biofilm formation. However, the sdiA mutant of E. cloacae GS1 was insensitive to NAHLs, suggesting that this NAHL-induced inhibition of root colonization and biofilm formation is SdiA dependent. Therefore, it is proposed that NAHLs produced by both plant and microbes in the rice rhizosphere act as cross-kingdom and interspecies signals to negatively impact cellular adhesion and, thereby, root colonization in E. cloacae GS1. PMID:23086212

  8. Current Status of Antibiograms of Listeria ivanovii and Enterobacter cloacae Isolated from Ready-To-Eat Foods in Alice, South Africa

    PubMed Central

    Nyenje, Mirriam E.; Tanih, Nicoline F.; Green, Ezekiel; Ndip, Roland N.

    2012-01-01

    This study assessed the antimicrobial susceptibility of 51 Listeria ivanovii and 33 Enterobacter cloacae strains isolated from various ready-to-eat foods sold in Alice, South Africa. Isolates were identified using standard microbiological tests and further confirmed using API 20E and API Listeria kits. The disc diffusion technique was used to screen for antimicrobial susceptibility against 15 antimicrobials; minimum inhibitory concentration of five antibiotics was determined by the broth dilution method. All the strains of E. cloacae (100%) and 96% of L. ivanovii isolates were resistant to at least four or more of the antibiotics; nineteen antibiotypes were obtained based on the antibiotics used in the study. Antibiotype A5: AR PGR VAR ER APR was predominant in both L. ivanovii (23.5%) and E. cloacae (57.5%) isolates. Marked susceptibility of Listeriaivanovii was observed against chloramphenicol, ciprofloxacin, streptomycin and trimethoprim/sulfamethoxazole (100%) each while E. cloacae registered 100% susceptibility to ciprofloxacin only. Various percentages of susceptibility was reported to chloramphenicol and gentamicin (91%) each, nalidixic acid (97%) and streptomycin (94%). The MIC90 ranged from 0.004–7.5 µg/mL with E. cloacae being the most susceptible organism. The study demonstrated the presence of multi-resistant strains of bacteria in ready-to-eat-foods and speculates that these foods could serve as important vehicles transmitting multi-resistant bacteria to humans. PMID:23202673

  9. Production and assay of cellulolytic enzyme activity of Enterobacter cloacae WPL 214 isolated from bovine rumen fluid waste of Surabaya abbatoir, Indonesia

    PubMed Central

    Lokapirnasari, W. P.; Nazar, D. S.; Nurhajati, T.; Supranianondo, K.; Yulianto, A. B.

    2015-01-01

    Aim: This study aims to produce and assay cellulolytic enzyme activity (endo-(1,4)-β-D-glucanase, exo-(1,4)-β-D-glucanase, and β-glucosidase, at optimum temperature and optimum pH) of Enterobacter cloacae WPL 214 isolated from bovine rumen fluid waste of Surabaya Abbatoir, Indonesia. Materials and Methods: To produce enzyme from a single colony of E. cloacae WPL 214, 98 × 1010 CFU/ml of isolates was put into 20 ml of liquid medium and incubated in a shaker incubator for 16 h at 35°C in accordance with growth time and optimum temperature of E. cloacae WPL 214. Further on, culture was centrifuged at 6000 rpm at 4°C for 15 min. Pellet was discarded while supernatant containing cellulose enzyme activity was withdrawn to assay endo-(1,4)-β-D-glucanase, exo-(1,4)-β-D-glucanase, and β-glucosidase. Results: Cellulase enzyme of E. cloacae WPL 214 isolates had endoglucanase activity of 0.09 U/ml, exoglucanase of 0.13 U/ml, and cellobiase of 0.10 U/ml at optimum temperature 35°C and optimum pH 5. Conclusion: E. cloacae WPL 214 isolated from bovine rumen fluid waste produced cellulose enzyme with activity as cellulolytic enzyme of endo-(1,4)-β-D-glucanase, exo-(1,4)-β-D-glucanase and β-glucosidase. PMID:27047099

  10. A Prolonged Outbreak of KPC-3-Producing Enterobacter cloacae and Klebsiella pneumoniae Driven by Multiple Mechanisms of Resistance Transmission at a Large Academic Burn Center.

    PubMed

    Kanamori, Hajime; Parobek, Christian M; Juliano, Jonathan J; van Duin, David; Cairns, Bruce A; Weber, David J; Rutala, William A

    2017-02-01

    Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacter cloacae has been recently recognized in the United States. Whole-genome sequencing (WGS) has become a useful tool for analysis of outbreaks and for determining transmission networks of multidrug-resistant organisms in health care settings, including carbapenem-resistant Enterobacteriaceae (CRE). We experienced a prolonged outbreak of CRE E. cloacae and K. pneumoniae over a 3-year period at a large academic burn center despite rigorous infection control measures. To understand the molecular mechanisms that sustained this outbreak, we investigated the CRE outbreak isolates by using WGS. Twenty-two clinical isolates of CRE, including E. cloacae (n = 15) and K. pneumoniae (n = 7), were sequenced and analyzed genetically. WGS revealed that this outbreak, which seemed epidemiologically unlinked, was in fact genetically linked over a prolonged period. Multiple mechanisms were found to account for the ongoing outbreak of KPC-3-producing E. cloacae and K. pneumoniae This outbreak was primarily maintained by a clonal expansion of E. cloacae sequence type 114 (ST114) with distribution of multiple resistance determinants. Plasmid and transposon analyses suggested that the majority of blaKPC-3 was transmitted via an identical Tn4401b element on part of a common plasmid. WGS analysis demonstrated complex transmission dynamics within the burn center at levels of the strain and/or plasmid in association with a transposon, highlighting the versatility of KPC-producing Enterobacteriaceae in their ability to utilize multiple modes to resistance gene propagation.

  11. Dynamics of MDR Enterobacter cloacae outbreaks in a neonatal unit in Nepal: insights using wider sampling frames and next-generation sequencing

    PubMed Central

    Stoesser, N.; Sheppard, A. E.; Shakya, M.; Sthapit, B.; Thorson, S.; Giess, A.; Kelly, D.; Pollard, A. J.; Peto, T. E. A.; Walker, A. S.; Crook, D. W.

    2015-01-01

    Objectives There are limited data on Enterobacter cloacae outbreaks and fewer describing these in association with NDM-1. With whole-genome sequencing, we tested the hypothesis that a cluster of 16 E. cloacae bacteraemia cases in a Nepali neonatal unit represented a single clonal outbreak, using a wider set of epidemiologically unrelated clinical E. cloacae isolates for comparison. Methods Forty-three isolates were analysed, including 23 E. cloacae and 3 Citrobacter sp. isolates obtained from blood cultures from 16 neonates over a 3 month period. These were compared with two contemporaneous community-associated drug-resistant isolates from adults, a unit soap dispenser isolate and a set of historical invasive isolates (n = 14) from the same geographical locality. Results There were two clear neonatal outbreaks and one isolated case in the unit. One outbreak was associated with an NDM-1 plasmid also identified in a historical community-associated strain. The smaller, second outbreak was likely associated with a contaminated soap dispenser. The two community-acquired adult cases and three sets of historical hospital-associated neonatal isolates represented four additional genetic clusters. Conclusions E. cloacae infections in this context represent several different transmission networks, operating at the community/hospital and host strain/plasmid levels. Wide sampling frames and high-resolution typing methods are needed to describe the complex molecular epidemiology of E. cloacae outbreaks, which is not appropriately reflected by routine susceptibility phenotypes. Soap dispensers may represent a reservoir for E. cloacae and bacterial strains and plasmids may persist in hospitals and in the community for long periods, sporadically being involved in outbreaks of disease. PMID:25558071

  12. Efficient 2,3-Butanediol Production from Cassava Powder by a Crop-Biomass-Utilizer, Enterobacter cloacae subsp. dissolvens SDM

    PubMed Central

    Ma, Cuiqing; Gao, Chao; Li, Lixiang; Wang, Yu; Tao, Fei; Xu, Ping

    2012-01-01

    Background 2,3-Butanediol (BD) is considered as one of the key platform chemicals used in a variety of industrial applications. It is crucial to find an efficient sugar-utilizing strain and feasible carbon source for the economical production of BD. Methodology/Principal Findings Efficient BD production by a newly isolated Enterobacter cloacae subsp. dissolvens SDM was studied using crop-biomass cassava powder as substrate. The culture conditions and fermentation medium for BD production were optimized. Under the optimal conditions, 78.3 g l−1 of BD was produced after 24 h in simultaneous saccharification and fermentation (SSF), with a yield of 0.42 g BD g−1 cassava powder and a specific productivity of 3.3 g l−1 h−1. A higher BD concentration (93.9 g l−1) was produced after 47 h in fed-batch SSF. Conclusions/Significance The results suggest that strain SDM is a good candidate for the BD production, and cassava powder could be used as an alternative substrate for the efficient production of BD. PMID:22792324

  13. Genetic and Biochemical Characterization of FRI-1, a Carbapenem-Hydrolyzing Class A β-Lactamase from Enterobacter cloacae.

    PubMed

    Dortet, Laurent; Poirel, Laurent; Abbas, Samia; Oueslati, Saoussen; Nordmann, Patrice

    2015-12-01

    An Enterobacter cloacae isolate was recovered from a rectal swab from a patient hospitalized in France with previous travel to Switzerland. It was resistant to penicillins, narrow- and broad-spectrum cephalosporins, aztreonam, and carbapenems but remained susceptible to expanded-spectrum cephalosporins. Whereas PCR-based identification of the most common carbapenemase genes failed, the biochemical Carba NP test II identified an Ambler class A carbapenemase. Cloning experiments followed by sequencing identified a gene encoding a totally novel class A carbapenemase, FRI-1, sharing 51 to 55% amino acid sequence identity with the closest carbapenemase sequences. However, it shared conserved residues as a source of carbapenemase activity. Purified β-lactamase FRI-1 hydrolyzed penicillins, aztreonam, and carbapenems but spared expanded-spectrum cephalosporins. The 50% inhibitory concentrations (IC50s) of clavulanic acid and tazobactam were 10-fold higher than those found for Klebsiella pneumoniae carbapenemase (KPC), IMI, and SME, leading to lower sensitivity of FRI-1 activity to β-lactamase inhibitors. The blaFRI-1 gene was located on a ca. 110-kb untypeable, transferable, and non-self-conjugative plasmid. A putative LysR family regulator-encoding gene at the 5' end of the β-lactamase gene was identified, leading to inducible expression of the blaFRI-1 gene.

  14. Genetic and Biochemical Characterization of FRI-1, a Carbapenem-Hydrolyzing Class A β-Lactamase from Enterobacter cloacae

    PubMed Central

    Dortet, Laurent; Poirel, Laurent; Abbas, Samia; Oueslati, Saoussen

    2015-01-01

    An Enterobacter cloacae isolate was recovered from a rectal swab from a patient hospitalized in France with previous travel to Switzerland. It was resistant to penicillins, narrow- and broad-spectrum cephalosporins, aztreonam, and carbapenems but remained susceptible to expanded-spectrum cephalosporins. Whereas PCR-based identification of the most common carbapenemase genes failed, the biochemical Carba NP test II identified an Ambler class A carbapenemase. Cloning experiments followed by sequencing identified a gene encoding a totally novel class A carbapenemase, FRI-1, sharing 51 to 55% amino acid sequence identity with the closest carbapenemase sequences. However, it shared conserved residues as a source of carbapenemase activity. Purified β-lactamase FRI-1 hydrolyzed penicillins, aztreonam, and carbapenems but spared expanded-spectrum cephalosporins. The 50% inhibitory concentrations (IC50s) of clavulanic acid and tazobactam were 10-fold higher than those found for Klebsiella pneumoniae carbapenemase (KPC), IMI, and SME, leading to lower sensitivity of FRI-1 activity to β-lactamase inhibitors. The blaFRI-1 gene was located on a ca. 110-kb untypeable, transferable, and non-self-conjugative plasmid. A putative LysR family regulator-encoding gene at the 5′ end of the β-lactamase gene was identified, leading to inducible expression of the blaFRI-1 gene. PMID:26392482

  15. Hydrolysis of 4-hydroxybenzoic acid esters (parabens) and their aerobic transformation into phenol by the resistant Enterobacter cloacae strain EM.

    PubMed

    Valkova, N; Lépine, F; Valeanu, L; Dupont, M; Labrie, L; Bisaillon, J G; Beaudet, R; Shareck, F; Villemur, R

    2001-06-01

    Enterobacter cloacae strain EM was isolated from a commercial dietary mineral supplement stabilized by a mixture of methylparaben and propylparaben. It harbored a high-molecular-weight plasmid and was resistant to high concentrations of parabens. Strain EM was able to grow in liquid media containing similar amounts of parabens as found in the mineral supplement (1,700 and 180 mg of methyl and propylparaben, respectively, per liter or 11.2 and 1.0 mM) and in very high concentrations of methylparaben (3,000 mg liter(-1), or 19.7 mM). This strain was able to hydrolyze approximately 500 mg of methyl-, ethyl-, or propylparaben liter(-1) (3 mM) in less than 2 h in liquid culture, and the supernatant of a sonicated culture, after a 30-fold dilution, was able to hydrolyze 1,000 mg of methylparaben liter(-1) (6.6 mM) in 15 min. The first step of paraben degradation was the hydrolysis of the ester bond to produce 4-hydroxybenzoic acid, followed by a decarboxylation step to produce phenol under aerobic conditions. The transformation of 4-hydroxybenzoic acid into phenol was stoichiometric. The conversion of approximately 500 mg of parabens liter(-1) (3 mM) to phenol in liquid culture was completed within 5 h without significant hindrance to the growth of strain EM, while higher concentrations of parabens partially inhibited its growth.

  16. Trapping of nonhydrolyzable cephalosporins by cephalosporinases in Enterobacter cloacae and Pseudomonas aeruginosa as a possible resistance mechanism.

    PubMed Central

    Then, R L; Angehrn, P

    1982-01-01

    Resistance to cefotaxime (CTA) and ceftriaxone (CTR) in Enterobacter cloacae and Pseudomonas aeruginosa was investigated in several strains which are susceptible or resistant to these agents. All strains produced a chromosomally mediated cephalosporinase of the Richmond type 1. beta-Lactamases in susceptible strains were inducible, whereas resistant strains produced the enzymes constitutively. CTA and CTR were very poor substrates but potent inhibitors of all enzymes. Binding to, rather than hydrolysis by, beta-lactamases was assumed to be a major reason for resistance, and combination experiments supported this assumption. Dicloxacillin, which did not inhibit the growth and which was a poor inducer but a strong inhibitor of these beta-lactamases, exerted strong synergistic activity when combined with CTA or CTR in strains which produced large amounts of beta-lactamase constitutively. Cefoxitin, on the other hand, poorly active alone, but a good inducer, strongly antagonized CTA or CTR in susceptible strains producing inducible enzymes. In marked contrast to CTA and CTR were the findings with cefsulodin. Cefsulodin was active against CTA- and CTR-resistant Pseudomonas, and its activity was hardly influenced by dicloxacillin or cefoxitin. Since cefsulodin was found to have a very low affinity for all cephalosporinases, these findings corroborate the assumption that binding of nonhydrolyzable cephalosporins, rather than hydrolysis by cephalosporinases, may play an important role in resistance to these agents and other newer cephalosporins in Enterobacteriaceae, as well as in other gram-negative bacteria. PMID:6808912

  17. Study on biodegradation of Mazut by newly isolated strain Enterobacter cloacae BBRC10061: improving and kinetic investigation

    PubMed Central

    2013-01-01

    Mazut as a source content of various hydrocarbons is hard to be degraded and its cracking could turn mazut into useful materials. Nevertheless degradation of mazut by routine methods is too expensive but application of indigenous microorganisms as biocatalysts could be effective and important to lower the costs and expand its consumption. Mazut biodegradation can be improved using various strategies; Therefore in this study newly isolated strain Enterobacter cloacae BBRC 10061 was used in a method of gradual addition of mazut into medium and its results were compared with simple addition method. To investigate degradation of mazut by BBRC 10061, influence of increase of mazut concentration was assayed based on gradual addition method. Also different kinetic models were used to evaluate kinetics of the process. Results showed that gradual addition method has been a beneficial technique for improvement of mazut degradation because bacterial induction to produce biosurfactant and essential enzymes for cracking mazut was higher during process. Although addition of more mazut increased the rate of biodegradation but percentage of degradation decreased. pH of medium decreased during biodegradation period while electric potential increased. Also the biodegradation kinetics was not fitted with the biokinetic models; therefore kinetics of biodegradation of mazut has to be studied by new models. PMID:23369455

  18. [First report of carbapenemases in Osijek-Baranja County in imported Enterobacter cloacae isolate in vitro susceptible to carbapenems].

    PubMed

    Bedenić, Branka; Zujić Atalić, Vlasta; Bogdan, Maja; Beader, Nataša; Godić Torkar, Karmen; Izaković, Senka

    2015-01-01

    Carbapenems are often the only therapeutic option to treat infections caused by multidrug-resistant Gram-negative bacteria. Emergence of carbapenemases in the isolates of Enterobacteriaceae limits therapeutic options. Carbapenem-resistant Enterobacteriaceae have emerged since 2008 throughout Croatia. In Osijek-Baranja County carbapenem-resistant strains of Enterobacteriaceae were not reported until 2013. The first carbapenem-resistant strain (Enterobacter cloacae) was identified in August 2013 in a patient previously hospitalized at University Hospital Center Zagreb for the treatment of acute lymphoblastic leukemia. Molecular analysis revealed the production of VIM-1 metallo-beta-lactamase (MBL). In spite of the metallo-beta-lactamase production the strain was not resistant to imipenem and meropenem in disk-diffusion and microdilution test. This report shows that routine susceptibility testing carried out in most laboratories does not necessarily detect carbapenemase production in Enterobacteriaceae. Since these enzymes are encoded on mobile genetic elements there is a risk of horizontal spread to other enterobacterial isolates and the development of hospital outbreaks.

  19. Genomic Characterization of Enterobacter cloacae Isolates from China That Coproduce KPC-3 and NDM-1 Carbapenemases.

    PubMed

    Du, Hong; Chen, Liang; Chavda, Kalyan D; Pandey, Ruchi; Zhang, Haifang; Xie, Xiaofang; Tang, Yi-Wei; Kreiswirth, Barry N

    2016-04-01

    Here, we report twoEnterobacter cloacaesequence type 231 isolates coproducing KPC-3 and NDM-1 that have caused lethal infections in a tertiary hospital in China. TheblaNDM-1-harboring plasmids carry IncA/C2and IncR replicons, showing a mosaic plasmid structure, and theblaNDM-1is harbored on a novel class I integron-like element.blaKPC-3is located on a Tn3-ΔblaTEM-1-blaKPC-3-ΔTn1722element, flanked by two 9-bp direct-repeat sequences and harbored on an IncX6 plasmid.

  20. Effects of Eliminating Pyruvate Node Pathways and of Coexpression of Heterogeneous Carboxylation Enzymes on Succinate Production by Enterobacter aerogenes

    PubMed Central

    Yamamoto, Yoko; Fukui, Keita; Nishio, Yousuke; Hashiguchi, Kenichi; Usuda, Yoshihiro; Sode, Koji

    2014-01-01

    Lowering the pH in bacterium-based succinate fermentation is considered a feasible approach to reduce total production costs. Newly isolated Enterobacter aerogenes strain AJ110637, a rapid carbon source assimilator under weakly acidic (pH 5.0) conditions, was selected as a platform for succinate production. Our previous work showed that the ΔadhE/PCK strain, developed from AJ110637 with inactivated ethanol dehydrogenase and introduced Actinobacillus succinogenes phosphoenolpyruvate carboxykinase (PCK), generated succinate as a major product of anaerobic mixed-acid fermentation from glucose under weakly acidic conditions (pH <6.2). To further improve the production of succinate by the ΔadhE/PCK strain, metabolically engineered strains were designed based on the elimination of pathways that produced undesirable products and the introduction of two carboxylation pathways from phosphoenolpyruvate and pyruvate to oxaloacetate. The highest production of succinate was observed with strain ES04/PCK+PYC, which had inactivated ethanol, lactate, acetate, and 2,3-butanediol pathways and coexpressed PCK and Corynebacterium glutamicum pyruvate carboxylase (PYC). This strain produced succinate from glucose with over 70% yield (gram per gram) without any measurable formation of ethanol, lactate, or 2,3-butanediol under weakly acidic conditions. The impact of lowering the pH from 7.0 to 5.5 on succinate production in this strain was evaluated under pH-controlled batch culture conditions and showed that the lower pH decreased the succinate titer but increased its yield. These findings can be applied to identify additional engineering targets to increase succinate production. PMID:25416770

  1. Effects of eliminating pyruvate node pathways and of coexpression of heterogeneous carboxylation enzymes on succinate production by Enterobacter aerogenes.

    PubMed

    Tajima, Yoshinori; Yamamoto, Yoko; Fukui, Keita; Nishio, Yousuke; Hashiguchi, Kenichi; Usuda, Yoshihiro; Sode, Koji

    2015-02-01

    Lowering the pH in bacterium-based succinate fermentation is considered a feasible approach to reduce total production costs. Newly isolated Enterobacter aerogenes strain AJ110637, a rapid carbon source assimilator under weakly acidic (pH 5.0) conditions, was selected as a platform for succinate production. Our previous work showed that the ΔadhE/PCK strain, developed from AJ110637 with inactivated ethanol dehydrogenase and introduced Actinobacillus succinogenes phosphoenolpyruvate carboxykinase (PCK), generated succinate as a major product of anaerobic mixed-acid fermentation from glucose under weakly acidic conditions (pH <6.2). To further improve the production of succinate by the ΔadhE/PCK strain, metabolically engineered strains were designed based on the elimination of pathways that produced undesirable products and the introduction of two carboxylation pathways from phosphoenolpyruvate and pyruvate to oxaloacetate. The highest production of succinate was observed with strain ES04/PCK+PYC, which had inactivated ethanol, lactate, acetate, and 2,3-butanediol pathways and coexpressed PCK and Corynebacterium glutamicum pyruvate carboxylase (PYC). This strain produced succinate from glucose with over 70% yield (gram per gram) without any measurable formation of ethanol, lactate, or 2,3-butanediol under weakly acidic conditions. The impact of lowering the pH from 7.0 to 5.5 on succinate production in this strain was evaluated under pH-controlled batch culture conditions and showed that the lower pH decreased the succinate titer but increased its yield. These findings can be applied to identify additional engineering targets to increase succinate production.

  2. In Vivo Evolution of Bacterial Resistance in Two Cases of Enterobacter aerogenes Infections during Treatment with Imipenem.

    PubMed

    Philippe, Nadège; Maigre, Laure; Santini, Sébastien; Pinet, Elizabeth; Claverie, Jean-Michel; Davin-Régli, Anne-Véronique; Pagès, Jean-Marie; Masi, Muriel

    2015-01-01

    Infections caused by multidrug resistant (MDR) bacteria are a major concern worldwide. Changes in membrane permeability, including decreased influx and/or increased efflux of antibiotics, are known as key contributors of bacterial MDR. Therefore, it is of critical importance to understand molecular mechanisms that link membrane permeability to MDR in order to design new antimicrobial strategies. In this work, we describe genotype-phenotype correlations in Enterobacter aerogenes, a clinically problematic and antibiotic resistant bacterium. To do this, series of clinical isolates have been periodically collected from two patients during chemotherapy with imipenem. The isolates exhibited different levels of resistance towards multiple classes of antibiotics, consistently with the presence or the absence of porins and efflux pumps. Transport assays were used to characterize membrane permeability defects. Simultaneous genome-wide analysis allowed the identification of putative mutations responsible for MDR. The genome of the imipenem-susceptible isolate G7 was sequenced to closure and used as a reference for comparative genomics. This approach uncovered several loci that were specifically mutated in MDR isolates and whose products are known to control membrane permeability. These were omp35 and omp36, encoding the two major porins; rob, encoding a global AraC-type transcriptional activator; cpxA, phoQ and pmrB, encoding sensor kinases of the CpxRA, PhoPQ and PmrAB two-component regulatory systems, respectively. This report provides a comprehensive analysis of membrane alterations relative to mutational steps in the evolution of MDR of a recognized nosocomial pathogen.

  3. In vivo development of carbapenem resistance in clinical isolates of Enterobacter aerogenes producing multiple beta-lactamases.

    PubMed

    Chen, Ya-Gang; Zhang, Ying; Yu, Yun-Song; Qu, Ting-Ting; Wei, Ze-Qing; Shen, Ping; Li, Lan-Juan

    2008-10-01

    Four clinical strains of extended-spectrum beta-lactamase- and AmpC-producing Enterobacter aerogenes were isolated successively from a liver transplantation patient. Isolates C(1) and C(2) were isolated prior to carbapenem therapy, whilst isolates C(3) and C(4) were recovered after 40 days of carbapenem therapy. The homology of these strains was analysed by pulsed-field gel electrophoresis (PFGE). beta-Lactamases were analysed by isoelectric focusing, polymerase chain reaction (PCR) and sequencing. Outer membrane proteins were analysed by PCR, sequencing, sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blot. Disruption of OmpE36 in C(1) in vitro was also performed by homologous gene recombination. The isolates demonstrated an indistinguishable PFGE pattern. Molecular characterisation revealed that, in addition to the pre-existing multiple beta-lactamases (DHA-1, TEM-1, SHV-5, CTX-M-3 and CTX-M-14) found in C(1) and C(2), isolates C(3) and C(4) failed to express OmpE36 owing to insertional inactivation by an IS903-like insertion sequence. Other resistance mechanisms, such as production of carbapenem-hydrolysing enzymes or expression of chromosomal efflux, were apparently not involved. Completely replacing OmpE36 by the kanamycin resistance gene (kan) resulted in a significant increase in carbapenem minimum inhibitory concentrations of an ompE36 mutant. Thus, C(3) and C(4) were apparently derived from the previously imipenem-susceptible isolates C(1) and C(2). Following carbapenem exposure, depletion of OmpE36 expression resulted in the collateral effect of carbapenem resistance.

  4. Electronic structure analysis of the dinuclear metal center in the bioremediator glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes.

    PubMed

    Hadler, Kieran S; Mitić, Natasa; Yip, Sylvia Hsu-Chen; Gahan, Lawrence R; Ollis, David L; Schenk, Gerhard; Larrabee, James A

    2010-03-15

    The glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a promiscuous, dinuclear metallohydrolase that has potential application in the remediation of organophosphate nerve agents and pesticides. GpdQ employs an unusual reaction mechanism in which the enzyme is predominantly mononuclear in the resting state, and substrate binding induces the formation of the catalytically competent dinuclear center (Hadler et al. J. Am. Chem. Soc. 2008, 130, 14129). Reactivity is further modulated by the coordination flexibility of Asn80, a ligand that binds to the second, loosely bound metal ion (Hadler et al. J. Am. Chem. Soc. 2009, 131, 11900). It is proposed that hydrolysis is initiated by a terminal, metal-bound hydroxide molecule which is activated at unusually low pH by electrostatic/hydrogen bonding interactions with a bridging hydroxide species. In this study, electronic structure analysis of the dinuclear center is employed to study the coordination environment of the dinuclear center at the resting and product-bound stage of catalysis. This is achieved through the use of variable temperature, variable field magnetic circular dichroism experiments involving the Co(II)-substituted wild type enzyme and its Asn80Asp variant. The data support the above model for the catalytic mechanism whereby the metal ion-bridging hydroxide molecule activates a terminally bound hydroxide nucleophile. Replacement of Asn80 by an aspartate residue does prevent coordination flexibility but also leads to cleavage of the mu-hydroxide bridge and reduced reactivity. This is the first study to investigate the electronic structure of an enzyme with a mu-1,1-carboxylate bridged dicobalt(II) center.

  5. New Delhi Metallo-β-Lactamase 1(NDM-1), the Dominant Carbapenemase Detected in Carbapenem-Resistant Enterobacter cloacae from Henan Province, China.

    PubMed

    Liu, Cailin; Qin, Shangshang; Xu, Hui; Xu, Lijuan; Zhao, Di; Liu, Xuchun; Lang, Shaolei; Feng, Xianju; Liu, Hong-Min

    2015-01-01

    The emergence of New Delhi metallo-β-lactamase 1 (NDM-1) has become established as a major public health threat and represents a new challenge in the treatment of infectious diseases. In this study, we report a high incidence and endemic spread of NDM-1-producing carbapenem-resistant Enterobacter cloacae isolates in Henan province, China. Eight (72.7%) out of eleven non-duplicated carbapenem-resistant E. cloacae isolates collected between June 2011 and May 2013 were identified as NDM-1 positive. The blaNDM-1 gene surrounded by an entire ISAba125 element and a bleomycin resistance gene bleMBL in these isolates were carried by diverse conjugatable plasmids (IncA/C, IncN, IncHI2 and untypeable) ranging from ~55 to ~360 kb. Molecular epidemiology analysis revealed that three NDM-1-producing E. cloacae belonged to the same multilocus sequence type (ST), ST120, two of which were classified as extensively drug-resistant (XDR) isolates susceptible only to tigecycline and colistin. The two XDR ST120 E. cloacae isolates co-harbored blaNDM-1, armA and fosA3 genes and could transfer resistance to carbapenems, fosfomycin and aminoglycosides simultaneously via a conjugation experiment. Our study demonstrated NDM-1 was the most prevalent metallo-β-lactamase (MBL) among carbapenem-resistant E.cloacae isolates and identified a potential endemic clone of ST120 in Henan province. These findings highlight the need for enhanced efforts to monitor the further spread of NDM-1 and XDR ST120 E. cloacae in this region.

  6. New Delhi Metallo-β-Lactamase 1(NDM-1), the Dominant Carbapenemase Detected in Carbapenem-Resistant Enterobacter cloacae from Henan Province, China

    PubMed Central

    Liu, Xuchun; Lang, Shaolei; Feng, Xianju; Liu, Hong-Min

    2015-01-01

    The emergence of New Delhi metallo-β-lactamase 1 (NDM-1) has become established as a major public health threat and represents a new challenge in the treatment of infectious diseases. In this study, we report a high incidence and endemic spread of NDM-1-producing carbapenem-resistant Enterobacter cloacae isolates in Henan province, China. Eight (72.7%) out of eleven non-duplicated carbapenem-resistant E. cloacae isolates collected between June 2011 and May 2013 were identified as NDM-1 positive. The blaNDM-1 gene surrounded by an entire ISAba125 element and a bleomycin resistance gene bleMBL in these isolates were carried by diverse conjugatable plasmids (IncA/C, IncN, IncHI2 and untypeable) ranging from ~55 to ~360 kb. Molecular epidemiology analysis revealed that three NDM-1-producing E. cloacae belonged to the same multilocus sequence type (ST), ST120, two of which were classified as extensively drug-resistant (XDR) isolates susceptible only to tigecycline and colistin. The two XDR ST120 E. cloacae isolates co-harbored blaNDM-1, armA and fosA3 genes and could transfer resistance to carbapenems, fosfomycin and aminoglycosides simultaneously via a conjugation experiment. Our study demonstrated NDM-1 was the most prevalent metallo-β-lactamase (MBL) among carbapenem-resistant E.cloacae isolates and identified a potential endemic clone of ST120 in Henan province. These findings highlight the need for enhanced efforts to monitor the further spread of NDM-1 and XDR ST120 E. cloacae in this region. PMID:26263489

  7. Se(VI) Reduction and the Precipitation of Se(0) Precipitation by the Facultative Bacterium Enterobacter Cloacae SLD1a-1 is Regulated by FNR

    SciTech Connect

    Yee,N.; Ma, J.; Dalia, A.; Boonfueng, T.; Kobayashi, D.

    2007-01-01

    The fate of selenium in the environment is controlled, in part, by microbial selenium oxyanion reduction and Se(0) precipitation. In this study, we identified a genetic regulator that controls selenate reductase activity in the Se-reducing bacterium Enterobacter cloacae SLD1a-1. Heterologous expression of the global anaerobic regulatory gene fnr (fumarate nitrate reduction regulator) from E. cloacae in the non-Se-reducing strain Escherichia coli S17-1 activated the ability to reduce Se(VI) and precipitate insoluble Se(0) particles. Se(VI) reduction by E. coli S17-1 containing the fnr gene occurred at rates similar to those for E. cloacae, with first-order reaction constants of k = 2.07 x 10{sup -2} h{sup -1} and k = 3.36 x 10{sup -2} h{sup -1}, respectively, and produced elemental selenium particles with identical morphologies and short-range atomic orders. Mutation of the fnr gene in E. cloacae SLD1a-1 resulted in derivative strains that were deficient in selenate reductase activity and unable to precipitate elemental selenium. Complementation by the wild-type fnr sequence restored the ability of mutant strains to reduce Se(VI). Our findings suggest that Se(VI) reduction and the precipitation of Se(0) by facultative anaerobes are regulated by oxygen-sensing transcription factors and occur under suboxic conditions.

  8. Effects of tazobactam on the frequency of the emergence of resistant strains from Enterobacter cloacae, Citrobacter freundii, and Proteus vulgaris (beta-lactamase derepressed mutants).

    PubMed

    Higashitani, F; Nishida, K; Hyodo, A; Inoue, M

    1995-09-01

    When Enterobacter cloacae, Citrobacter freundii, and Proteus vulgaris were treated with piperacillin (PIPC) in combination with tazobactam (TAZ), the in vitro frequency of emergence of resistant strains (beta-lactamase producing mutants) was lower than with PIPC or ceftazidime (CAZ) treated bacteria. In a mouse intraperitoneal infection model caused by E. cloacae, beta-lactamase derepressed mutants were detected following therapy with PIPC or CAZ, although no derepressed mutants were detected after treatment with PIPC in combination with TAZ. This suppression of the selection of derepressed mutants, which produce large amounts of beta-lactamases, by the combination of TAZ and PIPC suggests that the combination delays the increase of resistant mutants compared with PIPC alone.

  9. Detection and Characterization of VIM-31, a New Variant of VIM-2 with Tyr224His and His252Arg Mutations, in a Clinical Isolate of Enterobacter cloacae

    PubMed Central

    Bebrone, Carine; Huang, Te-Din; Bouchahrouf, Warda; DeGheldre, Yves; Deplano, Ariane; Hoffmann, Kurt; Glupczynski, Youri

    2012-01-01

    We report the first description of the metallo-β-lactamase VIM-31, a new variant of VIM-2 with Tyr224His and His252Arg mutations, in Enterobacter cloacae 11236, which was isolated from blood specimens of a patient with colonic adenocarcinoma in Belgium. blaVIM-31 was found on a class 1 integron located on a self-transferable but not typeable 42-kb plasmid. Compared to values published elsewhere for VIM-2, the purified VIM-31 enzyme showed weaker catalytic efficiency against all the tested beta-lactam agents (except for ertapenem), resulting from lower kcat (except for ertapenem) and higher Km values for VIM-31. PMID:22391550

  10. Coproduction of KPC-18 and VIM-1 Carbapenemases by Enterobacter cloacae: Implications for Newer β-Lactam–β-Lactamase Inhibitor Combinations

    PubMed Central

    Thomson, Gina K.; Snyder, James W.; McElheny, Christi L.; Thomson, Kenneth S.

    2015-01-01

    Enterobacter cloacae strain G6809 with reduced susceptibility to carbapenems was identified from a patient in a long-term acute care hospital in Kentucky. G6809 belonged to sequence type (ST) 88 and carried two carbapenemase genes, blaKPC-18 and blaVIM-1. Whole-genome sequencing localized blaKPC-18 to the chromosome and blaVIM-1 to a 58-kb plasmid. The strain was highly resistant to ceftazidime-avibactam. Insidious coproduction of metallo-β-lactamase with KPC-type carbapenemase has implications for the use of next-generation β-lactam–β-lactamase inhibitor combinations. PMID:26719440

  11. Coproduction of KPC-18 and VIM-1 Carbapenemases by Enterobacter cloacae: Implications for Newer β-Lactam-β-Lactamase Inhibitor Combinations.

    PubMed

    Thomson, Gina K; Snyder, James W; McElheny, Christi L; Thomson, Kenneth S; Doi, Yohei

    2016-03-01

    Enterobacter cloacae strain G6809 with reduced susceptibility to carbapenems was identified from a patient in a long-term acute care hospital in Kentucky. G6809 belonged to sequence type (ST) 88 and carried two carbapenemase genes, bla(KPC-18) and bla(VIM-1). Whole-genome sequencing localized bla(KPC-18) to the chromosome and bla(VIM-1) to a 58-kb plasmid. The strain was highly resistant to ceftazidime-avibactam. Insidious coproduction of metallo-β-lactamase with KPC-type carbapenemase has implications for the use of next-generation β-lactam-β-lactamase inhibitor combinations.

  12. Draft Genome Sequence of Hydrocarbon-Degrading Enterobacter cloacae Strain S1:CND1, Isolated from Crude Oil-Contaminated Soil from the Noonmati Oil Refinery, Guwahati, Assam, India.

    PubMed

    Mukherjee, Arghya; Chettri, Bobby; Langpoklakpam, James S; Singh, Arvind K; Chattopadhyay, Dhrubajyoti

    2016-05-12

    We report here the 4.57-Mb draft genome sequence of hydrocarbon-degrading Enterobacter cloacae strain S1:CND1 isolated from oil-contaminated soil in Guwahati, India. S1:CND1 contains 4,205 coding sequences and has a G+C content of 57.45%. This is the first report of the genome sequence of an E. cloacae adapted to an oil-contaminated environment.

  13. Draft Genome Sequence of Hydrocarbon-Degrading Enterobacter cloacae Strain S1:CND1, Isolated from Crude Oil-Contaminated Soil from the Noonmati Oil Refinery, Guwahati, Assam, India

    PubMed Central

    Mukherjee, Arghya; Chettri, Bobby; Langpoklakpam, James S.; Singh, Arvind K.

    2016-01-01

    We report here the 4.57-Mb draft genome sequence of hydrocarbon-degrading Enterobacter cloacae strain S1:CND1 isolated from oil-contaminated soil in Guwahati, India. S1:CND1 contains 4,205 coding sequences and has a G+C content of 57.45%. This is the first report of the genome sequence of an E. cloacae adapted to an oil-contaminated environment. PMID:27174279

  14. Occurrence and regulation of the ferric citrate transport system in Escherichia coli B, Klebsiella pneumoniae, Enterobacter aerogenes, and Photorhabdus luminescens.

    PubMed

    Mahren, Susanne; Schnell, Heidrun; Braun, Volkmar

    2005-11-01

    In Escherichia coli K-12, transcription of the ferric citrate transport genes fecABCDE is initiated by binding of diferric dicitrate to the outer membrane protein FecA which elicits a signaling cascade from the cell surface to the cytoplasm. The FecI sigma factor is only active in the presence of FecR, which transfers the signal across the cytoplasmic membrane. In other bacteria, fecIRA homologues control iron transport gene transcription by siderophores other than citrate. However, in most cases, the FecI homologues are active in the absence of the FecR homologues, which might function as anti-sigma factors. Since not all E. coli strains contain a fec system, we determined the occurrence of fec genes in selected Enterobacteriaceae and the dependence of FecI activity on FecR. Incomplete FecIRA systems were chromosomally encoded in Enterobacter aerogenes strains and plasmid-encoded in K. pneumoniae. E. coli B, Photorhabdus luminescens and one of three Klebsiella pneumoniae strains had a functional FecIRA regulatory system as in E. coli K-12. The cytoplasmic N-terminal FecR fragments caused constitutive FecI activity in the absence of ferric citrate. The PCR-generated mutant FecI(D40G) was inactive and FecI(S15P) was partially active. FecR of E. coli K-12 activated FecI of all tested strains except FecI encoded on the virulence plasmid pLVPK of K. pneumoniae, which differed from E. coli K-12 FecI by having mutations in region 4, which is important for interaction with FecR. The C-terminally truncated FecR homologue of pLVPK was inactive. pLVPK-encoded FecA contains a 38-residue sequence in front of the signal sequence that did not prevent processing and proper integration of FecA into the outer membrane of E. coli and lacks the signaling sequence required for transcription initiation of the fec transport genes, making it induction-incompetent but transport-competent. The evidence indicates that fecIRABCDE genes are acquired by horizontal DNA transfer and can undergo

  15. In Vitro Activity of Polymyxin B in Combination with Various Antibiotics against Extensively Drug-Resistant Enterobacter cloacae with Decreased Susceptibility to Polymyxin B.

    PubMed

    Cai, Yiying; Lim, Tze-Peng; Teo, Jocelyn; Sasikala, Suranthran; Lee, Winnie; Hong, Yanjun; Chan, Eric Chun Yong; Tan, Thean Yen; Tan, Thuan-Tong; Koh, Tse Hsien; Hsu, Li Yang; Kwa, Andrea L

    2016-09-01

    Against extensively drug-resistant (XDR) Enterobacter cloacae, combination antibiotic therapy may be the only option. We investigated the activity of various antibiotics in combination with polymyxin B using time-kill studies (TKS). TKS were conducted with four nonclonal XDR E. cloacae isolates with 5 log10 CFU/ml bacteria against maximum, clinically achievable concentrations of polymyxin B alone and in two-drug combinations with 10 different antibiotics. A hollow-fiber infection model (HFIM) simulating clinically relevant polymyxin B and tigecycline dosing regimens was conducted for two isolates over 240 h. Emergence of resistance was quantified using antibiotic-containing (3× MIC) media. Biofitness and stability of resistant phenotypes were determined. All XDR E. cloacae isolates were resistant to all antibiotics except for polymyxin B (polymyxin B MIC, 1 to 4 mg/liter). All isolates harbored metallo-β-lactamases (two with NDM-1, two with IMP-1). In single TKS, all antibiotics alone demonstrated regrowth at 24 h, except amikacin against two strains and polymyxin B and meropenem against one strain each. In combination TKS, only polymyxin B plus tigecycline was bactericidal against all four XDR E. cloacae isolates at 24 h. In HFIM, tigecycline and polymyxin B alone did not exhibit any killing activity. Bactericidal kill was observed at 24 h for both isolates for polymyxin B plus tigecycline; killing was sustained for one isolate but regrowth was observed for the second. Phenotypically stable resistant mutants with reduced in vitro growth rates were observed. Polymyxin B plus tigecycline is a promising combination against XDR E. cloacae However, prolonged and indiscriminate use can result in resistance emergence.

  16. Emergence in Spain of a Multidrug-Resistant Enterobacter cloacae Clinical Isolate Producing SFO-1 Extended-Spectrum β-Lactamase▿

    PubMed Central

    Fernández, Ana; Pereira, María José; Suárez, José Manuel; Poza, Margarita; Treviño, Mercedes; Villalón, Pilar; Sáez-Nieto, Juan Antonio; Regueiro, Benito José; Villanueva, Rosa; Bou, Germán

    2011-01-01

    Between February 2006 and October 2009, 38 patients in different wards at the A Coruña University Hospital (northwest Spain) were either infected with or colonized by an epidemic, multidrug-resistant (MDR), and extended-spectrum-β-lactamase (ESBL)-producing strain of Enterobacter cloacae (EbSF), which was susceptible only to carbapenems. Semiautomated repetitive extragenic palindromic sequence-based PCR (rep-PCR) and pulsed-field gel electrophoresis (PFGE) analysis revealed that all of the E. cloacae isolates belonged to the same clone. Cloning and sequencing enabled the detection of the SFO-1 ESBL in the epidemic strain and the description of its genetic environment. The presence of the ampR gene was detected upstream of blaSFO-1, and two complete sequences of IS26 surrounding ampR and ampA were detected. These IS26 sequences are bordered by complete left and right inverted repeats (IRL and IRR, respectively), which suggested that they were functional. The whole segment flanked by two IS26 copies may be considered a putative large composite transposon. A gene coding for aminoglycoside acetyltransferase (gentamicin resistance gene [aac3]) was found downstream of the 3′ IS26. Despite the implementation of strict infection control measures, strain EbSF spread through different areas of the hospital. A case-control study was performed to assess risk factors for EbSF acquisition. A multivariate analysis revealed that the prior administration of β-lactam antibiotics, chronic renal failure, tracheostomy, and prior hospitalization were statistically associated with SFO-1-producing E. cloacae acquisition. This study describes for the first time an outbreak in which an SFO-1-producing E. cloacae strain was involved. Note that so far, this β-lactamase has previously been isolated in only a single case of E. cloacae infection in Japan. PMID:21227991

  17. In Vitro Activity of Polymyxin B in Combination with Various Antibiotics against Extensively Drug-Resistant Enterobacter cloacae with Decreased Susceptibility to Polymyxin B

    PubMed Central

    Cai, Yiying; Lim, Tze-Peng; Sasikala, Suranthran; Lee, Winnie; Hong, Yanjun; Chan, Eric Chun Yong; Tan, Thean Yen; Tan, Thuan-Tong; Koh, Tse Hsien; Hsu, Li Yang

    2016-01-01

    Against extensively drug-resistant (XDR) Enterobacter cloacae, combination antibiotic therapy may be the only option. We investigated the activity of various antibiotics in combination with polymyxin B using time-kill studies (TKS). TKS were conducted with four nonclonal XDR E. cloacae isolates with 5 log10 CFU/ml bacteria against maximum, clinically achievable concentrations of polymyxin B alone and in two-drug combinations with 10 different antibiotics. A hollow-fiber infection model (HFIM) simulating clinically relevant polymyxin B and tigecycline dosing regimens was conducted for two isolates over 240 h. Emergence of resistance was quantified using antibiotic-containing (3× MIC) media. Biofitness and stability of resistant phenotypes were determined. All XDR E. cloacae isolates were resistant to all antibiotics except for polymyxin B (polymyxin B MIC, 1 to 4 mg/liter). All isolates harbored metallo-β-lactamases (two with NDM-1, two with IMP-1). In single TKS, all antibiotics alone demonstrated regrowth at 24 h, except amikacin against two strains and polymyxin B and meropenem against one strain each. In combination TKS, only polymyxin B plus tigecycline was bactericidal against all four XDR E. cloacae isolates at 24 h. In HFIM, tigecycline and polymyxin B alone did not exhibit any killing activity. Bactericidal kill was observed at 24 h for both isolates for polymyxin B plus tigecycline; killing was sustained for one isolate but regrowth was observed for the second. Phenotypically stable resistant mutants with reduced in vitro growth rates were observed. Polymyxin B plus tigecycline is a promising combination against XDR E. cloacae. However, prolonged and indiscriminate use can result in resistance emergence. PMID:27324776

  18. Effect of Transcriptional Activators SoxS, RobA, and RamA on Expression of Multidrug Efflux Pump AcrAB-TolC in Enterobacter cloacae

    PubMed Central

    Pérez, Astrid; Poza, Margarita; Aranda, Jesús; Latasa, Cristina; Medrano, Francisco Javier; Tomás, María; Romero, Antonio; Lasa, Iñigo

    2012-01-01

    Control of membrane permeability is a key step in regulating the intracellular concentration of antibiotics. Efflux pumps confer innate resistance to a wide range of toxic compounds such as antibiotics, dyes, detergents, and disinfectants in members of the Enterobacteriaceae. The AcrAB-TolC efflux pump is involved in multidrug resistance in Enterobacter cloacae. However, the underlying mechanism that regulates the system in this microorganism remains unknown. In Escherichia coli, the transcription of acrAB is upregulated under global stress conditions by proteins such as MarA, SoxS, and Rob. In the present study, two clinical isolates of E. cloacae, EcDC64 (a multidrug-resistant strain overexpressing the AcrAB-TolC efflux pump) and Jc194 (a strain with a basal AcrAB-TolC expression level), were used to determine whether similar global stress responses operate in E. cloacae and also to establish the molecular mechanisms underlying this response. A decrease in susceptibility to erythromycin, tetracycline, telithromycin, ciprofloxacin, and chloramphenicol was observed in clinical isolate Jc194 and, to a lesser extent in EcDC64, in the presence of salicylate, decanoate, tetracycline, and paraquat. Increased expression of the acrAB promoter in the presence of the above-described conditions was observed by flow cytometry and reverse transcription-PCR, by using a reporter fusion protein (green fluorescent protein). The expression level of the AcrAB promoter decreased in E. cloacae EcDC64 derivates deficient in SoxS, RobA, and RamA. Accordingly, the expression level of the AcrAB promoter was higher in E. cloacae Jc194 strains overproducing SoxS, RobA, and RamA. Overall, the data showed that SoxS, RobA, and RamA regulators were associated with the upregulation of acrAB, thus conferring antimicrobial resistance as well as a stress response in E. cloacae. In summary, the regulatory proteins SoxS, RobA, and RamA were cloned and sequenced for the first time in this species. The

  19. Expression of Zinc Transporter Genes in Rice as Influenced by Zinc-Solubilizing Enterobacter cloacae Strain ZSB14.

    PubMed

    Krithika, Selvaraj; Balachandar, Dananjeyan

    2016-01-01

    Zinc (Zn) deficiency in major food crops has been considered as an important factor affecting the crop production and subsequently the human health. Rice (Oryza sativa) is sensitive to Zn deficiency and thereby causes malnutrition to most of the rice-eating Asian populations. Application of zinc solubilizing bacteria (ZSB) could be a sustainable agronomic approach to increase the soil available Zn which can mitigate the yield loss and consequently the nutritional quality of rice. Understanding the molecular interactions between rice and unexplored ZSB is useful for overcoming Zn deficiency problems. In the present study, the role of zinc solubilizing bacterial strain Enterobacter cloacae strain ZSB14 on regulation of Zn-regulated transporters and iron (Fe)-regulated transporter-like protein (ZIP) genes in rice under iron sufficient and deficient conditions was assessed by quantitative real-time reverse transcription PCR. The expression patterns of OsZIP1, OsZIP4, and OsZIP5 in root and shoot of rice were altered due to the Zn availability as dictated by Zn sources and ZSB inoculation. Fe sufficiency significantly reduced the root and shoot OsZIP1 expression, but not the OsZIP4 and OsZIP5 levels. Zinc oxide in the growth medium up-regulated all the assessed ZIP genes in root and shoot of rice seedlings. When ZSB was inoculated to rice seedlings grown with insoluble zinc oxide in the growth medium, the expression of root and shoot OsZIP1, OsZIP4, and OsZIP5 was reduced. In the absence of zinc oxide, ZSB inoculation up-regulated OsZIP1 and OsZIP5 expressions. Zinc nutrition provided to the rice seedling through ZSB-bound zinc oxide solubilization was comparable to the soluble zinc sulfate application which was evident through the ZIP genes' expression and the Zn accumulation in root and shoot of rice seedlings. These results demonstrate that ZSB could play a crucial role in zinc fertilization and fortification of rice.

  20. Expression of Zinc Transporter Genes in Rice as Influenced by Zinc-Solubilizing Enterobacter cloacae Strain ZSB14

    PubMed Central

    Krithika, Selvaraj; Balachandar, Dananjeyan

    2016-01-01

    Zinc (Zn) deficiency in major food crops has been considered as an important factor affecting the crop production and subsequently the human health. Rice (Oryza sativa) is sensitive to Zn deficiency and thereby causes malnutrition to most of the rice-eating Asian populations. Application of zinc solubilizing bacteria (ZSB) could be a sustainable agronomic approach to increase the soil available Zn which can mitigate the yield loss and consequently the nutritional quality of rice. Understanding the molecular interactions between rice and unexplored ZSB is useful for overcoming Zn deficiency problems. In the present study, the role of zinc solubilizing bacterial strain Enterobacter cloacae strain ZSB14 on regulation of Zn-regulated transporters and iron (Fe)-regulated transporter-like protein (ZIP) genes in rice under iron sufficient and deficient conditions was assessed by quantitative real-time reverse transcription PCR. The expression patterns of OsZIP1, OsZIP4, and OsZIP5 in root and shoot of rice were altered due to the Zn availability as dictated by Zn sources and ZSB inoculation. Fe sufficiency significantly reduced the root and shoot OsZIP1 expression, but not the OsZIP4 and OsZIP5 levels. Zinc oxide in the growth medium up-regulated all the assessed ZIP genes in root and shoot of rice seedlings. When ZSB was inoculated to rice seedlings grown with insoluble zinc oxide in the growth medium, the expression of root and shoot OsZIP1, OsZIP4, and OsZIP5 was reduced. In the absence of zinc oxide, ZSB inoculation up-regulated OsZIP1 and OsZIP5 expressions. Zinc nutrition provided to the rice seedling through ZSB-bound zinc oxide solubilization was comparable to the soluble zinc sulfate application which was evident through the ZIP genes’ expression and the Zn accumulation in root and shoot of rice seedlings. These results demonstrate that ZSB could play a crucial role in zinc fertilization and fortification of rice. PMID:27092162

  1. Potential of phage cocktails in the inactivation of Enterobacter cloacae--An in vitro study in a buffer solution and in urine samples.

    PubMed

    Pereira, S; Pereira, C; Santos, L; Klumpp, J; Almeida, A

    2016-01-04

    The objective of this study was to compare the dynamics of three previously isolated phages for Enterobacter cloacae in order to evaluate their ability to treat urinary tract infections (UTI). The phages genomes, survival, host range, were characterized, and the host-phage dynamics was determined in culture medium and urine samples. The presence of prophages in bacteria, host recovery and development of resistance to phage after treatment was also evaluated. The growth of the E. cloacae was inhibited by the three phages, resulting in a decrease of ≈3 log. The use of cocktails with two or three phages was significantly more effective (decrease of ≈4 log). In urine, the inactivation was still effective (≈2 log). Both phages were considered safe to inactivate the bacteria (no integrase and toxin codifying genes). Some bacteria remained viable in the presence of the phages, but their colonies were smaller than those of the non-treated control and were visible only after 5 days of incubation (visible after 24h in the control). A high bacterial inactivation efficiency with phage cocktails combined with the safety of the phages and their long periods of survival, even in urine samples, paves the way for depth studies, especially in vivo studies, to control urinary tract infection and to overcome the development of resistances by the nosocomial bacterium E. cloacae.

  2. Carbapenem susceptibility among Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae isolates obtained from patients in intensive care units in Taiwan in 2005, 2007, and 2009.

    PubMed

    Jean, Shio-Shin; Lee, Wen-Sen; Bai, Kuan-Jen; Yu, Kwok-Woon; Hsu, Chin-Wang; Yu, Kwok-Woon; Liao, Chun-Hsing; Chang, Feng-Yi; Ko, Wen-Chien; Wu, Jiunn-Jong; Chen, Yen-Hsu; Chen, Yao-Shen; Liu, Jien-Wei; Lu, Min-Chi; Liu, Cheng-Yi; Chen, Ray-Jade; Hsueh, Po-Ren

    2015-04-01

    To investigate the evolutionary trends in non-susceptibility of carbapenems against the isolates of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae from patients hospitalized in intensive care units (ICUs) of major teaching hospitals throughout Taiwan during 2005-2009, we applied the breakpoints of MICs recommended by Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing in 2013. Escalations in imipenem MIC levels for overall E. coli and E. cloacae isolates and extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae isolates were noted during this period. The overall MIC levels against imipenem and meropenem for subgroups of ESBL producers of 3 Enterobacteriaceae species were significantly higher than those of respective overall groups in 2007 and 2009. Compared with meropenem, we found that significant evidence of imipenem MIC creep and evidence of extraordinarily high rates of non-susceptibility to ertapenem among isolates of 3 species in 2009 existed. The prominent rises in rates of ertapenem non-susceptibility for ESBL-producing E. coli and K. pneumoniae during 2005-2009 and rate of ESBL positivity for E. cloacae between 4 years were notably found. Based on our findings, ertapenem should be used cautiously in management of the ICU infections caused by these potentially ESBL-producing Enterobacteriaceae isolates in Taiwan.

  3. Characterization of a Novel Putative Xer-Dependent Integrative Mobile Element Carrying the bla(NMC-A) Carbapenemase Gene, Inserted into the Chromosome of Members of the Enterobacter cloacae Complex.

    PubMed

    Antonelli, Alberto; D'Andrea, Marco Maria; Di Pilato, Vincenzo; Viaggi, Bruno; Torricelli, Francesca; Rossolini, Gian Maria

    2015-10-01

    An Enterobacter ludwigii strain was isolated during routine screening of a Japanese patient for carriage of carbapenem-resistant Enterobacteriaceae. PCR analysis revealed the blaNMC-A carbapenemase gene. Whole-genome sequencing revealed that blaNMC-A was inserted in the chromosome and associated with a novel 29.1-kb putative Xer-dependent integrative mobile element, named EludIMEX-1. Bioinformatic analysis identified similar elements in the genomes of an Enterobacter asburiae strain and of other Enterobacter cloacae complex strains, confirming the mobile nature of this element.

  4. Characterization of a Novel Putative Xer-Dependent Integrative Mobile Element Carrying the blaNMC-A Carbapenemase Gene, Inserted into the Chromosome of Members of the Enterobacter cloacae Complex

    PubMed Central

    Antonelli, Alberto; D'Andrea, Marco Maria; Di Pilato, Vincenzo; Viaggi, Bruno; Torricelli, Francesca

    2015-01-01

    An Enterobacter ludwigii strain was isolated during routine screening of a Japanese patient for carriage of carbapenem-resistant Enterobacteriaceae. PCR analysis revealed the blaNMC-A carbapenemase gene. Whole-genome sequencing revealed that blaNMC-A was inserted in the chromosome and associated with a novel 29.1-kb putative Xer-dependent integrative mobile element, named EludIMEX-1. Bioinformatic analysis identified similar elements in the genomes of an Enterobacter asburiae strain and of other Enterobacter cloacae complex strains, confirming the mobile nature of this element. PMID:26248383

  5. Outbreak of Extended-Spectrum Beta-Lactamase Producing Enterobacter cloacae with High MICs of Quaternary Ammonium Compounds in a Hematology Ward Associated with Contaminated Sinks

    PubMed Central

    Chapuis, Angélique; Amoureux, Lucie; Bador, Julien; Gavalas, Arthur; Siebor, Eliane; Chrétien, Marie-Lorraine; Caillot, Denis; Janin, Marion; de Curraize, Claire; Neuwirth, Catherine

    2016-01-01

    Objective: To investigate an outbreak of extended-spectrum beta-lactamase (ESBL) producing Enterobacter cloacae that occurred in the Hematology ward (24-bed unit) of the François Mitterrand University Hospital (Dijon, France) between January 2011 and December 2013. The outbreak involved 43 patients (10 infected and 33 colonized). Design: We performed environmental analysis to detect multiresistant E. cloacae for comparison with clinical isolates (genotyping by pulsed-field gel electrophoresis and MLST as well as ESBL-typing) and determined the MICs of the quaternary ammonium compounds (QACs) alkyldimethylbenzylammonium chloride (ADBAC) and didecyldimethylammonium chloride (DDAC). A bleach-based cleaning-disinfection program was implemented in December 2012 after mechanical removal of the biofilm in all sinks. Results: We have detected 17 ESBL-producing E. cloacae in patients sink drains, shower drains and medical sink drains. Sequencing of the bla genes performed on 60 strains recovered from patients and environment (n = 43 clinical and n = 17 environmental) revealed that bla CTX−M15 was predominant (37 isolates) followed by bla CTX−M9 plus bla SHV−12 (20 isolates). We observed a great diversity among the isolates: 14 pulsotypes (11 STs) in clinical isolates and 9 pulsotypes (7 STs) in environmental isolates. Six pulsotypes were identical between clinical and environmental isolates. MICs of the quaternary ammonium compounds widely used for disinfection were very high in clinical and environmental isolates. Immediately after the implementation of the disinfection program we noticed a substantial fall in cases number. Our findings demonstrate the role of drains as important reservoir of ESBL-producing E. cloacae and highlight the necessity to settle drains accessible to achieve correct cleaning as well as to use disinfectant with proved activity against nosocomial pathogens. PMID:27462306

  6. Mutation of rpiA in Enterobacter cloacae decreases seed and root colonization and biocontrol of damping-off caused by Pythium ultimum on cucumber.

    PubMed

    Lohrke, Scott M; Dery, Pierre D; Li, Wei; Reedy, Ralph; Kobayashi, Donald Y; Roberts, Daniel R

    2002-08-01

    Strains of Enterobacter cloacae show promise as biocontrol agents for Pythium ultimum-induced damping-off on cucumber and other crops. E. cloacae A145 is a mini-Tn5 Km transposon mutant of strain 501R3 that was significantly reduced in suppression of damping-off on cucumber caused by P. ultimum. Strain A145 was deficient in colonization of cucumber, sunflower, and wheat seeds and significantly reduced in colonization of corn and cowpea seeds relative to strain 501R3. Populations of strain A145 were also significantly lower than those of strain 501R3 at all sampling times in cucumber, wheat, and sunflower rhizosphere. Populations of strain A145 were not detectable in any rhizosphere after 42 days, while populations of strain 501R3 remained at substantial levels throughout all experiments. Molecular characterization of strain A145 indicated mini-Tn5 Km was inserted in a region of the E. cloacae genome with a high degree of DNA and amino acid sequence similarity to rpiA, which encodes ribose-5-phosphate isomerase. In Escherichia coli, RpiA catalyzes the interconversion of ribose-5-phosphate and ribulose-5-phosphate and is a key enzyme in the pentose phosphate pathway. Ribose-5-phosphate isomerase activity in cell lysates from strain A145 was approximately 3.5% of that from strain 501R3. In addition, strain A145 was a ribose auxotroph, as expected for an rpiA mutant. Introduction of a 1.0-kb DNA fragment containing only the rpiA homologue into strain A145 restored ribose phosphate isomerase activity, prototrophy, seedling colonization, and disease suppression to levels similar to those associated with strain 501R3. Experiments reported here indicate a key role for rpiA and possibly the pentose phosphate pathway in suppression of damping-off and colonization of subterranean portions of plants by E. cloacae.

  7. First report of metallo-β-lactamases producing Enterobacter spp. strains from Venezuela.

    PubMed

    Martínez, Dianny; Rodulfo, Hectorina E; Rodríguez, Lucy; Caña, Luisa E; Medina, Belkis; Guzman, Militza; Carreño, Numirin; Marcano, Daniel; De Donato, Marcos

    2014-01-01

    Clinical strains of Enterobacter were isolated from Cumana's Central Hospital in Venezuela, and classified as E. cloacae (21), E. aerogenes (7), E. intermedium (1), E. sakazakii (1) and three unclassified. The strains showed high levels of resistance, especially to SXT (58.1%), CRO (48.8%), CAZ (46.6%), PIP (46.4%), CIP (45.2%) and ATM (43.3%). This is the first report for South America of blaVIM-2 in two E. cloacae and one Enterobacter sp., which also showed multiple mechanisms of resistance. Both E. cloacae showed blaTEM-1, but only one showed blaCTX-M-15 gene, while no blaSHV was detected.

  8. Epidemiology and molecular characterization of extended-spectrum beta-lactamase-producing Enterobacter spp., Pantoea agglomerans, and Serratia marcescens isolates from a Bulgarian hospital.

    PubMed

    Markovska, Rumyana Donkova; Stoeva, Temenuga Jekova; Bojkova, Kalina Dineva; Mitov, Ivan Gergov

    2014-04-01

    Forty-two extended-spectrum beta-lactamase (ESBL)-producing isolates of Enterobacter aerogenes, Enterobacter cloacae, Pantoea agglomerans, and Serratia marcescens, collected consecutively during the period January-November 2011 from the University Hospital in Varna, Bulgaria, were studied to characterize their ESBLs by isoelectric focusing, group-specific PCR, and sequencing. The epidemiological relationship was evaluated by random amplified polymorphic DNA analysis (RAPD). Transferability of ESBL genes was determined by conjugation experiments. Plasmid analysis was done by replicon typing and PstI fingerprinting. The overall rate of ESBL production was 20%. The most widespread enzyme was CTX-M-3, found in 64%. It was dominant in E. aerogenes (100%) and S. marcescens (83%). SHV-12, CTX-M-3, and CTX-M-15 were found among E. cloacae isolates in 50%, 35%, and 45%, respectively. Three main CTX-M-3-producing epidemic clones of E. aerogenes and S. marcescens have been detected. Among E. cloacae isolates, six different RAPD profiles were discerned. The plasmids harboring blaCTX-M-3 belonged to IncL/M type and demonstrated similar PstI fingerprinting profiles. IncFII plasmids were detected in two CTX-M-15-producing E. cloacae isolates. Our results demonstrate wide intrahospital dissemination of clonal E. aerogenes and S. marcescens isolates, carrying IncL/M conjugative plasmids.

  9. High-dose cefepime as an alternative treatment for infections caused by TEM-24 ESBL-producing Enterobacter aerogenes in severely-ill patients.

    PubMed

    Goethaert, K; Van Looveren, M; Lammens, C; Jansens, H; Baraniak, A; Gniadkowski, M; Van Herck, K; Jorens, P G; Demey, H E; Ieven, M; Bossaert, L; Goossens, H

    2006-01-01

    This study evaluated retrospectively the efficacy of treatment with cefepime vs. a carbapenem, in combination with amikacin or ciprofloxacin, for seriously-ill patients infected with ESBL-producing Enterobacter aerogenes who were admitted to an intensive care unit. Forty-four episodes of infection were investigated in 43 patients: 21 treated with cefepime; 23 with a carbapenem. The two treatment groups did not differ statistically in terms of age, APACHE II scores, and infection sites, but the average duration of antibiotic exposure was significantly shorter in the cefepime group (8.5 days vs. 11.4 days; p 0.04). Clinical improvement was seen in 62% of patients receiving cefepime vs. 70% of patients receiving a carbapenem (p 0.59). Bacteriological eradication was achieved in 14% of patients receiving cefepime vs. 22% of patients receiving a carbapenem (p 0.76). The 30-day mortality rates related to infection were 33% in the cefepime group and 26% in the carbapenem group (p 0.44). Thus, outcome parameters did not differ significantly between the two groups. Nevertheless, a statistically significant increase in failure to eradicate ESBL-producing E. aerogenes was observed as the MICs of cefepime rose (p 0.017). Pulsed-field gel electrophoresis revealed three distinct clones, but one predominant clone harbouring the bla(TEM-24) gene was associated with most (42/44) of the episodes of infection. It was concluded that cefepime may be an alternative agent for therapy of severe infections caused by TEM-24 ESBL-producing E. aerogenes, although further studies are required to confirm these observations.

  10. A comparative study on phosphotransferase activity of acid phosphatases from Raoultella planticola and Enterobacter aerogenes on nucleosides, sugars, and related compounds.

    PubMed

    Médici, Rosario; Garaycoechea, Juan I; Valino, Ana L; Pereira, Claudio A; Lewkowicz, Elizabeth S; Iribarren, Adolfo M

    2014-04-01

    Natural and modified nucleoside-5'-monophosphates and their precursors are valuable compounds widely used in biochemical studies. Bacterial nonspecific acid phosphatases (NSAPs) are a group of enzymes involved in the hydrolysis of phosphoester bonds, and some of them exhibit phosphotransferase activity. NSAP containing Enterobacter aerogenes and Raoultella planticola whole cells were evaluated in the phosphorylation of a wide range of nucleosides and nucleoside precursors using pyrophosphate as phosphate donor. To increase the productivity of the process, we developed two genetically modified strains of Escherichia coli which overexpressed NSAPs of E. aerogenes and R. planticola. These new recombinant microorganisms (E. coli BL21 pET22b-phoEa and E. coli BL21 pET22b-phoRp) showed higher activity than the corresponding wild-type strains. Reductions in the reaction times from 21 h to 60 min, from 4 h to 15 min, and from 24 h to 40 min in cases of dihydroxyacetone, inosine, and fludarabine, respectively, were obtained.

  11. Susceptibility of the multi-drug resistant strain of Enterobacter aerogenes EA289 to the terpene alcohols from Cistus ladaniferus essential oil.

    PubMed

    Guinoiseau, Elodie; Lorenzi, Vannina; Luciani, Anne; Tomi, Félix; Casanova, Joseph; Berti, Liliane

    2011-08-01

    The essential oil (EO) of Cistus ladaniferus was separated into non polar, moderately polar and polar fractions by column chromatography. The EO and its fractions were analysed by gas chromatography in combination with retention indices [GC-(RI)] and 13C nuclear magnetic resonance (13C NMR) spectroscopy. A minimum inhibitory concentration (MIC) assay was used to evaluate their antibacterial activity against Gram-positive and Gram-negative pathogens of clinical relevance, including a multi-drug resistant (MDR) strain. The most polar fraction, constituted by mono- and sesquiterpene alcohols, strongly inhibited the growth of all tested bacteria with MIC values ranging from 0.05 to 0.8 mg/mL. More importantly, this fraction displayed high activity against the MDR strain of Enterobacter aerogenes EA289. Transmission electron microscopy (TEM) observations of the MDR bacteria treated with the terpene alcohol-rich fraction revealed cell wall distortion with an outer cytoplasmic membrane detachment. The susceptibility of the MDR strain of E. aerogenes EA289 to the polar fraction of C. ladaniferus oil suggests the possible use of these natural products to treat infections caused by highly resistant bacteria.

  12. Quantifying the effect of hand wash duration, soap use, ground beef debris, and drying methods on the removal of Enterobacter aerogenes on hands.

    PubMed

    Jensen, Dane A; Danyluk, Michelle D; Harris, Linda J; Schaffner, Donald W

    2015-04-01

    Hand washing is recognized as a crucial step in preventing foodborne disease transmission by mitigating crosscontamination among hands, surfaces, and foods. This research was undertaken to establish the importance of several keys factors (soap, soil, time, and drying method) in reducing microorganisms during hand washing. A nonpathogenic nalidixic acid-resistant Enterobacter aerogenes surrogate for Salmonella was used to assess the efficacy of using soap or no soap for 5 or 20 s on hands with or without ground beef debris and drying with paper towel or air. Each experiment consisted of 20 replicates, each from a different individual with ∼ 6 log CFU/ml E. aerogenes on their hands. A reduction of 1.0 ± 0.4 and 1.7 ± 0.8 log CFU of E. aerogenes was observed for a 5-s wash with no soap and a 20-s wash with soap, respectively. When there was no debris on the hands, there was no significant difference between washing with and without soap for 20 s (P > 0.05). Likewise, there was no significant difference in the reductions achieved when washing without soap, whether or not debris was on the hands (P > 0.05). A significantly greater reduction (P < 0.05) in E. aerogenes (0.5 log CFU greater reduction) was observed with soap when there was ground beef debris on the hands. The greatest difference (1.1 log CFU greater average reduction) in effectiveness occurred when ground beef debris was on the hands and a 20-s wash with water was compared with a 20-s wash with soap. Significantly greater (P < 0.05) reductions were observed with paper towel drying compared with air (0.5 log CFU greater reductions). Used paper towels may contain high bacterial levels (>4.0 log CFU per towel) when hands are highly contaminated. Our results support future quantitative microbial risk assessments needed to effectively manage risks of foodborne illness in which food workers' hands are a primary cause.

  13. KPC-4 Is Encoded within a Truncated Tn4401 in an IncL/M Plasmid, pNE1280, Isolated from Enterobacter cloacae and Serratia marcescens

    PubMed Central

    Bryant, Kendall A.; Van Schooneveld, Trevor C.; Thapa, Ishwor; Bastola, Dhundy; Williams, Laurina O.; Safranek, Thomas J.; Hinrichs, Steven H.; Rupp, Mark E.

    2013-01-01

    We describe the transfer of blaKPC-4 from Enterobacter cloacae to Serratia marcescens in a single patient. DNA sequencing revealed that KPC-4 was encoded on an IncL/M plasmid, pNE1280, closely related to pCTX-M360. Further analysis found that KPC-4 was encoded within a novel Tn4401 element (Tn4401f) containing a truncated tnpA and lacking tnpR, ISKpn7 left, and Tn4401 IRL-1, which are conserved in other Tn4401 transposons. This study highlights the continued evolution of Tn4401 transposons and movement to multiple plasmid backbones that results in acquisition by multiple species of Gram-negative bacilli. PMID:23070154

  14. Resistome Analysis of Enterobacter cloacae CY01, an Extensively Drug-Resistant Strain Producing VIM-1 Metallo-β-Lactamase from China

    PubMed Central

    Yang, Ling; Wu, Ai-Wu; Su, Dan-Hong; Lin, Yong-Ping

    2014-01-01

    Resistome analysis of clinical VIM-1-producing Enterobacter cloacae strain CY01 from China revealed the presence of multiple resistance determinants. Two resistance plasmids were identified in CY01. The pCY-VIM plasmid was 14 kb in size and possessed a replicase gene (repA), a gene cluster encoding the partitioning function (parABC), and a carbapenemase gene (blaVIM-1). Another 5.9-kb plasmid, pCY-MdT, with an aac(6′)-Ib gene, was very closely related (13 nucleotide differences) to pMdT1, a ColE1 plasmid carrying aac(6′)-Ib-cr4. PMID:25114139

  15. Prevalence and characteristics of aac(6')-Ib-cr in AmpC-producing Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens: a multicenter study from Korea.

    PubMed

    Kim, Soo-Young; Park, Yeon-Joon; Yu, Jin Kyung; Kim, Yeong Sic; Han, Kyungja

    2009-03-01

    We investigated the prevalence of aac(6')-Ib-cr and its association with other resistance genes in AmpC-producing Enterobacteriaceae without any selection criteria. A total of 479 clinical isolates of Enterobacter cloacae (179), Citrobacter freundii (134), and Serratia marcescens (166) from 12 laboratories between March and July 2005 were examined. We performed polymerase chain reaction for aac(6')-Ib, bla(OXA-1), ISEcp1, and class 1 integron. The aac(6')-Ib-cr was further identified by digestion with BstF5I and sequencing. The aac(6')-Ib was detected in 110 (23%) of 479 isolates, and 15 isolates (3.1%) were cr variants (8 E. cloacae, 5 C. freundii, and 2 S. marcescens). The aac(6')-Ib-cr was significantly associated with various resistance genes (bla(OXA-1), qnrS, qnrA, bla(CTX-M-3), and bla(CTX-M-14)), mobile elements (ISEcp1, ISCR1, and class 1 integron), and quinolone resistance. Eleven of 15 aac(6')-Ib-cr producers coharbored qnr genes. Although aac(6')-Ib-cr was uncommon in Korean AmpC producers, its association with various resistance genes and mobile elements would facilitate the dissemination of this variant.

  16. Survey of Clinical Extended-Spectrum Beta-Lactamase-Producing Enterobacter cloacae Isolates in a Chinese Tertiary Hospital, 2012-2014.

    PubMed

    Cao, Xiao-Li; Cheng, Li; Zhang, Zhi-Feng; Ning, Ming-Zhe; Zhou, Wan-Qing; Zhang, Kui; Shen, Han

    2017-01-01

    A total of 72 consecutive and nonduplicate clinical extended-spectrum β-lactamase (ESBL)-producing Enterobacter cloacae isolates were collected from our hospital from 2012 to 2014 for analyzing the prevalence of plasmid-mediated quinolone resistance (PMQR) genes, 16S rRNA methyltransferase (16S-RMTase) encoding genes, and carbapenem-hydrolyzing β-lactamase (CHβL) genes, as well as integrons. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were carried out to characterize the genetic relatedness. The isolates mainly harbored blaCTX-M (n = 51, 70.8%) and blaSHV (n = 46, 63.9%) genes. High prevalence of PMQR genes qnrA1 (n = 24, 33.3%), qnrB (n = 4, 5.6%), qnrS1 (n = 2, 2.8%), and aac(6')-Ib-cr (n = 21, 29.2%) was observed. Furthermore, CHβLs IMP-4 (n = 6, 8.3%) and IMP-8 (n = 4, 5.6%), as well as class I integrons (n = 29, 40.3%), were found in the ESBL-producing E. cloacae isolates. PFGE revealed 69 pulsotypes. MLST distinguished 44 sequence types (STs) with ST124 (n = 7, 9.7%), ST50 (n = 3, 4.2%), ST45 (n = 3, 4.2%), and ST93 (n = 3, 4.2%) being the predominant STs. The results indicate a possible clonal transmission of ST124 isolates in the hospital that needs further surveillance. The genetic diversity of the other numerous distinctive STs indicates that most of the ESBL-producing E. cloacae in our hospital might arise through stepwise accumulations of multiple drug-resistance determinants in different clones.

  17. Multiclonal spread of VIM-1-producing Enterobacter cloacae isolates associated with In624 and In488 integrons located in an IncHI2 plasmid.

    PubMed

    Villa, Jennifer; Viedma, Esther; Brañas, Patricia; Orellana, M Angeles; Otero, Joaquín R; Chaves, Fernando

    2014-05-01

    Over a 6-year period (2007-2012), the emergence of Enterobacter cloacae isolates resistant to β-lactams and with reduced susceptibility to carbapenems was observed in Hospital Universitario 12 de Octubre (Madrid, Spain). To determine the possible role of metallo-β-lactamases (MBLs) in the resistance profile of these isolates, a molecular and clinical epidemiological study was performed, including determination of patients' clinical characteristics, genetic diversity of strains, resistance mechanisms to carbapenems, and the genetic environment of VIM-1. A total of 73 E. cloacae isolates showed resistance to extended-spectrum cephalosporins and reduced susceptibility to at least one carbapenem during 2007-2012. PCR amplification revealed the presence of bla(VIM-1) gene in 37 isolates, bla(VIM-2) in 1 isolate and bla(KPC) in 5 isolates. Molecular typing showed high clonal diversity of E. cloacae isolates carrying bla(VIM-1). The genetic environment of bla(VIM-1) was investigated and two integron structures were found: intI-bla(VIM-1)-aacA4-dfrB1-aadA1-catB2-qacEΔ1/sul1 (In624); and intI-bla(VIM-1)-aacA4-aadA1-qacEΔ1/sul1 (In488). Isolates belonging to three clones (A, F and G) harboured different types of integron (In624 or In488) despite belonging to the same clone. Conjugal experiments showed an association with a conjugative plasmid of ca. 300 kb belonging to IncHI2 group, which is common in Spanish hospitals, suggesting that the widespread dissemination of bla(VIM-1) may be due to horizontal transfer of mobile genetic determinants rather than the result of spreading of a few clones. These results have implications for infection control programmes in the hospital.

  18. New Monoclonal Antibodies against a Novel Subtype of Shiga Toxin 1 Produced by Enterobacter cloacae and Their Use in Analysis of Human Serum.

    PubMed

    Skinner, Craig; Patfield, Stephanie; Khalil, Rowaida; Kong, Qiulian; He, Xiaohua

    2016-01-01

    Shiga toxin (Stx) is a major virulence factor of several bacterial pathogens that cause potentially fatal illness, including Escherichia coli and Shigella spp. The continual emergence of new subtypes of Stxs presents challenges for the clinical diagnosis of infections caused by Stx-producing organisms. Here, we report the development of four new monoclonal antibodies (MAbs) against Stx1e, a novel subtype of Stx1 that was produced by an Enterobacter cloacae strain and had limited reactivity with existing anti-Stx1 antibodies. Western blot analysis indicates that these MAbs were Stx1 specific, bound to the A subunit, and had distinct preferences for subtypes of Stx1. Of the four MAbs, Stx1e-2 was capable of partially neutralizing cytotoxicities derived from Stx1e in Vero cells. Enzyme-linked immunosorbent assays assembled with these high-affinity MAbs detected Stx1e at concentrations as low as 4.8 pg/ml in phosphate-buffered saline and 53.6 pg/ml in spiked human serum samples and were also capable of distinguishing Stx1e-producing strains in enriched cultures. These assays may therefore have clinical value in diagnosing Stx1e-producing bacterial infection. Additionally, characteristics of Stx1e, such as the origin of stx1e genes, conditions for toxin expression, receptor binding, and cytotoxicity, were investigated with the new antibodies developed in this study. This information should be useful for further understanding the clinical significance and prevalence of Stx1e-harboring E. cloacae and other organisms. IMPORTANCE Stxs are among the most clinically important virulence factors of Shigella and enterohemorrhagic Escherichia coli. There are many varieties of Stx, and although Stx1a and Stx2a are the most common and widely distributed types of Stx, new variants of Stx are continually emerging. These new variants of Stx can be challenging to detect, since most Stx detection kits are optimized for the detection of Stx1a and Stx2a. Stx1e, recently discovered in

  19. New Monoclonal Antibodies against a Novel Subtype of Shiga Toxin 1 Produced by Enterobacter cloacae and Their Use in Analysis of Human Serum

    PubMed Central

    Skinner, Craig; Patfield, Stephanie; Khalil, Rowaida; Kong, Qiulian

    2016-01-01

    ABSTRACT Shiga toxin (Stx) is a major virulence factor of several bacterial pathogens that cause potentially fatal illness, including Escherichia coli and Shigella spp. The continual emergence of new subtypes of Stxs presents challenges for the clinical diagnosis of infections caused by Stx-producing organisms. Here, we report the development of four new monoclonal antibodies (MAbs) against Stx1e, a novel subtype of Stx1 that was produced by an Enterobacter cloacae strain and had limited reactivity with existing anti-Stx1 antibodies. Western blot analysis indicates that these MAbs were Stx1 specific, bound to the A subunit, and had distinct preferences for subtypes of Stx1. Of the four MAbs, Stx1e-2 was capable of partially neutralizing cytotoxicities derived from Stx1e in Vero cells. Enzyme-linked immunosorbent assays assembled with these high-affinity MAbs detected Stx1e at concentrations as low as 4.8 pg/ml in phosphate-buffered saline and 53.6 pg/ml in spiked human serum samples and were also capable of distinguishing Stx1e-producing strains in enriched cultures. These assays may therefore have clinical value in diagnosing Stx1e-producing bacterial infection. Additionally, characteristics of Stx1e, such as the origin of stx1e genes, conditions for toxin expression, receptor binding, and cytotoxicity, were investigated with the new antibodies developed in this study. This information should be useful for further understanding the clinical significance and prevalence of Stx1e-harboring E. cloacae and other organisms. IMPORTANCE Stxs are among the most clinically important virulence factors of Shigella and enterohemorrhagic Escherichia coli. There are many varieties of Stx, and although Stx1a and Stx2a are the most common and widely distributed types of Stx, new variants of Stx are continually emerging. These new variants of Stx can be challenging to detect, since most Stx detection kits are optimized for the detection of Stx1a and Stx2a. Stx1e, recently

  20. The rhizome of the multidrug-resistant Enterobacter aerogenes genome reveals how new "killer bugs" are created because of a sympatric lifestyle.

    PubMed

    Diene, Seydina M; Merhej, Vicky; Henry, Mireille; El Filali, Adil; Roux, Véronique; Robert, Catherine; Azza, Saïd; Gavory, Frederick; Barbe, Valérie; La Scola, Bernard; Raoult, Didier; Rolain, Jean-Marc

    2013-02-01

    Here, we sequenced the 5,419,609 bp circular genome of an Enterobacter aerogenes clinical isolate that killed a patient and was resistant to almost all current antibiotics (except gentamicin) commonly used to treat Enterobacterial infections, including colistin. Genomic and phylogenetic analyses explain the discrepancies of this bacterium and show that its core genome originates from another genus, Klebsiella. Atypical characteristics of this bacterium (i.e., motility, presence of ornithine decarboxylase, and lack of urease activity) are attributed to genomic mosaicism, by acquisition of additional genes, such as the complete 60,582 bp flagellar assembly operon acquired "en bloc" from the genus Serratia. The genealogic tree of the 162,202 bp multidrug-resistant conjugative plasmid shows that it is a chimera of transposons and integrative conjugative elements from various bacterial origins, resembling a rhizome. Moreover, we demonstrate biologically that a G53S mutation in the pmrA gene results in colistin resistance. E. aerogenes has a large RNA population comprising 8 rRNA operons and 87 cognate tRNAs that have the ability to translate transferred genes that use different codons, as exemplified by the significantly different codon usage between genes from the core genome and the "mobilome." On the basis of our findings, the evolution of this bacterium to become a "killer bug" with new genomic repertoires was from three criteria that are "opportunity, power, and usage" to indicate a sympatric lifestyle: "opportunity" to meet other bacteria and exchange foreign sequences since this bacteria was similar to sympatric bacteria; "power" to integrate these foreign sequences such as the acquisition of several mobile genetic elements (plasmids, integrative conjugative element, prophages, transposons, flagellar assembly system, etc.) found in his genome; and "usage" to have the ability to translate these sequences including those from rare codons to serve as a translator of

  1. Successive emergence of extended-spectrum beta-lactamase-producing and carbapenemase-producing Enterobacter aerogenes isolates in a university hospital.

    PubMed

    Biendo, M; Canarelli, B; Thomas, D; Rousseau, F; Hamdad, F; Adjide, C; Laurans, G; Eb, F

    2008-03-01

    Sixty-two clinical isolates of Enterobacter aerogenes resistant to expanded-spectrum cephalosporins were collected between July 2003 and May 2005. Among these isolates, 23 (37.1%) were imipenem (IPM) susceptible, and 39 (62.9%) were IPM insusceptible, of which 89.7% (35/39) were resistant and 10.3% (4/39) were intermediate. Isolate genotypes were compared by pulsed-field gel electrophoresis. Of 62 isolates, 48 belonged to epidemic pulsotype A (77.4%). This pulsotype included 37.5% and 58.4% of beta-lactam phenotypes b and a, respectively. Nine isolates (14.5%) belonged to pulsotype E, which included 22.3% and 77.7% of phenotypes b and a, respectively. The beta-lactamases with pIs of 5.4, 6.5, 8.2, and 8.2 corresponded to extended-spectrum beta-lactamases (ESBLs) TEM-20, TEM-24, SHV-5, and SHV-12, respectively. Of 39 IPM-insusceptible E. aerogenes isolates, 26 (66.6%) were determined to be metallo-beta-lactamase producers, by using a phenotypic method. Of these isolates, 24 harbored a bla(IMP-1) gene encoding a protein with a pI of >9.5, and two carried the bla(VIM-2) gene encoding a protein with a pI of 5.3, corresponding to beta-lactamases IMP-1 and VIM-2, respectively. The remaining 13 (33.4%) isolates were negative for the bla(IMP-1) and bla(VIM-2) genes but showed an alteration of their outer membrane proteins (OMPs). Ten of these isolates produced the two possible OMPs (32 and 42 kDa), with IPM MICs between 8 and 32 microg/ml, and three others produced only a 32-kDa OMP with IPM MICs >32 microg/ml. This work demonstrates that, in addition to resistance to expanded-spectrum cephalosporins, IPM resistance can occur in ESBL-producing E. aerogenes isolates by carbapenemase production or by the loss of porin in the outer membrane.

  2. Overexpression and purification of the three components of the Enterobacter aerogenes AcrA-AcrB-TolC multidrug efflux pump.

    PubMed

    Masi, Muriel; Pagès, Jean-Marie; Pradel, Elizabeth

    2003-03-25

    The tripartite AcrA-AcrB-TolC system is the major efflux pump of the nosocomial pathogen Enterobacter aerogenes. AcrA is a trimeric periplasmic lipoprotein anchored in the inner membrane, AcrB is an inner membrane transporter and TolC is a trimeric outer membrane channel. In order to reconstitute the AcrA-AcrB-TolC system of E. aerogenes in artificial membranes, we overexpressed and purified the three proteins. The E. aerogenes acrA, acrB and tolC open reading frames were individually inserted in the expression vector pET24a(+), in frame with a sequence coding a C-terminal hexahistidine tag to allow purification by INAC (Immobilized Nickel Affinity Chromatography). The mature AcrA-6His was overproduced in a soluble form in the cytoplasm of Escherichia coli BL21(DE3). AcrA-6His was purified under native conditions in two steps using INAC and gel permeation chromatography. We obtained about 25 mg of 97% pure AcrA-6His per liter of culture. AcrB-6His was solubilized from the membrane fraction of E. coli C43(DE3) in 300 mM NaCl, 5% Triton X-100 and purified in one step by INAC. The AcrB-6His enriched fraction was eluted with 100 mM imidazole. The final yield was 1-2 mg of 95% pure AcrB-6His per liter of culture. The membrane fraction of E. coli BL21(DE3)pLysS containing TolC-6His was first treated with 2% Triton X-100, 30 mM MgCl(2) to solubilize the inner membrane proteins. After ultracentrifugation, the pellet was treated with 5% Triton X-100, 5 mM EDTA to solubilize the outer membrane proteins. Approximately 5 mg of 95% pure TolC-6His trimers per liter of culture was purified by INAC.

  3. Carbapenem resistance in a clinical isolate of Enterobacter aerogenes is associated with decreased expression of OmpF and OmpC porin analogs.

    PubMed

    Yigit, Hesna; Anderson, Gregory J; Biddle, James W; Steward, Christine D; Rasheed, J Kamile; Valera, Lourdes L; McGowan, John E; Tenover, Fred C

    2002-12-01

    We investigated the mechanism of imipenem resistance in Enterobacter aerogenes strain 810, a clinical isolate from the United States for which the imipenem MIC was 16 micro g/ml and the meropenem MIC was 8 micro g/ml. An imipenem-susceptible revertant, strain 810-REV, was obtained after multiple passages of the strain on nonselective media. For the revertant, the imipenem MIC was /=128 micro g/ml), cefoxitin (>/=32 micro g/ml), and cefotaxime (>/=64 micro g/ml) remained the same. The beta-lactamase and porin profiles of the parent, the revertant, and carbapenem-susceptible type strain E. aerogenes ATCC 13048 were determined. Strains 810 and 810-REV each produced two beta-lactamases with pIs of 8.2 and 5.4. The beta-lactamase activities of the parent and revertant were similar, even after induction with subinhibitory concentrations of imipenem. While 810-REV produced two major outer membrane proteins of 42 and 39 kDa that corresponded to Escherichia coli porins OmpC and OmpF, respectively, the parent strain appeared to produce similar quantities of the 39-kDa protein (OmpF) but decreased amounts of the 42-kDa protein (OmpC). When the parent strain was grown in the presence of imipenem, the 42-kDa protein was not detectable by gel electrophoresis. However, Western blot analysis of the outer membrane proteins of the parent and revertant with polyclonal antisera raised to the OmpC and OmpF analogs of Klebsiella pneumoniae (anti-OmpK36 and anti-OmpK35, respectively) showed that strain 810 expressed only the 42-kDa OmpC analog in the absence of imipenem (the 39-kDa protein was not recognized by the anti-OmpF antisera) and neither the OmpC nor the OmpF analog in the presence of imipenem. The OmpC analog is apparently down-regulated in the presence of imipenem; however, 810-REV expressed both OmpC and OmpF analogs. These data

  4. Carbapenem Resistance among Enterobacter Species in a Tertiary Care Hospital in Central India

    PubMed Central

    Khajuria, Atul; Praharaj, Ashok Kumar; Kumar, Mahadevan; Grover, Naveen

    2014-01-01

    Objective. To detect genes encoding carbapenem resistance among Enterobacter species in a tertiary care hospital in central India. Methods. Bacterial identification of Enterobacter spp. isolates from various clinical specimens in patients admitted to intensive care units was performed by routine conventional microbial culture and biochemical tests using standard recommended techniques. Antibiotic sensitivity test was performed by standard Kirby Bauer disc diffusion technique. PCR amplification and automated sequencing was carried out. Transfer of resistance genes was determined by conjugation. Results. A total of 70/130 (53.84%) isolates of Enterobacter spp. were found to exhibit reduced susceptibility to imipenem (diameter of zones of inhibition ≤13 mm) by disc diffusion method. Among 70 isolates tested, 48 (68.57%) isolates showed MIC values for imipenem and meropenem ranging from 32 to 64 mg/L as per CLSI breakpoints. All of these 70 isolates were found susceptible to colistin in vitro as per MIC breakpoints (<0.5 mg/L). PCR carried out on these 48 MBL (IP/IPI) E-test positive isolates (12 Enterobacter aerogenes, 31 Enterobacter cloacae, and 05 Enterobacter cloacae complex) was validated by sequencing for beta-lactam resistance genes and result was interpreted accordingly. Conclusion. The study showed MBL production as an important mechanism in carbapenem resistance in Enterobacter spp. and interspecies transfer of these genes through plasmids suggesting early detection by molecular methods. PMID:25180095

  5. Risk factors for Enterobacter septicemia in a neonatal unit: case-control study.

    PubMed

    Fok, T F; Lee, C H; Wong, E M; Lyon, D J; Wong, W; Ng, P C; Cheung, K L; Cheng, A F

    1998-11-01

    Thirty cases of Enterobacter aerogenes or Enterobacter cloacae septicemia diagnosed over a 32-month period in a tertiary care neonatal unit were enrolled in a case-control study. Each case patient was matched with two controls (patients occupying the cots nearest the case patient when the latter developed septicemia). Of the 32 perinatal characteristics evaluated, 11 were identified by univariate analysis to be significantly associated with the infection. These included parents being residents of the Vietnamese refugee camps, respiratory distress syndrome, necrotizing enterocolitis, umbilical arterial catheterization, umbilical venous catheterization, bladder catheterization, mechanical ventilation, antibiotic treatment, peripheral venous catheterization, nasogastric intubation, and parenteral nutrition. Multivariate analysis, however, showed that preceding bladder catheterization and ongoing parenteral nutrition were the only independent risk factors for enterobacter septicemia. Strict aseptic technique in the preparation of parenteral nutrition fluid and avoidance of bladder catheterization are measures that may reduce the risk of enterobacter sepsis for newborns.

  6. Activity of Moxifloxacin, Imipenem, and Ertapenem against Escherichia coli, Enterobacter cloacae, Enterococcus faecalis, and Bacteroides fragilis in Monocultures and Mixed Cultures in an In Vitro Pharmacokinetic/Pharmacodynamic Model Simulating Concentrations in the Human Pancreas

    PubMed Central

    Schubert, Sabine

    2012-01-01

    The activities of moxifloxacin, imipenem, and ertapenem against pathogens causing severe necrotizing pancreatitis were studied in an in vitro pharmacokinetics/pharmacodynamics (PK/PD) model. Escherichia coli, Enterobacter cloacae, Enterococcus faecalis, and Bacteroides fragilis were exposed in monocultures and mixed cultures to concentrations of the three agents comparable to those in the human pancreas. Moxifloxacin was more active than the two carbapenems in monocultures and mixed cultures, reducing the numbers of CFU more drastically and more rapidly. PMID:23070164

  7. Hydrogen evolution of Enterobacter aerogenes depending on culture pH: mechanism of hydrogen evolution from NADH by means of membrane-bound hydrogenase.

    PubMed

    Tanisho, S; Kamiya, N; Wakao, N

    1989-01-26

    The pH dependency of cell mass productivity, the hydrogen evolution rate and the yield of hydrogen from glucose was measured by controlling the pH of the culture automatically. The cell mass productivity of Enterobacter aerogenes increased in a linear fashion up to a pH value of approx. 7.0. In contrast, both the evolution rate and the yield of hydrogen showed convex relationships up to a pH value of 7.0, both having maximum values at a pH of approx. 5.8. The maximum evolution rate was approx. 11.3 mmol H2 per g dry cell per h at 38 degrees C. A hypothetical mechanism for hydrogen evolution was proposed by taking our results and other research work into consideration. The proposed mechanism of hydrogen evolution was that NADH was oxidized on the inside surface of the cell membrane and protons were reduced on the outside surface by means of membrane-bound hydrogenase. This mechanism explains in a thermodynamic context the relation between the activity of the hydrogen evolution and the pH of the culture.

  8. A biological method for in-situ synthesis of hydroxyapatite-coated magnetite nanoparticles using Enterobacter aerogenes: Characterization and acute toxicity assessments.

    PubMed

    Ahmadzadeh, Elham; Talebnia Rowshan, Farid; Hosseini, Morteza

    2017-04-01

    Hydroxyapatite (HA)-coated magnetite nanoparticles (MNPs) are being widely investigated for various applications in medical engineering and wastewater treatment. In this work, the MNPs were thoroughly coated by bacterial synthesized HA nanoparticles during biomineralization process using Enterobacter aerogenes. The resulting bacterial-induced precipitate was then calcined at 600°C and investigated with respect to structural characteristics, particle size and magnetic strength by XRD, FT-IR, SEM, EDS, TEM and VSM analyses. The effects of MNPs and HA-coated MNPs (HA-MNPs) on the viability of human MCF-7 cell lines were also investigated via mitochondrial activity test (MTT) and lactate dehydrogenase (LDH) assays. The powder characterization results showed appropriate structural properties for HA-MNPs samples. The particles diameter size of the MNPs and HA-MNPs were in the range of 3-25nm and 20-80nm, respectively. The biologically-synthesized HA-MNPs formed a stable suspension in water while keeping their magnetic property. The saturation magnetization (Ms) of HA-MNPs was measured at ~10emug(-1) which was in good agreement with the structural composition of this sample. Finally, the results of the cell lines viability indicated that coating of toxic MNPs via biomineralization was a promising approach in order to synthesize bio-compatible magnetic nanoparticles with suitable physical and chemical structural characteristics. The toxicity level of MNPs was reduced by 10 fold when coated by bacterial-synthesized HA.

  9. NDM-1 encoded by a pNDM-BJ01-like plasmid p3SP-NDM in clinical Enterobacter aerogenes

    PubMed Central

    Chen, Zhenhong; Li, Hongxia; Feng, Jiao; Li, Yuxue; Chen, Xin; Guo, Xuemin; Chen, Weijun; Wang, Li; Lin, Lei; Yang, Huiying; Yang, Wenhui; Wang, Jie; Zhou, Dongsheng; Liu, Changting; Yin, Zhe

    2015-01-01

    A carbapenem-nonsusceptible Enterobacter aerogenes strain named 3-SP was isolated from a human case of pneumonia in a Chinese teaching hospital. NDM-1 carbapenemase is produced by a pNDM-BJ01-like conjugative plasmid designated p3SP-NDM to account for carbapenem resistance of 3-SP. p3SP-NDM was fully sequenced and compared with all publically available pNDM-BJ01-like plasmids. The genetic differences between p3SP-NDM and pNDM-BJ01 include only 18 single nucleotide polymorphisms, a 1 bp deletion and a 706 bp deletion. p3SP-NDM and pNDM-BJ01 harbor an identical Tn125 element organized as ISAba125, blaNDM−1, bleMBL, ΔtrpF, dsbC, cutA, ΔgroES, groEL, ISCR27, and ISAba125. The blaNDM−1 surrounding regions in these pNDM-BJ01-like plasmids have a conserved linear organization ISAba14-aphA6-Tn125-unknown IS, with considerable genetic differences identified within or immediately downstream of Tn125. All reported pNDM-BJ01-like plasmids are exclusively found in Acinetobacter, whereas this is the first report of identification of a pNDM-BJ01-like plasmid in Enterobacteriaceae. PMID:25926823

  10. Malonate-bound structure of the glycerophosphodiesterase from Enterobacter aerogenes (GpdQ) and characterization of the native Fe[supscript 2+] metal-ion preference

    SciTech Connect

    Jackson, Colin J.; Hadler, Kieran S.; Carr, Paul D.; Oakley, Aaron J.; Yip, Sylvia; Schenk, Gerhard; Ollis, David L.

    2010-09-20

    The structure of a malonate-bound form of the glycerophosphodiesterase from Enterobacter aerogenes, GpdQ, has been refined at a resolution of 2.2 {angstrom} to a final R factor of 17.1%. The structure was originally solved to 2.9 {angstrom} resolution using SAD phases from Zn{sup 2+} metal ions introduced into the active site of the apoenzyme [Jackson et al. (2007), J. Mol. Biol. 367, 1047-1062]. However, the 2.9 {angstrom} resolution was insufficient to discern significant details of the architecture of the binuclear metal centre that constitutes the active site. Furthermore, kinetic analysis revealed that the enzyme lost a significant amount of activity in the presence of Zn{sup 2+}, suggesting that it is unlikely to be a catalytically relevant metal ion. In this communication, a higher resolution structure of GpdQ is presented in which malonate is visibly coordinated in the active site and analysis of the native metal-ion preference is presented using atomic absorption spectroscopy and anomalous scattering. Catalytic implications of the structure and its Fe{sup 2+} metal-ion preference are discussed.

  11. Malonate-bound structure of the glycerophosphodiesterase from Enterobacter aerogenes (GpdQ) and characterization of the native Fe[superscript 2+] metal-ion preference

    SciTech Connect

    Jackson, Colin J.; Hadler, Kieran S.; Carr, Paul D.; Oakley, Aaron J.; Yip, Sylvia; Schenk, Gerhard; Ollis, David L.

    2011-09-28

    The structure of a malonate-bound form of the glycerophosphodiesterase from Enterobacter aerogenes, GpdQ, has been refined at a resolution of 2.2 {angstrom} to a final R factor of 17.1%. The structure was originally solved to 2.9 {angstrom} resolution using SAD phases from Zn{sup 2+} metal ions introduced into the active site of the apoenzyme [Jackson et al. (2007), J. Mol. Biol. 367, 1047-1062]. However, the 2.9 {angstrom} resolution was insufficient to discern significant details of the architecture of the binuclear metal centre that constitutes the active site. Furthermore, kinetic analysis revealed that the enzyme lost a significant amount of activity in the presence of Zn2+, suggesting that it is unlikely to be a catalytically relevant metal ion. In this communication, a higher resolution structure of GpdQ is presented in which malonate is visibly coordinated in the active site and analysis of the native metal-ion preference is presented using atomic absorption spectroscopy and anomalous scattering. Catalytic implications of the structure and its Fe{sup 2+} metal-ion preference are discussed.

  12. Malonate-bound structure of the glycerophosphodiesterase from Enterobacter aerogenes (GpdQ) and characterization of the native Fe2+ metal-ion preference.

    PubMed

    Jackson, Colin J; Hadler, Kieran S; Carr, Paul D; Oakley, Aaron J; Yip, Sylvia; Schenk, Gerhard; Ollis, David L

    2008-08-01

    The structure of a malonate-bound form of the glycerophosphodiesterase from Enterobacter aerogenes, GpdQ, has been refined at a resolution of 2.2 A to a final R factor of 17.1%. The structure was originally solved to 2.9 A resolution using SAD phases from Zn2+ metal ions introduced into the active site of the apoenzyme [Jackson et al. (2007), J. Mol. Biol. 367, 1047-1062]. However, the 2.9 A resolution was insufficient to discern significant details of the architecture of the binuclear metal centre that constitutes the active site. Furthermore, kinetic analysis revealed that the enzyme lost a significant amount of activity in the presence of Zn2+, suggesting that it is unlikely to be a catalytically relevant metal ion. In this communication, a higher resolution structure of GpdQ is presented in which malonate is visibly coordinated in the active site and analysis of the native metal-ion preference is presented using atomic absorption spectroscopy and anomalous scattering. Catalytic implications of the structure and its Fe2+ metal-ion preference are discussed.

  13. NDM-1 encoded by a pNDM-BJ01-like plasmid p3SP-NDM in clinical Enterobacter aerogenes.

    PubMed

    Chen, Zhenhong; Li, Hongxia; Feng, Jiao; Li, Yuxue; Chen, Xin; Guo, Xuemin; Chen, Weijun; Wang, Li; Lin, Lei; Yang, Huiying; Yang, Wenhui; Wang, Jie; Zhou, Dongsheng; Liu, Changting; Yin, Zhe

    2015-01-01

    A carbapenem-nonsusceptible Enterobacter aerogenes strain named 3-SP was isolated from a human case of pneumonia in a Chinese teaching hospital. NDM-1 carbapenemase is produced by a pNDM-BJ01-like conjugative plasmid designated p3SP-NDM to account for carbapenem resistance of 3-SP. p3SP-NDM was fully sequenced and compared with all publically available pNDM-BJ01-like plasmids. The genetic differences between p3SP-NDM and pNDM-BJ01 include only 18 single nucleotide polymorphisms, a 1 bp deletion and a 706 bp deletion. p3SP-NDM and pNDM-BJ01 harbor an identical Tn125 element organized as ISAba125, bla NDM-1, ble MBL, ΔtrpF, dsbC, cutA, ΔgroES, groEL, ISCR27, and ISAba125. The bla NDM-1 surrounding regions in these pNDM-BJ01-like plasmids have a conserved linear organization ISAba14-aphA6-Tn125-unknown IS, with considerable genetic differences identified within or immediately downstream of Tn125. All reported pNDM-BJ01-like plasmids are exclusively found in Acinetobacter, whereas this is the first report of identification of a pNDM-BJ01-like plasmid in Enterobacteriaceae.

  14. UV-B Radiation Stress Causes Alterations in Whole Cell Protein Profile and Expression of Certain Genes in the Rice Phyllospheric Bacterium Enterobacter cloacae.

    PubMed

    Kumar, Jay; Babele, Piyoosh K; Singh, Divya; Kumar, Ashok

    2016-01-01

    Among the different types of UV radiation, UV-B radiation (280-315 nm) has gained much attention mainly due to its increasing incidence on the Earth's surface leading to imbalances in natural ecosystems. This study deals with the effects of UV-B radiation on the proteome and gene expression in a rice phyllospheric bacterium, Enterobacter cloacae. Of the five bacteria isolated from rice leaves, E. cloacae showed the highest level of resistance to UV-B and total killing occurred after 8 h of continuous exposure to UV-B. Reactive oxygen species were induced by UV-B exposure and increased with increasing duration of exposure. Protein profiling by SDS-PAGE and 2-dimensional gel electrophoresis (2-DE) revealed major changes in the number as well as expression of proteins. Analysis of 2-DE gel spots indicated up/down-regulation of several proteins under the stress of UV-B radiation. Thirteen differentially expressed proteins including two hypothetical proteins were identified by MALDI-TOF MS and assigned to eight functional categories. Both the hypothetical proteins (gi 779821175 and gi 503938301) were over-expressed after UV-B irradiation; gi 503938301 was characterized as a member of FMN reductase superfamily whereas gi 779821175 seems to be a structural protein as it did not show any functional domain. That the expression of certain proteins under UV-B stress is indeed up-regulated was confirmed by qRT-PCR. Transcript analysis of selected gene including genes of hypothetical proteins (cp011650 and cp002886) showed over-expression under UV-B stress as compared to untreated control cultures. Although this study deals with a limited number of proteins, identification of differentially expressed proteins reported herein may prove useful in future studies especially for assessing their significance in the protection mechanism of bacteria against UV-B radiation stress.

  15. Characterisation and clinical features of Enterobacter cloacae bloodstream infections occurring at a tertiary care university hospital in Switzerland: is cefepime adequate therapy?

    PubMed Central

    Hilty, Markus; Sendi, Parham; Seiffert, Salome N.; Droz, Sara; Perreten, Vincent; Hujer, Andrea M.; Bonomo, Robert A.; Mühlemann, Kathrin; Endimiani, Andrea

    2014-01-01

    Despite many years of clinical experience with cefepime, data regarding the outcome of patients suffering from bloodstream infections (BSIs) due to Enterobacter cloacae (Ecl) are scarce. To address the gap in our knowledge, 57 Ecl responsible for 51 BSIs were analysed implementing phenotypic and molecular methods (microarrays, PCRs for bla and other genes, rep-PCR to analyse clonality). Only two E. cloacae (3.5%) were ESBL-producers, whereas 34 (59.6%) and 18 (31.6%) possessed inducible (Ind-Ecl) or derepressed (Der-Ecl) AmpC enzymes, respectively. All isolates were susceptible to imipenem, meropenem, gentamicin and ciprofloxacin. Der-Ecl were highly resistant to ceftazidime and piperacillin/tazobactam (both MIC90 ≥ 256 µg/mL), whereas cefepime retained its activity (MIC90 of 3 µg/mL). rep-PCR indicated that the isolates were sporadic, but Ecl collected from the same patients were indistinguishable. In particular, three BSIs initially due to Ind-Ecl evolved (under ceftriaxone or piperacillin/tazobactam treatment) into Der-Ecl because of mutations or a deletion in ampD or insertion of IS4321 in the promoter. These last two mechanisms have never been described in Ecl. Mortality was higher for BSIs due to Der-Ecl than Ind-Ecl (3.8% vs. 29.4%; P = 0.028) and was associated with the Charlson co-morbidity index (P = 0.046). Using the following directed treatments, patients with BSI showed a favourable treatment outcome: cefepime (16/18; 88.9%); carbapenems (12/13; 92.3%); ceftriaxone (4/7; 57.1%); piperacillin/tazobactam (5/7; 71.4%); and ciprofloxacin (6/6; 100%). Cefepime represents a safe therapeutic option and an alternative to carbapenems to treat BSIs due to Ecl when the prevalence of ESBL-producers is low. PMID:23313399

  16. UV-B Radiation Stress Causes Alterations in Whole Cell Protein Profile and Expression of Certain Genes in the Rice Phyllospheric Bacterium Enterobacter cloacae

    PubMed Central

    Kumar, Jay; Babele, Piyoosh K.; Singh, Divya; Kumar, Ashok

    2016-01-01

    Among the different types of UV radiation, UV-B radiation (280-315 nm) has gained much attention mainly due to its increasing incidence on the Earth’s surface leading to imbalances in natural ecosystems. This study deals with the effects of UV-B radiation on the proteome and gene expression in a rice phyllospheric bacterium, Enterobacter cloacae. Of the five bacteria isolated from rice leaves, E. cloacae showed the highest level of resistance to UV-B and total killing occurred after 8 h of continuous exposure to UV-B. Reactive oxygen species were induced by UV-B exposure and increased with increasing duration of exposure. Protein profiling by SDS-PAGE and 2-dimensional gel electrophoresis (2-DE) revealed major changes in the number as well as expression of proteins. Analysis of 2-DE gel spots indicated up/down-regulation of several proteins under the stress of UV-B radiation. Thirteen differentially expressed proteins including two hypothetical proteins were identified by MALDI-TOF MS and assigned to eight functional categories. Both the hypothetical proteins (gi 779821175 and gi 503938301) were over-expressed after UV-B irradiation; gi 503938301 was characterized as a member of FMN reductase superfamily whereas gi 779821175 seems to be a structural protein as it did not show any functional domain. That the expression of certain proteins under UV-B stress is indeed up-regulated was confirmed by qRT-PCR. Transcript analysis of selected gene including genes of hypothetical proteins (cp011650 and cp002886) showed over-expression under UV-B stress as compared to untreated control cultures. Although this study deals with a limited number of proteins, identification of differentially expressed proteins reported herein may prove useful in future studies especially for assessing their significance in the protection mechanism of bacteria against UV-B radiation stress. PMID:27672388

  17. Mobilization of the genetically engineered plasmid pHSV106 from Escherichia coli HB101(pHSV106) to Enterobacter cloacae in drinking water.

    PubMed

    Sandt, C H; Herson, D S

    1991-01-01

    We have used triparental matings to demonstrate transfer (mobilization) of the nonconjugative genetically engineered plasmid pHSV106, which contains the thymidine kinase gene of herpes simplex virus cloned into pBR322, from Escherichia coli HB101 to an environmental isolate of Enterobacter cloacae in sterile drinking water. This is the first demonstration of a two-step mobilization of a genetically engineered plasmid in any type of fresh water, including drinking water. Transfer was mediated by R plasmid R100-1 of E. coli ED2149(R100-1). Matings in drinking water at 15, 25, and 35 degrees C yielded recombinants, the number of which increased with increasing temperature. Numbers of recombinants obtained were 2 orders of magnitude lower than those obtained from matings in Trypticase soy broth. High concentrations of parental organisms (2.6 x 10(8) to 2.0 x 10(9) CFU/ml) were required. During 1 week of incubation in drinking water, number of parental organisms and recombinants resulting from mobilization remained constant in the absence of indigenous organisms and declined in their presence. Using oligonucleotide probes for the cloned foreign DNA (thymidine kinase gene) and plasmid vector DNA (ampicillin resistance gene), we demonstrated that both genes were transferred to E. cloacae in the mobilization process. In one recombinant selected for detailed study, the plasmids containing these genes differed in size from all forms of pHSV106 present in E. coli HB101(pHSV106), indicating that DNA rearrangement had occurred. This recombinant maintained its plasmids in unchanged form for 15 days in drinking water. A second rearrangement occurred during serial passage of this recombinant on selective media.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. The three-dimensional structure of VIM-31--a metallo-β-lactamase from Enterobacter cloacae in its native and oxidized form.

    PubMed

    Kupper, Michaël B; Herzog, Konrad; Bennink, Sandra; Schlömer, Philipp; Bogaerts, Pierre; Glupczynski, Youri; Fischer, Rainer; Bebrone, Carine; Hoffmann, Kurt M

    2015-06-01

    The metallo-β-lactamase VIM-31 differs from VIM-2 by only two Tyr224His and His252Arg substitutions. Located close to the active site, the Tyr224His substitution is also present in VIM-1, VIM-4, VIM-7 and VIM-12. The VIM-31 variant was reported in 2012 from Enterobacter cloacae and kinetically characterized. It exhibits globally lower catalytic efficiencies than VIM-2. In the present study, we report the three-dimensional structures of VIM-31 in its native (reduced) and oxidized forms. The so-called 'flapping-loop' (loop 1) and loop 3 of VIM-31 were not positioned as in VIM-2 but instead were closer to the active site as in VIM-4, resulting in a narrower active site in VIM-31. Also, the presence of His224 in VIM-31 disrupts hydrogen-bonding networks close to the active site. Moreover, a third zinc-binding site, which also exists in VIM-2 structures, could be identified as a structural explanation for the decreased activity of VIM-MBLs at high zinc concentrations.

  19. Silver nanoparticles production by two soil isolated bacteria, Bacillus thuringiensis and Enterobacter cloacae, and assessment of their cytotoxicity and wound healing effect in rats.

    PubMed

    Pourali, Parastoo; Razavian Zadeh, Nasrin; Yahyaei, Behrooz

    2016-09-01

    Production of silver nanoparticles by Bacillus thuringiensis and Enterobacter cloacae was performed and confirmed through UV-visible spectrophotometry, transmission electron microscopy (TEM), and x-ray diffraction (XRD) analyses. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using mouse fibroblast cell line NIH-3T3 D4 was carried out and IC50s of AgNPs were obtained. The nontoxic dose of each AgNPs solution was selected for wound healing assay. Thirty-two rats were divided into four groups; two were used as the controls and two were treated by AgNPs that were produced by two bacterial strains. Results revealed that the produced AgNPs were amorphous, spherical in shapes, and had sizes under 100 nm. Histological analysis showed that AgNPs had better wound healing efficacy than the control groups. In conclusion, when the biologically produced AgNPs were used in vivo, they induced the epithelization, formation of the collagen bundles and fibroplasia and reduced the duration of completion of the epithelization and the angiogenesis.

  20. Enterobacter cloacae as biosurfactant producing bacterium: differentiating its effects on interfacial tension and wettability alteration Mechanisms for oil recovery during MEOR process.

    PubMed

    Sarafzadeh, Pegah; Hezave, Ali Zeinolabedini; Ravanbakhsh, Moosa; Niazi, Ali; Ayatollahi, Shahab

    2013-05-01

    Microbial enhanced oil recovery (MEOR) process utilizes microorganisms or their metabolites to mobilize the trapped oil in the oil formation after primary and secondary oil recovery stages. MEOR technique is considered as more environmentally friendly and low cost process. There are several identified mechanisms for more oil recovery using MEOR processes however; wettability alteration and interfacial tension (IFT) reduction are the important ones. Enterobacter Cloacae, a facultative bio-surfactant producer bacterium, was selected as a bacterial formulation due to its known performance on IFT reduction and wettability alteration. To quantify the effects of these two mechanisms, different tests including oil spreading, in situ and ex situ core flooding, wettability measurement (Amott), IFT, viscosity and pH measurements were performed. The obtained results revealed that the experimental procedure used in this study was able to quantitatively identify the individual effects of both mechanisms on the ultimate microbial oil recovery. The results demonstrated considerable effects of both mechanisms on the tertiary oil recovery; however after a proper shut in time period, more tertiary oil was recovered because of wettability alteration mechanism. Finally, SEM images taken from the treated cores showed biofilm formation on the rock pore surfaces, which is responsible for rock surface wettability alteration.

  1. Antifungal and sprout regulatory bioactivities of phenylacetic acid, indole-3-acetic acid, and tyrosol isolated from the potato dry rot suppressive bacterium Enterobacter cloacae S11:T:07.

    PubMed

    Slininger, P J; Burkhead, K D; Schisler, D A

    2004-12-01

    Enterobacter cloacae S11: T:07 (NRRL B-21050) is a promising biological control agent that has significantly reduced both fungal dry rot disease and sprouting in laboratory and pilot potato storages. The metabolites phenylacetic acid (PAA), indole-3-acetic acid (IAA), and tyrosol (TSL) were isolated from S11:T:07 liquid cultures provided with three different growth media. The bioactivities of these metabolites were investigated via thin-layer chromatography bioautography of antifungal activity, wounded potato assays of dry rot suppressiveness, and cored potato eye assays of sprout inhibition. Relative accumulations of PAA, IAA, and TSL in cultures were nutrient dependent. For the first time, IAA, TSL, and PAA were shown to have antifungal activity against the dry rot causative pathogen Gibberella pulicaris, and to suppress dry rot infection of wounded potatoes. Disease suppression was optimal when all three metabolites were applied in combination. Dosages of IAA that resulted in disease suppression also resulted in sprout inhibition. These results suggest the potential for designing culture production and formulation conditions to achieve a dual purpose biological control agent able to suppress both dry rot and sprouting of stored potatoes.

  2. Regulated Inflammation and Lipid Metabolism in Colon mRNA Expressions of Obese Germfree Mice Responding to Enterobacter cloacae B29 Combined with the High Fat Diet.

    PubMed

    Yan, Huiying; Fei, Na; Wu, Guojun; Zhang, Chenhong; Zhao, Liping; Zhang, Menghui

    2016-01-01

    Increased evidences have demonstrated that gut microbiota targeted diet intervention can alleviate obesity and related metabolic disorders. The underlying mechanism of interactions among diet, microbiota, and host still remains unclear. Enterobacter cloacae B29, an endotoxin-producing strain dominated in the gut of a morbidly obese volunteer (weight 174.8 kg, BMI 58.8 kg m(-2)) was isolated and transplanted to germfree mice (inoculated 10(10) cells of B29 per day for 1 week). Using deep mRNA sequencing technology, we compared different gene expression profiles in the colon samples of the germfree mice treated with/without B29 and/or high fat diet (HFD) for 16 weeks and identified 279 differential expressed genes in total, including up-regulated genes Apoa4 (fold change, 2.77), Ido1 (2.66), Cyp4a10 (7.01), and down-regulated genes Cyp2e1 (0.11), Cyp26b1 (0.34), Akr1b7 (0.42), Adipoq (0.36), Cyp1a1 (0.11), Apoa1 (0.44), Npc1l1 (0.37), Tff2 (0.13), Apoc1 (0.30), Ctla2a (0.34), Mttp (0.49), Lpl (0.48). Fifty-nine GO biological processes and five KEGG pathways, particularly the peroxisome proliferator-activated receptors signaling pathway, were significantly enriched in response to HFD+B29, which were mainly relevant to inflammation and the metabolism of lipid, lipoprotein, and sterols. These functional changes were consistent with the developed obesity, insulin-resistance, and aggravated inflammatory conditions of the HFD+B29 mice. This work provides insight into the gene expression changes in response to HFD+B29, helping to understand the mechanism of the interactions among HFD, B29 and the germfree mice.

  3. Regulated Inflammation and Lipid Metabolism in Colon mRNA Expressions of Obese Germfree Mice Responding to Enterobacter cloacae B29 Combined with the High Fat Diet

    PubMed Central

    Yan, Huiying; Fei, Na; Wu, Guojun; Zhang, Chenhong; Zhao, Liping; Zhang, Menghui

    2016-01-01

    Increased evidences have demonstrated that gut microbiota targeted diet intervention can alleviate obesity and related metabolic disorders. The underlying mechanism of interactions among diet, microbiota, and host still remains unclear. Enterobacter cloacae B29, an endotoxin-producing strain dominated in the gut of a morbidly obese volunteer (weight 174.8 kg, BMI 58.8 kg m-2) was isolated and transplanted to germfree mice (inoculated 1010 cells of B29 per day for 1 week). Using deep mRNA sequencing technology, we compared different gene expression profiles in the colon samples of the germfree mice treated with/without B29 and/or high fat diet (HFD) for 16 weeks and identified 279 differential expressed genes in total, including up-regulated genes Apoa4 (fold change, 2.77), Ido1 (2.66), Cyp4a10 (7.01), and down-regulated genes Cyp2e1 (0.11), Cyp26b1 (0.34), Akr1b7 (0.42), Adipoq (0.36), Cyp1a1 (0.11), Apoa1 (0.44), Npc1l1 (0.37), Tff2 (0.13), Apoc1 (0.30), Ctla2a (0.34), Mttp (0.49), Lpl (0.48). Fifty-nine GO biological processes and five KEGG pathways, particularly the peroxisome proliferator-activated receptors signaling pathway, were significantly enriched in response to HFD+B29, which were mainly relevant to inflammation and the metabolism of lipid, lipoprotein, and sterols. These functional changes were consistent with the developed obesity, insulin-resistance, and aggravated inflammatory conditions of the HFD+B29 mice. This work provides insight into the gene expression changes in response to HFD+B29, helping to understand the mechanism of the interactions among HFD, B29 and the germfree mice. PMID:27877172

  4. Complete Sequence of pSAM7, an IncX4 Plasmid Carrying a Novel blaCTX-M-14b Transposition Unit Isolated from Escherichia coli and Enterobacter cloacae from Cattle

    PubMed Central

    AbuOun, M.; Umur, S.; Wu, G.; Partridge, S. R.; Mevius, D. J.; Coldham, N. G.

    2013-01-01

    The same plasmid carrying blaCTX-M-14b was identified from an Escherichia coli isolate and an Enterobacter cloacae isolate collected from cattle in the United Kingdom by complete plasmid sequencing. This 35,341-bp plasmid, pSAM7, had an IncX4 backbone that is 99% identical to that of pJIE143 from a human isolate in Australia. PCR screening identified pSAM7-like plasmids in three other E. coli isolates of different multilocus sequence types isolated from cattle on different farms in the United Kingdom. PMID:23836183

  5. Spread of Enterobacter cloacae carrying blaNDM-1, blaCTX-M-15, blaSHV-12 and plasmid-mediated quinolone resistance genes in a surgical intensive care unit in Croatia.

    PubMed

    Petrosillo, N; Vranić-Ladavac, M; Feudi, C; Villa, L; Fortini, D; Barišić, N; Bedenić, B; Ladavac, R; D'Arezzo, S; Andrašević, A Tambić; Capone, A

    2016-03-01

    The objective of this study was to describe a hospital cluster of NDM-1-producing Enterobacter cloacae infections observed in the surgical intensive care unit (ICU) of a tertiary-care hospital at Pula, Croatia. NDM-1-producing E. cloacae strains isolated from clinical samples were screened by PCR for the presence of carbapenemases. Genetic relatedness of NDM-1-producing E. cloacae strains was determined by multilocus sequence typing (MLST). During the period October 2013 to April 2014, four patients, with overlapping hospital stay in the surgical ICU, developed severe infections caused by E. cloacae demonstrated to produce carbapenemases. According to MLST, all strains belonged to ST133 and were positive by PCR for the blaNDM-1 carbapenemase gene, for blaCTX-M-15 and blaSHV-12 extended-spectrum β-lactamase (ESBL) genes, and for blaTEM-1 and blaOXA-1 narrow-spectrum β-lactamase genes. They were negative for other carbapenemases genes including blaOXA-48, blaVIM and blaKPC as well as for AmpC and the armA and rmtB aminoglycoside resistance genes. All strains were positive for the HI2 replicon, suggesting that an IncHI2 plasmid is likely the plasmid carrying the blaNDM-1 gene. Infection control measures were implemented after the first case although they were not effective in avoiding spread of this organism to other patients in the surgical ICU. In conclusion, the evolving epidemiology of NDM-producing micro-organisms and the interspecies diffusion of this resistance mechanism to emerging pathogens such as E. cloacae necessitate the setting up of strong and urgent joint measures to control the spread of NDM carbapenemase especially in the ICU setting.

  6. [Profiles of the utilization of 20 amino acids as the only source of nitrogen and carbon in bacteria of the genera Klebsiella, Enterobacter, Serratia, Escherichia].

    PubMed

    Sivolodskiĭ, E P

    2005-01-01

    The profiles of the utilization of 20 protein amino acids in 118 Klebsiella pneumoniae sub- sp. pneumoniae, K. oxytoca, K. planticola, K. mobilis, Enterobacter cloacae, Serratia marscescens, S. liquefaciens, Escherichia coli strains isolated from clinical material were studied. The utilization of amino acids was determined on minimal saline agar containing amino acid as the only source of nitrogen and carbon; the results were evaluated after 72-hour incubation at 37 degrees C. 17 profiles of amino-acid utilization were thus determined, most of them genus-specific in enterobacteria: Klebsiella (profiles No. 1--6, 9, 10), Enterobacter (No. 11--13), Serratia (No. 14--16), Escherichia (No. 17). The full coincidence of amino-acid utilization profiles in bacteria of K. mobilis (No. 1, 6) and K. pneumoniae subsp. pneumoniae with out of such profiles in bacteria of the genera Enterobacter, Serratia, Escherichia was established, which confirmed that K. mobilis (formerly Enterobacter aerogenes) belonged to the genus Klebsiella.

  7. Purification and Characterization of Glutaminase Free Asparaginase from Enterobacter cloacae: In-Vitro Evaluation of Cytotoxic Potential against Human Myeloid Leukemia HL-60 Cells

    PubMed Central

    Husain, Islam; Sharma, Anjana; Kumar, Suresh; Malik, Fayaz

    2016-01-01

    Asparaginase is an important antileukemic agent extensively used worldwide but the intrinsic glutaminase activity of this enzymatic drug is responsible for serious life threatening side effects. Hence, glutaminase free asparaginase is much needed for upgradation of therapeutic index of asparaginase therapy. In the present study, glutaminase free asparaginase produced from Enterobacter cloacae was purified to apparent homogeneity. The purified enzyme was found to be homodimer of approximately 106 kDa with monomeric size of approximately 52 kDa and pI 4.5. Purified enzyme showed optimum activity between pH 7–8 and temperature 35–40°C, which is close to the internal environment of human body. Monovalent cations such as Na+ and K+ enhanced asparaginase activity whereas divalent and trivalent cations, Ca2+, Mg2+, Zn2+, Mn2+, and Fe3+ inhibited the enzyme activity. Kinetic parameters Km, Vmax and Kcat of purified enzyme were found to be 1.58×10−3 M, 2.22 IU μg-1 and 5.3 × 104 S-1, respectively. Purified enzyme showed prolonged in vitro serum (T1/2 = ~ 39 h) and trypsin (T1/2 = ~ 32 min) half life, which is therapeutically remarkable feature. The cytotoxic activity of enzyme was examined against a panel of human cancer cell lines, HL-60, MOLT-4, MDA-MB-231 and T47D, and highest cytotoxicity observed against HL-60 cells (IC50 ~ 3.1 IU ml-1), which was comparable to commercial asparaginase. Cell and nuclear morphological studies of HL-60 cells showed that on treatment with purified asparaginase symptoms of apoptosis were increased in dose dependent manner. Cell cycle progression analysis indicates that enzyme induces apoptosis by cell cycle arrest in G0/G1 phase. Mitochondrial membrane potential loss showed that enzyme also triggers the mitochondrial pathway of apoptosis. Furthermore, the enzyme was found to be nontoxic for human noncancerous cells FR-2 and nonhemolytic for human erythrocytes. PMID:26891220

  8. Purification and Characterization of Glutaminase Free Asparaginase from Enterobacter cloacae: In-Vitro Evaluation of Cytotoxic Potential against Human Myeloid Leukemia HL-60 Cells.

    PubMed

    Husain, Islam; Sharma, Anjana; Kumar, Suresh; Malik, Fayaz

    2016-01-01

    Asparaginase is an important antileukemic agent extensively used worldwide but the intrinsic glutaminase activity of this enzymatic drug is responsible for serious life threatening side effects. Hence, glutaminase free asparaginase is much needed for upgradation of therapeutic index of asparaginase therapy. In the present study, glutaminase free asparaginase produced from Enterobacter cloacae was purified to apparent homogeneity. The purified enzyme was found to be homodimer of approximately 106 kDa with monomeric size of approximately 52 kDa and pI 4.5. Purified enzyme showed optimum activity between pH 7-8 and temperature 35-40°C, which is close to the internal environment of human body. Monovalent cations such as Na+ and K+ enhanced asparaginase activity whereas divalent and trivalent cations, Ca2+, Mg2+, Zn2+, Mn2+, and Fe3+ inhibited the enzyme activity. Kinetic parameters Km, Vmax and Kcat of purified enzyme were found to be 1.58×10-3 M, 2.22 IU μg-1 and 5.3 × 104 S-1, respectively. Purified enzyme showed prolonged in vitro serum (T1/2 = ~ 39 h) and trypsin (T1/2 = ~ 32 min) half life, which is therapeutically remarkable feature. The cytotoxic activity of enzyme was examined against a panel of human cancer cell lines, HL-60, MOLT-4, MDA-MB-231 and T47D, and highest cytotoxicity observed against HL-60 cells (IC50 ~ 3.1 IU ml-1), which was comparable to commercial asparaginase. Cell and nuclear morphological studies of HL-60 cells showed that on treatment with purified asparaginase symptoms of apoptosis were increased in dose dependent manner. Cell cycle progression analysis indicates that enzyme induces apoptosis by cell cycle arrest in G0/G1 phase. Mitochondrial membrane potential loss showed that enzyme also triggers the mitochondrial pathway of apoptosis. Furthermore, the enzyme was found to be nontoxic for human noncancerous cells FR-2 and nonhemolytic for human erythrocytes.

  9. Biochemical Characterization of CTX-M-15 from Enterobacter cloacae and Designing a Novel Non-β-Lactam-β-Lactamase Inhibitor

    PubMed Central

    Danishuddin, Mohd; Khan, Asad U.

    2013-01-01

    The worldwide dissemination of CTX-M type β-lactamases is a threat to human health. Previously, we have reported the spread of blaCTX-M-15 gene in different clinical strains of Enterobacteriaceae from the hospital settings of Aligarh in north India. In view of the varying resistance pattern against cephalosporins and other β-lactam antibiotics, we intended to understand the correlation between MICs and catalytic activity of CTX-M-15. In this study, steady-state kinetic parameters and MICs were determined on E. coli DH5α transformed with blaCTX-M-15 gene that was cloned from Enterobacter cloacae (EC-15) strain of clinical background. The effect of conventional β-lactamase inhibitors (clavulanic acid, sulbactam and tazobactam) on CTX-M-15 was also studied. We have found that tazobactam is the best among these inhibitors against CTX-M-15. The inhibition characteristic of tazobactam is defined by its very low IC50 value (6 nM), high affinity (Ki = 0.017 µM) and better acylation efficiency (k+2/K′ = 0.44 µM−1s−1). It forms an acyl-enzyme covalent complex, which is quite stable (k+3 = 0.0057 s−1). Since increasing resistance has been reported against conventional β-lactam antibiotic-inhibitor combinations, we aspire to design a non-β-lactam core containing β-lactamase inhibitor. For this, we screened ZINC database and performed molecular docking to identify a potential non-β-lactam based inhibitor (ZINC03787097). The MICs of cephalosporin antibiotics in combination with this inhibitor gave promising results. Steady-state kinetics and molecular docking studies showed that ZINC03787097 is a reversible inhibitor which binds non-covalently to the active site of the enzyme through hydrogen bonds and hydrophobic interactions. Though, it’s IC50 (180 nM) is much higher than tazobactam, it has good affinity for CTX-M-15 (Ki = 0.388 µM). This study concludes that ZINC03787097 compound can be used as seed molecule to design more efficient non

  10. MALDI-TOF MS as a Tool To Detect a Nosocomial Outbreak of Extended-Spectrum-β-Lactamase- and ArmA Methyltransferase-Producing Enterobacter cloacae Clinical Isolates in Algeria

    PubMed Central

    Khennouchi, Nour Chems el Houda; Loucif, Lotfi; Boutefnouchet, Nafissa; Allag, Hamoudi

    2015-01-01

    Enterobacter cloacae is among the most important pathogens responsible for nosocomial infections and outbreaks. In this study, 77 Enterobacter isolates were collected: 27 isolates from Algerian hospitals (in Constantine, Annaba, and Skikda) and 50 isolates from Marseille, France. All strains were identified by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Antibiotic susceptibility testing was performed by the disk diffusion method. PCR was used to detect extended-spectrum-beta-lactamase (ESBL)-encoding, fluoroquinolone resistance-encoding, and aminoglycoside-modifying enzyme (AME) genes. Epidemiological typing was performed using MALDI-TOF MS with data mining approaches, along with multilocus sequence typing (MLST). Sixty-eight isolates (27 from Algeria, 41 from Marseille) were identified by MALDI-TOF MS as E. cloacae. Resistance to antibiotics in the Algerian isolates was significantly higher than that in the strains from Marseille, especially for beta-lactams and aminoglycosides. Eighteen of the 27 Algerian isolates and 11 of the 41 Marseille isolates possessed at least one ESBL-encoding gene: blaCTX-M and/or blaTEM. AME genes were detected in 20 of the 27 Algerian isolates and 8 of the 41 Marseille isolates [ant(2″)-Ia, aac(6′)-Ib-cr, aadA1, aadA2, and armA]. Conjugation experiments showed that armA was carried on a transferable plasmid. MALDI-TOF typing showed three separate clusters according to the geographical distribution and species level. An MLST-based phylogenetic tree showed a clade of 14 E. cloacae isolates from a urology unit clustering together in the MALDI-TOF dendrogram, suggesting the occurrence of an outbreak in this unit. In conclusion, the ability of MALDI-TOF to biotype strains was confirmed, and surveillance measures should be implemented, especially for Algerian patients hospitalized in France. PMID:26239991

  11. MALDI-TOF MS as a Tool To Detect a Nosocomial Outbreak of Extended-Spectrum-β-Lactamase- and ArmA Methyltransferase-Producing Enterobacter cloacae Clinical Isolates in Algeria.

    PubMed

    Khennouchi, Nour Chems el Houda; Loucif, Lotfi; Boutefnouchet, Nafissa; Allag, Hamoudi; Rolain, Jean-Marc

    2015-10-01

    Enterobacter cloacae is among the most important pathogens responsible for nosocomial infections and outbreaks. In this study, 77 Enterobacter isolates were collected: 27 isolates from Algerian hospitals (in Constantine, Annaba, and Skikda) and 50 isolates from Marseille, France. All strains were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Antibiotic susceptibility testing was performed by the disk diffusion method. PCR was used to detect extended-spectrum-beta-lactamase (ESBL)-encoding, fluoroquinolone resistance-encoding, and aminoglycoside-modifying enzyme (AME) genes. Epidemiological typing was performed using MALDI-TOF MS with data mining approaches, along with multilocus sequence typing (MLST). Sixty-eight isolates (27 from Algeria, 41 from Marseille) were identified by MALDI-TOF MS as E. cloacae. Resistance to antibiotics in the Algerian isolates was significantly higher than that in the strains from Marseille, especially for beta-lactams and aminoglycosides. Eighteen of the 27 Algerian isolates and 11 of the 41 Marseille isolates possessed at least one ESBL-encoding gene: blaCTX-M and/or blaTEM. AME genes were detected in 20 of the 27 Algerian isolates and 8 of the 41 Marseille isolates [ant(2″)-Ia, aac(6')-Ib-cr, aadA1, aadA2, and armA]. Conjugation experiments showed that armA was carried on a transferable plasmid. MALDI-TOF typing showed three separate clusters according to the geographical distribution and species level. An MLST-based phylogenetic tree showed a clade of 14 E. cloacae isolates from a urology unit clustering together in the MALDI-TOF dendrogram, suggesting the occurrence of an outbreak in this unit. In conclusion, the ability of MALDI-TOF to biotype strains was confirmed, and surveillance measures should be implemented, especially for Algerian patients hospitalized in France.

  12. Emergence of TEM, SHV, and CTX-M-extended spectrum β-lactamases and class 1 integron among Enterobacter cloacae isolates collected from hospitals of Tehran and Qazvin, Iran.

    PubMed

    Peymani, Amir; Farivar, Taghi Naserpour; Sanikhani, Rahimeh; Javadi, Amir; Najafipour, Reza

    2014-10-01

    Extended-spectrum β-lactamase (ESBL) production is an important resistance mechanism among clinical isolates of Enterobacter cloacae. TEM, SHV, and CTX-M are the most common ESBL genotypes among Enterobacter spp. The main aims of this study were to determine the antimicrobial susceptibility pattern and to detect ESBL-encoding genes as well as intI1 genes. One hundred twenty isolates of E. cloacae were collected from hospitals of Tehran and Qazvin, Iran. The isolates were identified by standard laboratory methods and API 20E strips. ESBL screening was performed by the combined disk method. PCR and sequencing were conducted for detection of ESBL-encoding genes as well as intI1 genes. Clonal relatedness of ESBL-producing isolates was assessed by the enterobacterial repetitive intergenic consensus (ERIC)-PCR method. Of 120 isolates, 57 (47.5%) were characterized as multidrug resistant among those 48 (84.2%) isolates carried class 1 integron. Fifty-three (44.2%) isolates were found to be ESBL producers, in which bla(CTX-M-15) (60.4%) was the most common gene followed by bla(TEM-1) (32.1%), bla(TEM-169) (13.2%), and bla(SHV-12) (7.5%) either alone or in combination. Forty-four of the 53 (83.01%) ESBL-producing isolates were genetically unrelated. For the first time, this study describes the emergence of TEM-169, SHV-12, and CTX-M-15 ESBL genotypes in E. cloacae isolates in Iran.

  13. Molecular characteristics of extended-spectrum beta-lactamases and qnr determinants in Enterobacter species from Japan.

    PubMed

    Kanamori, Hajime; Yano, Hisakazu; Hirakata, Yoichi; Hirotani, Ayako; Arai, Kazuaki; Endo, Shiro; Ichimura, Sadahiro; Ogawa, Miho; Shimojima, Masahiro; Aoyagi, Tetsuji; Hatta, Masumitsu; Yamada, Mitsuhiro; Gu, Yoshiaki; Tokuda, Koichi; Kunishima, Hiroyuki; Kitagawa, Miho; Kaku, Mitsuo

    2012-01-01

    The incidence of extended-spectrum β-lactamases (ESBLs) has been increasing worldwide, but screening criteria for detection of ESBLs are not standardized for AmpC-producing Enterobacteriaceae such as Enterobacter species. In this study, we investigated the prevalence of ESBLs and/or AmpC β-lactamases in Japanese clinical isolates of Enterobacter spp. and the association of plasmid-mediated quinolone resistance (PMQR) determinants with ESBL producers. A total of 364 clinical isolates of Enterobacter spp. collected throughout Japan between November 2009 and January 2010 were studied. ESBL-producing strains were assessed by the CLSI confirmatory test and the boronic acid disk test. PCR and sequencing were performed to detect CTX-M, TEM, and SHV type ESBLs and PMQR determinants. For ESBL-producing Enterobacter spp., pulsed-field gel electrophoresis (PFGE) was performed using XbaI restriction enzyme. Of the 364 isolates, 22 (6.0%) were ESBL producers. Seven isolates of Enterobacter cloacae produced CTX-M-3, followed by two isolates producing SHV-12. Two isolates of Enterobacter aerogenes produced CTX-M-2. Of the 22 ESBL producers, 21 had the AmpC enzyme, and six met the criteria for ESBL production in the boronic acid test. We found a significant association of qnrS with CTX-M-3-producing E. cloacae. The 11 ESBL-producing Enterobacter spp. possessing bla(CTX-M), bla(SHV), or bla(TEM) were divided into six unique PFGE types. This is the first report about the prevalence of qnr determinants among ESBL-producing Enterobacter spp. from Japan. Our results suggest that ESBL-producing Enterobacter spp. with qnr determinants are spreading in Japan.

  14. Modification of rock/fluid and fluid/fluid interfaces during MEOR processes, using two biosurfactant producing strains of Bacillus stearothermophilus SUCPM#14 and Enterobacter cloacae: a mechanistic study.

    PubMed

    Sarafzadeh, Pegah; Zeinolabedini Hezave, Ali; Mohammadi, Sahar; Niazi, Ali; Ayatollahi, Shahab

    2014-05-01

    During any microbial enhanced oil recovery process, both cells and the metabolic products of bacteria govern the tertiary oil recovery efficiency. However, very accurate examination is needed to find the functionality of these tiny creatures at different reservoir conditions. In this regard, the effect of cell structure on ultimate microbial recovery efficiency which is the most dominant mechanism based on the microorganism types (gram-negative or gram-positive) was systematically investigated. At the first stage, possible different active mechanisms using Bacillus stearothermophilus SUCPM#14 strain were tested using specially designed injection protocol, in situ and ex situ core flooding experiments, interfacial tension, viscosity, pH and Amott wettability index measurements. At the second stage, comparing functionality of B. stearothermophilus SUCPM#14 (a gram-positive type) with the previously examined strain namely Enterobacter cloacae as a gram-negative type, proposed this hypothesis that the cell structure significantly affects the interfacial behaviors. New designed protocols were utilized to check the individual effects of cells, bioproducts and interaction of these together on the oil/water and also fluids/rock interfaces. The final results showed that the cells of B. stearothermophilus SUCPM#14 adhere more into the oil/water interface compared to E. cloacae and change its rheological properties; e.g. its elastic properties which affect the ultimate microbial oil recovery efficiency. Eventually, contradicting results revealed that biosurfactant produced by E. cloacae was able to considerably reduce the interfacial tension and alter the wettability of the rock (to neutral conditions) while biosurfactant produced by B. stearothermophilus SUCPM#14 was not very effective.

  15. Emergence of CMY-2- and DHA-1-type AmpC β-lactamases in Enterobacter cloacae isolated from several hospitals of Qazvin and Tehran, Iran

    PubMed Central

    Peymani, Amir; Naserpour-Farivar, Taghi; Yeylagh-Beygi, Moein; Bolori, Shahiin

    2016-01-01

    Background and Objectives: The emergence of plasmid-mediated AmpC (pAmpC) β-lactamases conferring resistance to third-generation cephalosporins has become a major clinical concern worldwide. The aims of this study were to determine the prevalence of pAmpC-producing E. cloacae isolates and typing of them in Qazvin and Tehran provinces, Iran. Materials and Methods: A total of 120 cefoxitin non-susceptible isolates of E. cloacae were obtained from educational hospitals of Qazvin and Tehran, Iran. Bacterial identification was performed by standard laboratory methods and API 20E strips. Susceptibility to cefoxitin was determined by Kirby-Bauer disk diffusion method. PCR and sequencing were employed to detect pAmpC families’ genes (ACC, FOX, MOX, DHA, CIT and EBC) and the clonal relatedness of pAmpC-positive isolates was evaluated by enterobacterial repetitive intergenic consensus (ERIC)-PCR method. Results: In total, 20 (16.7%) isolates of E. cloacae were positive for presence of pAmpC genes among those blaDHA-1 (14.2%) was the most common gene followed by blaCMY-2 (2.5%). Results of ERIC-PCR showed that that the prevalence of DHA-1 and CMY-2-producing E. cloacae isolates was not due to clonal outbreaks. Conclusion: In present study, we showed the first emergence of DHA-1 and CMY-2 types of pAmpC-producing E. cloacae isolates in Iran. The appearance of pAmpC should be considered as a warning for the implementation of appropriate infection control and therapeutic policies in order to prevent the dissemination of these resistant organisms in our hospital settings. PMID:27928483

  16. Phenotypic and molecular characterization of antimicrobial resistance in Enterobacter spp. isolates from companion animals in Japan

    PubMed Central

    Harada, Kazuki; Shimizu, Takae; Mukai, Yujiro; Kuwajima, Ken; Sato, Tomomi; Kajino, Akari; Usui, Masaru; Tamura, Yutaka; Kimura, Yui; Miyamoto, Tadashi; Tsuyuki, Yuzo; Ohki, Asami; Kataoka, Yasushi

    2017-01-01

    The emergence of antimicrobial resistance among Enterobacter spp., including resistance to extended-spectrum cephalosporins (ESC), is of great concern in both human and veterinary medicine. In this study, we investigated the prevalence of antimicrobial resistance among 60 isolates of Enterobacter spp., including E. cloacae (n = 44), E. aerogenes (n = 10), and E. asburiae (n = 6), from clinical specimens of dogs and cats from 15 prefectures in Japan. Furthermore, we characterized the resistance mechanisms harbored by these isolates, including extended-spectrum β-lactamases (ESBLs) and plasmid-mediated quinolone resistance (PMQR); and assessed the genetic relatedness of ESC-resistant Enterobacter spp. strains by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Antimicrobial susceptibility testing demonstrated the resistance rates to ampicillin (93.3%), amoxicillin-clavulanic acid (93.3%), cefmetazole (93.3%), chloramphenicol (46.7%), ciprofloxacin (43.3%), tetracycline (40.0%), ceftazidime (33.3%), cefotaxime (33.3%), trimethoprim/sulfamethoxazole (28.3%), gentamicin (23.3%), and meropenem (0%). Phenotypic testing detected ESBLs in 16 of 18 ESC-resistant E. cloacae isolates but not in the other species. The most frequent ESBL was CTX-M-15 (n = 8), followed by SHV-12 (n = 7), and CTX-M-3 (n = 1). As for AmpC β-lactamases, CMY-2 (n = 2) and DHA-1 (n = 2) were identified in ESC-resistant E. cloacae strains with or without ESBLs. All of the ESC-resistant E. cloacae strains also harbored one or two PMQRs, including qnrB (n = 15), aac(6’)-Ib-cr (n = 8), and qnrS (n = 2). Based on MLST and PFGE analysis, E. cloacae clones of ST591-SHV-12, ST171-CTX-M-15, and ST121-CTX-M-15 were detected in one or several hospitals. These results suggested intra- and inter-hospital dissemination of E. cloacae clones co-harboring ESBLs and PMQRs among companion animals. This is the first report on the large-scale monitoring of antimicrobial-resistant isolates

  17. Phenotypic and molecular characterization of antimicrobial resistance in Enterobacter spp. isolates from companion animals in Japan.

    PubMed

    Harada, Kazuki; Shimizu, Takae; Mukai, Yujiro; Kuwajima, Ken; Sato, Tomomi; Kajino, Akari; Usui, Masaru; Tamura, Yutaka; Kimura, Yui; Miyamoto, Tadashi; Tsuyuki, Yuzo; Ohki, Asami; Kataoka, Yasushi

    2017-01-01

    The emergence of antimicrobial resistance among Enterobacter spp., including resistance to extended-spectrum cephalosporins (ESC), is of great concern in both human and veterinary medicine. In this study, we investigated the prevalence of antimicrobial resistance among 60 isolates of Enterobacter spp., including E. cloacae (n = 44), E. aerogenes (n = 10), and E. asburiae (n = 6), from clinical specimens of dogs and cats from 15 prefectures in Japan. Furthermore, we characterized the resistance mechanisms harbored by these isolates, including extended-spectrum β-lactamases (ESBLs) and plasmid-mediated quinolone resistance (PMQR); and assessed the genetic relatedness of ESC-resistant Enterobacter spp. strains by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Antimicrobial susceptibility testing demonstrated the resistance rates to ampicillin (93.3%), amoxicillin-clavulanic acid (93.3%), cefmetazole (93.3%), chloramphenicol (46.7%), ciprofloxacin (43.3%), tetracycline (40.0%), ceftazidime (33.3%), cefotaxime (33.3%), trimethoprim/sulfamethoxazole (28.3%), gentamicin (23.3%), and meropenem (0%). Phenotypic testing detected ESBLs in 16 of 18 ESC-resistant E. cloacae isolates but not in the other species. The most frequent ESBL was CTX-M-15 (n = 8), followed by SHV-12 (n = 7), and CTX-M-3 (n = 1). As for AmpC β-lactamases, CMY-2 (n = 2) and DHA-1 (n = 2) were identified in ESC-resistant E. cloacae strains with or without ESBLs. All of the ESC-resistant E. cloacae strains also harbored one or two PMQRs, including qnrB (n = 15), aac(6')-Ib-cr (n = 8), and qnrS (n = 2). Based on MLST and PFGE analysis, E. cloacae clones of ST591-SHV-12, ST171-CTX-M-15, and ST121-CTX-M-15 were detected in one or several hospitals. These results suggested intra- and inter-hospital dissemination of E. cloacae clones co-harboring ESBLs and PMQRs among companion animals. This is the first report on the large-scale monitoring of antimicrobial-resistant isolates

  18. Molecular epidemiology of environmental and clinical carbapenemase-producing Gram-negative bacilli from hospitals in Guelma, Algeria: Multiple genetic lineages and first report of OXA-48 in Enterobacter cloacae.

    PubMed

    Bouguenoun, Widad; Bakour, Sofiane; Bentorki, Ahmed Aimen; Al Bayssari, Charbel; Merad, Tarek; Rolain, Jean-Marc

    2016-12-01

    This study was designed to investigate environmental colonisation in Algerian hospitals by carbapenem-resistant Gram-negative bacilli (GNB), including molecular characterisation of their resistance, and to perform a comparative molecular analysis between clinical and environmental strains. GNB isolated from hospitalised patients and the hospital environment were identified using microbiological methods and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Antibiotic susceptibility testing was performed by disk diffusion and Etest methods. Carbapenemase- and extended-spectrum β-lactamase (ESBL)-encoding genes were searched for using PCR and sequencing. Clonality of the environmental and clinical strains was assessed by multilocus sequencing typing (MLST). A total of 32 carbapenem-resistant GNB were isolated, including 16 (29%) of 56 multidrug-resistant (MDR) GNB from clinical specimens and 16 (48%) of 33 MDR-GNB from inanimate surfaces. Of the 32 carbapenem-resistant isolates, 14 produced a carbapenemase. The blaOXA-48 gene was detected both in clinical and surface isolates of Klebsiella pneumoniae (n=3) and Enterobacter cloacae (n=2). Clinical and surface isolates of Acinetobacter baumannii were found to produce the carbapenemases NDM-1 (7 isolates) and OXA-23 (2 isolates). MLST revealed clonal diversity and a relationship between environmental and clinical strains with identical sequence types. Here we report the first description of an OXA-48-producing E. cloacae isolate in Algeria. We also highlight the important role of inanimate surfaces in the spread of carbapenem-resistant bacteria and the emergence of nosocomial infections.

  19. Epidemiological typing of isolates from an outbreak of infection with multidrug-resistant Enterobacter cloacae by repetitive extragenic palindromic unit b1-primed PCR and pulsed-field gel electrophoresis.

    PubMed Central

    Shi, Z Y; Liu, P Y; Lau, Y J; Lin, Y H; Hu, B S

    1996-01-01

    An outbreak of multidrug-resistant Enterobacter cloacae infection lasted for 4 months in a neonatal intensive care unit (NICU). Forty-six isolates from the NICU and 20 epidemiologically unrelated strains were characterized by pulsed-field gel electrophoresis (PFGE) and repetitive extragenic palindromic unit b1-primed PCR (REPUb1-PCR) typing. The PFGE patterns after XbaI restriction of the bacterial DNA were analyzed by computer software (Gelcompar) using the UPGMA (unweighted pair group method with arithmetic averages) clustering method and the Dice coefficient. The 46 isolates from the NICU were classified by PFGE typing into five clusters: A (further classified into 7 subtypes, A1 to A7), B, C, D, and E. This outbreak was attributed to multiple genetically related strains of cluster A which had a similarity of 85.8% +/- 4.6%. The minor band differences among strains of cluster A were probably due to minor genetic mutations. The type A1 and A3 strains were isolated from the clinical specimens of patients and hands of nurses. It was probable that these outbreak strains were transmitted among patients via the hands of personnel. REPUb1-PCR typing of the 46 isolates also demonstrated five types, in agreement with results obtained by the PFGE technique, but could not detect the minor mutations among the cluster A strains. Twenty epidemiologically unrelated strains were well distinguished by both PFGE and REPUb1-PCR typing. We conclude that PFGE is a highly discriminatory but time-consuming method for epidemiological typing of E. cloacae and that REPUb1-PCR is a more rapid method with good reproducibility and discriminatory power comparable to that of PFGE. PMID:8897183

  20. Genetic and Structural Insights into the Dissemination Potential of the Extremely Broad-Spectrum Class A β-Lactamase KPC-2 Identified in an Escherichia coli Strain and an Enterobacter cloacae Strain Isolated from the Same Patient in France▿

    PubMed Central

    Petrella, Stephanie; Ziental-Gelus, Nathalie; Mayer, Claudine; Renard, Murielle; Jarlier, Vincent; Sougakoff, Wladimir

    2008-01-01

    Two clinical strains of Escherichia coli (2138) and Enterobacter cloacae (7506) isolated from the same patient in France and showing resistance to extended-spectrum cephalosporins and low susceptibility to imipenem were investigated. Both strains harbored the plasmid-contained blaTEM-1 and blaKPC-2 genes. blaKLUC-2, encoding a mutant of the chromosomal β-lactamase of Kluyvera cryocrescens, was also identified at a plasmid location in E. cloacae 7506, suggesting the ISEcp1-assisted escape of blaKLUC from the chromosome. Determination of the KPC-2 structure at 1.6 Å revealed that the binding site was occupied by the C-terminal (C-ter) residues coming from a symmetric KPC-2 monomer, with the ultimate C-ter Glu interacting with Ser130, Lys234, Thr235, and Thr237 in the active site. This mode of binding can be paralleled to the inhibition of the TEM-1 β-lactamase by the inhibitory protein BLIP. Determination of the 1.23-Å structure of a KPC-2 mutant in which the five C-ter residues were deleted revealed that the catalytic site was filled by a citrate molecule. Structure analysis and docking simulations with cefotaxime and imipenem provided further insights into the molecular basis of the extremely broad spectrum of KPC-2, which behaves as a cefotaximase with significant activity against carbapenems. In particular, residues 104, 105, 132, and 167 draw a binding cavity capable of accommodating both the aminothiazole moiety of cefotaxime and the 6α-hydroxyethyl group of imipenem, with the binding of the former drug being also favored by a significant degree of freedom at the level of the loop at positions 96 to 105 and by an enlargement of the binding site at the end of strand β3. PMID:18625772

  1. Enterobacter and Klebsiella species isolated from fresh vegetables marketed in Valencia (Spain) and their clinically relevant resistances to chemotherapeutic agents.

    PubMed

    Falomir, María Pilar; Rico, Hortensia; Gozalbo, Daniel

    2013-12-01

    Occurrence of antibiotic-resistant pathogenic or commensal enterobacteria in marketed agricultural foodstuffs may contribute to their incorporation into the food chain and constitutes an additional food safety concern. In this work, we have determined the clinically relevant resistances to 11 common chemotherapeutic agents in Enterobacter and Klebsiella isolates from fresh vegetables from various sources (supermarkets and greengrocers' shops in Valencia, Spain). A total of 96 isolates were obtained from 160 vegetables analyzed (50% positive samples): 68 Enterobacter isolates (59 E. cloacae, two E. aerogenes, two E. cancerogenus, one E. gergoviae, and four E. sakazakii, currently Cronobacter spp.), and 28 Klebsiella isolates (19 K. oxytoca and 9 K. pneumoniae). Only seven isolates were susceptible to all agents tested, and no resistances to ceftazidime, ciprofloxacin, gentamicin, and chloramphenicol were detected. Most isolates were resistant to amoxicillin/clavulanic acid (74 [58 Enterobacter and 16 Klebsiella]) or to ampicillin (80 [55/25]). Other resistances were less frequent: nitrofurantoin (13 isolates [12/1]), tetracycline (6 [5/1]), co-trimoxazole (3 [3/0]), cefotaxime (1 [1/0]), and streptomycin (2 [1/1]). Multiresistant isolates to two (56 [41/15]), three (10 E. cloacae isolates), four (one E. cloacae and one K. pneumoniae isolate), and five (two E. cloacae isolates) chemotherapeutic agents were also detected. The presence of potential pathogens points to marketed fresh produce, which often is eaten raw, as a risk factor for consumer health. In addition, these results support the usefulness of these bacterial species as indicators of the spreading of antibiotic resistances into the environment, particularly in the food chain, and suggest their role as carriers of resistance determinants from farms to consumers, which may constitute an additional "silent" food safety concern. Therefore, there is a need to improve the hygienic quality of marketed fresh

  2. Mathematical modeling and assessment of microbial migration during the sprouting of alfalfa in trays in a nonuniformly contaminated seed batch using Enterobacter aerogenes as a surrogate for Salmonella Stanley.

    PubMed

    Liu, Bin; Schaffner, Donald W

    2007-11-01

    Raw seed sprouts have been implicated in several food poisoning outbreaks in the past 10 years. The U.S. Food and Drug Administration recommends that sprout growers use interventions (such as testing of spent irrigation water) to control the presence of pathogens in the finished product. During the sprouting process, initially low concentrations of pathogen may increase, and contamination may spread within a batch of sprouting seeds. A model of pathogen growth as a function of time and distance from the contamination spot during the sprouting of alfalfa in trays has been developed with Enterobacter aerogenes. The probability of detecting contamination was assessed by logistic regression at various time points and distances by sampling from sprouts or irrigation water. Our results demonstrate that microbial populations and possibility of detection were greatly reduced at distances of > or = 20 cm from the point of contamination in a seed batch during tray sprouting; however, the probability of detecting microbial contamination at distances less than 10 cm from the point of inoculation was almost 100% at the end of the sprouting process. Our results also show that sampling irrigation water, especially large volumes of water, is highly effective at detecting contamination: by collecting 100 ml of irrigation water for membrane filtration, the probability of detection was increased by three to four times during the first 6 h of seed germination. Our findings have quantified the degree to which a small level of contamination will spread throughout a tray of sprouting alfalfa seeds and subsequently be detected by either sprout or irrigation water sampling.

  3. Description of Enterobacter ludwigii sp. nov., a novel Enterobacter species of clinical relevance.

    PubMed

    Hoffmann, Harald; Stindl, Sibylle; Stumpf, Anita; Mehlen, Andre; Monget, Daniel; Heesemann, Jürgen; Schleifer, Karl H; Roggenkamp, Andreas

    2005-04-01

    A new species, Enterobacter ludwigii, is presented on the basis of the characteristics of 16 strains, which were isolated from clinical specimens. These bacteria form a distinct genetic cluster in phylogenetic analyses of the population structure of the Enterobacter cloacae complex. As determined by DNA-DNA cross-hybridization experiments in microplates, this genetic cluster can be delineated from the other species of the E. cloacae complex with deltaTm values equal to or above 5 degrees C with Enterobacter hormaechei being the closest relative. The bacteria are gram-negative, fermentative, motile rods with the general characteristics of the genus Enterobacter and the E. cloacae complex in particular. E. ludwigii can be differentiated from the other Enterobacter species by its growth on myo-inositol and 3-0-methyl-D-glucopyranose. The type strain is EN-119 (= DSM 16688T = CIP 108491T).

  4. Comprehensive Genome Analysis of Carbapenemase-Producing Enterobacter spp.: New Insights into Phylogeny, Population Structure, and Resistance Mechanisms

    PubMed Central

    Chavda, Kalyan D.; Chen, Liang; Fouts, Derrick E.; Sutton, Granger; Brinkac, Lauren; Jenkins, Stephen G.; Bonomo, Robert A.

    2016-01-01

    ABSTRACT Knowledge regarding the genomic structure of Enterobacter spp., the second most prevalent carbapenemase-producing Enterobacteriaceae, remains limited. Here we sequenced 97 clinical Enterobacter species isolates that were both carbapenem susceptible and resistant from various geographic regions to decipher the molecular origins of carbapenem resistance and to understand the changing phylogeny of these emerging and drug-resistant pathogens. Of the carbapenem-resistant isolates, 30 possessed blaKPC-2, 40 had blaKPC-3, 2 had blaKPC-4, and 2 had blaNDM-1. Twenty-three isolates were carbapenem susceptible. Six genomes were sequenced to completion, and their sizes ranged from 4.6 to 5.1 Mbp. Phylogenomic analysis placed 96 of these genomes, 351 additional Enterobacter genomes downloaded from NCBI GenBank, and six newly sequenced type strains into 19 phylogenomic groups—18 groups (A to R) in the Enterobacter cloacae complex and Enterobacter aerogenes. Diverse mechanisms underlying the molecular evolutionary trajectory of these drug-resistant Enterobacter spp. were revealed, including the acquisition of an antibiotic resistance plasmid, followed by clonal spread, horizontal transfer of blaKPC-harboring plasmids between different phylogenomic groups, and repeated transposition of the blaKPC gene among different plasmid backbones. Group A, which comprises multilocus sequence type 171 (ST171), was the most commonly identified (23% of isolates). Genomic analysis showed that ST171 isolates evolved from a common ancestor and formed two different major clusters; each acquiring unique blaKPC-harboring plasmids, followed by clonal expansion. The data presented here represent the first comprehensive study of phylogenomic interrogation and the relationship between antibiotic resistance and plasmid discrimination among carbapenem-resistant Enterobacter spp., demonstrating the genetic diversity and complexity of the molecular mechanisms driving antibiotic resistance in this

  5. In vivo selection of Enterobacter aerogenes with reduced susceptibility to cefepime and carbapenems associated with decreased expression of a 40 kDa outer membrane protein and hyperproduction of AmpC beta-lactamase.

    PubMed

    Fernández-Cuenca, Felipe; Rodríguez-Martínez, Jose Manuel; Martínez-Martínez, Luis; Pascual, Alvaro

    2006-06-01

    The mechanism(s) of resistance or decreased susceptibility to cefepime (FEP) and/or imipenem (IMP) in three consecutive isolates of Enterobacter aerogenes (Ea1, Ea2 and Ea3) cultured from bronchial aspirates of the same patient after treatment with ceftriaxone and FEP were studied. Identification was performed with the VITEK 2 system. All three isolates showed identical pulsed-field gel electrophoresis patterns and were resistant (minimum inhibitory concentrations (MICs)) to cefoxitin (MIC, >1024 mg/L), cefotaxime (CTX; MIC, 32-128 mg/L) and ceftazidime (CAZ; MIC, 32-128 mg/L) but susceptible to meropenem (MIC, aerogenes strain deposited in GenBank (accession no.). For Ea3, however, a point mutation in position 311 of ampC caused a change of Val-->Glu. Three outer membrane proteins (OMPs) of 51 k

  6. Relationship Between β-Lactamase Activity and Resistance of Enterobacter to Cephalothin

    PubMed Central

    Farrar, W. Edmund; Krause, Jane M.

    1970-01-01

    The relationship between cephalosporin β-lactamase activity and resistance to cephalothin was investigated in strains of Enterobacter cloacae and E. aerogenes. β-Lactamase activity was detected in all strains, but a quantitative correlation between amount of β-lactamase activity and level of resistance to cephalothin was not observed. Permeability barriers to cephalothin were observed and varied from strain to strain. β-Lactamase activity was increased by growing organisms in the presence of penicillin G. These enzymes hydrolyzed cephalosporins more rapidly than penicillins. Penicillinase-resistant penicillins, especially those of the isoxazolyl series, effectively inhibited Enterobacter β-lactamase. A synergistic antibacterial effect was observed when organisms were exposed to cephalothin and oxacillin in combination, and the resistance of even very small inocula to cephalothin was reduced by addition of oxacillin. Oxacillin probably exerts its effect by inhibiting β-lactamase at an intracellular site. Intracellular β-lactamase may make an important contribution to the resistance of even small inocula of gram-negative bacilli to cephalosporin and penicillin antibiotics. Although β-lactamase plays a significant role in the resistance of Enterobacter to cephalothin, other factors, such as permeability barriers, also participate in determining the level of resistance. PMID:16557885

  7. Relation of β-Lactamase Activity and Cellular Location to Resistance of Enterobacter to Penicillins and Cephalosporins

    PubMed Central

    Neu, Harold C.; Winshell, Elaine B.

    1972-01-01

    The Enterobacter species E. aerogenes, E. cloacae, and E. hafnia were examined for resistance to penicillin and cephalosporin derivatives. All were resistant to benzyl penicillin, ampicillin, 6 [d(−)α-amino-p-hydroxyphenylacetamido] penicillanic acid, cephaloridine, cephalothin, and cephalexin. A significant number were sensitive to carbenicillin and 6 [d(−)α-carboxy-3-thienylacetamido] penicillanic acid. No differences among the three species were noted. The β-lactamase activity was cell-bound, and was not released by osmotic shock, toluene treatment, or diphenylamine treatment. It was rarely released into the growth medium. The β-lactamase activity was primarily directed against cephalosporin derivatives. Synthesis of β-lactamase was chromosomally mediated. Resistance to ampicillin seemed to be partly related to entry of the molecule into the bacteria since exposure to ethylenediaminetetraacetate lowered the minimal inhibitory concentration. PMID:4218941

  8. Association of Novel Nonsynonymous Single Nucleotide Polymorphisms in ampD with Cephalosporin Resistance and Phylogenetic Variations in ampC, ampR, ompF, and ompC in Enterobacter cloacae Isolates That Are Highly Resistant to Carbapenems

    PubMed Central

    Ellington, Matthew J.; Hopkins, Katie L.; Turton, Jane F.; Doumith, Michel; Loy, Richard; Staves, Peter; Hinic, Vladimira; Frei, Reno; Woodford, Neil

    2016-01-01

    In Enterobacter cloacae, the genetic lesions associated with derepression of the AmpC β-lactamase include diverse single nucleotide polymorphisms (SNPs) and/or indels in the ampD and ampR genes and SNPs in ampC, while diverse SNPs in the promoter region or SNPs/indels within the coding sequence of outer membrane proteins have been described to alter porin production leading to carbapenem resistance. We sought to define the underlying mechanisms conferring cephalosporin and carbapenem resistance in a collection of E. cloacae isolates with unusually high carbapenem resistance and no known carbapenemase and, in contrast to many previous studies, considered the SNPs we detected in relation to the multilocus sequence type (MLST)-based phylogeny of our collection. Whole-genome sequencing was applied on the most resistant isolates to seek novel carbapenemases, expression of ampC was measured by reverse transcriptase PCR, and porin translation was detected by SDS-PAGE. SNPs occurring in ampC, ampR, ompF, and ompC genes (and their promoter regions) were mostly phylogenetic variations, relating to the isolates' sequence types, whereas nonsynonymous SNPs in ampD were associated with derepression of AmpC and cephalosporin resistance. The additional loss of porins resulted in high-level carbapenem resistance, underlining the clinical importance of chromosomal mutations among carbapenem-resistant E. cloacae. PMID:26856839

  9. Enterobacter aerogenes Hormaeche and Edwards 1960 (Approved Lists 1980) and Klebsiella mobilis Bascomb et al. 1971 (Approved Lists 1980) share the same nomenclatural type (ATCC 13048) on the Approved Lists and are homotypic synonyms, with consequences for the name Klebsiella mobilis Bascomb et al. 1971 (Approved Lists 1980).

    PubMed

    Tindall, B J; Sutton, G; Garrity, G M

    2017-02-01

    Enterobacter aerogenes Hormaeche and Edwards 1960 (Approved Lists 1980) and Klebsiella mobilis Bascomb et al. 1971 (Approved Lists 1980) were placed on the Approved Lists of Bacterial Names and were based on the same nomenclatural type, ATCC 13048. Consequently they are to be treated as homotypic synonyms. However, the names of homotypic synonyms at the rank of species normally are based on the same epithet. Examination of the Rules of the International Code of Nomenclature of Bacteria in force at the time indicates that the epithet mobilis in Klebsiella mobilis Bascomb et al. 1971 (Approved Lists 1980) was illegitimate at the time the Approved Lists were published and according to the Rules of the current International Code of Nomenclature of Prokaryotes continues to be illegitimate.

  10. Evidence that a DEGS homologue in Enterobacter clocae is important for colonization and disease suppression on cucumber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Enterobacter cloacae 501R3 shows promise as a biocontrol agent for damping-off of cucumber caused by Pythium ultimum. Enterobacter cloacae C10 is a mini-Tn5 Km transposon mutant of 501R3 that was reduced in colonization of cucumber roots and in suppression of damping-off of cucumber. Molecular char...

  11. Association of Novel Nonsynonymous Single Nucleotide Polymorphisms in ampD with Cephalosporin Resistance and Phylogenetic Variations in ampC, ampR, ompF, and ompC in Enterobacter cloacae Isolates That Are Highly Resistant to Carbapenems.

    PubMed

    Babouee Flury, Baharak; Ellington, Matthew J; Hopkins, Katie L; Turton, Jane F; Doumith, Michel; Loy, Richard; Staves, Peter; Hinic, Vladimira; Frei, Reno; Woodford, Neil

    2016-04-01

    InEnterobacter cloacae, the genetic lesions associated with derepression of the AmpC β-lactamase include diverse single nucleotide polymorphisms (SNPs) and/or indels in theampDandampRgenes and SNPs inampC, while diverse SNPs in the promoter region or SNPs/indels within the coding sequence of outer membrane proteins have been described to alter porin production leading to carbapenem resistance. We sought to define the underlying mechanisms conferring cephalosporin and carbapenem resistance in a collection ofE. cloacaeisolates with unusually high carbapenem resistance and no known carbapenemase and, in contrast to many previous studies, considered the SNPs we detected in relation to the multilocus sequence type (MLST)-based phylogeny of our collection. Whole-genome sequencing was applied on the most resistant isolates to seek novel carbapenemases, expression ofampCwas measured by reverse transcriptase PCR, and porin translation was detected by SDS-PAGE. SNPs occurring inampC,ampR,ompF, andompCgenes (and their promoter regions) were mostly phylogenetic variations, relating to the isolates' sequence types, whereas nonsynonymous SNPs inampDwere associated with derepression of AmpC and cephalosporin resistance. The additional loss of porins resulted in high-level carbapenem resistance, underlining the clinical importance of chromosomal mutations among carbapenem-resistantE. cloacae.

  12. Complete genome of the switchgrass endophyte Enterobacter clocace P101

    PubMed Central

    Humann, Jodi L.; Wildung, Mark; Pouchnik, Derek; Bates, Austin A.; Drew, Jennifer C.; Zipperer, Ursula N.; Triplett, Eric W.; Main, Dorrie; Schroeder, Brenda K.

    2014-01-01

    The Enterobacter cloacae complex is genetically very diverse. The increasing number of complete genomic sequences of E. cloacae is helping to determine the exact relationship among members of the complex. E. cloacae P101 is an endophyte of switchgrass (Panicum virgatum) and is closely related to other E. cloacae strains isolated from plants. The P101 genome consists of a 5,369,929 bp chromosome. The chromosome has 5,164 protein-coding regions, 100 tRNA sequences, and 8 rRNA operons. PMID:25197457

  13. Identification and phylogeny of Enterobacter sakazakii relative to Enterobacter and Citrobacter Species.

    PubMed

    Iversen, Carol; Waddington, Michael; On, Stephen L W; Forsythe, Stephen

    2004-11-01

    The phylogenetic relationships of Enterobacter sakazakii strains were investigated using 16S ribosomal DNA (rDNA) and hsp60 sequencing. Each analysis distributed E. sakazakii strains among four clusters, indicating substantial taxonomic heterogeneity. The E. sakazakii type strain 16S rDNA sequence was 97.8% similar to that of Citrobacter koseri but 97.0% similar to that of Enterobacter cloacae.

  14. Accumulation of plasmid-mediated fluoroquinolone resistance genes, qepA and qnrS1, in Enterobacter aerogenes co-producing RmtB and class A beta-lactamase LAP-1.

    PubMed

    Park, Yeon-Joon; Yu, Jin Kyung; Kim, Sang-Il; Lee, Kyungwon; Arakawa, Yoshichika

    2009-01-01

    A new plasmid-mediated fluoroquinolone efflux pump gene, qepA, is known to be associated with the rmtB gene, which confers high-level resistance to aminoglycosides. We investigated the qepA gene in 573 AmpC-producing Enterobacteriaceae including one Citrobacter freundii known to harbor rmtB. Of them, two clonally unrelated E. aerogenes harbored qepA. Both isolates co-harbored rmtB, qnrS1, qepA, and bla(LAP-1) on an IncFI type plasmid. The qepA was flanked by two copies of IS26 containing ISCR3C, tnpA, tnpR, bla(TEM), and rmtB. The qnrS1 and bla(LAP-1) were located upstream of qepA. All the resistance determinants (qepA, qnrS1, rmtB, and bla(LAP-1)) were co-transferred to E. coli J53 by filter mating from both isolates. Although the prevalence of qepA is currently low, considering the presence of ISCR3C and the possibility of co-selection and co-transferability of plasmids, more active surveillance for these multi-drug resistant bacteria and prudent use of antimicrobials are needed.

  15. Angiosarcoma of the Eyelid With Superimposed Enterobacter Infection.

    PubMed

    Hamill, Eric B; Agrawal, Megha; Diwan, A Hafeez; Winthrop, Kevin L; Marx, Douglas P

    2016-01-01

    Angiosarcoma is a rare, aggressive, malignant endothelial neoplasm with a variable clinical presentation. The authors describe a case of angiosarcoma involving the eyelid that was complicated by a superimposed Enterobacter infection. Following positive cultures for E. aerogenes and multiple biopsies suspicious but not definitive for angiosarcoma, a final biopsy was consistent with angiosarcoma.

  16. Phage-mediated Shiga toxin (Stx) horizontal gene transfer and expression in non-Shiga toxigenic Enterobacter and Escherichia coli strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    M12X01451, an Enterobacter cloacae strain recently identified from a clinical specimen, produces a new Stx1e that was not neutralized by existing anti-Stx1 monoclonal antibodies. Acquisition of stx by Ent. cloacae is rare and information regarding the origin and stability of the stx1e in M12X01451 i...

  17. Aerogenic Dissemination of Aphtae Epizooticae

    DTIC Science & Technology

    1980-03-14

    FTD-ID(RS)T-0112-80 FOREIGN TECHNOLOGY DIVISION AEROGENIC DISSEMINATION OF APHTAE EPIZOOTICAE by Jerzy Wisniewski DTIC A Approved for public release...0112-8o Date14 Mar 19.80 AEROGENIC DISSEMINATION oF APHTAE EPIZOOTICAE Jerzy Wisniewski During aphtae epizooticae the principal cause of the virus...8217 e saliva foam assists in spreading the virus nn the air. The aerosol containing the virus can also be found in evaporation from wet floors, as well

  18. Enterobacter siamensis sp. nov., a transglutaminase-producing bacterium isolated from seafood processing wastewater in Thailand.

    PubMed

    Khunthongpan, Suwannee; Bourneow, Chaiwut; H-Kittikun, Aran; Tanasupawat, Somboon; Benjakul, Soottawat; Sumpavapol, Punnanee

    2013-01-01

    A novel strain of Enterobacter, C2361(T), a Gram-negative, non-spore-forming, rod-shaped and facultative anaerobic bacterium with the capability to produce transglutaminase, was isolated from seafood processing wastewater collected from a treatment pond of a seafood factory in Songkhla Province, Thailand. Phylogenetic analyses and phenotypic characteristics, including chemotaxonomic characteristics, showed that the strain was a member of the genus Enterobacter. The 16S rRNA gene sequence similarities between strain C2361(T) and Enterobacter cloacae subsp. cloacae ATCC 13047(T) and Enterobacter cloacae subsp. dissolvens LMG 2683(T) were 97.5 and 97.5%, respectively. Strain C2361(T) showed a low DNA-DNA relatedness with the above-mentioned species. The major fatty acids were C16:0, C17:0cyclo and C14:0. The DNA G+C content was 53.0 mol%. On the basis of the polyphasic evidence gathered in this study, it should be classified as a novel species of the genus Enterobacter for which the name Enterobacter siamensis sp. nov. is proposed. The type strain is C2361(T) (= KCTC 23282(T) = NBRC 107138(T)).

  19. Vaccination against Klebsiella aerogenes.

    PubMed Central

    Roe, E. A.; Jones, R. J.

    1984-01-01

    Klebsiella vaccine was prepared from strains of Klebsiella aerogenes with capsular types K1, K36, K44 and K Cross (a type which cross-reacts in vitro with sera from many klebsiella capsular types). The vaccine was extracted by dialysis and ultrafiltration from capsular material released during growth of the bacteria in a five-day batch culture. Mice given one dose of vaccine from K1a (1.0 microgram/mouse) survived lethal intraperitoneal challenge of 11/11 homologous klebsiella strains four days after vaccination; 14 days after vaccination protection against the same challenge strains had declined to 5/11 strains. Vaccines from K1a, b, c, K36, K44 and K Cross induced homologous protection and protected mice against different ranges of heterologous klebsiella capsular types. The protective response of the mice was greatly enhanced by administering three doses of the vaccines. Vaccines from K1, K36, K44 and K Cross protected mice against 14/20, 11/20, 10/20 and 9/20 homologous and heterologous klebsiella challenge strains respectively. None of the klebsiella vaccines was toxic for mice at the immunizing dose (1.0 microgram/mouse). Vaccine from K36 was the most lethal, killing mice at 10(3) immunizing doses. The least toxic vaccine was from K44, which killed mice at 10(4) immunizing doses. PMID:6389699

  20. Atypical internal yellowing of papaya fruit in Hawaii caused by Enterobacter sakazakii

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Internal yellowing (IY), characterized by yellow discolored tissue around the papaya (Carica papaya) seed cavity, diffuse margins and the presence of a distinctly rotten odor, was first reported in 1987. These symptoms were associated with the causal agent Enterobacter cloacae. Here we report the fo...

  1. Prenatal diagnosis of persistent cloaca.

    PubMed

    Suzumori, Nobuhiro; Obayashi, Shintaro; Hattori, Yukio; Kaneko, Saori; Suzuki, Yoshikatsu; Sugiura-Ogasawara, Mayumi

    2009-09-01

    We report four cases of persistent cloaca diagnosed at 32-33 weeks of gestation. In cases of persistent cloaca, serial prenatal ultrasonography shows transient fetal ascites, enlarged cystic structures arising from the fetal pelvis. Our four cases of persistent cloaca were diagnosed prenatally. Persistent cloaca should be considered in any female fetus presenting with hydronephrosis and a large cystic lesion arising from the pelvis as assessed by ultrasound and magnetic resonance imaging. Neither pulmonary hypoplasia nor severe oligohydramnios were found in any of our four cases, and they each had a good prognosis. Prenatal diagnosis allows time for parental counseling and delivery planning at a tertiary care center for neonatal intensive care and pediatric surgery.

  2. Microbiological features of KPC-producing Enterobacter isolates identified in a U.S. hospital system.

    PubMed

    Ahn, Chulsoo; Syed, Alveena; Hu, Fupin; O'Hara, Jessica A; Rivera, Jesabel I; Doi, Yohei

    2014-10-01

    Microbiological data regarding Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacter spp. are scarce. In this study, 11 unique KPC-producing Enterobacter isolates were identified among 44 ertapenem-nonsusceptible Enterobacter isolates collected between 2009 and 2013 at a hospital system in Western Pennsylvania. All cases were healthcare-associated and occurred in medically complex patients. While pulsed-field gel electrophoresis showed diverse restriction patterns overall, multilocus sequence typing identified Enterobacter cloacae isolates with sequence types 93 and 171 from 2 hospitals each. The levels of carbapenem minimum inhibitory concentrations were highly variable. All isolates remained susceptible to colistin and tigecycline, and the majority, to amikacin and doxycycline. A blaKPC-carrying IncN plasmid conferring trimethoprim-sulfamethoxazole resistance was identified in 3 of the isolates. Spread of blaKPC in Enterobacter spp. appears to be due to a combination of plasmid-mediated and clonal processes.

  3. Microbiological Features of KPC-Producing Enterobacter Isolates Identified in a U.S. Hospital System

    PubMed Central

    Ahn, Chulsoo; Syed, Alveena; Hu, Fupin; O’Hara, Jessica A.; Rivera, Jesabel I.; Doi, Yohei

    2014-01-01

    Microbiological data regarding KPC-producing Enterobacter spp. are scarce. In this study, 11 unique KPC-producing Enterobacter isolates were identified among 44 ertapenem-non-susceptible Enterobacter isolates collected between 2009 and 2013 at a hospital system in Western Pennsylvania. All cases were healthcare-associated and occurred in medically complex patients. While pulsed-field gel electrophoresis (PFGE) showed diverse restriction patterns overall, multilocus sequence typing (MLST) identified Enterobacter cloacae isolates with sequence types (STs) 93 and 171 from two hospitals each. The levels of carbapenem minimum inhibitory concentrations were highly variable. All isolates remained susceptible to colistin, tigecycline, and the majority to amikacin and doxycycline. A blaKPC-carrying IncN plasmid conferring trimethoprim-sulfamethoxazole resistance was identified in three of the isolates. Spread of blaKPC in Enterobacter spp. appears to be due to a combination of plasmid-mediated and clonal processes. PMID:25053203

  4. Aerogen Bonding Interaction: A New Supramolecular Force?

    PubMed

    Bauzá, Antonio; Frontera, Antonio

    2015-06-15

    We report evidence of the favorable noncovalent interaction between a covalently bonded atom of Group 18 (known as noble gases or aerogens) and a negative site, for example, a lone pair of a Lewis base or an anion. It involves a region of positive electrostatic potential (σ-hole), therefore it is a totally new and unexplored σ-hole-based interaction, namely aerogen bonding. We demonstrate for the first time the existence of σ-hole regions in aerogen derivatives by means of high-level ab initio calculations. In addition, several crystal structures retrieved from the Cambridge Structural Database (CSD) give reliability to the calculations. Energetically, aerogen bonds are comparable to hydrogen bonds and other σ-hole-based interactions but less directional. They are expected to be important in xenon chemistry.

  5. Molecular identification of aiiA homologous gene from endophytic Enterobacter species and in silico analysis of putative tertiary structure of AHL-lactonase.

    PubMed

    Rajesh, P S; Rai, V Ravishankar

    2014-01-03

    The aiiA homologous gene known to encode AHL- lactonase enzyme which hydrolyze the N-acylhomoserine lactone (AHL) quorum sensing signaling molecules produced by Gram negative bacteria. In this study, the degradation of AHL molecules was determined by cell-free lysate of endophytic Enterobacter species. The percentage of quorum quenching was confirmed and quantified by HPLC method (p<0.0001). Amplification and sequence BLAST analysis showed the presence of aiiA homologous gene in endophytic Enterobacter asburiae VT65, Enterobacter aerogenes VT66 and Enterobacter ludwigii VT70 strains. Sequence alignment analysis revealed the presence of two zinc binding sites, "HXHXDH" motif as well as tyrosine residue at the position 194. Based on known template available at Swiss-Model, putative tertiary structure of AHL-lactonase was constructed. The result showed that novel endophytic strains of Enterobacter genera encode the novel aiiA homologous gene and its structural importance for future study.

  6. Risk factors and treatment outcomes of bloodstream infection caused by extended-spectrum cephalosporin-resistant Enterobacter species in adults with cancer.

    PubMed

    Huh, Kyungmin; Kang, Cheol-In; Kim, Jungok; Cho, Sun Young; Ha, Young Eun; Joo, Eun-Jeong; Chung, Doo Ryeon; Lee, Nam Yong; Peck, Kyong Ran; Song, Jae-Hoon

    2014-02-01

    Treatment of Enterobacter infection is complicated due to its intrinsic resistance to cephalosporins. Medical records of 192 adults with cancer who had Enterobacter bacteremia were analyzed retrospectively to evaluate the risk factors for and the treatment outcomes in extended-spectrum cephalosporin (ESC)-resistant Enterobacter bacteremia in adults with cancer. The main outcome measure was 30-day mortality. Of the 192 patients, 53 (27.6%) had bloodstream infections caused by ESC-resistant Enterobacter species. Recent use of a third-generation cephalosporin, older age, tumor progression at last evaluation, recent surgery, and nosocomial acquisition were associated with ESC-resistant Enterobacter bacteremia. The 30-day mortality rate was significantly higher in the resistant group. Multivariate analysis showed that respiratory tract infection, tumor progression, septic shock at presentation, Enterobacter aerogenes as the culprit pathogen, and diabetes mellitus were independent risk factors for mortality. ESC resistance was significantly associated with mortality in patients with E. aerogenes bacteremia, although not in the overall patient population.

  7. Enterobacter radicincitans sp. nov., a plant growth promoting species of the family Enterobacteriaceae.

    PubMed

    Kämpfer, Peter; Ruppel, Silke; Remus, Rainer

    2005-04-01

    A plant growth promoting bacterial isolate (D5/23T) from the phyllosphere of winter wheat, able to fix atmospheric nitrogen and to produce auxines and cytokinins was investigated in a polyphasic taxonomy approach. Phylogenetic analyses using the 16S rRNA gene sequence of the strain clearly indicated that the strain belonged to the family Enterobacteriaceae, most closely related to Enterobacter cloacae with 99.0% and Enterobacter dissolvens with 98.5% sequence similarity. Phylogenetic analysis derived from the sequence of the rpoB gene showed the highest sequence similarities to Enterobacter cowanii (93.0%) but supported the distinct position of strain D5/23T. The isolate produced a fatty acid pattern typical for members of the family Enterobacteriaceae. On the basis of the phylogenetic analyses, DNA-DNA hybridizations, and the unique physiological and biochemical characteristics, we propose that strain D5/23T represents a new species of the genus Enterobacter for which we propose the name Enterobacter radicincitans sp. nov.

  8. Yersiniabactin and other siderophores produced by clinical isolates of Enterobacter spp. and Citrobacter spp.

    PubMed

    Mokracka, Joanna; Koczura, Ryszard; Kaznowski, Adam

    2004-01-15

    We analyzed the ability of extraintestinal strains of Enterobacter spp. and Citrobacter spp. to employ different siderophore-mediated strategies of iron acquisition. All strains produced iron-chelating compounds. Cross-feeding assays indicated that most isolates of both Enterobacter spp. and Citrobacter spp. excreted catecholate siderophore enterobactin, less produced aerobactin, and single strains excreted hydroxamates different from aerobactin. Besides, we analyzed if the strains had the ability to produce the siderophore yersiniabactin coded by the Yersinia high-pathogenicity island (HPI). The presence of HPI genes was observed in single isolates of three species: E. cloaceae, E. aerogenes and C. koseri. A detailed polymerase chain reaction analysis revealed differences in the genetic organization of the HPIs; however, in a cross-feeding test we proved that yersiniabactin was produced and the island was functional.

  9. Prevalence and characterization of multidrug-resistant zoonotic Enterobacter spp. in poultry of Bangladesh.

    PubMed

    Nandi, Shuvro Prokash; Sultana, Munawar; Hossain, M Anwar

    2013-05-01

    Poultry and poultry products are major contributors of zoonotic pathogens. Limited data are available on Enterobacter spp. as a potent zoonotic pathogen in poultry. The present study is a first endeavor on the emergence of multidrug-resistant zoonotic Enterobacter spp. and its prevalence arising from poultry in Bangladesh. Cloacal swabs from poultry samples of five different farms at Savar, Dhaka, Bangladesh were collected and from 106 isolates, 18 presumptive Enterobacter spp. were obtained. Antibiogram using 19 used antibiotics belonging to 15 major groups revealed that all of the 18 isolates were completely resistant to penicillin and rifampicin, but differed in their drug resistance pattern against ampicillin (94.4%), clindamycin (94.4%), erythromycin (94.4%), vancomycin (88.9%), sulfonamides (72.2%), imipenem (66.6%), streptomycin (55.6%), nitrofurantoin (33.3%), doxycycline (33.3%), tetracyclines (33.3%), cefepime (11.1%), and gentamicin (5.6%). All Enterobacter spp. were found to be plasmid free, implying that multidrug-resistant properties are chromosomal borne. The vanA and sulI were detected by polymerase chain reaction assay in 17 and 13 isolates, respectively. Amplified ribosomal DNA restriction analysis and randomly amplified polymorphic DNA distributed the 18 multidrug-resistant Enterobacter spp. into three genotypes. Phylogenetic analysis of the representatives of the three genotypes using partial 16S rRNA gene sequence (approximately 900 bp) showed that the genotypically diverse groups belonged to Enterobacter hormaechei, E. cloacae, and E. cancerogenus, respectively. The clinical significance of the close relative Enterobacter spp. is indicative of their zoonotic potential. Therefore, urgent intervention is required to limit the emergence and spread of these bacteria in poultry feed as well as prudent use of antibiotics among poultry farmers in Bangladesh.

  10. Kinetics of biological decolorisation of anthraquinone based Reactive Blue 19 using an isolated strain of Enterobacter sp.F NCIM 5545.

    PubMed

    Holkar, Chandrakant R; Pandit, Aniruddha B; Pinjari, Dipak V

    2014-12-01

    In the present study, an attempt was made to evaluate the bacterial decolorisation of Reactive Blue 19 by an Enterobacter sp.F which was isolated from a mixed culture from anaerobic digester for biogas production. Phenotypic characterization and phylogenetic analysis based on DNA sequencing comparisons indicate that Enterobacter sp.F was 99.7% similar to Enterobacter cloacae ATCC13047. The kinetics of Reactive Blue 19 dye decolorisation by bacterium had been estimated. Effects of substrate concentration, oxygen, temperature, pH, glucose and glucose to microbe weight ratio on the rate of decolorisation were investigated to understand key factor that determines the performance of dye decolorisation. The maximum decolorisation efficiency of Reactive Blue 19 was 90% over period of 24 h for optimized parameter. To the best of our knowledge, this research study is the report where Enterobacter sp.F has been reported with about 90% decolorizing ability against anthraquinone based Reactive Blue 19 dye.

  11. π-Hole aerogen bonding interactions.

    PubMed

    Bauzá, Antonio; Frontera, Antonio

    2015-10-14

    In this manuscript we combine high level ab initio calculations (RI-MP2/aug-cc-pVTZ) and the analysis of several crystal structures to demonstrate the existence of π-hole aerogen bonding interactions in Xe(iv) compounds. The ability of XeF4 and Xe(OMe)4 to interact with electron rich molecules is rationalized using several computational tools, including molecular electrostatic potential surfaces, energetic and geometric features of the complexes and "atoms in molecules" (AIM) and Natural Bond Orbital (NBO) analyses. We have found support for the π-hole interaction involving the xenon atom from the solid state architecture of several X-ray structures retrieved from the crystal structural depot. Particularly, π-hole aerogen bonding interactions are quite common in the solid state of Xe(IV) compounds.

  12. Whole genome sequence of Enterobacter ludwigii type strain EN-119T, isolated from clinical specimens.

    PubMed

    Li, Gengmi; Hu, Zonghai; Zeng, Ping; Zhu, Bing; Wu, Lijuan

    2015-04-01

    Enterobacter ludwigii strain EN-119(T) is the type strain of E. ludwigii, which belongs to the E. cloacae complex (Ecc). This strain was first reported and nominated in 2005 and later been found in many hospitals. In this paper, the whole genome sequencing of this strain was carried out. The total genome size of EN-119(T) is 4952,770 bp with 4578 coding sequences, 88 tRNAs and 10 rRNAs. The genome sequence of EN-119(T) is the first whole genome sequence of E. ludwigii, which will further our understanding of Ecc.

  13. Subpubic sinus: a remnant of cloaca.

    PubMed

    Chou, T D; Chu, C C; Diau, G Y; Chiang, J H

    1995-05-01

    A 14-month-old girl had purulent discharge from a sinus over the subpubic region for 2 weeks. Radiography and voiding cystourethrography revealed a 4.5 cm. long fistula extending to the retropubic region without any connection to the lower urinary tract. The fistula was excised. Histological findings revealed that the fistula had 3 different types of epithelium: stratified squamous, transitional and columnar. Clinical and pathological findings indicated that the sinus was most likely a remnant of the cloaca.

  14. Sequence and properties of pentaerythritol tetranitrate reductase from Enterobacter cloacae PB2.

    PubMed

    French, C E; Nicklin, S; Bruce, N C

    1996-11-01

    Pentaerythritol tetranitrate reductase, which reductively liberates nitrite from nitrate esters, is related to old yellow enzyme. Pentaerythritol tetranitrate reductase follows a ping-pong mechanism with competitive substrate inhibition by NADPH, is strongly inhibited by steroids, and is capable of reducing the unsaturated bond of 2-cyclohexen-1-one.

  15. Effect of Hydrazines on Substrate Utilization by a Strain of Enterobacter Cloacae

    DTIC Science & Technology

    1983-01-01

    response of bacterial systems to hydrazines. LONDON (1979) showed the toxicity of hydrazine (Hz), monomethylhydrazine (MMH), and 1 ,l- dimethylhydrazine ...hydrazine; M, monomethyl- hydrazine; and U, 1,1- dimethylhydrazine Hz-adapted cultures are presented in this manner (TABLES 1 and 2). The responses of D-31...adapted cells was obtained by *This article is also published as AFAMRL-TI-2-0011. 83 4 1 0404 growing D-31 in SMS plus glucose containing 10 ppm (p1

  16. Group IIC Intron with an Unusual Target of Integration in Enterobacter cloacae

    PubMed Central

    Rodríguez-Martínez, José-Manuel; Poirel, Laurent

    2012-01-01

    A potential role of group IIC-attC introns in integron gene cassette formation, that is, the way in which they could provide the attC sequence essential for recombination, has been proposed. Group IIC introns usually target the attC site of gene cassettes and more specifically their inverse core. Here we characterized a novel group IIC intron targeting the core site of the aadA1 gene cassette attC site (aadA1-qacEΔ1 gene cassette junction) from enterobacterial isolates. Intron mobility (retrohoming) was analyzed using a two-plasmid assay performed in Escherichia coli. Intron mobility assays confirmed the mobilization-integration of the group II intron into the core site of the aadA2, blaVIM-2, blaCARB-2, aac(6′)-Ib, dfrXVb, arr2, cmlA4, and aadB gene cassettes but not into the attI site. This mobility was dependent on maturase activity. Reverse transcriptase PCR showed that this intron was transcriptionally active, and an intermediate circular form was detected by inverse PCR. This element was linked to the blaVEB-1 extended-spectrum β-lactamase gene in a high number of enterobacterial isolates. A phylogenetic tree showed that the identified element was located in a branch separate from group IIC-attC introns, being an IIC intron possessing the ability to integrate using the core site of the attC sites as target. PMID:22020643

  17. Influence of host seed on metabolic activity by Enterobacter cloacae in the spermosphere

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little is known regarding the influences of nutrients released from plants on the metabolic activity of colonizing microbes. To gain a better understanding of these influences, we used bioluminescence- and oxygen consumption-based methods to compare bacterial metabolic activity expressed during col...

  18. Effects of selected hydrazines on the early death rates of Enterobacter cloacae

    SciTech Connect

    London, S.A.; Mantel, C.R.; Robinson, J.D.; Luking, S.

    1983-09-01

    The toxicity of hydrazine and several of its methylated derivatives has been studied in a variety of biological systems. The measurements used in these studies were concerned with growth kinetics, i.e., time and concentration parameters describing the growth cycle of bacteria. This method provided useful information but was not sufficiently sensitive at the extremes of cell culture density. Since the major indication of intoxication at the test concentrations used (10 ppm hydrazine (HZ); 20 ppm monomethylhydrazine (MMH); and 50 ppm 1,1-dimethylhydrazine (UDMH)) was an extension of the lag period, a possible mechanism of action is a random or selective killing of inoculum cells. Since experiments based on turbidimetric data can not address this aspect, the authors studied the early death rate kinetics of hydrazine-exposed cultures using a standard viable cell counting procedure as a more reliable quantitative method to enumerate cell death rate at low culture concentrations.

  19. Spondylodiscitis Caused by Enterobacter agglomerans

    PubMed Central

    Kothalawala, Mahen; Devakanthan, Balachandran; Arunan, Sinnappoo; Galgamuwa, Dinithi; Rathnayake, Manori

    2016-01-01

    All over the globe, the incidence of vertebral infection is rising. Nowadays, compared to tuberculous variety, pyogenic spondylodiscitis incidence is high. The increase in the susceptible population and improved diagnostics summatively contributed to this. In clinical grounds, differentiation of pyogenic and tuberculous spondylodiscitis is well defined. Enterobacter agglomerans is a hospital contaminant and associated with infections in immunocompromised individuals and intravenous lines. It causes a wide array of infections. Enterobacter agglomerans spondylodiscitis is unusual and there are, around the globe, only less than 31 suspected cases that have been previously reported. Enterobacter agglomerans histology mimics tuberculous rather than pyogenic spondylodiscitis. A 65-year-old farming lady, while being in hospital, developed sudden onset spastic paraparesis with hyperreflexia. Later blood culture revealed Enterobacter agglomerans with 41-hour incubation in 99.9% probability from Ramel identification system. Her initial ESR was 120 mm/first hour. Isolate was susceptible to ciprofloxacin and intravenous followed with oral therapy shows a drastic ESR fall and improved clinical response. Differentiation of tuberculous and pyogenic spondylodiscitis is very much important in management point of view. Therefore, blood culture has a role in diagnosis of spondylodiscitis. ESR can be used as important inflammatory marker in monitoring the response to treatment. Retrospectively, ESR would aid in reaching a definitive diagnosis. PMID:28127480

  20. Partial hydrolysis of dieldrin by Aerobacter aerogenes

    USGS Publications Warehouse

    Wedemeyer, Gary

    1968-01-01

    Although dieldrin (1,2,3,4,10,10-hexachloro- 6,7-epoxy-1 ,4 ,4a ,5 ,6 ,7 ,8, 8a-octahydro-1 ,4-endo, exo-5, 8-dimethanonaphthalene) metabolism by mammals (F. Korte and H. Arent, Life Sci. 4:2017, 1965) and insects (D. F. Heath and M. Vanderkar, Brit. J. Ind. Med. 21:269, 1964) has been reported, little is known about the degradation of this important pesticide by microorganisms. Korte et al. (Ann. Chem. Liebigs 656:135, 1962) and Chacko et al. (Science 154: 893, 1966) reported that a number of ubiquitous microorganisms were incapable of degrading dieldrin; however, more recently Matsumura and Boush (Science 156:959, 1967) isolated several species of Pseudomonas and Bacillus which could degrade dieldrin, from a number of soil samples having similar activity. They did not specifically attempt to identify the dieldrin metabolites formed, but they did suggest, on the basis of an identical RF value with an authentic control that 6,7-trans-dihydroxydihydroaldrin (aldrin diol) might be a major product. Work carried out concurrently in this laboratory has shown that another ubiquitous bacterium, Aerobacter aerogenes, converts dieldrin in vitro to a compound chromatographically similar to 6,7-trans-dihydroxydihydroaldrin.

  1. Partial hydrolysis of dieldrin by Aerobacter aerogenes

    USGS Publications Warehouse

    Wedemeyer, G.

    1968-01-01

    Although dieldrin (1,2,3 ,4,10,10-hexachloro- 6,7-epoxy-1 ,4 ,4a ,5 ,6 ,7 ,8, 8a-octahydro-1 ,4-endo, exo-5, 8-dimethanonaphthalene) metabolism by mammals (F. Korte and H. Arent, Life Sci. 4:2017, 1965) and insects (D. F. Heath and M. Vanderkar, Brit. J. Ind. Med. 21:269, 1964) has been reported, little is known about the degradation of this important pesticide by microorganisms. Korte et al. (Ann. Chem. Liebigs 656:135, 1962) and Chacko et al. (Science 154: 893, 1966) reported that a number of ubiquitous microorganisms were incapable of degrading dieldrin; however, more recently Matsumura and Boush (Science 156:959, 1967) isolated several species of Pseudomonas and Bacillus which could degrade dieldrin, from a number of soil samples having similar activity. They did not specifically attempt to identify the dieldrin metabolites formed, but they did suggest, on the basis of an identical RF value with an authentic control that 6,7-trans-dihydroxydihydroaldrin (aldrin diol) might be a major product. Work carried out concurrently in this laboratory has shown that another ubiquitous bacterium, Aerobacter aerogenes, converts dieldrin in vitro to a compound chromatographically

  2. An ab initio study on anionic aerogen bonds

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Mohammadian-Sabet, Fariba

    2017-01-01

    An ab initio study is carried out to investigate the anionic aerogen bonds in complexes of KrO3, XeO3 and XeOF2 with F-, Cl-, Br-, CN-, NC-, N3-, SH-, SCN-, NCS-, OH- and OCH3- anions. All of the anionic aerogen bonds analyzed here have a partial covalent character. Charge transfer from the anion to the Kr-O or Xe-O σ∗ orbital stabilizes these complexes and leads to a sizable redshift in the corresponding stretching frequencies. The J(Kr-O) or J(Xe-O) spin-spin coupling constants can be regarded as a useful tool for the characterization of strength of the anionic aerogen-bonded complexes.

  3. Enterobacter soli sp. nov.: a lignin-degrading γ-proteobacteria isolated from soil.

    PubMed

    Manter, Daniel K; Hunter, William J; Vivanco, Jorge M

    2011-03-01

    A Gram-negative bacterium that formed cream-colored colonies designated strain LF7 was isolated from soil collected in the Tambopata National Reserve in Madre de Dios, Peru. 16S rRNA sequence comparisons indicate that LF7 is a novel Enterobacter sp. closely related to E. asburiae JCM 6051(T) [AB004744] and E. aerogenes JCM 1235(T) [AB004750] based on their sequence homologies (p-distance: 1.06 and 1.19%, respectively). DNA G + C content was 52.8 mol% which is within the range reported for E. asburiae (55-57 mol%). The major cellular fatty acids present in the LF7 strain were C(16:0) (27.3%), C(16:1) ω7c and/or C(16:1) ω6c (16.3%), C(18:1) ω7c (16.1%), C(17:0) cyclo (12.4%), C(14:0) 3-OH and/or C(16:1) iso-I (8.9%), C(14:0) (7.6%), C(12:0) (3.9%), C(17:0) (2.4%), C(13:0) 3-OH and/or C(15:1) iso-H (1.7%), C(13:0) (1.1%), and C(18:2) ω6,9c and/or C(18:0) ante (0.5%). The cellular fatty acid profile, G + C content, phenotypic and biochemical characteristics were consistent with its placement in the genus Enterobacter. The name Enterobacter soli is proposed for this bacterium.

  4. Study of bio-degradation and bio-decolourization of azo dye by Enterobacter sp. SXCR.

    PubMed

    Prasad, Shiv Shankar; Aikat, Kaustav

    2014-01-01

    The objective of this study was to evaluate the decolourization potential of textile dyes by a relatively newly identified bacteria species, Enterobacter sp. SXCR which was isolated from the petroleum polluted soil samples. The bacterial strain was identified by 16S rRNA gene sequence analysis. The effects of operational conditions like initial dye concentration, pH, and temperature were optimized to develop an economically feasible decolourization process. The isolate was able to decolourize sulphonated azo dye (Congo red) over a wide range (0.1-1 gl(-1)), pH 5-9, and temperature 22-40 degrees C in static condition. Anaerobic condition with minimal salt medium supplemented with 2 gl(-1) glucose, pH 7 and 34 degrees C were considered to be the optimum decolourizing condition. The bacterial isolate SXCR showed a strong ability to decolourize dye (0.2 gl(-1)) within 93 h. The biodegradation was monitored by UV-vis, fourier transform infra-red spectroscopy (FTIR) spectroscopy and high performance liquid chromatography (HPLC). Furthermore, the involvement of azoreductase in the decolourization process was identified in this strain. Cells of Enterobacter cloacae were immobilized by entrapment in calcium-alginate beads. Immobilized bacterial cells were able to reduced azo bonds enzymatically and used as a biocatalyst for decolourization of azo dye Congo red. Michaelis-Menten kinetics was used to describe the correlation between the decolourization rate and the dye concentration.

  5. Enterobacter Strains Might Promote Colon Cancer.

    PubMed

    Yurdakul, Dilşad; Yazgan-Karataş, Ayten; Şahin, Fikrettin

    2015-09-01

    Many studies have been performed to determine the interaction between bacterial species and cancer. However, there has been no attempts to demonstrate a possible relationship between Enterobacter spp. and colon cancer so far. Therefore, in the present study, it is aimed to investigate the effects of Enterobacter strains on colon cancer. Bacterial proteins were isolated from 11 Enterobacter spp., one Morganella morganii, and one Escherichia coli strains, and applied onto NCM460 (Incell) and CRL1790 (ATCC) cell lines. Cell viability and proliferation were determined in MTS assay. Flow Cytometry was used to detect CD24 level and apoptosis. Real-Time PCR studies were performed to determine NFKB and Bcl2 expression. Graphpad Software was used for statistical analysis. The results showed that proteins, isolated from the Enterobacter spp., have significantly increased cell viability and proliferation, while decreasing the apoptosis of the cell lines tested. The data in the present study indicated that Enterobacter strains might promote colon cancer. Moreover, Enterobacter spp. could be a clinically important factor for colon cancer initiation and progression. Studies can be extended on animal models in order to develop new strategies for treatment.

  6. Single-electron aerogen bonds: Do they exist?

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Mohammadian-Sabet, Fariba; Solimannejad, Mohammad

    2016-08-01

    A novel type of σ-hole interaction is characterized between some noble gas containing molecules (KrOF2, KrO3, XeOF2 and XeO3) and methyl (CH3) or ethyl (C2H5) radical by means of ab initio calculations. This interaction is named as single-electron aerogen bond (SEAB), in view of the concepts of aerogen bond and single-electron bond interactions. The properties of SEABs are studied by molecular electrostatic potential, quantum theory of atom in molecules, natural bonding orbital and noncovalent interaction index analyses. The formation of an O⋯H interaction tends to increase the strength of the SEAB, when they coexist in a ternary complex.

  7. Pre-Clinical Testing of a Real-Time PCR Assay for Diahhreal Disease Agent Cryptosporidium

    DTIC Science & Technology

    2014-05-16

    tests on freeze-dried Shigella ipaH, enterotoxigenic E . coli (ETEC) ST1b, ETEC LT, ETEC ST1a, Cryptosporidium, and Leptospira (Idaho Technologies, Salt...Citrobacter freundii 1 Negative EHEC 1 Negative Enterobacter aerogenes 1 Negative Enterobacter cloacae 1 Negative Enterotoxigenic E . coli (ETEC...2 Negative Enteroinvasive E . coli (EIEC) 1 Negative Escherichia coli 1 Negative K. pneumoniae 1 Negative P. aeruginosa 1 Negative Proteus

  8. Analysis of Anaerobic Blood Cultures in Burned Patients

    DTIC Science & Technology

    2007-01-01

    34 3 (9.0) Escherichia coli 14 (4.1) 17 (2.8) – – Enterobacter cloacae 13 (3.8) 24 (3.9) 18 2 (11.1) Enterobacter aerogenes 13 (3.8) 18 (2.9...cultures: patient characteristics and potential risk factors. Clin Chem Lab Med 2003;41(3):293–7. [10] James PA, Al-Shafi KM. Clinical value of anaerobic

  9. Deep Ultraviolet Laser Diode for UV-Resonance Enhanced Raman Identification of Biological Agents

    DTIC Science & Technology

    2007-03-31

    8217 - 2 9 Enterobacter aerogenes 5.a - 1 10 Alcaligenes faecalis 54.8a - 1 11I Enterobacter cloacae 55.48 - 1 12 Aeromonas hydraphila 55.7a - I___...beam characteristics for the electron gun. The cathode will then be quite sensitive to moisture and atmospheric gas contamination, and may require...regeneration after it is installed in other vacuum systems. It would be most desirable to avoid this. If the e-guns have reasonably similar characteristics

  10. Biochemical parameters of glutamine synthetase from Klebsiella aerogenes.

    PubMed Central

    Bender, R A; Janssen, K A; Resnick, A D; Blumenberg, M; Foor, F; Magasanik, B

    1977-01-01

    The glutamine synthetase (GS) from Klebsiella aerogenes is similar to that from Escherichia coli in several respects: (i) it is repressed by high levels of ammonia in the growth medium; (ii) its biosynthetic activity is greatly reduced by adenylylation; and (iii) adenylylation lowers the pH optimum and alters the response of the enzymes to various inhibitors in the gamma-glutamyl transferase (gammaGT) assay. There are, however, several important differences: (i) the isoactivity point for the adenylylated and non-adenylylated forms in the gammaGT assay occurs at pH 7.55 in K. aerogenes and at pH 7.15 in E. coli; (ii) the non-adenylylated form of the GS from K. aerogenes is stimulated by 60 mM MgCl2 in the gammaGT assay at pH 7.15. A biosynthetic reaction assay that correlates well with number of non-adenylylated enzyme subunits, as determined by the method of Mg2+ inhibition of the gammaGT assay, is described. Finally, we have found that it is necessary to use special methods to harvest growing cells to prevent changes in the adenylylation state of GS from occurring during harvesting. PMID:14104

  11. Molecular Analysis of Tetracycline Resistance in Pasteurella aerogenes

    PubMed Central

    Kehrenberg, Corinna; Schwarz, Stefan

    2001-01-01

    Tetracycline-resistant Pasteurella aerogenes isolates obtained from the intestinal tract of swine were investigated for their tet genes by PCR analysis and hybridization experiments. In contrast to Pasteurella isolates from the respiratory tract, tet(H) genes were detected in the chromosomal DNA of only 2 of the 24 isolates, one of which also carried two copies of a tet(B) gene. All other P. aerogenes isolates carried tet(B) genes, which are the predominant tet genes among Enterobacteriaceae. A single isolate harbored a tet(B) gene as part of a truncated Tn10 element on the 4.8-kb plasmid pPAT2. Comparative analysis of the pPAT2 sequence suggested that the Tn10 relic on plasmid pPAT2 is the result of several illegitimate recombination events. The remaining 21 P. aerogenes isolates carried one or two copies of the tet(B) gene in their chromosomal DNA. In the majority of the cases, these tet(B) genes were associated with copies of Tn10 as confirmed by their SfuI and BamHI hybridization patterns. No correlation between the number of tet gene copies and the MICs of tetracycline, doxycyline and minocycline was observed. PMID:11557485

  12. Chemical Kinetic and Molecular Genetic Study of Selenium Oxyanion Reduction by Enterobactor cloacae SLD1a-1

    SciTech Connect

    Ma,J.; Kobayashi, D.; Yee, N.

    2007-01-01

    Microbial processes play an important role in the redox transformations of toxic selenium oxyanions. In this study, we employed chemical kinetic and molecular genetic techniques to investigate the mechanisms of Se(IV) and Se(VI) reduction by the facultative anaerobe Enterobacter cloacae SLD1a-1. The rates of microbial selenium oxyanion reduction were measured as a function of initial selenium oxyanion concentration (0-1.0 mM) and temperature (10-40 C), and mutagenesis studies were performed to identify the genes involved in the selenium oxyanion reduction pathway. The results indicate that Se(IV) reduction is significantly more rapid than the reduction of Se(VI). The kinetics of the reduction reactions were successfully quantified using the Michaelis-Menten kinetic equation. Both the rates of Se(VI) and Se(IV) reduction displayed strong temperature-dependence with Ea values of 121 and 71.2 kJ/mol, respectively. X-ray absorption near-edge spectra collected for the precipitates formed by Se(VI) and Se(IV) reduction confirmed the formation of Se(0). A miniTn5 transposon mutant of E. cloacae SLD1a-1 was isolated that had lost the ability to reduce Se(VI) but was not affected in Se(IV) reduction activity. Nucleotide sequence analysis revealed the transposon was inserted within a tatC gene, which encodes for a central protein in the twin arginine translocation system. Complementation by the wild-type tatC sequence restored the ability of mutant strains to reduce Se(VI). The results suggest that Se(VI) reduction activity is dependent on enzyme export across the cytoplasmic membrane and that reduction of Se(VI) and Se(IV) are catalyzed by different enzymatic systems.

  13. Quinazoline derivatives are efficient chemosensitizers of antibiotic activity in Enterobacter aerogenes, Klebsiella pneumoniae and Pseudomonas aeruginosa resistant strains.

    PubMed

    Chevalier, Jacqueline; Mahamoud, Abdallah; Baitiche, Milad; Adam, Elissavet; Viveiros, Miguel; Smarandache, Adriana; Militaru, Andra; Pascu, Mihail L; Amaral, Leonard; Pagès, Jean-Marie

    2010-08-01

    Amongst the three series of quinazoline derivatives synthesised and studied in this work, some molecules increase the antibiotic susceptibility of Gram-negative bacteria presenting multidrug-resistant phenotypes. N-alkyl compounds induced an increase in the activity of chloramphenicol, nalidixic acid and sparfloxacin, which are substrates of the AcrAB-TolC and MexAB-OprM efflux pumps in clinical isolates. These molecules are able to increase the intracellular concentration of chloramphenicol in efflux pump-overproducing strains. Their activity depends on the antibiotic structure, suggesting that different sites may be involved for the recognition of substrates by a given efflux pump. Quinazoline molecules exhibiting a nitro functional group are more active, and structure-activity relationship studies may be undertaken to identify the pharmacophoric group involved in the AcrB and MexB affinity sites.

  14. [Isolation and characterization of injured coliforms from the drinking water distribution network of La Plata, Argentina].

    PubMed

    Basualdo, J A; Córdoba, M A; De Luca, M M; Roccia, I L; Pezzani, B C; Vay, C; Ageron, E; Grimont, P A

    2001-01-01

    We screened the La Plata drinking water distribution network for fecal and total coliform bacterial indicator by purification procedures, cultivating 66 membrane-filtered samples from the two networks on m-T7 agar. Subterranean and river-derived water yielded 13 and 18 confirmed gram-negative bacillus isolates, with 54% and 72% representing total coliforms, respectively. Those from the former source were Klebsiella oxytoca, Enterobacter agglomerans, and Enterobacter aerogenes and from the latter Klebsiella oxytoca, Enterobacter agglomerans, and Enterobacter cloacae, genomic group 3. Since 58% of the samples were positive using m-T7 medium it is suggested that the inclusion in standard quality control protocols should be implemented.

  15. Molecular epidemiological survey of Citrobacter freundii misidentified as Cronobacter spp. (Enterobacter sakazakii) and Enterobacter hormaechei isolated from powdered infant milk formula.

    PubMed

    Giammanco, Giovanni M; Aleo, Aurora; Guida, Ivana; Mammina, Caterina

    2011-04-01

    A total of 75 powdered infant milk formula (PIF) samples collected from pharmacies and drugstores in Western Sicily, Italy, and representative of 12 different brands were analyzed in this study to evaluate their microbiological quality. According to the U.S. Food and Drug Administration protocol, 32 samples out of 75 were contaminated by enterobacteria. Commercial biochemical API(r) 20E-system identification method indicated that six PIF samples were presumptively contaminated by Cronobacter spp., but further characterization by alpha-glucosidase based polymerase chain reaction (PCR) assay identification strongly suggested that these strains did not belong to the genus Cronobacter. Phylogenetic analysis of partial 16S rRNA (rrs) sequences combined with the results of biochemical tests allowed to identify the six strains as Citrobacter freundii. Similarly, rrs sequence analysis identified as Enterobacter hormaechei 23 strains originally ascribed to Enterobacter cloacae by the API 20E system. Characterization of C. freundii and E. hormaechei PIF isolates by the DiversiLab(r) repetitive sequence-based PCR (rep-PCR) typing method revealed a variety of amplification patterns, but the recovery of the same rep-PCR genotype in several products might indicate a special adaptation of genetic clones to this food or cross-contamination through common ingredients. Antibiotic-resistance profiles were also determined, but none of the strains tested was resistant to third-generation cephalosporins or fluoroquinolones and extended-spectrum beta-lactamase activity was not detected. Our results confirm that E. hormaechei contamination of PIF is widespread, thus making it a cause for concern. Similarly to what was demonstrated for E. hormaechei, we suggest that C. freundii also may be an under-reported cause of bacterial infection, especially in high-risk neonates, due to misidentification.

  16. The TyrR Transcription Factor Regulates the Divergent akr-ipdC Operons of Enterobacter cloacae UW5

    PubMed Central

    Coulson, Thomas J. D.; Patten, Cheryl L.

    2015-01-01

    The TyrR transcription factor regulates genes involved in the uptake and biosynthesis of aromatic amino acids in Enterobacteriaceae. Genes may be positively or negatively regulated depending on the presence or absence of each aromatic amino acid, all three of which function as cofactors for TyrR. In this report we detail the transcriptional control of two divergently transcribed genes, akr and ipdC, by TyrR, elucidated by promoter fusion expression assays and electrophoretic mobility shift assays to assess protein-DNA interactions. Expression of both genes was shown to be controlled by TyrR via interactions with two TyrR boxes located within the akr-ipdC intergenic region. Expression of ipdC required TyrR bound to the proximal strong box, and is strongly induced by phenylalanine, and to a lesser extent by tryptophan and tyrosine. Down-regulation of akr was reliant on interactions with the weak box, and may also require a second, as yet unidentified protein for further repression. Tyrosine enhanced repression of akr. Electrophoretic mobility shift assays demonstrated that TyrR interacts with both the strong and weak boxes, and that binding of the weak box in vitro requires an intact adjacent strong box. While the strong box shows a high degree of conservation with the TyrR binding site consensus sequence, the weak box has atypical spacing of the two half sites comprising the palindromic arms. Site-directed mutagenesis demonstrated sequence-specific interaction between TyrR and the weak box. This is the first report of TyrR-controlled expression of two divergent protein-coding genes, transcribed from independent promoters. Moreover, the identification of a predicted aldo-keto reductase as a member of the TyrR regulon further extends the function of the TyrR regulon. PMID:25811953

  17. Pneumonia due to Enterobacter cancerogenus infection.

    PubMed

    Demir, Tülin; Baran, Gamze; Buyukguclu, Tuncay; Sezgin, Fikriye Milletli; Kaymaz, Haci

    2014-11-01

    Enterobacter cancerogenus (formerly known as CDC Enteric Group 19; synonym with Enterobacter taylorae) has rarely been associated with human infections, and little is known regarding the epidemiology and clinical significance of this organism. We describe a community-acquired pneumonia case in a 44-year-old female due to E. cancerogenus. Identification and antimicrobial susceptibility of the microorganism was performed by the automatized VITEK 2 Compact system (bioMerieux, France). The clinical case suggests that E. cancerogenus is a potentially pathogenic microorganism in determined circumstances; underlying diseases such as bronchial asthma, empiric antibiotic treatment, wounds, diagnostic, or therapeutic instruments.

  18. Spore germination promoter of Dictyostelium discoideum excreted by Aerobacter aerogenes.

    PubMed

    Hashimoto, Y; Tanaka, Y; Yamada, T

    1976-07-01

    The nutrient medium in which Aerobacter aerogenes was grown, contains a spore germination promoter (SGP) for the cellular slime mould Dictyostelium discoideum. SGP can cuase synchronous spore germination in a short time, and triggers the germination process in just a few minutes. Germination-promoting capacity of SGP decreases as it comes in contact with increasing number of spores. When spores activated by SGP are stored at 4 degrees C, they gradually return to the dormant state. SGP is comparatively heat-stable, but is unstable at pH above 10 or under 3.

  19. Thermobacteriological characterization of Enterobacter sakazakii.

    PubMed

    Arroyo, C; Condón, S; Pagán, R

    2009-11-30

    In the present study the influence of various environmental and physiological factors on the heat resistance of Enterobacter sakazakii (Cronobacter) have been investigated. Our results demonstrated that the heat resistance of E. sakazakii depended on the strain studied, the growth conditions - phase and temperature - the characteristics of treatment medium and the recovery conditions. The strain STCC 858 (ATCC type strain 29544) showed maximum heat resistance among the strains tested and it was selected for the further study. Stationary-phase cells grown between 20 and 37 degrees C (mean D(60)=0.9 min) resulted to be more resistant than cells grown at 10 degrees C (D(60)=0.2 min). Resistance decreased when the treatment medium pH was lower than pH 6.0, and it increased with decreasing water activity of the treatment medium, with a 32-fold increase in resistance when lowering water activity to 0.96. z value at pH 4.0 (z=4.79 degrees C) was significantly higher than at pH 7.0 (z=4.06 degrees C), although E. sakazakii cells were approximately 10 times more heat resistant at pH 7.0 than at pH 4.0 within the range of temperatures tested. Contrary to pH, the magnitude of the influence of a(w) on heat resistance did not significantly change with treatment temperature. The proportion of sublethally damaged cells was similar regardless of the treatment medium pH, but it decreased when lowering the water activity. Nevertheless, increasing treatment temperature would not result in a decreased proportion of sublethally injured E. sakazakii cells within the surviving population. Thus, the design of a theoretical combined process that could take advantage of the occurrence of sublethally injured cells would be similarly effective at low and high temperatures. E. sakazakii proved to be more heat resistant in four different liquid food matrixes than in buffers at the same pH, and this disagreement was especially higher in orange juice, which resulted to be the product that induced

  20. Enterobacter turicensis sp. nov. and Enterobacter helveticus sp. nov., isolated from fruit powder.

    PubMed

    Stephan, Roger; Van Trappen, Stefanie; Cleenwerck, Ilse; Vancanneyt, Marc; De Vos, Paul; Lehner, Angelika

    2007-04-01

    Four Gram-negative, facultatively anaerobic, non-spore-forming isolates of coccoid rods were obtained from fruit powder and investigated in a polyphasic taxonomic study. Comparative 16S rRNA gene sequence analysis allocated the isolates to the family Enterobacteriaceae. Their phylogenetic position within the family Enterobacteriaceae was confirmed by rpoB sequence analysis and as the highest rpoB sequence similarities were obtained with Enterobacter radicincitans, Enterobacter cowanii and Enterobacter sakazakii, the isolates clearly belong to the genus Enterobacter. Biochemical data revealed that the isolates can be separated into two distinct groups that represent two novel species, as confirmed by DNA-DNA hybridizations. The two novel species can be differentiated from their nearest neighbours by the following characteristics: the utilization of sucrose, D-sorbitol, putrescine and mucate, the hydrolysis of aesculin and a negative result in the Voges-Proskauer reaction. It is therefore proposed that these novel isolates are classified as Enterobacter turicensis sp. nov. (type strain 508/05(T)=LMG 23730(T)=DSM 18397(T)) and Enterobacter helveticus sp. nov. (type strain 513/05(T)=LMG 23732(T)=DSM 18396(T)).

  1. Purification and characterization of a GH43 β-xylosidase from Enterobacter sp. identified and cloned from forest soil bacteria.

    PubMed

    Campos, Eleonora; Negro Alvarez, María José; Sabarís di Lorenzo, Gonzalo; Gonzalez, Sergio; Rorig, Marcela; Talia, Paola; Grasso, Daniel H; Sáez, Felicia; Manzanares Secades, Paloma; Ballesteros Perdices, Mercedes; Cataldi, Angel A

    2014-01-01

    The use of lignocellulosic biomass for second generation biofuels requires optimization of enzymatic breakdown of plant cell walls. In this work, cellulolytic bacteria were isolated from a native and two cultivated forest soil samples. Amplification of glycosyl hydrolases was attempted by using a low stringency-degenerate primer PCR strategy, using total soil DNA and bulk DNA pooled from positive colonies as template. A set of primers was designed based on Acidothermus cellulolyticus genome, by search of conserved domains of glycosyl hydrolases (GH) families of interest. Using this approach, a fragment containing an open reading frame (ORF) with 98% identity to a putative GH43 beta-xylosidase coding gene from Enterobacter cloacae was amplified and cloned. The full protein was expressed in Escherichia coli as N-terminal or C-terminal His-tagged fusions and purified under native conditions. Only N-terminal fusion protein, His-Xyl43, presented beta-xylosidase activity. On pNPX, optimal activity was achieved at pH 6 and 40 °C and Km and Kcat values were 2.92 mM and 1.32 seg(-1), respectively. Activity was also demonstrated on xylobiose (X2), with Km 17.8 mM and Kcat 380 s(-1). These results demonstrated that Xyl43 is a functional beta-xylosidase and it is the first evidence of this activity for Enterobacter sp.

  2. Klebsiella and Enterobacter organisms isolated from horses.

    PubMed

    Platt, H; Atherton, J G; Orskov, I

    1976-12-01

    An account is given of K. pneumoniae capsule types occurring in horses, with particular reference to strains originating from the genital tract in the mare and the external genitalia of the stallion. A survey of the prevalence of K. pneumoniae and E. aerogenes strains in the preputial flora of healthy stallions is described. The majority of horses were found to be carriers of these organisms. The cultural characteristics of these preputial strains are described and compared with those of K. pneumoniae strains associated with epidemic metritis in mares. The epidemiological significance of certain K. pneumoniae capsule types is discussed.

  3. Enterobacter Meningitis and Challenges in Treatment

    PubMed Central

    Noor, Jawad; Yegneswaran, Balaji; Kodali, Hanish

    2016-01-01

    Neurosurgical interventions are rarely associated with meningitis with a very low incidence rate ranging from 1.1% to 2.5%. Gram negative bacillary meningitis first described in the 1940’s, previously uncommon has been increasing in the recent past associated with advanced age, immunosuppression and neurosurgery. Enterobacter meningitis though relatively uncommon is recently increasing in incidence and treatment is frequently complicated due to resistance to antibiotics making this a challenging, difficult to treat infection that may be associated with adverse clinical outcomes. Here, we describe a case of a 27-year-old patient diagnosed with brain sarcoma at the age of four years, who presented with Enterobacter meningitis following a neurosurgical intervention for resection of a recurrent brain tumor (meningioma on pathology) and had a prolonged hospital stay with a difficult to treat infection. PMID:28208914

  4. d-Apiose Reductase from Aerobacter aerogenes1

    PubMed Central

    Neal, Donna L.; Kindel, Paul K.

    1970-01-01

    A strain of Aerobacter aerogenes PRL-R3 has been isolated which utilizes d-apiose as its sole source of carbon. A new enzyme, d-apiose reductase, was discovered in this strain. The enzyme was not present when the strain was grown on d-glucose. d-Apiose reductase catalyzes the nicotinamide adenine dinucleotide-dependent interconversion of d-apiose and d-apiitol. The enzyme is specific for d-apiose and d-apiitol, with a few possible exceptions. The Km for d-apiose is 0.02 m. The Km for d-apiitol is 0.01 m. The enzyme is almost completely specific for the reduced and oxidized forms of nicotinamide adenine dinucleotide. When cell-free extracts were centrifuged at 100,000 × g for 1 hr, the enzyme remained in solution. Optimal activity for the reduction of d-apiose was obtained at pH 7.5 in glycylglycine buffer, whereas for the oxidation of d-apiitol it was obtained at pH 10.5 in glycine buffer. Enzymatic reduction of d-apiose was not appreciably affected by the presence of 0.02 m ethylenediaminetetraacetate. Paper chromatography and specific spray reagents were used to identify d-apiitol and d-apiose as the products of this reversible reaction. d-Apiose and d-apiitol did not serve as substrates for ribitol dehydrogenase and d-arabitol dehydrogenase from A. aerogenes PRL-R3. PMID:4314545

  5. Outbreak of a novel Enterobacter sp. carrying blaCTX-M-15 in a neonatal unit of a tertiary care hospital in Tanzania.

    PubMed

    Mshana, Stephen E; Gerwing, Lisa; Minde, Mercy; Hain, Torsten; Domann, Eugen; Lyamuya, Eligius; Chakraborty, Trinad; Imirzalioglu, Can

    2011-09-01

    Enterobacter hormaechei and Cronobacter sakazakii are amongst the most important causes of outbreaks of neonatal sepsis associated with powdered milk. In this study, we report for the first time an outbreak of a novel Enterobacter sp. harbouring bla(CTX-M-15) in a neonatal unit in Tanzania. Seventeen Gram-negative enteric isolates from neonatal blood cultures were studied. Antibiotic susceptibility was assessed by disc diffusion testing, and the presence of the bla(CTX-M-15) gene was established by polymerase chain reaction (PCR) and sequencing. Isolates were typed by pulsed-field gel electrophoresis (PFGE). Identification by biochemical profiling was followed by nucleotide sequencing of 16S ribosomal DNA (rDNA), rpoB and hsp60 alleles. Environmental sampling was done and control measures were established. Isolates were initially misidentified based on their fermentation characteristics and agglutination as Salmonella enterica serotype Paratyphi. All isolates were resistant to multiple antibiotics, except for ciprofloxacin and carbapenems, and were found to harbour bla(CTX-M-15) on a 291-kb narrow-range plasmid. PFGE analysis indicated the clonal outbreak of a single strain, infecting 17 neonates with a case fatality rate of 35%. The same strain was isolated from a milk bucket. Phylogenetic analysis using 16S rDNA, rpoB and hsp60 sequences permitted no definitive identification, clustering the strains in the Enterobacter cloacae complex with similarities of 92-98.8%. The data describe an outbreak of a novel bla(CTX-M-15)-positive, multiresistant Enterobacter strain in an African neonatal unit that can easily be misidentified taxonomically. These data highlight the need for constant surveillance of bacteria harbouring extended-spectrum β-lactamases as well as improvements in hygiene measures in developing countries.

  6. Enterobacter morus sp. nov., a novel Enterobacter species associated with bacterial wilt on mulberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A mulberry pathogenetic bacterial strain R18-2T isolated from the diseased mulberry root was analyzed by a polyphasic taxonomic study. Comparative 16S rRNA gene sequence analysis combined with rpoB gene sequence analysis allocated the strain R18-2T to the genus Enterobacter. The strain was Gram nega...

  7. Phage-mediated Shiga toxin (Stx) horizontal gene transfer and expression in non-Shiga toxigenic Enterobacter and Escherichia coli strains.

    PubMed

    Khalil, Rowaida K S; Skinner, Craig; Patfield, Stephanie; He, Xiaohua

    2016-07-01

    Enterobacter cloacae M12X01451 strain recently identified from a clinical specimen produces a new Stx1 subtype (Stx1e) that was not neutralized by existing anti-Stx1 monoclonal antibodies. Acquisition of stx by Ent. cloacae is rare and origin/stability of stx1e in M12X01451 is not known. In this study, we confirmed the ability of Stx1a- and Stx1e-converting phages from an Escherichia coli O157:H7 strain RM8530 and M12X01451 respectively to infect several E. coli and Ent. cloacae strains. stx1e was detected in 97.5% and 72.5% of progenies of strains lysogenized by stx1e phage after 10 (T10) and 20 (T20) subcultures, versus 65% and 17.5% for stx1a gene. Infection of M12X01451 and RM8530 with each other's phages generated double lysogens containing both phages. stx1a was lost after T10, whereas the stx1e was maintained even after T20 in M12X01451 lysogens. In RM8530 lysogens, the acquired stx1e was retained with no mutations, but 20% of stx1a was lost after T20 ELISA and western blot analyses demonstrated that Stx1e was produced in all strains lysogenized by stx1e phage; however, Stx1a was not detected in any lysogenized strain. The study results highlight the potential risks of emerging Stx-producing strains via bacteriophages either in the human gastrointestinal tract or in food production environments, which are matters of great concern and may have serious impacts on human health.

  8. Methionine-to-Cysteine Recycling in Klebsiella aerogenes

    PubMed Central

    Seiflein, Thomas A.; Lawrence, Jeffrey G.

    2001-01-01

    In the enteric bacteria Escherichia coli and Salmonella enterica, sulfate is reduced to sulfide and assimilated into the amino acid cysteine; in turn, cysteine provides the sulfur atom for other sulfur-bearing molecules in the cell, including methionine. These organisms cannot use methionine as a sole source of sulfur. Here we report that this constraint is not shared by many other enteric bacteria, which can use either cysteine or methionine as the sole source of sulfur. The enteric bacterium Klebsiella aerogenes appears to use at least two pathways to allow the reduced sulfur of methionine to be recycled into cysteine. In addition, the ability to recycle methionine on solid media, where cys mutants cannot use methionine as a sulfur source, appears to be different from that in liquid media, where they can. One pathway likely uses a cystathionine intermediate to convert homocysteine to cysteine and is induced under conditions of sulfur starvation, which is likely sensed by low levels of the sulfate reduction intermediate adenosine-5′-phosphosulfate. The CysB regulatory proteins appear to control activation of this pathway. A second pathway may use a methanesulfonate intermediate to convert methionine-derived methanethiol to sulfite. While the transsulfurylation pathway may be directed to recovery of methionine, the methanethiol pathway likely represents a general salvage mechanism for recovery of alkane sulfide and alkane sulfonates. Therefore, the relatively distinct biosyntheses of cysteine and methionine in E. coli and Salmonella appear to be more intertwined in Klebsiella. PMID:11114934

  9. Use of aiiA gene amplification for AHL-lactonase production from endophytic bacterium Enterobacter species.

    PubMed

    Rajesh, P S; Rai, V Ravishankar

    2015-01-01

    AHL-lactonase has gained renewed interest due to biotechnological applications such as antiquorum sensing, antibiofilm strategies, biofouling, etc. In our study, the production of AHL-lactonase from endophytic bacteria Enterobacter aerogenes VT66 was optimized by response surface methodology (RSM) using central composite design (CCD) for four different cultural conditions. The relative activity of AHL-lactonase was correlated with amplification of aiiA homologous gene amplification with respect to cultural conditions. Statistical analysis by ANOVA of the quadratic regression model showed that the RSM model constructed is highly significant, as indicated by F-test with a low probability value (p(model) < 0.0001) and high regression coefficient (0.9997) as well as lower coefficient of variation (1.86%) indicate that suitability of variable parameters. The quadratic regression model of AHL-lactonase production in terms of relative activity was built and the optimal cultural conditions for maximum enzyme production were determined as 32.5 °C temperature, pH 7.0, 350 μM of substrate concentration and 33 h of incubation time. The enhanced AHL-lactonase yielded 1.33 fold increases in relative activity and it positively correlated with the amplification of aiiA gene.

  10. Root colonization and growth promotion of sunflower (Helianthus annuus L.) by phosphate solubilizing Enterobacter sp. Fs-11.

    PubMed

    Shahid, Muhammad; Hameed, Sohail; Imran, Asma; Ali, Saira; van Elsas, Jan Dirk

    2012-08-01

    An Enterobacter sp. Fs-11 was isolated from sunflower rhizosphere, identified on the basis of 16S rRNA gene sequence analysis (GeneBank accession no. GQ179978) and studied for its root colonization and growth promotion ability in sunflower. Morphologically, it was rod shaped Gram-negative, motile bacterium, producing 4.5 μg mL(-1) indole acetic acid in tryptophan-supplemented medium. It utilized 27 out of 95 substrates in BIOLOG GN2 micro plate system. It was able to convert insoluble tri-calcium phosphate to soluble phosphorus up to 43.5 μg mL(-1) with decrease in pH of the medium up to 4.5 after 10 days incubation at 28 ± 2 °C in the Pikovskaya's broth. High performance liquid chromatography of cell free supernatant showed that Fs-11 produced malic acid and gluconic acid (2.43 and 16.64 μg mL(-1), respectively) in Pikovskaya's broth. Analysis of 900 bp fragment of pyrroloquinoline quinine pqqE gene sequence showed 98 % homology with that of E. cloacae pqqE gene. Confocal laser scanning microscope revealed strong colonization of fluorescently labeled Fs-11 with sunflower roots. Sunflower inoculation with Fs-11 and its rifampicin resistant derivative in sterile sand and natural soil showed that Fs-11 colonized sunflower roots up to 30 days after transplanting in both sterile sand as well as natural soil. Moreover, Fs-11 inoculation resulted in increased plant height, fresh weight, dry weight and total phosphorus contents as compared to un-inoculated plants. The data showed that Enterobacter sp. Fs-11 is an efficient phosphate solubilizing and plant growth promoting rhizobacterium and has great potential to be used as bio-inoculant for sunflower under phosphorus deficient conditions.

  11. The nac (nitrogen assimilation control) gene from Klebsiella aerogenes.

    PubMed Central

    Schwacha, A; Bender, R A

    1993-01-01

    The Klebsiella aerogenes nac gene, whose product is necessary for nitrogen regulation of a number of operons, was identified and its DNA sequence determined. The nac sequence predicted a protein a 305 amino acids with a strong similarity to members of the LysR family of regulatory proteins, especially OxyR from Escherichia coli. Analysis of proteins expressed in minicells showed that nac is a single-gene operon whose product has an apparent molecular weight of about 32 kDa as measured in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immediately downstream from nac is a two-gene operon, the first gene of which encodes another member of the LysR family. Upstream from nac is a tRNAAsn gene transcribed divergently from nac. About 60 bp upstream from the nac open reading frame lies a sequence nearly identical to the consensus for sigma 54-dependent promoters, with the conserved GG and GC nucleotides at -26 and -14 relative to the start of transcription. About 130 bp farther upstream (at -153 relative to the start of transcription) is a sequence nearly identical to the transcriptional activator NTRC-responsive enhancer consensus. Another weaker NTRC-binding site is located adjacent to this site (at -133 relative to the start of transcription). Thus, we propose that nac is transcribed by RNA polymerase carrying sigma 54 in response to the nitrogen regulatory (NTR) system. A transposon located between the promoter and the nac ORF prevented NTR-mediated expression of nac, supporting this identification of the promoter sequence. The insertion of over 5 kb of transposon DNA between the enhancer and its target promoter had only a weak effect on enhancer-mediated regulation, suggesting that enhancers may be able to act at a considerable distance on the bacterial chromosome. Images PMID:8458853

  12. Phytases from Enterobacter and Serratia species with desirable characteristics for food and feed applications.

    PubMed

    Kalsi, Harpreet Kaur; Singh, Rajveer; Dhaliwal, Harcharan Singh; Kumar, Vinod

    2016-06-01

    Phytases are enzymes of great industrial importance with wide range of applications in animal and human nutrition. These catalyze the hydrolysis of phosphomonoester bonds in phytate, thereby releasing lower forms of myo-inositol phosphates and inorganic phosphate. Addition of phytase to plant-based foods can improve its nutritional value and increase mineral bioavailability by decreasing nutritional effect of phytate. In the present investigation, 43 phytase positive bacteria on PSM plates were isolated from different sources and characterized for phytase activity. On the basis of phytase activity and zone of hydrolysis, two bacterial isolates (PSB-15 and PSB-45) were selected for further characterization studies, i.e., pH and temperature optima and stability, kinetic properties and effect of modulators. The phytases from both isolates were optimally active at the pH value from 3 to 8 and in the temperature range of 50-70 °C. Further, the stability of isolates was good in the pH range of 3.0-8.0. Much variation was observed in temperature and storage stability, responses of phytases to metal ions and modulators. The K m and V max values for PSB-15 phytase were 0.48 mM and 0.157 μM/min, while for PSB-45 these were 1.25 mM and 0.140 μM/min, respectively. Based on 16S rDNA gene sequence, the isolates were identified as Serratia sp. PSB-15 (GenBank Accession No. KR133277) and Enterobacter cloacae strain PSB-45 (GenBank Accession No. KR133282). The novel phytases from these isolates have multiple characteristics of high thermostability and good phytase activity at desirable range of pH and temperature for their efficient use in food and feed to facilitate hydrolysis of phytate-metal ion complex and in turn, increased bioavailability of important metal ions to monogastric animals.

  13. Escherichia fergusonii and Enterobacter taylorae, two new species of Enterobacteriaceae isolated from clinical specimens.

    PubMed

    Farmer, J J; Fanning, G R; Davis, B R; O'Hara, C M; Riddle, C; Hickman-Brenner, F W; Asbury, M A; Lowery, V A; Brenner, D J

    1985-01-01

    Escherichia fergusonii (formerly known as Enteric Group 10) and Enterobacter taylorae (formerly known as Enteric Group 19) are proposed as new species in the family Enterobacteriaceae. By DNA hybridization (32P, 60 degrees C, hydroxyapatite), strains of E. fergusonii were 90 to 97% related to the type strain (holotype) ATCC 35469. They were most closely related to Escherichia coli and more distantly related to species in other genera. E. fergusonii strains are positive for indole production, methyl red, lysine decarboxylase, ornithine decarboxylase, and motility. They ferment D-glucose with gas production and also ferment adonitol, L-arabinose, L-rhamnose, maltose, D-xylose, trehalose, cellobiose, and D-arabitol. They are negative for Voges-Proskauer, citrate utilization (17% positive), urea hydrolysis, phenylalanine deamination, arginine dihydrolase, growth in KCN, and fermentation of lactose, sucrose, myo-inositol, D-sorbitol, raffinose, and alpha-methyl-D-glucoside. By DNA hybridization (32P, 60 degrees C, hydroxyapatite), strains of E. taylorae were 84 to 95% related to the type strain (holotype) ATCC 35317. Their nearest relative was E. cloacae, to which they were 61% related. Other named species were more distantly related. Strains of E. taylorae are positive for Voges-Proskauer, citrate utilization, arginine dihydrolase, ornithine decarboxylase, motility, growth in KCN medium, and malonate utilization. They ferment D-glucose with gas production and also ferment D-mannitol, L-arabinose, L-rhamnose, maltose, D-xylose, trehalose, and cellobiose. They are negative for indole production, methyl red, H2S production on triple sugar-iron agar, urea hydrolysis, phenylalanine deamination, lysine decarboxylase, gelatin hydrolysis, and fermentation of adonitol, i-inositol, D-sorbitol, and raffinose. Both new species occur in human clinical specimens. Two strains of E. fergusonii were isolated from blood. Five stains of E. taylorae were isolated from blood, and one was

  14. Construction of intergeneric hybrids using bacteriophage P1CM: transfer of the Klebsiella aerogenes ribitol dehydrogenase gene to Escherichia coli.

    PubMed

    Rigby, P W; Gething, M J; Hartley, B S

    1976-02-01

    Study of many of the interesting properties of Klebsiella aerogenes is limited by the lack of a well-characterized genetic system for this organism. Our investigations of the evolution of the enzyme ribitol dehydrogenase (EC 1.1.1.56) in K. aerogenes would be greatly facilitated by the availability of such a system, and we here report two approaches to developing one. We have isolated mutants sensitive to the coliphage P1, which will efficiently tranduce genetic markers between such sensitive strains and which will thus make detailed mapping studies possible. Derivatives of K. aerogenes lysogenic for P1 can be readily isolated by using the specialized transducing particle P1CMclr100. Bacteria lysogenic for this phage are chloramphenicol resistant and temperature sensitive. Phage particles produced by temperature induction of such lysogens can be used to transfer K. aerogenes genes to the natural host of P1 phage. Escherichia coli. We have used this method to prepare derivatives of E. coli K-12 carrying the K. aerogenes genes conferring the ability to metabolize the pentitols ribitol and D-arabitol. We have shown that these E. coli-K. aerogenes hybrids synthesize a ribitol dehydrogenase with the properties of the K. aerogenes enzyme and have mapped the position of the transferred gene on the E. coli chromosome. The ramifications of this methodology are discussed.

  15. Characterization of extended-spectrum β-lactamase (ESBL)-producing Klebsiella, Enterobacter, and Citrobacter obtained in environmental samples of a Tunisian hospital.

    PubMed

    Dziri, Raoudha; Klibi, Naouel; Alonso, Carla Andrea; Said, Leila Ben; Bellaaj, Ridha; Slama, Karim Ben; Boudabous, Abdellatif; Torres, Carmen

    2016-10-01

    The assessment of the hospital environment as a reservoir of ESBL-producing Enterobacteriaceae in Tunisian hospitals is scarcely analyzed, except for Escherichia coli. The aim of this study was to evaluate the presence of ESBL-producing non-E. coli Enterobacteriaceae (ESBL-EbNoEc) in 300 samples of abiotic surfaces and the hands of patients and staff of a Tunisian Hospital, and to characterize the ESBL genes of the recovered isolates. ESBL-EbNoEc were recovered in 28 of 300 (9.3%) analyzed samples and were identified as Klebsiella pneumoniae (n= 11), Enterobacter cloacae (n=11), Citrobacter freundii (n=4) and Klebsiella oxytoca (n=2). The bla genes identified by PCR and sequencing among the strains were as follows: 11 K.pneumoniae strains [blaCTX-M-15+ blaTEM-1+ blaSHV-11 (n=6); blaCTX-M-15+ blaTEM-1+ blaSHV-28 (n=3); blaCTX-M-15+ blaTEM-1+ blaSHV-1 (n=2)], 11 E. cloacae strains [blaCTX-M-15 (n=6); blaCTX-M-15+ blaTEM-1b (n=2); blaCTX-M-15+ blaTEM-1b+ blaOXA-1 (n=1);blaCTX-M-15+ blaOXA-1 (n=1);blaSHV-12 (n=1)], 4 C. freundii strains [blaCTX-M-15] and 2 K. oxytoca strains [blaCTX-M-15 (n=1); blaSHV-12 (n=1)]. The ISEcp1 and orf477 sequences were identified upstream and downstream of the blaCTX-M-15 gene, respectively, in 3 K. pneumoniae and 3 E. cloacae isolates. The PFGE analysis demonstrated three unrelated pulsotypes in K. pneumoniae strains and five pulsotypes in E. cloacae. The uncontrolled dissemination of ESBL-producing bacteria, even in the hospital environment, has become a real problem and new strategies and hygienic rules are needed to stop this bacterial dissemination.

  16. Enterobacter bugandensis sp. nov., from a neonatal unit in Tanzania.

    PubMed

    Doijad, Swapnil; Imirzalioglu, Can; Yao, Yancheng; Pati, Niladri Bhusan; Falgenhauer, Linda; Hain, Torsten; Foesel, Bärbel U; Abt, Birte; Overmann, Jorg; Mirambo, Mariam M; Mshana, Stephen E; Chakraborty, Trinad

    2015-12-04

    A total of 17 'Enterobacter-like' isolates obtained from a septicemic outbreak from a neonatal unit, Tanzania, that could not be assigned based on phenotypic tests to any existing Enterobacter species. Eight representative outbreak isolates were investigated in detail. Fermentation characteristics, biochemical assays and fatty acid profiles for taxonomic analysis were determined and supplemented with information derived from whole genome sequences. Phenotypic and morphological tests revealed that these isolates are Gram-negative, rod-shaped, highly motile and facultatively anaerobic. The fatty acid profile was similar to all other Enterobacter type strains, with quantitative differences in C17:0, C18:1 ω7c and C17:0 cyclo fatty acids. We performed whole genome sequencing and examined it for taxonomically relevant characteristics i.e. 16S rDNA, multi-locus sequence analysis (MLSA), in silico DNA-DNA hybridisation (isDDH) and average nucleotide identity (ANI). Draft genomes were approximately 4.9 Mb in size with a G+C content of 56.0%. The 16S rDNA sequence of these eight isolates showed > 97% similarity to all the Enterobacter species, while MLSA clustered them closely with type strains of E. xiangfangensis and E. hormaechei, respectively. These eight strains showed less than 70% isDDH identity with type strains of the Enterobacter species. In addition, less than 95% ANI to type strains of Enterobacter species was observed. From these results, we conclude that these isolates possess sufficient characteristics that different them from all known Enterobacter species, and should therefore be considered as a novel species. The name Enterobacter bugandensis sp. nov. is proposed with EB-247T as the type strain (=DSM 29888T=NCCB 100573T).

  17. Induction by Klebsiella aerogenes of a melanin-like pigment in Cryptococcus neoformans.

    PubMed

    Frases, Susana; Chaskes, Stuart; Dadachova, Ekaterina; Casadevall, Arturo

    2006-02-01

    While studying the interaction of Cryptococcus neoformans with Dictyostelium discoideum, we noticed that yeast colonies in agar with a feeder lawn of Klebsiella aerogenes were brown. This finding was intriguing because C. neoformans colonies are not pigmented unless they are provided with precursors for melanization. Strains of all C. neoformans serotypes produced brown pigment in response to K. aerogenes at 22, 30, and 37 degrees C. Pigment production required fungal laccase and was suppressed by high concentrations of glucose. Treatment of brown cells with guanidinium isothiocyanate and hot concentrated HCl yielded particulate material that had the physical and chemical characteristics of melanins. No pigment formation was observed when C. neoformans was exposed to live Escherichia coli or heat-killed K. aerogenes. Analysis of K. aerogenes supernatants revealed the presence of dopamine, which can be a substrate for melanin synthesis by C. neoformans. Our findings illustrate a remarkable interaction between a pathogenic fungus and a gram-negative bacterium, in which the bacterium produces a substrate that promotes fungal melanization. This observation provides a precedent that could explain the source of a substrate for C. neoformans melanization in the environment.

  18. The new species Enterobacter oryziphilus sp. nov. and Enterobacter oryzendophyticus sp. nov. are key inhabitants of the endosphere of rice

    PubMed Central

    2013-01-01

    Background Six independent Gram-negative, facultatively anaerobic, non-spore-forming, nitrogen-fixing rod-shaped isolates were obtained from the root endosphere of rice grown at the International Rice Research Institute (IRRI) and investigated in a polyphasic taxonomic study. Results The strains produced fatty acid patterns typical for members of the family Enterobacteriaceae. Comparative sequence analyses of the 16S rRNA as well as rpoB genes allocated the strains to two well-defined groups within the genus Enterobacter, family Enterobacteriaceae. The analyses indicated Enterobacter radicincitans, Enterobacter arachidis and Enterobacter oryzae to be the closest related species. An RpoB (translated) protein comparison supported the placement in the genus Enterobacter and the relatedness of our isolates to the aforementioned species. Genomic DNA:DNA hybridization analyses and biochemical analyses provided further evidence that the novel strains belong to two new species within the genus Enterobacter. The two species can be differentiated from each other and from existing enteric species by acid production from L-rhamnose and D-melibiose, decarboxylation of ornithine and utilization of D-alanine, D-raffinose L-proline and L-aspartic acid, among other characteristics. Members of both species revealed capacities to colonise rice roots, including plant-growth-promoting capabilities such as an active supply of fixed nitrogen to the plant and solubilisation of inorganic phosphorus, next to traits allowing adaptation to the plant. Conclusions Two novel proposed enterobacterial species, denominated Enterobacter oryziphilus sp. nov. (type strain REICA_142T=LMG 26429T=NCCB 100393T) and Enterobacter oryzendophyticus sp. nov. (type strain REICA_082T=LMG 26432T =NCCB 100390T) were isolated from rice roots. Both species are capable of promoting rice growth by supplying nitrogen and phosphorus. PMID:23865888

  19. Enterobacter tabaci sp. nov., a novel member of the genus Enterobacter isolated from a tobacco stem.

    PubMed

    Duan, Yan-Qing; Zhou, Xing-Kui; Di-Yan, Li; Li, Qing-Qing; Dang, Li-Zhi; Zhang, Yong-Guang; Qiu, Li-Hong; Nimaichand, Salam; Li, Wen-Jun

    2015-11-01

    A Gram-stain negative, motile, rod-shaped bacterium, designated strain YIM Hb-3(T), was isolated from the stem of a tobacco plant. The strain was observed to form convex, circular and yellow-colored colonies. The predominant respiratory quinone was identified as Q-8. The major fatty acids (>5%) detected were C(16:1)ω7c and/or C(16:1)ω6c (summed feature 3), C(16:0), C(17:0)cyclo, C(18:1)ω7c and/or C(18:1)ω6c (summed feature 8), C(14:0)3-OH and/or iso-C(16:1)I (summed feature 2), C(14:0) and C(12:0). The genomic DNA G+C content was determined to be 54.8 mol%. Phylogenetic trees based on 16S rRNA gene sequences and multilocus sequence analysis showed that strain YIM Hb-3(T) had the closest phylogenetic relationship with Enterobacter mori LMG 25706(T). DNA-DNA relatedness value between strain YIM Hb-3(T) and E. mori LMG 25706(T) was 46.9 ± 3.8%. On the basis of phenotypic and chemotaxonomic data, phylogenetic analysis, and DNA-DNA relatedness value, strain YIM Hb-3(T) is considered to represent a novel species of the genus Enterobacter, for which the name Enterobacter tabaci sp. nov. is proposed. The type strain is YIM Hb-3(T) (=KACC 17832(T) =KCTC 42694(T)).

  20. Genotypic and Phenotypic Detection of AmpC β-lactamases in Enterobacter spp. Isolated from a Teaching Hospital in Malaysia

    PubMed Central

    Mohd Khari, Fatin Izzati; Karunakaran, Rina; Rosli, Roshalina; Tee Tay, Sun

    2016-01-01

    Objectives The objective of this study was to determine the occurrence of chromosomal and plasmid-mediated β-lactamases (AmpC) genes in a collection of Malaysian isolates of Enterobacter species. Several phenotypic tests for detection of AmpC production of Enterobacter spp. were evaluated and the agreements between tests were determined. Methods Antimicrobial susceptibility profiles for 117 Enterobacter clinical isolates obtained from the Medical Microbiology Diagnostic Laboratory, University Malaya Medical Centre, Malaysia, from November 2012—February 2014 were determined in accordance to CLSI guidelines. AmpC genes were detected using a multiplex PCR assay targeting the MIR/ACT gene (closely related to chromosomal EBC family gene) and other plasmid-mediated genes, including DHA, MOX, CMY, ACC, and FOX. The AmpC β-lactamase production of the isolates was assessed using cefoxitin disk screening test, D69C AmpC detection set, cefoxitin-cloxacillin double disk synergy test (CC-DDS) and AmpC induction test. Results Among the Enterobacter isolates in this study, 39.3% were resistant to cefotaxime and ceftriaxone and 23.9% were resistant to ceftazidime. Ten (8.5%) of the isolates were resistant to cefepime, and one isolate was resistant to meropenem. Chromosomal EBC family gene was amplified from 36 (47.4%) E. cloacae and three (25%) E. asburiae. A novel blaDHA type plasmid-mediated AmpC gene was identified for the first time from an E. cloacae isolate. AmpC β-lactamase production was detected in 99 (89.2%) of 111 potential AmpC β-lactamase producers (positive in cefoxitin disk screening) using D69C AmpC detection set. The detection rates were lower with CC-DDS (80.2%) and AmpC induction tests (50.5%). There was low agreement between the D69C AmpC detection set and the other two phenotypic tests. Of the 40 isolates with AmpC genes detected in this study, 87.5%, 77.5% and 50.0% of these isolates were positive by the D69C AmpC detection set, CC-DDS and Amp

  1. Modification of the Double-Disk Test for Detection of Enterobacteriaceae Producing Extended-Spectrum and AmpC β-Lactamases

    PubMed Central

    Pitout, J. D. D.; Reisbig, M. D.; Venter, E. C.; Church, D. L.; Hanson, N. D.

    2003-01-01

    Detection of extended-spectrum β-lactamases (ESBLs) in AmpC-producing Enterobacteriaceae is problematic. A modification of the double-disk test (MDDT) has been developed for successful detection of ESBLs in gram-negative bacilli producing well-characterized β-lactamases as well as 212 clinical isolates of Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, and Citrobacter freundii. MDDT accurately differentiated between ESBL producers and derepressed chromosomal AmpC mutants. MDDT provides a cost-effective alternative approach for clinical microbiology laboratories for routine susceptibility testing with simultaneous detection of ESBLs in Enterobacteriaceae. PMID:12904422

  2. Predominance of KPC-3 in a Survey for Carbapenemase-Producing Enterobacteriaceae in Portugal

    PubMed Central

    Manageiro, Vera; Ferreira, Eugénia; Almeida, Joana; Barbosa, Stephanie; Simões, Constança; Bonomo, Robert A.

    2015-01-01

    Among the 2,105 Enterobacteriaceae tested in a survey done in Portugal, 165 were nonsusceptible to carbapenems, from which 35 (26 Klebsiella pneumoniae, 3 Escherichia coli, 2 Enterobacter aerogenes, and 3 Enterobacter cloacae isolates and 1 Klebsiella oxytoca isolate) were confirmed to be carbapenemase producers by the presence of 30 Tn4401d-blaKPC-3, 4 intI3-blaGES-5, and one intI1-blaVIM-2 gene, alone or in combination with other bla genes. The dissemination of blaKPC-3 gene carried by an IncF plasmid suggests lateral gene transfer as a major mechanism of dissemination. PMID:25779587

  3. Biohydrogen production by co-fermentation of crude glycerol and apple pomace hydrolysate using co-culture of Enterobacter aerogenes and Clostridium butyricum.

    PubMed

    Pachapur, Vinayak Laxman; Sarma, Saurabh Jyoti; Brar, Satinder Kaur; Le Bihan, Yann; Buelna, Gerardo; Verma, Mausam

    2015-10-01

    Co-substrate utilization of various wastes with complementary characteristics can provide a complete medium for higher hydrogen production. This study evaluated potential of apple pomace hydrolysate (APH) co-fermented with crude glycerol (CG) for increased H2 production and decreased by-products formation. The central composite design (CCD) along with response surface methodology (RSM) was used as tool for optimization and 15 g/L of CG, 5 g/L of APH and 15% (v/v) inoculum were found to be optimum to produce as high as 26.07 ± 1.57 mmol H2/L of medium. The p-value of 0.0017 indicated that APH at lower concentration had a significant effect on H2 production. By using CG as sole carbon source, reductive pathway of glycerol metabolism was favored with 19.46 mmol H2/L. However, with APH, oxidative pathway was favored with higher H2 production (26.07 ± 1.57 mmol/L) and decrease in reduced by-products (1,3-propanediol and ethanol) formation. APH inclusion enhanced H2 production, and decreased substrate inhibition.

  4. Nanoparticles functionalized with ampicillin destroy multiple-antibiotic-resistant isolates of Pseudomonas aeruginosa and Enterobacter aerogenes and methicillin-resistant Staphylococcus aureus.

    PubMed

    Brown, Ashley N; Smith, Kathryn; Samuels, Tova A; Lu, Jiangrui; Obare, Sherine O; Scott, Maria E

    2012-04-01

    We show here that silver nanoparticles (AgNP) were intrinsically antibacterial, whereas gold nanoparticles (AuNP) were antimicrobial only when ampicillin was bound to their surfaces. Both AuNP and AgNP functionalized with ampicillin were effective broad-spectrum bactericides against Gram-negative and Gram-positive bacteria. Most importantly, when AuNP and AgNP were functionalized with ampicillin they became potent bactericidal agents with unique properties that subverted antibiotic resistance mechanisms of multiple-drug-resistant bacteria.

  5. Kinetic model for microbial growth and desulphurisation with Enterobacter sp.

    PubMed

    Liu, Long; Guo, Zhiguo; Lu, Jianjiang; Xu, Xiaolin

    2015-02-01

    Biodesulphurisation was investigated by using Enterobacter sp. D4, which can selectively desulphurise and convert dibenzothiophene into 2-hydroxybiphenyl (2-HBP). The experimental values of growth, substrate consumption and product generation were obtained at 95 % confidence level of the fitted values using three models: Hinshelwood equation, Luedeking-Piret and Luedeking-Piret-like equations. The average error values between experimental values and fitted values were less than 10 %. These kinetic models describe all the experimental data with good statistical parameters. The production of 2-HBP in Enterobacter sp. was by "coupled growth".

  6. Non-Mucinous Lepidic Predominant Adenocarcinoma Presenting with Extensive Aerogenous Spread

    PubMed Central

    Takanashi, Yusuke; Tsukui, Masaru; Shinmura, Kazuya; Hayakawa, Takamitsu; Takahashi, Tsuyoshi; Neyatani, Hiroshi; Funai, Kazuhito

    2016-01-01

    An extremely rare case of non-mucinous lepidic-predominant invasive adenocarcinoma (LPA) showing extensive aerogenous spread with a pneumonic presentation is reported. A 73-year-old woman was referred to our hospital because of an infiltrative shadow on chest xray. Chest computed tomography revealed extensive ground glass opacities in the right lower lobe, which was accompanied by infiltrative shadow with a pneumonic presentation. Invasive mucinous adenocarcinoma was presumed, and a partial resection of the right lower lobe was done. Histopathological examination revealed lepidic growth-predominant invasive adenocarcinoma with Clara type tumor cells, and there were innumerable aerogenous metastases also consisting of Clara cells. Because Alcian Blue and periodic acid-Schiff staining disclosed no mucus, the tumor was diagnosed as a non-mucinous LPA. The patient showed a poor response to 5 courses of pemetrexed, and she died one year after the diagnosis due to cancer progression. Nonmucinous LPA showed a rare presentation characterized by extensive aerogenous spread followed by a poor prognosis. PMID:28058100

  7. New monoclonal antibodies against a novel subtype of Shiga toxin 1 produced by Enterobacter cloacae and their use in analysis of human serum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin (Stx) is a major virulence factor for several bacterial pathogens that cause potentially fatal illness, including Escherichia coli and Shigella spp. The continual emergence of new subtypes of Stxs presents challenges in clinical diagnosis of infections caused by Shiga toxin-producing org...

  8. [Cloning and function identification of gene 'admA' and up-stream regulatory sequence related to antagonistic activity of Enterobacter cloacae B8].

    PubMed

    Zhu, Jun-Li; Li, De-Bao; Yu, Xu-Ping

    2012-04-01

    To reveal the antagonistic mechanism of B8 strain to Xanthomonas oryzae pv. oryzae, transposon tagging method and chromosome walking were deployed to clone antagonistic related fragments around Tn5 insertion site in the mutant strain B8B. The function of up-stream regulatory sequence of gene 'admA' involved in the antagonistic activity was further identified by gene knocking out technique. An antagonistic related left fragment of Tn5 insertion site, 2 608 bp in length, was obtained by tagging with Kan resistance gene of Tn5. A 2 354 bp right fragment of Tn5 insertion site was amplified with 2 rounds of chromosome walking. The length of the B contig around the Tn5 insertion site was 4 611 bp, containing 7 open reading frames (ORFs). Bioinformatic analysis revealed that these ORFs corresponded to the partial coding regions of glyceraldehyde-3-phosphate dehydrogenase, two LysR family transcriptional regulators, hypothetical protein VSWAT3-20465 of Vibrionales and admA, admB, and partial sequence of admC gene of Pantoea agglomerans biosynthetic gene cluster, respectively. Tn5 was inserted in the up-stream of 200 bp or 894 bp of the sequence corresponding to anrP ORF or admA gene on B8B, respectively. The B-1 and B-2 mutants that lost antagonistic activity were selected by homeologuous recombination technology in association with knocking out plasmid pMB-BG. These results suggested that the transcription and expression of anrP gene might be disrupted as a result of the knocking out of up-stream regulatory sequence by Tn5 in B8B strain, further causing biosythesis regulation of the antagonistic related gene cluster. Thus, the antagonistic related genes in B8 strain is a gene family similar as andrimid biosynthetic gene cluster, and the upstream regulatory region appears to be critical for the antibiotics biosynthesis.

  9. Morphology and putative function of the colon and cloaca of marine and freshwater snakes.

    PubMed

    Babonis, Leslie S; Womack, Molly C; Evans, David H

    2012-01-01

    Among tetrapods, evidence for postrenal modification of the urine by the distal digestive tract (including the colon and cloaca) is highly variable. Birds and bladderless reptiles are of interest because the colon and cloaca represent the only sites from which water and ions can be reclaimed from the urine secreted by the kidney. For animals occupying desiccating environments (e.g., deserts and marine environments), postrenal modification of the urine may directly contribute to the maintenance of hypo-osmotic body fluids. We compared the morphology and distribution of key proteins in the colon, cloaca, and urogenital ducts of watersnakes from marine (Nerodia clarkii clarkii) and freshwater (Nerodia fasciata) habitats. Specifically, we examined the epithelia of each tissue for evidence of mucus production by examining the distribution of mucopolysaccharides, and for evidence of water/ion regulation by examining the distribution of Na(+) /K(+) -ATPase (NKA), Na(+) /K(+) /Cl(-) cotransporter (NKCC), and aquaporin 3 (AQP3). NKCC localized to the basolateral epithelium of the colon, urodeal sphincter, and proctodeum, consistent with a role in secretion of Na(+), Cl(-) , and K(+) from the tissue, but NKA was not detected in the colon or any compartment of the cloaca. Interestingly, NKA was detected in the basolateral epithelium of the ureters, suggesting the urothelium may play a role in active ion transport. AQP3 was detected in the ureters and coprodeal complex, consistent with a role in urinary and fecal dehydration or, potentially, in the production of the watery component of the mucus secreted by the coprodeal complex. Since no differences in general cloacal morphology, production of mucus, or the distribution of ion transporters/water channels were detected between the two species, cloacal osmoregulation may either be regulated by proteins not examined in this study or may not be responsible for the differential success of N. c. clarkii and N. fasciata in marine

  10. Morphogenesis and patterning of the phallus and cloaca in the American alligator, alligator mississippiensis.

    PubMed

    Gredler, Marissa L; Seifert, Ashley W; Cohn, Martin J

    2015-01-01

    In most animals, reproduction by internal fertilization is facilitated by an intromittent organ, such as the penis in amniote vertebrates. Recent progress has begun to uncover the mechanisms of mammalian external genital development; however, comparatively little is known about the development of the reptilian penis and clitoris. Here, we describe the development of the phallus and cloaca in the American alligator, Alligator mississippiensis. The embryonic precursor of the penis and clitoris is the genital tubercle, which forms by the budding of genital mesenchyme beneath the ventral body wall ectoderm, adjacent to the cloacal membrane. The cloacal lips develop from another pair of outgrowths, the lateral swellings. Early development of the alligator phallus, cloaca, and urogenital ducts generally resembles that of other reptiles, suggesting that differences in adult reptilian phallus and cloacal anatomy arise at later stages. The phallic sulcus is derived from the cloacal endoderm, indicating that the crocodilian sulcus is functionally and developmentally homologous to the mammalian urethra. Initial external genital outgrowth and patterning occur prior to temperature-dependent sex determination. Our analysis of alligator phallus and cloaca development suggests that modifications of an ancestral program of urogenital development could have generated the morphological diversity found in the external genitalia of modern amniotes.

  11. Mineral nutrition of Aerobacter aerogenes for valine production in a synthetic medium.

    PubMed

    Mukhopadhyay, A K; Majumdar, S K

    1985-01-01

    The effect of a number of mineral salts, like dipotassium hydrogen phosphate, magnesium sulphate, and sodium chloride, and of some trace elements including iron, copper, cobalt, nickel, molybdenum, and calcium, on the production of valine by Aerobacter aerogenes in a synthetic medium was investigated. It was found that all the mineral salts were necessary for valine formation. Among the trace elements, iron and molybdenum were found to be necessary in minute concentrations for the optimum yield of the amino acid, while all the others had an adverse effect on valine production, even at lower levels.

  12. Ribitol dehydrogenase of Klebsiella aerogenes. Sequence and properties of wild-type and mutant strains.

    PubMed Central

    Dothie, J M; Giglio, J R; Moore, C B; Taylor, S S; Hartley, B S

    1985-01-01

    Evidence is presented for the sequence of 249 amino acids in ribitol dehydrogenase-A from Klebsiella aerogenes. Continuous culture on xylitol yields strains that superproduce 'wild-type' enzyme but mutations appear to have arisen in this process. Other strains selected by such continuous culture produce enzymes with increased specific activity for xylitol but without loss of ribitol activity. One such enzyme, ribitol dehydrogenase-D, has Pro-196 for Gly-196. Another, ribitol dehydrogenase-B, has a different mutation. PMID:3904726

  13. Urease of Klebsiella aerogenes: control of its synthesis by glutamine synthetase.

    PubMed Central

    Friedrich, B; Magasanik, B

    1977-01-01

    Urease was purified 24-fold from extracts of Klebsiella aerogenes. The enzyme has a molecular weight of 230,000 as determined by gel filtration, is highly substrate specific, and has a Km for urea of 0.7 mM. A mutant strain lacking urease was isolated; it failed to grow with urea as the sole source of nitrogen but did grow on media containing other nitrogen sources such as ammonia, histidine, or arginine. Urease was present at a high level when the cells were starved for nitrogen; its synthesis was repressed when the external ammonia concentration was high. Formation of urease did not require induction by urea and was not subject to catabolite repression. Its synthesis was controlled by glutamine synthetase. Mutants lacking glutamine synthetase failed to produce urease, and mutants forming glutamine synthetase at a high constitutive level also formed urease constitutively. Thus, the formation of urease is regulated like that of other enzymes of K. aerogenes capable of supplying the cell with ammonia or glutamate. PMID:18438

  14. Characterization of PaxA and Its Operon: a Cohemolytic RTX Toxin Determinant from Pathogenic Pasteurella aerogenes

    PubMed Central

    Kuhnert, Peter; Heyberger-Meyer, Bénédicte; Nicolet, Jacques; Frey, Joachim

    2000-01-01

    Pasteurella aerogenes is known as a commensal bacterium or as an opportunistic pathogen, as well as a primary pathogen found to be involved in abortion cases of humans, swine, and other mammals. Using broad-range DNA probes for bacterial RTX toxin genes, we cloned and subsequently sequenced a new operon named paxCABD encoding the RTX toxin PaxA in P. aerogenes. The pax operon is organized analogous to the classical RTX operons containing the activator gene paxC upstream of the structural toxin gene paxA, which is followed by the secretion protein genes paxB and paxD. The highest sequence similarity of paxA with known RTX toxin genes is found with apxIIIA (82%). PaxA is structurally similar to ApxIIIA and also shows functional analogy to ApxIIIA, since it shows cohemolytic activity with the sphingomyelinase of Staphylococcus aureus, known as the CAMP effect, but is devoid of direct hemolytic activity. In addition, it shows to some extent immunological cross-reactions with ApxIIIA. P. aerogenes isolated from various specimens showed that the pax operon was present in about one-third of the strains. All of the pax-positive strains were specifically related to swine abortion cases or septicemia of newborn piglets. These strains were also shown to produce the PaxA toxin as determined by the CAMP phenomenon, whereas none of the pax-negative strains did. This indicated that the PaxA toxin is involved in the pathogenic potential of P. aerogenes. The examined P. aerogenes isolates were phylogenetically analyzed by 16S rRNA gene (rrs) sequencing in order to confirm their species. Only a small heterogeneity (<0.5%) was observed between the rrs genes of the strains originating from geographically distant farms and isolated at different times. PMID:10603361

  15. Genome Sequence of Enterobacter radicincitans DSM16656T, a Plant Growth-Promoting Endophyte

    PubMed Central

    Witzel, Katja; Gwinn-Giglio, Michelle; Nadendla, Suvarna; Shefchek, Kent

    2012-01-01

    Enterobacter radicincitans sp. nov. DSM16656T represents a new species of the genus Enterobacter which is a biological nitrogen-fixing endophytic bacterium with growth-promoting effects on a variety of crop and model plant species. The presence of genes for nitrogen fixation, phosphorous mobilization, and phytohormone production reflects this microbe's potential plant growth-promoting activity. PMID:22965092

  16. Genome sequence of Enterobacter radicincitans DSM16656(T), a plant growth-promoting endophyte.

    PubMed

    Witzel, Katja; Gwinn-Giglio, Michelle; Nadendla, Suvarna; Shefchek, Kent; Ruppel, Silke

    2012-10-01

    Enterobacter radicincitans sp. nov. DSM16656(T) represents a new species of the genus Enterobacter which is a biological nitrogen-fixing endophytic bacterium with growth-promoting effects on a variety of crop and model plant species. The presence of genes for nitrogen fixation, phosphorous mobilization, and phytohormone production reflects this microbe's potential plant growth-promoting activity.

  17. Diffusely infiltrated lymphoid areas of the bursa of Fabricius (DIA) and of the cloaca: an embryological study with morphological analogies.

    PubMed Central

    Dolfi, A; Lupetti, M; Bianchi, F; Michelucci, S

    1988-01-01

    The aim of the present experiment was to verify whether the origin of the DIA is ectodermal or endodermal. A rabbit serum against the epithelial cells of the final portion of the cloaca was prepared. The indirect immunofluorescence method was applied to strips obtained with a cryostat, carefully cut in such a way as to include a part of the cloaca, the burso-cloacal stalk, the DIA, and the bursal plicae. In this way, it was possible to demonstrate that the epithelium of the cloaca, of the burso-cloacal stalk, and of the DIA exhibited an intense fluorescence that could not be observed at the level of the epithelium of the bursal plicae. These findings would appear to indicate that the DIA, like the cloaca and the burso-cloacal stalk, is ectodermal in origin. Furthermore, histological study revealed that the DIA exhibits close structural analogies with the dorsal wall of the cloaca. In both areas, unorganized lymphoid infiltrations of the tunica propria can be seen, and the epithelium does not show any follicle-associated epithelial cells. The glands often assume the aspect of dilated crypts containing intestinal transit material. The epithelium of these glands reveals lymphoid infiltrations at various points, and it is not uncommon to detect accumulations of cells in their lumina. Several groups of eosinophilic granulocytes can also be observed in the tunica propria of these two areas, with a clear predominance at the level of the DIA. These similarities between the cloaca and the DIA might lead one to suppose the existence of a functional as well as a morphological correspondence. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 PMID:3417544

  18. High-Quality Draft Whole-Genome Sequences of Three Strains of Enterobacter Isolated from Jamaican Dioscorea cayenensis (Yellow Yam).

    PubMed

    Gan, Han Ming; Triassi, Alexander J; Wheatley, Matthew S; Savka, Michael A; Hudson, André O

    2014-03-13

    Here we report the whole-genome sequences of three endophytic bacteria, Enterobacter sp. strain DC1, Enterobacter sp. strain DC3, and Enterobacter sp. strain DC4, from root tubers of the yellow yam plant, Dioscorea cayenensis. Preliminary analyses suggest that the genomes of the three bacteria contain genes involved in acetoin and indole-3-acetic acid metabolism.

  19. High-Quality Draft Whole-Genome Sequences of Three Strains of Enterobacter Isolated from Jamaican Dioscorea cayenensis (Yellow Yam)

    PubMed Central

    Gan, Han Ming; Triassi, Alexander J.; Wheatley, Matthew S.; Savka, Michael A.

    2014-01-01

    Here we report the whole-genome sequences of three endophytic bacteria, Enterobacter sp. strain DC1, Enterobacter sp. strain DC3, and Enterobacter sp. strain DC4, from root tubers of the yellow yam plant, Dioscorea cayenensis. Preliminary analyses suggest that the genomes of the three bacteria contain genes involved in acetoin and indole-3-acetic acid metabolism. PMID:24625871

  20. Susceptibility of Austrian Clinical Klebsiella and Enterobacter Isolates Linked to Patient-Related Data

    PubMed Central

    Badura, Alexandra; Pregartner, Gudrun; Holzer, Judith C.; Feierl, Gebhard; Grisold, Andrea J.

    2016-01-01

    The aim of the study was to analyze the antimicrobial susceptibility of Austrian clinical Klebsiella sp. and Enterobacter sp. isolates linked to patient-related data over a time period from 1998 to 2014. The main findings of this study were (i) a marked difference of antibiotic susceptibility rates between different infection sites for both Klebsiella sp. and Enterobacter sp., (ii) significantly greater percentages of resistant isolates among both Klebsiella sp. and Enterobacter sp. in male patients compared to female patients and (iii) significantly greater percentages of resistant isolates among both Klebsiella sp. and Enterobacter sp. from hospital-derived samples compared to samples from the community. In conclusion, our statistical data analysis clearly indicated a strong association of patient-related data and Klebsiella sp. and Enterobacter sp. susceptibility profiles. PMID:26903953

  1. Cronobacter ('Enterobacter sakazakii'): current status and future prospects.

    PubMed

    Chenu, J W; Cox, J M

    2009-08-01

    The genus Cronobacter accommodates the 16 biogroups of the emerging opportunistic pathogen known formerly as Enterobacter sakazakii. Cronobacter spp. are occasional contaminants of milk powder and, consequently, powdered infant formula and represent a significant health risk to neonates. This review presents current knowledge of the food safety aspects of Cronobacter, particularly in infant formula milk powder. Sources of contamination, ecology, disease characteristics and risk management strategies are discussed. Future directions for research are indicated, with a particular focus on the management of this increasingly important bacterium in the production environment.

  2. Biodegradation of dichlorodiphenyltrichloroethane: intermediates in dichlorodiphenylacetic acid metabolism by aerobacter aerogenes

    USGS Publications Warehouse

    Wedemeyer, Gary

    1967-01-01

    The final product of dichlorodiphenyltrichloroethane (DDT) degradation by vertebrates is commonly considered to be dichlorodiphenylacetic acid, DDA. Recently, certain organisms have been found to degrade further DDA to dichlorobenzophenone (DBP), but the possibility that such degradation was due to microbial action could not be excluded. Significantly, dichlorobenzhydrol (DBH), dichlorophenylmethane (DPM), and dichlorodiphenylethylene (DDE) have been tentatively identified in rats fed DDA. Since DDA as well as DDT is degraded by the ubiquitous microorganism Aerobacter aerogenes, it seemed reasonable that the intestinal microflora might be involved in DBP formation, DPM and DBH being intermediates in its pathway from DDA. Since DDA is a (3,y-unsaturated acid, ketone formation via an alkene and an alcohol would be expected.

  3. Enterobacter asburiae and Aeromonas hydrophila: soft tissue infection requiring debridement.

    PubMed

    Koth, Kevin; Boniface, James; Chance, Elisha A; Hanes, Marina C

    2012-06-01

    Enterobacter asburiae and Aeromonas hydrophila are gram-negative bacilli that have been isolated in soil and water. Enterobacter asburiae can cause an array of diseases, and exposure to A hydrophila can cause soft tissue infections, including necrotizing faciitis.A healthy-appearing 22-year-old man presented with an innocuous soft tissue injury to his leg due to an all-terrain vehicle crash. He received intravenous antibiotics and was discharged with prophylactic oral antibiotics. After the rapid onset of high fevers (102°F-103°F) <24 hours postinjury, he returned to the emergency department. Emergent surgical debridement was performed, and broad-spectrum intravenous antibiotics were started. Fevers persisted, and the patient underwent repeat extensive surgical debridement and antibiotic bead placement <30 hours after the initial surgical debridement and broad-spectrum antibiotics. Intraoperative cultures found E asburiae and A hydrophila in the wound. Following a long course of antibiotics and a skin graft, he fully recovered and had no functional deficits 1 year postoperatively.Extensive research revealed that these organisms are rare in soft tissue infections. E asburiae is opportunistic but has not been reported as a primary wound organism, and A hydrophila infections have been reported following motor vehicle crashes involving wound contamination. At presentation, it is challenging to determine rare organisms in a timely fashion; however, emergent extensive surgical intervention of an accelerated aberrant disease process should be considered to avoid catastrophic outcomes.

  4. Fermentation of polysaccharides by Klebsielleae and other facultative bacilli.

    PubMed

    Ochuba, G U; von Riesen, V L

    1980-05-01

    Fermentations of 10 polysaccharides by species of the family Enterobacteriaceae were examined. Algin, guar, karaya, xanthan, and xylan were not fermented by any of the strains tested. Most of the activity was found in the tribe Klebsielleae. Klebsiella oxytoca fermented amylopectin (97% of the strains studied), carrageenan (100%), inulin (68%), polypectate (100%), and tragacanth (100%). Klebsiella pneumoniae fermented amylopectin (91%), carrageenan (100%), and tragacanth (86%). Carrageenan was also fermented by Enterobacter aerogenes (100%), Enterobacter agglomerans (63%), Enterobacter cloacae (95%), and Pectobacterium (38%). Pectobacterium shared polypectate fermentation (100%) with K. oxytoca. With one exception, Serratia strains were negative on all polysaccharides. These results, along with other evidence, indicate that (i) the genus Klebsiella is biochemically the most versatile genus of the tribe, (ii) because of its distinct characteristics, K. oxytoca warrants species designation separate from K. pneumoniae, and (iii) some food additives generally considered indigestible can be metabolized by a few species of facultative bacilli, whereas others appear to be resistant.

  5. Fermentation of polysaccharides by Klebsiella and other facultative bacilli

    SciTech Connect

    Ochuba, G.U.; Von Riesen, V.L.

    1980-05-01

    Fermentations of 10 polysaccharides by species of the family Enterobacteriaceae were examined. Algin, guar, karaya, xanthan, and xylan were not fermented by any of the strains tested. Most of the activity was found in the tribe Klebsielleae. Klebseilla oxytoca fermented amylopectin (97% of the strains studied), carrageenan (100%), inulin (68%), polypectate (100%), and tragacanth (100%). Klebsiella pneumoniae fermented amylopectin (91%), carrageenan (100%), and tragacanth (86%). Carraggeenan was also fermented by Enterobacter aerogenes (100%), Enterobacter agglomerans (63%), Enterobacter cloacae (95%), and pectobacterium (38%). pectobacterium shared polypectate fermentation (100%) with K. oxytoca. With one exception, Serratia strains were negative on all polysaccharides. These results, along with other evidence, indicate that (i) the genus Klebsiella is biochemically the most versatile genus of the tribe, (ii) because of its distinct characteristics, K. oxytoca warrants species designation separate from K. pneumoniae, and (iii) some food additives generally considered indigestible can be metabolized by a few species of facultative bacilli, whereas others appear to be resistant.

  6. Exploring "aerogen-hydride" interactions between ZOF2 (Z = Kr, Xe) and metal hydrides: An ab initio study

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Mohammadian-Sabet, Fariba

    2016-06-01

    In this work, a new σ-hole interaction formed between ZOF2 (Z = Kr and Xe) as the Lewis acid and a series of metal-hydrides HMX (M = Be, Mg, Zn and X = H, F, CN, CH3) is reported. The nature of this interaction, called "aerogen-hydride" interaction, is unveiled by molecular electrostatic potential, non-covalent interaction, quantum theory of atoms in molecules and natural bond orbital analyses. Our results indicate that the aerogen-hydride interactions are quite strong and can be comparable in strength to other σ-hole bonds. An important charge-transfer interaction is also associated with the formation of OF2Z⋯HMX complexes.

  7. Anaerobic facultative bacteria isolated from the gut of rabbits fed different diets.

    PubMed

    Canganella, F; Zirletta, G; Gualterio, L; Massa, S; Trovatelli, L D

    1992-11-01

    Anaerobic facultative bacteria colonizing the intestinal tract of conventional rabbits fed three different diets (standard pellet, hay and pellet/hay mixture) were enumerated in brain heart infusion agar. Colony counts recovered from homogenized samples of small intestine, caecum and rectum differed with reference to the diet given. Among anaerobic groups, identified from rabbit fed pellet/hay mixture, Enterococci (E. faecalis, E. avium, E. faecium and E. durans) represented the predominant flora. Enterobacters (E. cloacae and E. aerogenes) accounted for about 10 to 25% of the bacteria in the rectum and colon respectively, whereas Staphylococci (S. intermedius, S. epidermidis and S. lentus) represented 11% of the bacteria isolated from colon.

  8. Enterobacter xiangfangensis sp. nov., isolated from Chinese traditional sourdough, and reclassification of Enterobacter sacchari Zhu et al. 2013 as Kosakonia sacchari comb. nov.

    PubMed

    Gu, Chun Tao; Li, Chun Yan; Yang, Li Jie; Huo, Gui Cheng

    2014-08-01

    A Gram-stain-negative bacterial strain, 10-17(T), was isolated from traditional sourdough in Heilongjiang Province, China. The bacterium was characterized by a polyphasic approach, including 16S rRNA gene sequence analysis, RNA polymerase β subunit (rpoB) gene sequence analysis, DNA gyrase (gyrB) gene sequence analysis, initiation translation factor 2 (infB) gene sequence analysis, ATP synthase β subunit (atpD) gene sequence analysis, fatty acid methyl ester analysis, determination of DNA G+C content, DNA-DNA hybridization and an analysis of phenotypic features. Strain 10-17(T) was phylogenetically related to Enterobacter hormaechei CIP 103441(T), Enterobacter cancerogenus LMG 2693(T), Enterobacter asburiae JCM 6051(T), Enterobacter mori LMG 25706(T), Enterobacter ludwigii EN-119(T) and Leclercia adecarboxylata LMG 2803(T), having 99.5%, 99.3%, 98.7%, 98.5%, 98.4% and 98.4% 16S rRNA gene sequence similarity, respectively. On the basis of polyphasic characterization data obtained in the present study, a novel species, Enterobacter xiangfangensis sp. nov., is proposed and the type strain is 10-17(T) ( = LMG 27195(T) = NCIMB 14836(T) = CCUG 62994(T)). Enterobacter sacchari Zhu et al. 2013 was reclassified as Kosakonia sacchari comb. nov. on the basis of 16S rRNA, rpoB, gyrB, infB and atpD gene sequence analysis and the type strain is strain SP1(T)( = CGMCC 1.12102(T) = LMG 26783(T)).

  9. Complete genome sequence of “Enterobacter lignolyticus” SCF1

    PubMed Central

    D’Haeseleer, Patrik; Chivian, Dylan; Fortney, Julian L.; Khudyakov, Jane; Simmons, Blake; Woo, Hannah; Arkin, Adam P.; Davenport, Karen Walston; Goodwin, Lynne; Chen, Amy; Ivanova, Natalia; Kyrpides, Nikos C.; Mavromatis, Konstantinos; Woyke, Tanja; Hazen, Terry C.

    2011-01-01

    In an effort to discover anaerobic bacteria capable of lignin degradation, we isolated “Enterobacter lignolyticus” SCF1 on minimal media with alkali lignin as the sole source of carbon. This organism was isolated anaerobically from tropical forest soils collected from the Short Cloud Forest site in the El Yunque National Forest in Puerto Rico, USA, part of the Luquillo Long-Term Ecological Research Station. At this site, the soils experience strong fluctuations in redox potential and are net methane producers. Because of its ability to grow on lignin anaerobically, we sequenced the genome. The genome of “E. lignolyticus” SCF1 is 4.81 Mbp with no detected plasmids, and includes a relatively small arsenal of lignocellulolytic carbohydrate active enzymes. Lignin degradation was observed in culture, and the genome revealed two putative laccases, a putative peroxidase, and a complete 4-hydroxyphenylacetate degradation pathway encoded in a single gene cluster. PMID:22180812

  10. Persistent cloaca, fused kidneys, female pseudohermaphroditism and skeletal anomalies in a simmental calf.

    PubMed

    Gulbahar, M Y; Kabak, M; Yarim, M; Guvenc, T; Kabak, Y B

    2009-06-01

    A 5-day-old Simmental calf was referred to our department for atresia ani and postural abnormalities caused by skeletal deformities. The calf had a short and deviated tail and a bowed hind limb. The calf appeared like a male because of the prepuce and penis located just near the teats and the absence of female external genitalia. During the necropsy, a horseshoe kidney, single ureter that originated from the kidney, and bilateral uterine horns with one ovary each were detected. The ureter, blind-ended large intestine, and bilateral uterine horns were connected to a dilated cloaca having two sacs, which were filled with a yellowish brown viscous fluid admixed with meconium and urine. Skeletal deformities found included scoliosis, partial synostosis of vertebrae, deviation of rudimentary sacrum and coccygeal vertebrae, and narrowed pelvic cavity. This is the first report of an anomalous combination including urogenital, large intestinal, and skeletal deformities in cattle.

  11. Kinetic characterization of a novel acid ectophosphatase from Enterobacter asburiae.

    PubMed

    Sato, Vanessa Sayuri; Galdiano Júnior, Renato F; Rodrigues, Gisele Regina; Lemos, Eliana G M; Pizauro Junior, João Martins

    2016-02-01

    Expression of acid ectophosphatase by Enterobacter asburiae, isolated from Cattleya walkeriana (Orchidaceae) roots and identified by the 16S rRNA gene sequencing analysis, was strictly regulated by phosphorus ions, with its optimal activity being observed at an inorganic phosphate concentration of 7 mM. At the optimum pH 3.5, intact cells released p-nitrophenol at a rate of 350.76 ± 13.53 nmol of p-nitrophenolate (pNP)/min/10(8) cells. The membrane-bound enzyme was obtained by centrifugation at 100,000 × g for 1 h at 4 °C. p-Nitrophenylphosphate (pNPP) hydrolysis by the enzyme follows "Michaelis-Menten" kinetics with V = 61.2 U/mg and K0.5 = 60 μM, while ATP hydrolysis showed V = 19.7 U/mg, K0.5 = 110 μM, and nH = 1.6 and pyrophosphate hydrolysis showed V = 29.7 U/mg, K0.5 = 84 μM, and nH = 2.3. Arsenate and phosphate were competitive inhibitors with K i = 0.6 mM and K i = 1.8 mM, respectively. p-Nitrophenyl phosphatase (pNPPase) activity was inhibited by vanadate, while p-hydroxymercuribenzoate, EDTA, calcium, copper, and cobalt had no inhibitory effects. Magnesium ions were stimulatory (K0.5 = 2.2 mM and nH = 0.5). Production of an acid ectophosphatase can be a mechanism for the solubilization of mineral phosphates by microorganisms such as Enterobacter asburiae that are versatile in the solubilization of insoluble minerals, which, in turn, increases the availability of nutrients for plants, particularly in soils that are poor in phosphorus.

  12. Generation of Enterobacter sp. YSU auxotrophs using transposon mutagenesis.

    PubMed

    Caguiat, Jonathan James

    2014-10-31

    Prototrophic bacteria grow on M-9 minimal salts medium supplemented with glucose (M-9 medium), which is used as a carbon and energy source. Auxotrophs can be generated using a transposome. The commercially available, Tn5-derived transposome used in this protocol consists of a linear segment of DNA containing an R6Kγ replication origin, a gene for kanamycin resistance and two mosaic sequence ends, which serve as transposase binding sites. The transposome, provided as a DNA/transposase protein complex, is introduced by electroporation into the prototrophic strain, Enterobacter sp. YSU, and randomly incorporates itself into this host's genome. Transformants are replica plated onto Luria-Bertani agar plates containing kanamycin, (LB-kan) and onto M-9 medium agar plates containing kanamycin (M-9-kan). The transformants that grow on LB-kan plates but not on M-9-kan plates are considered to be auxotrophs. Purified genomic DNA from an auxotroph is partially digested, ligated and transformed into a pir+ Escherichia coli (E. coli) strain. The R6Kγ replication origin allows the plasmid to replicate in pir+ E. coli strains, and the kanamycin resistance marker allows for plasmid selection. Each transformant possesses a new plasmid containing the transposon flanked by the interrupted chromosomal region. Sanger sequencing and the Basic Local Alignment Search Tool (BLAST) suggest a putative identity of the interrupted gene. There are three advantages to using this transposome mutagenesis strategy. First, it does not rely on the expression of a transposase gene by the host. Second, the transposome is introduced into the target host by electroporation, rather than by conjugation or by transduction and therefore is more efficient. Third, the R6Kγ replication origin makes it easy to identify the mutated gene which is partially recovered in a recombinant plasmid. This technique can be used to investigate the genes involved in other characteristics of Enterobacter sp. YSU or of a

  13. Isolation of Cronobacter spp. (Enterobacter Sakazakii) from Artisanal Mozzarella

    PubMed Central

    Rippa, Paola; Battaglia, Luciana; Parisi, Nicola

    2014-01-01

    Cronobacter spp. (Enterobacter sakazakii) is an opportunistic bacterial pathogen capable of causing disease and even fatalities in newborn infants within the first weeks of life if consumed as part of the diet. Premature and immunocompromised newborn infants are at particular risk. The microorganism has been isolated from a variety of foods including contaminated infant milk formula powder and milk powder substitute. The study aimed to evaluate the level of microbiological contamination in 47 samples of mozzarella cheese made with cow’s milk collected from artisan cheese producers in Southern Italy. Samples were collected from commercial sales points and underwent qualitative and quantitative microbiological analyses to test for the bacterial contaminants most commonly found in milk and cheese products. The 47 samples underwent qualitative and quantitative microbiological tests according to ISO UNI EN standards. Analyses focused on Staphylococcus aures, Salmonella spp., Listeria monocytogenes, Pseudomonas spp., E. coli, Yersinia spp., total coliforms and Cronobacter sakazakii. The ISO/TS 22964:2006 method was used to investigate possible contamination by C. sakazakii. Biochemical identification was carried out using an automated system for identification and susceptibility tests. None of the samples examined resulted positive for Salmonella spp. or Listeria spp. Only one sample resulted positive for Staphylococcus aureus. Pseudomonas spp. was isolated in 10 (21%) of 47 samples. High levels of total coliforms were found in 10 of 47 samples. Cronobacter spp. (Enterobacter sakazakii) was isolated in one sample. This is the first study to confirm isolation of C. sakazakii in artisan mozzarella cheese made from cow’s milk. The presence of C. sakazakii could be related to external contamination during the phases of production or to the use of contaminated milk. Since mozzarella is recommended in the diet of children and adults of all ages, this present study helps

  14. Isolation, identification, characterization, and evaluation of cadmium removal capacity of Enterobacter species.

    PubMed

    Abbas, Syed Zaghum; Rafatullah, Mohd; Ismail, Norli; Lalung, Japareng

    2014-12-01

    This study focused on the isolation and characterization of high cadmium-resistant bacterial strains, possible exploitation of its cadmium-accumulation and cadmium-induced proteins. Cadmium-resistant bacterial strains designated as RZ1 and RZ2 were isolated from industrial wastewater of Penang, Malaysia. These isolates were identified as Enterobacter mori and Enterobacter sp. WS12 on the basis of phenotypic, biochemical and 16S rDNA sequence based molecular phylogenetic characteristics. Both isolates were Gram negative, cocci, and growing well in Lauria-Bertani broth medium at 35 °C temperature and pH 7.0. Results also indicated that Enterobacter mori and Enterobacter sp. WS12are capable to remove 87.75 and 85.11% of the cadmium from 100 µg ml(-1) concentration, respectively. This study indicates that these strains can be useful as an inexpensive and efficient bioremediation technology to remove and recover the cadmium from wastewater.

  15. Long Chain N-acyl Homoserine Lactone Production by Enterobacter sp. Isolated from Human Tongue Surfaces

    PubMed Central

    Yin, Wai-Fong; Purmal, Kathiravan; Chin, Shenyang; Chan, Xin-Yue; Chan, Kok-Gan

    2012-01-01

    We report the isolation of N-acyl homoserine lactone-producing Enterobacter sp. isolate T1-1 from the posterior dorsal surfaces of the tongue of a healthy individual. Spent supernatants extract from Enterobacter sp. isolate T1-1 activated the biosensor Agrobacterium tumefaciens NTL4(pZLR4), suggesting production of long chain AHLs by these isolates. High resolution mass spectrometry analysis of these extracts confirmed that Enterobacter sp. isolate T1-1 produced a long chain N-acyl homoserine lactone, namely N-dodecanoyl-homoserine lactone (C12-HSL). To the best of our knowledge, this is the first isolation of Enterobacter sp., strain T1-1 from the posterior dorsal surface of the human tongue and N-acyl homoserine lactones production by this bacterium. PMID:23202161

  16. First report of IMI-1-producing colistin-resistant Enterobacter clinical isolate in Ireland, March 2013.

    PubMed

    Boo, T W; O'Connell, N; Power, L; O'Connor, M; King, J; McGrath, E; Hill, R; Hopkins, K L; Woodford, N

    2013-08-01

    We report the first case in Ireland of an IMI-1 carbapenemase-producing Enterobacter asburiae, which was resistant to both colistin and fosfomycin. The circumstances under which this isolate was acquired were unclear. Several reports of IMI-producing Enterobacter spp. have emerged in recent years, and colistin resistance in Enterobacteriaceae is also increasingly reported. Laboratories should be aware of the unusual antibiograms of IMI-producing isolates.

  17. Laminin 5 expression protects against anoikis at aerogenous spread and lepidic growth of human lung adenocarcinoma.

    PubMed

    Kodama, Keiji; Ishii, Gen'ichiro; Miyamoto, Shin'ichi; Goya, Masato; Zhang, Shi-Chuan; Sangai, Takafumi; Yoshikawa, Takeshi; Hasebe, Takahiro; Hitomi, Yoshiaki; Izumi, Keisuke; Ochiai, Atsushi

    2005-10-10

    Adenocarcinoma of the lung is characterized by frequent aerogenous spread (AE) and advancement along the alveolar wall (BAC growth). To elucidate the mechanism of AE metastasis and BAC growth in human lung adenocarcinoma, we established an in vivo orthotopic animal model and an in vitro culture. Investigation of expression levels of integrins, laminins and Type IV collagens, which are the major regulating molecules for cell attachment and anoikis was carried out and a clear correlation between the expression level of laminin 5 (LN5) and the BAC growth was observed using an orthotopic animal model. Introduction of LN5 cDNA to A549 cells increased anoikis resistance in an expression dependent manner. Cells with LN5 overexpression resisted with anoikis after treatment with PI3K-Akt and ERK inhibitors. The amount of phosphorylated focal adhesion kinase (FAK) was also higher in LN5 overexpressing cells. Major tyrosine residues of the EGF receptor at 1068, 1086 and 1173, except at 1148, remained phosphorylated only in the LN5 overexpressing cells even without EGF stimulation, that indicates the ligand independent activation of EGF receptor. BAC growth ratio and AE was confirmed to be significantly correlated with LN5 expression in surgically resected human lung adenocarcinomas by immunohistochemistry. Our results indicate that the activation of the EGF receptor by overexpressing LN5-integrin-FAK signaling pathway may play a crucial role in BAC growth and AE metastasis in human lung adenocarcinoma.

  18. [A case of poorly differentiated lung adenocarcinoma showing air-space consolidation caused by aerogenic metastasis].

    PubMed

    Fujita, Kazue; Kurihara, Takeyuki; Ohba, Hideo; Nakamura, Junichi; Okimoto, Niro

    2004-05-01

    A 78-year-old woman was admitted to our hospital because of dyspnea. A chest radiograph and a computed tomogram on admission showed air-space consolidation in the left upper lung field, and so pneumonia was diagnosed. Although antibiotics were administered, the air-space consolidation did not improve. A transbronchial lung biopsy was performed, yielding a pathologic diagnosis of poorly differentiated lung adenocarcinoma. Despite combination chemotherapy with docetaxel and UFT, the air-space consolidation expanded, and the patient finally died of respiratory failure 3 months after diagnosis. Autopsy revealed air-space consolidation due to poorly differentiated lung adenocarcinoma, with large atypical cells diffusely floating in the alveolar spaces. It has been recognized that bronchiolo-alveolar carcinoma and well-differentiated lung adenocarcinoma present with air-space consolidation, reflecting the cancer cells lining the alveolar walls. However, in this case, the air-space consolidation was due to cancer cells diffusely floating in the alveolar spaces in aerogenic metastasis. It was considered that this is a rare case, which presented with a very interesting development pattern.

  19. Structural and kinetic studies on beta-lactamase K1 from Klebsiella aerogenes.

    PubMed Central

    Emanuel, E L; Gagnon, J; Waley, S G

    1986-01-01

    beta-Lactamase K1 from Klebsiella aerogenes 1082E hydrolyses both penicillins and cephalosporins comparably and is inhibited by mercurials but not by cloxacillin. These properties distinguish it from those other beta-lactamases that have been allotted to classes on the basis of their amino sequences. beta-Lactamase K1 has been isolated by affinity chromatography; its composition shows resemblances to class A beta-lactamases. Moreover, the N-terminal sequence is similar to those of class A beta-lactamases: there is about 30% identity over the first 32 residues. Furthermore, a putative active-site octapeptide has been isolated and its sequence is similar to the region around the active-site serine residue in class A beta-lactamases. There is one thiol group in beta-lactamase K1; it is not essential for activity. The pH-dependence of kcat. and kcat./Km for the hydrolysis of benzylpenicillin by beta-lactamase K1 were closely similar, suggesting that the rate-determining step is cleavage of the beta-lactam ring. PMID:3521585

  20. Part of respiratory nitrate reductase of Klebsiella aerogenes is intimately associated with the peptidoglycan.

    PubMed

    Abraham, P R; Wientjes, F B; Nanninga, N; Van't Riet, J

    1987-02-01

    Lysozyme digestion and sonication of sodium dodecyl sulfate (SDS)-purified Klebsiella aerogenes murein sacculi resulted in the quantitative release of both subunits of nitrate reductase, as well as a number of other cytoplasmic membrane polypeptides (5.2%, by weight, of the total membrane proteins). Similar results were obtained after lysozyme digestion of SDS-prepared peptidoglycan fragments, which excluded the phenomenon of simple trapping of the polypeptides by the surrounding peptidoglycan matrix. About 28% of membrane-bound nitrate reductase appears to be tightly associated with the peptidoglycan. Additional evidence for this association was demonstrated by positive immunogold labeling of SDS-murein sacculi and thin sections of plasmolyzed bacteria. Qualitative amino acid analysis of trypsin-treated sacculi, a tryptic product of holo-nitrate reductase, and amino- and carboxypeptidase digests of both nitrate reductase subunits indicated the possible existence of a terminal anchoring peptide containing the following amino acids: (Gly)n, Trp, Ser, Pro, Ile, Leu, Phe, Cys, Tyr, Asp, and Lys.

  1. Biodegradation of ichlorodiphenyltrichloroe-thane: Intermediates in dichlorodiphenylacetic acid metabolism by Aerobacter aerogenes

    USGS Publications Warehouse

    1967-01-01

    The final product of dichlorodiphenyltrichloroethane (DDT) degradation by vertebrates is commonly considered to be dichlorodiphenylacetic acid, DDA (J. E. Peterson and W. H. Robison, Toxicol. Appl. Pharmacol. 6:321, 1964). Recently, certain organisms (A. S. Perry, S. Miller, and A. J. Buckner. J. Agr. Food Chem. 11:457, 1963; J. D. Pinto, M. N. Comien, and M. S. Dunn. J. Biol. Chem. 240:2148, 1965) have been found to degrade further DDA to dichlorobenzophenone (DBP), but the possibility that such degradation was due to microbial action could not be excluded. Significantly, dichlorobenzhydrol (DBH), dichlorophenylmethane (DPM), and dichlorodiphenylethylene (DDE) have been tentatively identified in rats fed DDA (Pinto et al., J. Biol. Chem. 240:2148, 1965). Since DDA as well as DDT is degraded by the ubiquitous microorganism Aerobacter aerogenes (G. Wedemeyer, Appl. Microbiol. 15:569, 1967; J. L. Mendel, and M. S. Walton, Science 151:1527, 1966), it seemed reasonable that the intestinal microflora might be involved in DBP formation, DPM and DBH being intermediates in its pathway from DDA. Since DDA is a (3,y-unsaturated acid, ketone formation via an alkene and an alcohol would be expected (S. G. Waley, Mechanisms of Organic and Enzymatic Reactions, Oxford University Press, London, England 1962).

  2. The beta-glucoside genes of Klebsiella aerogenes: conservation and divergence in relation to the cryptic bgl genes of Escherichia coli.

    PubMed

    Raghunand, Tirumalai R; Mahadevan, S

    2003-06-27

    The ability to metabolize aromatic beta-glucosides such as salicin and arbutin varies among members of the Enterobacteriaceae. The ability of Escherichia coli to degrade salicin and arbutin appears to be cryptic, subject to activation of the bgl genes, whereas many members of the Klebsiella genus can metabolize these sugars. We have examined the genetic basis for beta-glucoside utilization in Klebsiella aerogenes. The Klebsiella equivalents of bglG, bglB and bglR have been cloned using the genome sequence database of Klebsiella pneumoniae. Nucleotide sequencing shows that the K. aerogenes bgl genes show substantial similarities to the E. coli counterparts. The K. aerogenes bgl genes in multiple copies can also complement E. coli mutants deficient in bglG encoding the antiterminator and bglB encoding the phospho-beta-glucosidase, suggesting that they are functional homologues. The regulatory region bglR of K. aerogenes shows a high degree of similarity of the sequences involved in BglG-mediated regulation. Interestingly, the regions corresponding to the negative elements present in the E. coli regulatory region show substantial divergence in K. aerogenes. The possible evolutionary implications of the results are discussed.

  3. Biochemical basis of mercury remediation and bioaccumulation by Enterobacter sp. EMB21.

    PubMed

    Sinha, Arvind; Kumar, Sumit; Khare, Sunil Kumar

    2013-01-01

    The aims of this study were to isolate metal bioaccumulating bacterial strains and to study their applications in removal of environmental problematic heavy metals like mercury. Five bacterial strains belonging to genera Enterobacter, Bacillus, and Pseudomonas were isolated from oil-spilled soil. Among these, one of the strains Enterobacter sp. EMB21 showed mercury bioaccumulation inside the cells simultaneous to its bioremediation. The bioaccumulation of remediated mercury was confirmed by transmission electron microscopy and energy dispersive X-ray. The mercury-resistant loci in the Enterobacter sp. EMB21 cells were plasmid-mediated as confirmed by transformation of mercury-sensitive Escherichia coli DH5α by Enterobacter sp. EMB21 plasmid. Effect of different culture parameters viz-a-viz inoculum size, pH, carbon, and nitrogen source revealed that alkaline pH and presence of dextrose and yeast extract favored better remediation. The results indicated the usefulness of Enterobacter sp. EMB21 for the effective remediation of mercury in bioaccumulated form. The Enterobacter sp. EMB21 seems promising for heavy metal remediation wherein the remediated metal can be trapped inside the cells. The process can further be developed for the synthesis of valuable high-end functional alloy, nanoparticles, or metal conjugates from the metal being remediated.

  4. Enterobacter pulveris sp. nov., isolated from fruit powder, infant formula and an infant formula production environment.

    PubMed

    Stephan, Roger; Van Trappen, Stefanie; Cleenwerck, Ilse; Iversen, Carol; Joosten, Han; De Vos, Paul; Lehner, Angelika

    2008-01-01

    Six Gram-negative, facultatively anaerobic, non-spore-forming, coccoid rod-shaped isolates were obtained from fruit powder (n=3), infant formula (n=2) and an infant formula production environment (n=1) and investigated in a polyphasic taxonomic study. Comparative 16S rRNA gene sequence analysis combined with rpoB gene sequence analysis allocated the isolates to the family Enterobacteriaceae. The highest rpoB gene sequence similarities (91.2-95.8%) were obtained with Enterobacter helveticus, Enterobacter radicincitans, Enterobacter turicensis and Enterobacter sakazakii and the phylogenetic branch formed by these species was supported by a high bootstrap value. Biochemical data revealed that the isolates could be differentiated from their nearest neighbours by their ability to utilize melibiose, sucrose, D-arabitol, mucate and 1-O-methyl-alpha-galactopyranoside and their negative reactions for D-sorbitol utilization and the Voges-Proskauer test. On the basis of the phylogenetic analyses, DNA-DNA hybridization data, and unique physiological and biochemical characteristics, it is proposed that the isolates represent a novel species of the genus Enterobacter, Enterobacter pulveris sp. nov. The type strain is 601/05(T) (=LMG 24057(T)=DSM 19144(T)).

  5. Biohydrogen production by dark fermentation of glycerol using Enterobacter and Citrobacter Sp.

    PubMed

    Maru, Biniam T; Constanti, Magda; Stchigel, Alberto M; Medina, Francesc; Sueiras, Jesus E

    2013-01-01

    Glycerol is an attractive substrate for biohydrogen production because, in theory, it can produce 3 mol of hydrogen per mol of glycerol. Moreover, glycerol is produced in substantial amounts as a byproduct of producing biodiesel, the demand for which has increased in recent years. Therefore, hydrogen production from glycerol was studied by dark fermentation using three strains of bacteria: namely, Enterobacter spH1, Enterobacter spH2, and Citrobacter freundii H3 and a mixture thereof (1:1:1). It was found that, when an initial concentration of 20 g/L of glycerol was used, all three strains and their mixture produced substantial amounts of hydrogen ranging from 2400 to 3500 mL/L, being highest for C. freundii H3 (3547 mL/L) and Enterobacter spH1 (3506 mL/L). The main nongaseous fermentation products were ethanol and acetate, albeit in different ratios. For Enterobacter spH1, Enterobacter spH2, C. freundii H3, and the mixture (1:1:1), the ethanol yields (in mol EtOH/mol glycerol consumed) were 0.96, 0.67, 0.31, and 0.66, respectively. Compared to the individual strains, the mixture (1:1:1) did not show a significantly higher hydrogen level, indicating that there was no synergistic effect. Enterobacter spH1 was selected for further investigation because of its higher yield of hydrogen and ethanol.

  6. Accumulation of radiocalcium from the aquatic medium via the cloaca and bucco-pharynx of Australian freshwater turtles (Chelidae).

    PubMed

    Jeffree, R A; Jones, M K

    1992-05-01

    1. The cloacal and bucco-pharyngeal regions of three species of Australian freshwater turtles were experimentally compared for their ability to take up radiocalcium directly from the aquatic medium. 2. The cloacal route was at least 4 times more important than the bucco-pharyngeal route for radiocalcium uptake, in each of the three species investigated. 3. Histological examination of anatomical regions in the cloaca showed that the cloacal bursae of three species (E. dentata, C. longicollis and E. signata) had abundant villi and infolded mucosal epithelia that increase the surface area of the epithelium exposed to the aquatic medium. 4. Electron microscopic studies on the mucosal epithelium of the cloacal bursae showed that it contained many structural characteristics indicative of an exchange function and consistent with the cloacal bursae being an important site of radiocalcium uptake within the cloaca.

  7. Theoretical Study on the Dual Behavior of XeO3 and XeF4 toward Aromatic Rings: Lone Pair-π versus Aerogen-π Interactions.

    PubMed

    Bauzá, Antonio; Frontera, Antonio

    2015-12-01

    In this study, several lone pair-π and aerogen-π complexes between XeO3 and XeF4 and aromatic rings with different electronic natures (benzene, trifluorobenzene, and hexafluorobenzene) are optimized at the RI-MP2/aug-cc-pVTZ level of theory. All complexes are characterized as true minima by frequency analysis calculations. The donor/acceptor role of the ring in the complexes is analyzed using the natural bond orbital computational tool, showing a remarkable contribution of orbital interactions to the global stabilization of the aerogen-π complexes. Finally, Bader's AIM analysis of several complexes is performed to further characterize the lone pair-π and aerogen-π interactions.

  8. Gross anatomical features of the gastrointestinal tract (GIT) of blue-and-yellow macaws (Ara ararauna) - oesophagus to cloaca.

    PubMed

    Aizawa, J; Tivane, C; Rodrigues, M N; Wagner, P G; Campos, D B; Guerra, R R; Miglino, M A

    2013-12-01

    Morphological studies of the gastrointestinal tract of blue-and-yellow macaws (Ara ararauna) are scarce. In view of the paucity of information regarding the digestive tract of macaws, this study aims to describe the gross anatomical features (oesophagus to cloaca) as part of a broad study of the gastrointestinal tract (GIT) of these birds. Three animals (two males and one female) adult macaws were anatomically dissected from the oropharynx to the cloaca to expose the GIT. The oesophagus was identified as a muscle-membranous tube continuous with the crop, which was intimately attached to the skin. The internal longitudinal folds of the cervical oesophagus were sparser cranial to the crop and less evident compared to the portion caudal to the crop. The duodenum began in the pylorus and was grey-coloured exhibiting a large lumen. The jejunum was formed by loops in a spiral-fashion model supported by mesojejunum. The ileum was also composed by small loops and was continuous with the colo-rectum forming the large intestine, because the caeca were absent. The large intestine was short, median in position, suspended in the dorsal wall of the abdominal cavity by mesentery and ended in the cloaca. The GIT was similar to the basic patterns in birds, in general, and also presented new unreported morphological data that might be important when studying nutrition and health of the macaws.

  9. Re-examination of the taxonomic status of Enterobacter helveticus, Enterobacter pulveris and Enterobacter turicensis as members of the genus Cronobacter and their reclassification in the genera Franconibacter gen. nov. and Siccibacter gen. nov. as Franconibacter helveticus comb. nov., Franconibacter pulveris comb. nov. and Siccibacter turicensis comb. nov., respectively.

    PubMed

    Stephan, Roger; Grim, Christopher J; Gopinath, Gopal R; Mammel, Mark K; Sathyamoorthy, Venugopal; Trach, Larisa H; Chase, Hannah R; Fanning, Séamus; Tall, Ben D

    2014-10-01

    Recently, a taxonomical re-evaluation of the genus Enterobacter, based on multi-locus sequence typing (MLST) analysis, has led to the proposal that the species Enterobacter pulveris, Enterobacter helveticus and Enterobacter turicensis should be reclassified as novel species of the genus Cronobacter. In the present work, new genome-scale analyses, including average nucleotide identity, genome-scale phylogeny and k-mer analysis, coupled with previously reported DNA-DNA hybridization values and biochemical characterization strongly indicate that these three species of the genus Enterobacter are not members of the genus Cronobacter, nor do they belong to the re-evaluated genus Enterobacter. Furthermore, data from this polyphasic study indicated that all three species constitute two new genera. We propose reclassifying Enterobacter pulveris and Enterobacter helveticus in the genus Franconibacter gen. nov. as Franconibacter pulveris comb. nov. (type strain 601/05(T) = LMG 24057(T) = DSM 19144(T)) and Franconibacter helveticus comb. nov. (type strain 513/05(T) = LMG 23732(T) = DSM 18396(T)), respectively, and Enterobacter turicensis in the genus Siccibacter gen. nov. as Siccibacter turicensis comb. nov. (type strain 508/05(T) = LMG 23730(T) = DSM 18397(T)).

  10. Enterobacter sakazakii: An Emerging Pathogen in Infants and Neonates

    PubMed Central

    Petrosyan, Mikael; Ford, Henri R.; Prasadarao, Nemani V.

    2008-01-01

    Abstract Background Enterobacter sakazakii (ES) is an emerging pathogen associated with the ingestion of contaminated reconstituted formula that causes necrotizing enterocolitis, sepsis, and meningitis in low-birth-weight preterm neonatal infants. Necrotizing enterocolitis remains the most common gastrointestinal surgical emergency in these infants. In recent years, the International Commission on Microbiological Specifications for Foods has ranked ES a “severe hazard for restricted populations.” Because of its resistance to certain antibiotics, better understanding of ES pathogenesis is needed to aid in the development of new preventive strategies. Methods Review of pertinent English-language literature. Results Neonatal and older infants appear to be at the highest risk, although adult ES infections have been reported. We discuss the origins of ES, the detection and pathogenesis of the disease, and potential prevention strategies. Conclusions The precise pathogenesis of ES remains a mystery. Appropriate measures by parents, infant formula manufacturers, and health care providers, as well as understanding of the pathogenesis, are important in the prevention of ES-related infections. PMID:18687047

  11. Powder infant formula milk contaminated with Enterobacter sakazakii.

    PubMed

    Oonaka, Kenji; Furuhata, Katsunori; Hara, Motonobu; Fukuyama, Masafumi

    2010-03-01

    To clarify the route and source of Enterobacter sakazakii infection in a basic study, we analyzed powder infant formula milk (PIF), which may be an important source of infantile infection, regarding contamination with Enterobacteriaceae including this type of bacteria, and conducted drug sensitivity tests with various antimicrobial agents. Enterobacteriaceae was isolated 36 (24.2%) of 149 PIF samples. These comprised of 12 (19.7%) of 61 domestically produced samples and 24 (27.3%) of 88 imported samples. E. sakazakii was isolated in 9 (6.6%) of the 149 PIF samples. These comprised 4 (6.6%) of 61 domestically produced samples and 5 (5.7%) of 88 imported samples. In 8 of the 9 samples in which E. sakazakii was isolated, the bacterial levels were estimated to be 0.36 MPN/100 g. However, one imported sample showed a bacterial level of 0.91 MPN/100 g. In the drug sensitivity tests of E. sakazakii isolated from PIF, we compared the MIC(90) values. E. sakazakii was highly sensitive to 9 agents: cefotaxime, ceftriaxone, cefoperazone, ceftazidime, cefpirome, cefozopran, gentamicin, meropenem, and ciprofloxacin, and moderately sensitive to 5 agents: piperacillin, erythromycin, minocycline, chloramphenicol, and rifampicin. However, it was resistant to 2 agents, ampicillin and lincomycin.

  12. Isolation and identification of Enterobacter sakazakii in infant milk formulas.

    PubMed

    Torres-Chavolla, Edith; Ramírez-Cerda, Elsa; Gutiérrez-Rojo, Rosalba

    2007-01-01

    Enterobacter sakazakii is a pathogen of increasing medical concern, due to it being implicated in cases of meningitis, sepis, and necrotizing enterocolitis associated with the consumption of contaminated infant milk formula. At present, the method adopted by the Mexican food industry for the isolation and identification of E. sakazakii is based on the methodology of the United States Food and Drug Administration (FDA). However, this procedure is laborious and requires 7 days to obtain a confirmative result. The objective of this study was to determine the presence of E. sakazakii in two types of powdered infant milk formula, using an alternative method that requires less time and a smaller sample size than the FDA protocol. We adapted Leuschner's procedure by eliminating violet red bile glucose agar (VRBG) plates and instead adopting white light incubation to stimulate yellow pigment development. This allowed for isolation of E. sakazakii from powdered infant milk formula using a smaller sample and requiring only 5 days for analysis. Results showed that 92% of formula 1 and 32% of formula 2 was positive for E. sakazakii. The high contamination level of E. sakazakii suggests the need for monitoring hygienic conditions in the manufacturing plant and to assess the prevalence of E. sakazakii in powdered infant milk formulas sold in México.

  13. Estimation of cultivable bacterial diversity in the cloacae and pharynx in Eurasian griffon vultures (Gyps fulvus).

    PubMed

    Vela, Ana I; Casas-Díaz, Encarna; Fernández-Garayzábal, José F; Serrano, Emmanuel; Agustí, Susana; Porrero, María C; Sánchez del Rey, Verónica; Marco, Ignasi; Lavín, Santiago; Domínguez, Lucas

    2015-04-01

    In this work, we describe the biodiversity of cloacal and pharynx culture-based bacteria (commensal and pathogenic), in 75 Eurasian griffon vultures (Gyps fulvus) from two geographic areas. We address the question of whether the cultivable microbiota of vultures is organised into assemblages occurring by chance. In addition, we assess bacterial diversity in both anatomic regions and geographic areas. Bacterial diversity was represented by 26 Gram-negative and 20 Gram-positive genera. The most common genera were Escherichia, Enterococcus, Staphylococcus, Clostridium and Lactococcus. Escherichia coli and Enterococcus faecalis were the most common species in cloacal and pharyngeal samples. Staphylococcus and Erysipelothrix were isolated from the pharynx and Salmonella and Corynebacterium from the cloacae, and no Campylobacter was isolated from the cloacal swabs. Ten cloacal swabs were positive for Salmonella, of which five isolates were Salmonella enterica serotype 4,(5),12:i:-, one isolate was S. enterica serotype Derby, three isolates were S. enterica serotype 61:k:1,5,7 and one isolate was S. enterica serotype Infantis. The null modelling approach revealed that the commensal bacteria of vultures are not structured in assemblages. On the other hand, differences in bacterial genus and species richness between cloacal and pharyngeal samples or between geographic areas were clear, with the pharynx in vultures from both geographic areas being richer. The results of this study indicate also that vultures can serve as a reservoir of certain pathogenic zoonotic bacteria. The dissemination of these zoonotic pathogens in wildlife could be prevented by periodic sanitary surveys.

  14. Dkk1 in the peri-cloaca mesenchyme regulates formation of anorectal and genitourinary tracts.

    PubMed

    Guo, Chaoshe; Sun, Ye; Guo, Chunming; MacDonald, Bryan T; Borer, Joseph G; Li, Xue

    2014-01-01

    Anorectal malformation (ARM) is a common birth defect but the developmental history and the underlying molecular mechanism are poorly understood. Using murine genetic models, we report here that a signaling molecule Dickkopf-1 (Dkk1) is a critical regulator. The anorectal and genitourinary tracts are major derivatives of caudal hindgut, or the cloaca.Dkk1 is highly expressed in the dorsal peri-cloacal mesenchymal (dPCM) progenitors. We show that the deletion of Dkk1 causes the imperforate anus with rectourinary fistula. Mutant genital tubercles exhibit a preputial hypospadias phenotype and premature urethral canalization.Dkk1 mutants have an ectopic expansion of the dPCM tissue, which correlates with an aberrant increase of cell proliferation and survival. This ectopic tissue is detectable before the earliest sign of the anus formation, suggesting that it is most likely the primary or early cause of the defect. Deletion of Dkk1 results in an elevation of the Wnt/ß-catenin activity. Signaling molecules Shh, Fgf8 and Bmp4 are also upregulated. Furthermore, genetic hyperactivation of Wnt/ß-catenin signal pathway in the cloacal mesenchyme partially recapitulates Dkk1 mutant phenotypes. Together, these findings underscore the importance ofDKK1 in regulating behavior of dPCM progenitors, and suggest that formation of anus and urethral depends on Dkk1-mediated dynamic inhibition of the canonical Wnt/ß-catenin signal pathway.

  15. Aerobic bacterial microbiota isolated from the cloaca of the European pond turtle (Emys orbicularis) in Poland.

    PubMed

    Nowakiewicz, Aneta; Ziółkowska, Grażyna; Zięba, Przemysław; Dziedzic, Barbara Majer; Gnat, Sebastian; Wójcik, Mariusz; Dziedzic, Roman; Kostruba, Anna

    2015-01-01

    We conducted a comparative analysis of the aerobic cloacal bacteria of European pond turtles (Emys orbicularis) living in their natural environment and juvenile turtles reared under controlled conditions in a breeding center. We included 130 turtles in the study. The aerobic bacteria isolated from the cloaca of the juvenile turtles were less diverse and more prevalent than the bacteria isolated from free-living adults. We isolated 17 bacterial species from juvenile captive turtles, among which the dominant species were Cellulomonas flavigena (77/96), Enterococcus faecalis (96/96), Escherichia coli (58/96), and Proteus mirabilis (41/96). From the adult, free-living turtles, we isolated 36 bacterial species, some of which are a potential threat to public health (e.g., Salmonella enterica serovars Newport, Daytona, and Braenderup; Listeria monocytogenes; Yersinia enterocolitica; Yersinia ruckeri; Klebsiella pneumoniae; Vibrio fluvialis; and Serratia marcescens), and pathogens that are etiologic agents of diseases of ectothermic animals (e.g., Aeromonas sobria, Aeromonas caviae, Hafnia alvei, Edwardsiella tarda, and Citrobacter braakii; the last two species were isolated from both groups of animals). The cloacal bacterial biota of the European pond turtle was characterized by numerous species of bacteria, and its composition varied with turtle age and environmental conditions. The small number of isolated bacteria that are potential human pathogens may indicate that the European pond turtle is of relatively minor importance as a threat to public health.

  16. [From the Cloaca Maxima to current sewage treatment works--historical aspects of waste disposal].

    PubMed

    Schadewaldt, H

    1983-09-01

    According to calculations made by the well-known hygienist Max Rubner in 1890, the annual quantity of waste made up of excreta, urine, kitchen refuse, ashes and water for general use than ran to 7,300 kgs. Thus it appears quite obvious that as early as in the ancient high cultures special waste disposal plants existed. In the Old Testament cesspools were in use, in Ancient Egypt sliding boxes served the same purpose, the Cretan palace of Knossos was provided with a really sophisticated water closet system and there is evidence that a similar facility existed in Mesopotamia. The Roman Cloaca maxima which functioned as a sanitary system for the entire capital, has never ceased to impress. With the advent of the so-called "miasma theory", public health legislations also started to take care of waste disposal, and as a result, various lavatories, slaughter-house and waste water facilities were created. When bacteriology began to establish itself, close attention was devoted to the ground water and the rivers. The "squatting closet" in Roman countries contrasted with the flush closet in England. For waste disposal, the so-called "Heidelberg barrel system" or the "Kiel exchange bucket system" were introduced. Of more recent date are the digestion chambers, the flow settling tanks and the "trickling or oxydation system" on the sprinkling fields.

  17. Whole-genome sequence of Enterobacter sp. strain SST3, an endophyte isolated from Jamaican sugarcane (Saccharum sp.) stalk tissue.

    PubMed

    Gan, Han Ming; McGroty, Sean E; Chew, Teong Han; Chan, Kok Gan; Buckley, Larry J; Savka, Michael A; Hudson, André O

    2012-11-01

    Enterobacter sp. strain SST3 is an endophytic bacterium isolated from Saccharum spp. Here we present its annotated draft genome that may shed light on its role as a bacterial endophyte of sugarcane. To our knowledge, this is the first genome announcement of a sugarcane-associated bacterium from the genus Enterobacter.

  18. Enterobacter spp.: pathogens poised to flourish at the turn of the century.

    PubMed Central

    Sanders, W E; Sanders, C C

    1997-01-01

    Knowledge of the genus Enterobacter and its role in human disease has expanded exponentially in recent years. The incidence of infection in the hospital and the community has increased. New clinical syndromes have been recognized. Enterobacter spp. have also been implicated as causes of other syndromes that traditionally have been associated almost exclusively with more easily treatable pathogens, such as group A streptococci and staphylococci. Rapid emergence of multiple-drug resistance has been documented in individual patients during therapy and in populations and environments with strong selective pressure from antimicrobial agents, especially the cephalosporins. Therapeutic options for patients infected with multiply resistant strains have become severely limited. Carbapenems or, alternatively, fluoroquinolones are the most predictively active options, although resistance to both classes has been observed on rare occasions. Enterobacter spp. appear well adapted for survival and even proliferation as the turn of the century approaches. PMID:9105752

  19. Comparison of two multimetal resistant bacterial strains: Enterobacter sp. YSU and Stenotrophomonas maltophilia ORO2.

    PubMed

    Holmes, Andrew; Vinayak, Anubhav; Benton, Cherise; Esbenshade, Aaron; Heinselman, Carlisle; Frankland, Daniel; Kulkarni, Samatha; Kurtanich, Adrienne; Caguiat, Jonathan

    2009-11-01

    The Y-12 plant in Oak Ridge, TN, which manufactured nuclear weapons during World War II and the Cold War, contaminated East Fork Poplar Creek with heavy metals. The multimetal resistant bacterial strain, Stenotrophomonas maltophilia Oak Ridge strain O2 (S. maltophilia O2), was isolated from East Fork Poplar Creek. Sequence analysis of 16s rDNA suggested that our working strain of S. maltophilia O2 was a strain of Enterobacter. Phylogenetic tree analysis and biochemical tests confirmed that it belonged to an Enterobacter species. This new strain was named Enterobacter sp. YSU. Using a modified R3A growth medium, R3A-Tris, the Hg(II), Cd(II), Zn(II), Cu(II), Au(III), Cr(VI), Ag(I), As(III), and Se(IV) MICs for a confirmed strain of S. maltophilia O2 were 0.24, 0.33, 5, 5, 0.25, 7, 0.03, 14, and 40 mM, respectively, compared to 0.07, 0.24, 0.8, 3, 0.05, 0.4, 0.08, 14, and 40 mM, respectively, for Enterobacter sp. YSU. Although S. maltophilia O2 was generally more metal resistant than Enterobacter sp. YSU, in comparison to Escherichia coli strain HB101, Enterobacter sp. YSU was resistant to Hg(II), Cd(II), Zn(II), Au(III), Ag(I), As(III), and Se(IV). By studying metal resistances in these two strains, it may be possible to understand what makes one microorganism more metal resistant than another microorganism. This work also provided benchmark MICs that can be used to evaluate the metal resistance properties of other bacterial isolates from East Fork Poplar Creek and other metal contaminated sites.

  20. [Taxonomy of Enterobacter sakazakii and the biological characteristics of the new species and genus].

    PubMed

    Zhao, Guiming; Yuan, Fei; Yang, Hairong; Zhao, Yongsheng; Chen, Ying

    2010-03-01

    Enterobacter sakazakii, one of the major pathogens affecting the safety of infant formula powder was defined as a species in 1980. However, the new names and new combinations about Enterobacter sakazakii notified in volume 58, part 6, of the International Journal of Systematic and Evolutionary Microbiology (IJSB). The taxonomic relationship of strains described as E. sakazakii, biological characteristics of its new genus and species, the development related to its isolation and identification were reviewed in this paper, in order to facilitate the related personnel to keep in touch with the latest developments on E. sakazakii. It's also conducive to unify and standardize the Chinese name for E. sakazakii.