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Toxin-producing Escherichia Coli (toxin-producing + escherichia_coli)
Kinds of Toxin-producing Escherichia Coli Selected AbstractsSensitivity of Shiga toxin-producing Escherichia coli (STEC) strains for colicins under different experimental conditionsFEMS MICROBIOLOGY LETTERS, Issue 2 2001Bart J.A.M. Jordi Abstract Twenty Escherichia coli strains producing well-characterised colicins were tested for their inhibitory activity against five Shiga toxin-producing E. coli (STEC) strains using different media under aerobic and anaerobic conditions. The five STEC strains used were of serotype O26, O111, O128, O145 and O157:H7 which are frequently isolated serotypes associated with disease in humans. The main route of infection for humans is through the eating of badly cooked or handled beef. The major reservoir for STEC strains in cattle is the rumen. To mimic the situation in the rumen of cattle, overlay assays were also performed under anaerobic conditions in the presence of 30% rumen fluid. Colicins E1, E4, E8-J, K and S4 are most active against STEC strains under anaerobic conditions in the absence or presence of rumen fluid. These colicins will be used in future experiments with the aim to eradicate the presence of STEC in cattle. [source] Inducible stx2 phages are lysogenized in the enteroaggregative and other phenotypic Escherichia coli O86:HNM isolated from patientsFEMS MICROBIOLOGY LETTERS, Issue 1 2000Sunao Iyoda Abstract We characterized two Shiga toxin-producing Escherichia coli (STEC) O86:HNM isolates from a patient with hemolytic uremic syndrome (HUS) or bloody diarrhea. Both of them did not possess the eaeA gene. However, the isolate from a HUS patient carried genetic markers of enteroaggregative E. coli (EAEC) and showed aggregative adherence pattern to HEp-2 cells. The other isolate from bloody diarrhea, which was negative with EAEC markers, was diffusely adhered to HEp-2 cells. The stx2 gene in both E. coli O86:HNM strains was encoded in each infectious phage, which was partially homologous to that of strain EDL933, a STEC O157:H7. These results will help to explain the genotypic divergences of STEC. [source] Survival and spread of Shiga toxin-producing Escherichia coli in alpine pasture grasslandsJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2010B. Fremaux Abstract Aims:, To determine the fate of Shiga toxin-producing Escherichia coli (STEC) strains defecated onto alpine grassland soils. Methods and Results:, During the summers of 2005 and 2006, the field survival of STEC was monitored in cowpats and underlying soils in four different alpine pasture units. A most probable number (MPN)-PCR stx assay was used to enumerate STEC populations. STEC levels ranged between 3·9 and 5·4 log10 CFU g,1 in fresh cowpats and slowly decreased until their complete decay (inactivation rates k < 0·04 day,1). PFGE typing of STEC strains isolated from faecal and soil samples assessed the persistence of various clonal types for at least 2 months in cowpats and their vertical dispersal down through the soil at a depth up to at least 20 cm. STEC cells counts in soil were always below 2 log10 CFU g,1, regardless of the pasture unit investigated. The soil became rapidly free of detectable STEC once the cowpat had decomposed. The eight STEC strains isolated during this study belonged to six distinct serotypes and tested positive for the gene(s) stx2, including the stx2g and stx2 NV206 variants. Conclusions:, STEC were able to persist in cowpats and disseminate down through the soil but were unable to establish. Significance and impact of the Study:, This study provides useful information concerning the ecology of STEC in alpine pasture grasslands and may have implications for land and cattle management. [source] Characterization of Shiga toxin-producing Escherichia coli isolated from dairy cows in ArgentinaLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2010D. Fernández Abstract Aims:, To feno-genotypically characterize the Shiga toxin-producing Escherichia coli (STEC) population in Argentinean dairy cows. Methods and Results:, From 540 STEC positive samples, 170 isolates were analyzed by multiplex PCR and serotyping. Of these, 11% carried stx1, 52%stx2 and 37%stx1/stx2. The ehxA, saa and eae were detected in 77%, 66% and 3%, respectively. Thirty-five per cent of strains harboured the profile stx1, stx2, saa, ehxA and 29%stx2, saa, ehxA. One hundred and fifty-six strains were associated with 29 different O serogroups, and 19 H antigens were distributed among 157 strains. STEC O113:H21, O130:H11 and O178:H19 were the most frequently found serotypes. The STEC O157:H7 were detected in low rate and corresponded to the stx2+, eae+, ehxA+ virulence pattern. Conclusions:, We detected a diversity of STEC strains in dairy cattle from Argentina, most of them carrying genes linked to human disease. Significance and Impact of the study:, The non-O157 STEC serotypes described in this study are associated worldwide with disease in humans and represent a risk for the public health. For this, any microbiological control in dairy farms should be targeted not only to the search of O157:H7 serotype. [source] Detection, isolation and characterization of Shiga toxin-producing Escherichia coli in retail-minced beef using PCR-based techniques, immunoassays and colony hybridizationLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2007F. Auvray Abstract Aims:, To provide information on detection of Shiga toxin-producing Escherichia coli (STEC) in retail-minced beef using an approach combining (i) PCR-based techniques and automated immunoassay for stx screening and detection of the five major serogroups associated with human infection, and (ii) immunomagnetic separation (IMS) and colony hybridization assays for bacterial strain isolation. Methods and Results:, Twenty-seven out of 164 minced beef samples were stx -positive by PCR-ELISA, nine of which were also positive by real-time PCR for at least one marker of the five main serogroups tested (O26, O103, O111, O145 and O157). Two E. coli O103 stx -negative strains were isolated from two out of 10 IMS and nine STEC strains that did not belong to the five main serogroups were isolated by colony hybridization. Conclusions:, PCR techniques are applicable for rapid screening of samples containing both an stx gene and an O-group marker of the five main pathogenic STEC serogroups. Isolation of STEC strains belonging to the main non-O157 serogroups remains difficult. Significance and Impact of the Study:, This study presents an evaluation of a multi-faceted approach for the detection of the most frequently reported human pathogenic STEC serogroups. The advantages and limits of this strategy are presented. [source] Production of Shiga toxin by Shiga toxin-expressing Escherichia coli (STEC) in broth media: from divergence to definitionLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2007L.B. Rocha Abstract Aims:, To determine the suitability of eight different commercial broth media for Shiga toxin (Stx) production. Methods and Results:, Shiga toxin-producing Escherichia coli (STEC) strains producing Stx1 or Stx2 were grown at 37°C (250 rev min,1) for 24 h in brain heart infusion broth, E. coli broth, Evans medium, Luria-Bertani broth, Penassay broth, buffered-peptone water, syncase broth and trypticase soy broth. Toxin production was measured by enzyme-linked immunosorbent assay (ELISA) in polymyxin-treated cell pellets and/or supernatants of cultures, ELISA optical densities reached 1 when isolates were grown for 2,4 h in E. coli broth in the presence of antibiotic. Besides, a collection of STEC-expressing Stx strains was evaluated and the Stx production was assayed in the supernatants and in polymyxin-treated pellets of bacterial growth after 4 h of cultivation in E. coli broth in the presence of antibiotic. Conclusions:, The most suitable medium for Stx production was E. coli broth when the bacterial isolates were grown for 4 h in the presence of ciprofloxacin and the Stx production is detected in the supernatant. Significance and Impact of the Study:, This study presents the first comprehensive comparison of different broth media with regard to Stx production to establish optimal culture conditions for STEC detection in routine diagnostic laboratories. [source] Phenotypical characteristics of Shiga-like toxin Escherichia coli isolated from sheep dairy productsLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2007I. Caro Abstract Aims: To analyse phenotypical characteristics of Shiga toxin-producing Escherichia coli (STEC) strains from ovine origin. Methods and Results: A total of 13 STEC strains (eight O157 and five non-O157) isolated from sheep dairy products were used in this study. Biochemical traits, motility, haemolytic activity, resistance to tellurite,cefixime, maximum growth temperature and antibiotic resistance were determined. The STEC strains were grouped into nine biochemical and physiological biotypes (five for the O157 and four for the non-O157 strains). All STEC strains showed resistance to bacitracin, cloxacilin, penicillin and tylosin. Conclusions: Different biotypes and antibiotic resistance patterns of STEC isolated from sheep dairy products were observed. Significance and Impact of the Study: This work will be a contribution to the better characterization of STEC isolated from sheep dairy products, which have, to date, been scarcely studied, and to the better understanding of the risks associated with its consumption. [source] Persistence of Shiga toxin-producing Escherichia coli O26 in cow slurryLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2007B. Fremaux Abstract Aims: The main objective of this study was to evaluate the growth and survival of Shiga toxin-producing Escherichia coli (STEC) O26 in cow slurry; this serogroup is regarded as an important cause of STEC-associated diseases. Methods and Results: Four STEC were examined by polymerase chain reaction (PCR) to determine whether they harbour key virulence determinants and also by pulsed-field gel electrophoresis (PFGE) to obtain overview fingerprints of their genomes. They were transformed with the pGFPuv plasmid and were separately inoculated at a level of 106 CFU ml,1 in 15 l of cow slurry. All STEC O26 strains could be detected for at least 3 months in cow slurry without any genetic changes. The moisture content of the slurry decreased over time to reach a final value of 75% while the pH increased from 8·5 to 9·5 units during the last 50 days. Conclusion: STEC O26 strains were able to survive in cow slurry for an extended period. Significance and Impact of the Study: Long-term storage of waste slurry should be required to reduce the pathogen load and to limit environmental contamination by STEC O26. [source] Investigation of shiga toxin-producing Escherichia coli in avian species in IndiaLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2004S.A. Wani Abstract Aims:, To investigate the presence or absence of shiga toxin-producing Escherichia coli (STEC) in avian species in India. Methods and Results:, Faecal samples originating from 500 chicken and 25 free flying pigeons were screened for the presence of E. coli. A total of 426 (chicken, 401; pigeons, 25) E. coli strains were isolated. Of 426 E. coli strains, 387 were grouped into 77 serogroups, while 70 and 59 strains were untypable and rough, respectively. All isolates were subjected to multiplex polymerase chain reaction (m-PCR) for the detection of stx1, stx2, eaeA, hlyA and saa genes. None of the E. coli strains studied showed the presence of stx1, stx2 or their variants and saa genes. Overall 11 (2·74%) and seven (1·74%) strains from chickens possessed eaeA and hlyA genes, respectively, while as only six (1·49%) strains from chickens possessed both eaeA and hlyA genes. O9, O8, O60 and O25 serogroups were most predominant of which there were 24 (5·63%), 23 (5·39%), 23 (5·39%) and 20 (4·69%) strains, respectively. None of the isolates from pigeons showed the presence of any of the virulence genes studied. Conclusions:, STEC are absent in chickens and pigeons. However, further studies are required in this direction to confirm or contradict our findings. E. coli strains originating from birds are carrying a low percentage eaeA or hlyA genes. Significance and Impact of the Study:, The present study is the first attempt to investigate STEC in chickens and free flying pigeons in India. The chickens and pigeons cannot be considered as important carrier of STEC in India. [source] Isolation of Shiga toxin-producing Escherichia coli O103 from sheep using automated immunomagnetic separation (AIMS) and AIMS-ELISA: sheep as the source of a clinical E. coli O103 case?LETTERS IN APPLIED MICROBIOLOGY, Issue 3 2002A.M. Urdahl Aims: To investigate whether a sheep flock was the original reservoir of a Shiga toxin-producing Escherichia coli (STEC) O103 strain causing a clinical human case and to compare the two diagnostic methods automated immunomagnetic separation (AIMS) and AIMS-ELISA. Methods and Results: AIMS detected Escherichia coli O103 in 36·5% of the samples and AIMS-ELISA detected E. coli O103 in 52·1% of the samples. Polymerase chain reaction detected stx1 and eae in three of 109 E. coli O103 isolates. Pulsed field gel electrophoresis showed that the sheep and human STEC O103 were characterized by distinctly different profiles. Conclusions: The sheep flock was shown to carry STEC O103, although an association between the sheep flock and the clinical human case could neither be proven nor eliminated. Substantial agreement was found between AIMS and AIMS-ELISA, but AIMS-ELISA was less time consuming and resulted in a higher recovery of E. coli O103. Significance and Impact of the Study: The study shows that sheep may be carriers of STEC that are associated with human disease and that the methods described can be used to increase the sensitivity of STEC detection. [source] Prevalence and characteristics of cytolethal distending toxin-producing Escherichia coli from children with diarrhea in JapanMICROBIOLOGY AND IMMUNOLOGY, Issue 4 2009Atsushi Hinenoya ABSTRACT In the present study, we examined the prevalence and characteristics of CTEC among diarrheal children in Japan during a year-long surveillance study. A PCR-RFLP assay for the detection and differentiation of five types of E. coli cdtB gene (types I through V) was developed, and 362 stool specimens collected from patients reporting to pediatric departments in two hospitals were analyzed. Of the 35 samples (9.7%) that were positive for the cdtB gene, 21 were positive for cdt-I, three for cdt-II, four for cdt-III, three for cdt-IV and four samples were positive for cdt-V, as determined by different molecular techniques. The recovery of CTEC having cdt alleles was a little less, which included 19 with cdt-I, one cdt-II, three cdt-III, three cdt-IV and four with cdt-V. Among 30 CTEC strains isolated, the majority of them (43%) belonged to serogroup O2. The other virulence genes such as astA, cnf1, eaeA, cnf2 and bfpA genes were detected in 14 (47%), 11 (37%), four (13%), three (10%) and one (3.3%) strains of CTEC, respectively. However, the other common virulence-associated genes specific for DEC were not detected in these strains. Interestingly, an untypable cdt gene was detected by PCR-RFLP in Providencia alcalifaciens. Our data indicate that CTEC may be associated with diarrheal children in Japan and most of them do not belong to a conventional enteropathogenic pathovar and thus differ from strains isolated in developing countries. [source] Human isolates of Aeromonas possess Shiga toxin genes (stx1 and stx2) highly similar to the most virulent gene variants of Escherichia coliCLINICAL MICROBIOLOGY AND INFECTION, Issue 10 2010A. Alperi Clin Microbiol Infect 2010; 16: 1563,1567 Abstract Strains producing Shiga toxins, encoded by stx1 and stx2 genes, can cause diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome. PCR screening of 80 clinical Aeromonas strains showed that 19 were stx1-positive and only one was positive for both stx1 and stx2. PCR bands were very faint for some strains and negative results were obtained after subculturing. The obtained sequences of Aeromonas stx1 and stx2 genes were highly similar to those of the most virulent stx gene variants of Shiga toxin-producing Escherichia coli. These results may lead to a better understanding of the potential pathogenicity and virulence mechanisms of Aeromonas. [source] | ||||||||||||||||||||||