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Enterohaemorrhagic E. Coli (enterohaemorrhagic + e._coli)
Selected AbstractsVirulence genes, serobiotypes and antibiotic resistance profile of Escherichia coli strains isolated from aquaculture and other sourcesAQUACULTURE RESEARCH, Issue 7 2010Surendraraj Alagarsamy Abstract In order to determine the prevalence of pathogenic Escherichia coli, a total number of 155 E. coli isolates from aquaculture, clinical and veterinary sources were screened for seven pathogenic virulence markers and a house-keeping gene by a polymerase chain reaction. The targeted virulence genes included eaeA of enteropathogenic E. coli, elt and est of enterotoxigenic E. coli (ETEC), ipaH of enteroinvasive E. coli, pCVD432 of enteroaggregative E. coli, stx, hlyA and eaeA of shigatoxigenic E. coli (STEC) and Enterohaemorrhagic E. coli. All the isolates were positive for phoA, the house-keeping gene for E. coli. Among the 155 isolates, seven numbers (4.5%) harboured the virulence markers belonging to the pathogenic group ETEC and STEC. The virulent genes detected in these groups were elt, est, hlyA and stx. The sources of these virulence genes were fish (hlyA), shrimp (elt), feeder canal water (hlyA and elt) of aquaculture origin and from diarrhoea affected cow (hlyA, est and stx). The isolates with pathogenic traits belonged to the serogroups O6 or O29 and the remaining could not be typed. They showed resistance to two to four antibiotics out of the 12 antibiotics tested. Biotyping revealed that three isolates belonged to a single biotype (7333) and the remaining isolates were of diverse types. In conclusion, a molecular tool such as PCR proves as more effective tool for detection of this pathogen than the conventional methods. Detection of these emerging pathogens in aquaculture samples warrants for strict adherence to hygienic handling at retail outlets and proper cooking by the consumer before consumption. [source] Prevalence of enterohaemorrhagic Escherichia coli from serotype O157 and other attaching and effacing Escherichia coli on bovine carcasses in AlgeriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2006A. Chahed Abstract Aims:, Bovine meat is the principal source of human contamination of attaching and effacing Escherichia coli, including enterohaemorrhagic E. coli O157. The aim was to study the prevalence of these strains on bovine carcasses in Algeria. Methods and Results:, Two-hundred and thirty carcasses were swabbed and analysed by classical microbiological methods for total E. coli counts and for the presence of pathogenic E. coli. The E. coli counts were high, with a 75th percentile of 444·75 CFUs cm,2. For pathogenic E. coli, more than 7% of the tested carcasses were positive for E. coli O157. Eighteen E. coli O157 strains were isolated and typed by multiplex PCR. The main isolated pathotype (78%) was eae+ stx2+ ehxA+. In addition to E. coli O157, other attaching and effacing E. coli (AEEC) were also detected from carcasses by colony hybridization after pre-enrichment and plating on sorbitol MacConkey agar using eae, stx1 and stx2 probes. Thirty carcasses (13%) on the 230 analysed harboured at least one colony positive for one of the tested probes. These positive carcasses were different from those positive for E. coli O157. Sixty-six colonies (2·9%) positive by colony hybridization were isolated. The majority (60·6%) of the positive strains harboured an enteropathogenic E. coli -like pathotype (eae+ stx,). Only three enterohaemorrhagic E. coli (EHEC)-like (eae+ stx1+) colonies were isolated from the same carcass. These strains did not belong to classical EHEC serotypes. Conclusions:, In this study, the global hygiene of the slaughterhouse was low, as indicated by the high level of E. coli count. The prevalence of both E. coli O157 and other AEEC was also high, representing a real hazard for consumers. Significance and Impact of the Study:, This is the first study of this type in Algeria, which indicates that the general hygiene of the slaughterhouse must be improved. [source] Effect of finishing diets on Escherichia coli populations and prevalence of enterohaemorrhagic E. coli virulence genes in cattle faecesJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2005R.A. Gilbert Abstract Aim:, To determine the effect of different carbohydrate-based finishing diets on fermentation characteristics and the shedding of Escherichia coli and enterohaemorrhagic E. coli (EHEC) virulence genes in cattle faeces. Methods and Results:, The size of faecal E. coli populations and fermentation characteristics were ascertained in three experiments where cattle were maintained on a range of finishing diets including high grain, roughage, and roughage + molasses (50%) diets. Increased E. coli numbers, decreased pH and enhanced butyrate and lactate fermentation pathways were associated with grain diets, whereas roughage and roughage + molasses diets resulted in decreased concentrations of ehxA, eaeA and stx1 genes, this trend remaining at lairage. In one experiment, faecal E. coli numbers were significantly lower in animals fed roughage and roughage + molasses, than animals fed grain (4·5, 5·2 and 6·3 mean log10 g,1 digesta respectively). In a second experiment, faecal E. coli numbers were 2 log lower in the roughage and roughage + molasses diets compared with grain-fed animals prior to lairage (5·6, 5·5 and 7·9 mean log10 g,1 digesta respectively) this difference increasing to 2·5 log at lairage. Conclusions:, The type of dietary carbohydrate has a significant effect on E. coli numbers and concentration of EHEC virulence genes in faeces of cattle. Significance and Impact of the Study:, The study provides a better understanding of the impact finishing diet and commercial lairage management practices may have on the shedding of E. coli and EHEC virulence factors, thus reducing the risk of carcass contamination by EHEC. [source] Structural and biochemical characterization of gentisate 1,2-dioxygenase from Escherichia coli O157:H7MOLECULAR MICROBIOLOGY, Issue 6 2006Melanie A. Adams Summary Gentisic acid (2,5-dihydroxybenzoic acid) is a key intermediate in aerobic bacterial pathways that are responsible for the metabolism of a large number of aromatic compounds. The critical step of these pathways is the oxygen-dependent reaction catalysed by gentisate 1,2-dioxygenase which opens the aromatic ring of gentisate to form maleylpyruvate. From gentisic acid, the cell derives carbon and energy through the conversion of maleylpyruvate to central metabolites. We have confirmed the annotation of a gentisate 1,2-dioygenase from the pathogenic O157:H7 Escherichia coli strain and present the first structural characterization of this family of enzymes. The identity of the reaction product was revealed using tandem mass spectroscopy. The operon responsible for the degradation of gentisate in this organism exhibits a high degree of conservation with the gentisate-degrading operons of other pathogenic bacteria, including the Shiga toxin-producing E. coli O103:H2, but does not appear to be present in non-pathogenic strains. The acquisition of the gentisate operon may represent a special adaptation to meet carbon source requirements under conditions of environmental stress and may provide a selective advantage for enterohaemorrhagic E. coli relative to their non-pathogenic counterparts. [source] | ||||||||||