title: Detection of Escherichia coli O157:H7 virulence genes in isolates from beef, pork, water, human and animal species in the northwest province, South Africa: public health implications.
abstract: The aim of the present study was to isolate and identify Escherichia coli O157:H7 from pigs, cattle, humans, beef, pork and water samples and to determine their putative virulence genes by PCR analysis. A total of 220 samples were analysed; 5600 presumptive E. coli O157:H7 were screened for the presence of rfb(O157) and fliC(H7) gene fragments by PCR and 130 isolates were confirmed. The prevalence of E. coli O157:H7 was higher in pigs and pork 88(67.7%) than in cattle and beef 36(27.7%), water 3(2.3%) or humans 1 (0.77%). Moreover, the pathogen was more frequently isolated from faecal (16.9%-43.1%) than from meat samples (10.8%-24.6%). A large proportion--73 (56.2%)--of the isolates possessed the hlyA gene, while 48 (36.9%) harboured the eaeA gene. Although there were no major differences in the number of isolates harbouring the stx(1) and stx(2) genes, respectively, only a small proportion 13(10%) harboured both shiga toxin genes. Despite this, the proportion of isolates that possessed the stx(1) 29(22.3%) was higher than those possessing the stx(2) gene. None of the E. coli O157:H7 isolates harboured all four shiga-toxin producing E. coli (STEC) virulence genes investigated. When comparing the proportion of isolates obtained from the different sample sources and/or stations, significant positive correlations were observed between isolates from Mafikeng and Lichtenburg (r = 0.981, p < 0.05) and those from Mafikeng and Rustenburg (r = 0.991, p < 0.05). These results therefore indicate that meat and faeces samples obtained from major cities in the northwest province were contaminated with E. coli O157:H7. We suggest that there is a need for improving the sanitary conditions of farms, abattoirs and butcher shops. This could reduce transmission of E. coli O157:H7 to humans.
authors.affiliation: Dale Beighle Centre for Animal Health Studies, School of Agricultural Sciences, North-West University-Mafikeng Campus, P. Bag X2046, Mmabatho 2735, South Africa. atebacollins1@hotmail.com
authors.forename: Collins Njie
authors.initials: CN
authors.lastname: Ateba
authors.forename: Moses
authors.initials: M
authors.lastname: Mbewe
mesh_terms: D000818:Animals; D002417:Cattle; D004269:DNA, Bacterial / Q000235:genetics; D004783:Environmental Microbiology; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology* / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000235:genetics / Q000302:isolation & purification*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005516:Food Microbiology; D006801:Humans; D016133:Polymerase Chain Reaction; D015995:Prevalence; D013019:South Africa / Q000453:epidemiology; D013552:Swine; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D037521:Virulence Factors