Prevalence and characterization of Escherichia coli O157 and O157:H7 in retail fresh raw meat in South China

Abstract

Escherichia coli O157 is an important food-borne pathogen that can cause diarrhoea, haemorrhagic colitis, and haemolytic uraemic syndrome. The aim of this study was to investigate the prevalence, virulence genes, antibiotic resistance, and genetic diversity of E. coli O157 and O157:H7 in retail fresh raw meat sold in the markets of South China. Of 551 samples collected, 21 (3.81 %) were contaminated with E. coli O157 and seven (1.27 %) with O157:H7. The highest prevalence rate was found in beef (13.32 %), followed by pork (6.90 %), chicken (3.28 %), duck (2.54 %), and mutton (0). The virulence genes stx1, stx2, eaeA, and hlyA were detected in 10.71, 21.43, 85.71, and 25 % of 28 isolates, respectively. The isolates were highly resistant to penicillin (100 %), chloramphenicol (64.29 %), ampicillin (57.14 %), and sensitive to gentamicin (100 %), cefotazidime (96.43 %), and ciprofloxacin (96.43 %). Enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) classified 28 isolates and two reference strains into 19 different profiles with a discrimination index (D) of 0.961. Four E. coli O157:H7 isolates from beef showed 83 % similarity with the two clinical reference strains, indicating a potential high virulence for consumers. The results of this study suggested that fresh raw meat could be potential vehicles for transmission of E. coli O157 to humans.