Isolation of Enterohaemorrhagic Escherichia coli O104 Strains from Raw Meat Products in the North West Province, South Africa

Abstract

Enterohaemorrhagic E. coli (EHEC) are Shiga toxin-producing E. coli strains that possess unique pathogenic properties and are characterized by certain seropathotypes that are frequently associated with outbreaks or sporadic cases of human infections. Although EHEC strains belonging to the serotype O104:H4 has rarely been associated with human diseases in the past, outbreaks of infections caused by this organism resulted to HUS and bloody diarrhoea in humans in countries that have advanced public health facilities. The aim of this study was to isolate E. coli O104 strains from meat samples obtained from supermarkets and retail shops in the North West Province, South Africa. A further objective was to determine the identities of the isolates using Gram staining, preliminary biochemical tests (oxidase test, Triple Sugar Iron (TSI) test, citrate utilization and Sorbitol fermentation test) and confirmatory (API 20E and PCR analysis) assays. A total of nineteen meat samples were collected from four butcheries and shops in the study area and Sorbitol MacConkey agar was used for selective isolation of bacteria. A total of 304 presumptive colonies were subjected to identification tests for E. coli. Large proportions (65.5% to 93%) of these isolates were oxidase negative; fermented the sugars in the TSI medium; utilized citrate and fermented sorbitol. On the contrary only a small proportion (27.3%) of the isolates produced hydrogen sulphide gas. Based on patterns obtained for the biochemical profiles of the isolates 102 (33.6%) were positively identified as E. coli. All the 304 E. coli isolates were subjected to specific PCR designed to amplify thewzxO104 gene fragment that facilitates identification of E. coli O104 strains and a total of 52 isolates were positively identified. Despite the fact that not all samples were positive for the pathogen, the presence of E. coli O104 strains in some of the meat samples was of great concern. These bacteria cells have the potential to cause severe health effects on consumers if present in undercooked food products.