Abstract
Escherichia coli O157 is an emerging foodborne pathogen of great public health concern. It has been associated with bloody diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome in humans. Most human infections have been traced to cattle and the consumption of contaminated cattle products. In order to understand the risk associated with the consumption of cattle products, this study sought to investigate the prevalence and identify virulence genes in E. coli O157 from cattle in Cameroon. A total of 512 rectal samples were obtained and analysed using conventional bacteriological methods (enrichment on modified Tryptone Soy Broth and selective plating on Cefixime-Tellurite Sorbitol Mac-Conkey Agar) for the isolation of E. coli O157. Presumptive E. coli O157 isolates were confirmed serologically using E. COLIPROTM O157 latex agglutination test and molecularly using PCR targeting the rfb gene in the isolates. Characterisation of the confirmed E. coli O157 strains was done by amplification of stx1, stx2, eaeA and hlyA virulence genes using both singleplex and multiplex PCR. E. coli O157 was detected in 56 (10.9%) of the 512 samples examined. The presence of the virulence genes stx2, eaeA and hylA was demonstrated in 96.4% (54/56) of the isolates and stx1 in 40 (71.4%) of the 54. The isolates exhibited three genetic profiles (I-III) with I (stx1, stx2, eaeA and hlyA) being the most prevalent (40/56; 71.4%) while two isolates had none of the virulence genes tested. A proportion of cattle slaughtered in abattoirs in Buea are infected with pathogenic E. coli O157 and could be a potential source of human infections. We recommend proper animal food processing measures and proper hygiene be prescribed and implemented to reduce the risk of beef contamination.
Highlights
The presence of the virulence genes stx2, eaeA and hylA was demonstrated in 96.4% (54/56) of the isolates and stx1 in 40 (71.4%) of the 54
Enterohemorrhagic Escherichia coli serotype O157 is a well recognised human pathogen associated with bloody diarrhoea, haemolytic uremic syndrome, and death in both developing and industrialised nations [1]
We investigated the presence of four genes associated with these virulence factors in all the 56 E. coli O157 isolates using PCR
Summary
Enterohemorrhagic Escherichia coli serotype O157 is a well recognised human pathogen associated with bloody diarrhoea, haemolytic uremic syndrome, and death in both developing and industrialised nations [1]. Human infections with E. coli O157 are often attributed to the consumption of contaminated food or water with cattle at the centre of the transmission cycle. Infections generally do not result in disease condition and the bacteria typically colonise the lower gastrointestinal tract [6] from where they are shed intermittently in bovine faeces [7]. Shedding is by both adult cattle and weaned calves [8]. Escherichia coli O157 is an emerging foodborne pathogen of great public health concern It has been associated with bloody diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome in humans. In order to understand the risk associated with the consumption of cattle products, this study sought to investigate the prevalence and identify virulence genes in E. coli O157 from cattle in Cameroon
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