Abstract
BackgroundCattle have been identified as a major reservoir of E. coli O157:H7 for human infection; the ecology of the organism in sheep and goats is less understood. This study was carried out to determine prevalence, source of infection, antibiotic resistance and molecular characterization of Escherichia coli O157: H7 isolated from sheep and goat.MethodsSystematic random sampling was carried out at Modjo export abattoir, Ethiopia, from November 2012 to April 2013 to collect 408 samples from 72 sheep and 32 goats. Samples collected were skin swabs, fecal samples, intestinal mucosal swabs and the inside and outside part of carcasses as well as carcass in contacts such as workers hands, knife, hook and carcass washing water. Then, samples were processed following standard bacteriological procedures. Non-Sorbitol fermenting colonies were tested on latex agglutination test and the positives are subjected to PCR for detection of attaching and effacing genes (eaeA) and shiga toxin producing genes (stx1 and stx2). All E. coli O157:H7 isolates were checked for their susceptibility pattern towards 15 selected antibiotics.ResultsE. coli O157:H7 were detected in only 20/408 samples (4.9%). Among these 20 positive samples, 70% (14/20), 25% (5/20) and 5% (1/20) were from sheep, goats and knife samples, respectively. No significant associations were found between carcasses and the assumed sources of contaminations. Of all the 20 isolates virulence genes were found in 10 (50%) of them; 3 (15%) with only the eaeA gene and 7(35%) expressing eaeA and stx2 genes. All the isolates were susceptible to Norfloxacin (NOR) (100%).ConclusionsThe presence of virulence genes shows E. coli O157:H7 is a potential source of human infection in Ethiopia.
Highlights
Cattle have been identified as a major reservoir of E. coli O157:H7 for human infection; the ecology of the organism in sheep and goats is less understood
Prevalence of E. coli O157:H7 From 408 samples examined for E. coli O157:H7 only 20 (4.9%) were found to be positive
Prevalence of E. coli O157:H7 While cattle are generally regarded as the main reservoir of E. coli O157:H7 for human infection on other studies [8], the results of the present study indicate that sheep and goats may be contributing sources, with sheep being more significant
Summary
Cattle have been identified as a major reservoir of E. coli O157:H7 for human infection; the ecology of the organism in sheep and goats is less understood. Most of microbial pathogens are zoonotic and have reservoirs in healthy food animals from which they spread to an increasing variety of foods. This makes foods of animal origin major. The organism produces shiga toxin types and 2 (stx and stx2) which are responsible for the death of intestinal, vascular, renal cells. They are encoded respectively, by the virulence genes stx and stx
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