Prevalence and Antimicrobial Susceptibility of Escherichia coli O157:H7 Isolated From Slaughtered Sheep, Goats, and the Surrounding Environment at Haramaya Municipal Abattoir, Eastern Ethiopia.

Shiga toxin-producing Escherichia coli O157:H7 (STEC) is a major foodborne pathogen associated with illnesses such as diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome. Due to the limited data regarding the prevalence of E. coli O157:H7 in the study area, this cross-sectional study was conducted at the Haramaya municipal abattoir in Ethiopia from February to August 2021 to evaluate the prevalence and antibiotic resistance profile of the pathogen in slaughtered sheep, goats, and the surrounding environment. Systematic random sampling was used to obtain 440 samples from 78 sheep and 32 goats. These samples consisted of swabs from the external and internal surfaces of carcasses, skin swabs, and fecal samples. Additionally, 24 environmental samples, comprising 12 separate hand and knife swabs, were purposefully collected. All the samples were enriched in modified tryptone broth containing novobiocin and then streaked onto EMB agar for preliminary E. coli detection. Colonies confirmed as E. coli through biochemical tests were further cultured on sorbitol MacConkey agar, and non-sorbitol-fermenting isolates were subjected to latex agglutination for serogroup identification. Susceptibility testing was performed on all E. coli O157:H7 isolates against eight selected antibiotics. Only 13 of the total 464 samples analyzed (2.8%) were positive, with most originating from sheep (69.2%, 9/13), followed by goats (23.1%, 3/13) and one from a knife (7.7%, 1/13). The prevalence results indicate that slaughtered sheep and goats are significant reservoirs of E. coli O157:H7, with the detection in environmental samples highlighting critical gaps in abattoir hygiene that facilitate carcass contamination. The isolates were fully susceptible to gentamicin and kanamycin but resistant to ampicillin, erythromycin, amoxicillin, and vancomycin, and all exhibited multidrug resistance. The presence of E. coli O157:H7 and antibiotic-resistant isolates signals a public health risk for meat handlers and consumers, reinforcing the necessity of applying proper control measures in abattoirs and during meat consumption.