Abstract
BACKGROUND: Food-borne pathogens are the foremost causes of food-borne human illness in the world. Escherichia coli O157:H7 (E. coli O157:H7) is one of the major food-borne pathogenic bacteria around the world. Though evidence is lacking; especially in developing countries like Ethiopia, the potential health impact of E. coli O157:H7 can be high where food production, handling and consumption is often taking place under unhygienic conditions. In Ethiopia, studies reported E. coli and E. coli O157: H7 from food of animal origin, mainly meat and milk, and also animal surfaces and feces. The objective of the present study was to investigate the occurrence of E. coli O157:H7 in raw milk and the dairy production farm environment and further assess the antimicrobial resistance pattern of the bacterium. METHODS: Samples of milk from individual lactating cows' and dairy farm environmental samples (feces, water and manure) were collected at Adami Tulu Jido Kombolcha district (ATJKD) and analyzed for the presence of E. coli O157:H7. Standard microbiological techniques including culture, biochemical testing and serological test were performed to isolate and identify the bacterium. The bacterial isolates were evaluated for antimicrobial susceptibility patterns using disk diffusion method. A questionnaire was used to collect possible factors affecting E. coli O157:H7 occurrence. RESULTS: The overall prevalence of E. coli O157:H7 was 4.7% (19/408) (95% CI: 2.6; 6.7). Out of 19 E. coli O157:H7 isolates, 4/50, 7/154, 2/50, and 6/154 were from water, milk, manure, and feces samples, respectively. From potential risk factors considered in this study area, floor type, cleaning of pens, milking location and hand washing during the time of milking were significantly associated with the occurrence of E. coli O157:H7. The antimicrobial susceptibility pattern indicated varying degrees of resistance. All of the isolates were found to be resistant ampicillin, cephalothin, and rifampin, and 100% susceptibility was observed against the drugs: chloramphenicol, ciprofloxacin, gentamicin, nalidixic acid, kanamycin, and tetracycline. Concerning streptomycin, 63.15% of the isolates were susceptible and 36.8% showed intermediate susceptibility. CONCLUSIONS: The occurrence of multi-drug resistance E. coli O157:H7 observed both in lactating cows and in dairy farm environments can sustain a continuous transmission of the bacteria. The occurrence of multidrug-resistant E. coli o157:H7could hamper the control and prevention efforts.