Prevalence, Antimicrobial Resistance Profiles and Assessment of the Risk Factors Associated with Microbial Quality and Shiga Toxin-producing Escherichia Coli (Stec) Along the Milk and Cottage Cheese Value Chains in Oromia, Ethiopia

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


Milk being a suitable medium for bacterial growth can serve as a source of bacterial pathogens. Pathogenic bacteria in milk pose a serious health threat to humans. Previous studies in Ethiopia lacked molecular confirmation of bacterial isolates, been small in terms of scope (i.e., failing to cover several high milk production areas), have not addressed all value-chains for milk and cottage cheese. Therefore, this study was designed to fill these gaps. aimed to assess the microbial quality, the prevalence of shiga-toxin producing Escherichia coli (STEC and E. coli O157:H7), antimicrobial resistance profiles, and associated risk factors in milk and cottage cheese sourced from the Oromia region of Ethiopia. First, a semi-structured questionnaire was administered to capture relevant information from identified respondents (producers, collectors, processors and retailers of milk and cottage cheese producers and retailers). Additionally, a total of 480 samples milk and cottage cheese were collected and analyzed for the presence of STEC and E. coli O157:H7. TCC and generic E. coli counts were completed utilizing 3M Petrifilm count plates, typical colonies were later confirmed through molecular methods. The antimicrobial resistance pattern of isolates was carried out using Kirby–Bauer method. The mean TBC and TCC of raw milk, pasteurized milk, and cottage cheese were (7.17, 5.53; 5.93, 3.36; 6.1, 1.73) log cfu/ml or g, respectively. The prevalence of generic E. coli was 53.1% (102/192), 35.9% (69/192) and 3.1% (3/48) in raw milk, pasteurized milk and cottage cheese samples, respectively. From the total samples, 12 % were positive for STEC, among this 3.7% were E. coli O157:H7. The highest prevalence of STEC and E. coli O157:H7 were found in raw milk samples 39 (20.31%) followed by pasteurized milk 17 (8.85%) and cottage cheese 2 (2.08%). Antimicrobial resistance analysis revealed that STEC and E. coli O157:H7 were highly sensitive to chloramphenicol (72.4%) and ciprofloxacin (75.8%); but resistant to ampicillin (56.8%), oxyteteracycline (44.8%) and tetracycline (84.4%). The significant association of possible sources (P<0.05) with STEC positivity were cleanness of the drying cloth , hygienic condition of the cattle barn and collection center, temperature during transportation, time to transport pasteurized milk to retail shop and the quality of packaging materials for cottage cheese. Hence, there is a need to identify preventive measures and direct interventions for the production, transportation, storage and pasteurization of milk and cottage cheese.



Milk, Cottage Cheese, Shiga Toxin-Producing Escherichia Coli (Stec), Antimicrobial Resistance, Risk Factors