MILK SAFETY ASSESSMENT, ISOLATION AND ANTIMICROBIAL SUSCEPTIBILITY PROFILE OF Staphylococcus aureus IN SELECTED DAIRY FARMS OF MUKATURI AND SULULTA TOWN, OROMIA REGIONAL STATE, ETHIOPIA

Abstract

Milk wished-for human consumption has to be free from potentially harmful bacteria. A crosssectional study was conducted from November 2017 to June 2018 to assess milk handling practice among dairy farms, to estimating the prevalence of S. aureus in raw milk and swab, to assess associated risk factor of S. aureus and S.aureus load in raw milk, and the antimicrobial susceptibility profile of S.aureus isolates in selected dairy farms of Mukaturi and Sululta Town, Oromia Regional State, Ethiopia. The possible risk factors for S.aureus contaminations in milk were evaluated face to face interviewed 77 respondents through a structured questionnaire randomly base on their intimate to the farm. A total of 247 samples (183 raw milk from lactating cow by simple random sampling technique collected from purposively selected dairy farms and depending on number of worker, frequencies of farm visit and material used 64 swab samples) were examined using standard microbiological techniques. The antimicrobial susceptibility profiles of the isolates were also investigated using disc diffusion method. In the study area with regard to milk handling, 72.1% of respondents (milk consumers) used plastic containers for milk handling meanwhile only 37.2% kept milk in refrigeration before consumption and 60.5% of milk users had habit of raw milk consumption. From milking personnel 47.1% store milk at room temperature temporarily between 6-12 hours till transport to collection center with no means of cooling aid. Overall, 16.6% (n= 41) of the samples were positive for S. aureus. The prevalence of S. aureus was 15.3% from udder milk and 25%, 20% and 10% from milkers’ hand, milking bucket and drying towel swab respectively. The prevalence of S.aureus in milk were statistically significant variation with respect to age (p=0.000), parity (P= 0.000) and regarding with drainage condition of milking area (P=0.035), farming area (P=0.035) and management system (P=0.035). The isolates were found to be resistant to penicillin G (97.6%), and Amoxicillin (43.9%). According to this study, 12(42.9%) raw milk samples had >104cfu/ml S.aureus count, which is above the recommended level for human consumption. The study revealed a prevalence of antimicrobial resistant S. aureus from raw milk cow and swabs, poor milk handling practices, raw milk consumption behavior in study area. Proper handling and hygiene decrease milk contamination by S.aureus and make it safe for human consumption.