Prevalence of Staphylococcus aureus contamination in bovine milk from local dairy herd in Oyo State, Nigeria

Abstract

Unhygienic practices, handling and transportation; pooling of milk from unscreened mastitic cows and indiscriminate prophylactic, therapeutic and growth promotion use of antibiotics in Nigerian cattle production could result in dissemination of resistant bacteria including Staphylococcus aureus and leading to food poisoning. This work aims to determine the prevalence of Methicllin Resistant Staphylococcus aureus (MRSA) in bovine milk from local herds. A total of 165 fresh bulk milk samples were collected from local herds at Ibarapa, Oyo and Oke-Ogun in Oyo State for isolation of Staphylococcus aureus. Standard bacteriological methods were used to determine the bacterial load, isolate and characterize Staphylococcus aureus in fresh bovine bulk milk from dairy herds in Oyo State. Antibiotics sensitivity of the isolates was determined using disc diffusion method. Bacteriological assay revealed high total mean bacterial counts ranging from 1.5+0.069 to 6.1+23.19 log cfu/ml, with the highest contamination in 13.9% of milk from Oke-Ogun, followed by 4.2% from Oyo and Ibarapa respectively. There was a prevalence of 31.5% coagulase positive Staphylococcus aureus with 7.9% isolates indentified as MSRA. The isolates showed very high resistance to several antibiotics with the highest resistance to augmentin (88.5%) and the highest sensitivity to ofloxacin (96.1%). This study established the presence of Staphylococcus aureus in milk from local herds with a prevalence of 33.1%. This signified the high risk of mastitis in the dairy cows from the study area. The high prevalence of MRSA is of food safety concern and could have resulted from indiscriminate use of antibiotics. Enforcement of milk hygiene practices, constant screening and treatment of mastitic cow as well as effective milk pasteurization are hereby suggested to ensure food safety.

Keywords: Animal, Antimicrobial agents, Bulk milk, Staphylococcus aureus