Isolation and Identification of Methicilin Resistant Staphylcoccus aureus (MRSA) from Bovine Mastitic Milk in and around Wolaita Sodo, Southern Ethiopia

In recent years, there has been increased concern about antibiotic resistant strains of Staphylococcus aureus and multiple antibiotic resistant strains have started to emerge. Development of resistance has been attributed to the extensive therapeutic use of antimicrobials. A cross sectional study was conducted from November 2013 to May 2014 in and around Wolaita Sodo town, Southern Ethiopia, to isolate and identify MRSA and their resistance to different antimicrobials and also identify risk factors associated with occurrence of dairy cow mastitis. A total of 257 dairy cows were included during the study period. Total of 1010 quarters were examined to detect clinical and subclinical mastitis by physical examinations of udder and milk and California mastitis Test (CMT), respectively. Milk samples were collected from each of clinically and sub clinically mastitic non-blind quarters of the selected cows for bacterial isolation. The Staphylococcus aureus isolates were tested for anti-microbial susceptibility by disc diffusion method. The occurence of mastitis was 40.9%. Out of this, 4.66% and 36.18% were clinical and subclinical respectively. The univariate logistic regression showed that among potential risk factors considered from the farm attributes, age, milking hygiene, parity, lactation period, farm floor and previous mastitis treatment had significant (p=<0.05) effect on the prevalence of mastitis. The present study showed the resistance of Staphylococcus aureus to penicillin G (100%), cefoxitin (71.8%), amoxicillin-clavulinic acid (61.5%), tetracycline (69.2%), streptomycin (66.7%), chloramphenicol (35.9%), sulphamethoxazole-trimethoprim (43.6%) and vancomycin (56.4%). In the present observation, 28 (71.8%) Staphylococcus aureus isolates not only showed MRSA but also multidrug resistance (MRSA). The present study emphasizes the importance of MRSA on dairy farms in and around Wolaita Sodo, Southern Ethiopia. The development of antimicrobial resistance is nearly always as a result of repeated therapeutic and/or indiscriminate use of them. Regular antimicrobial sensitivity testing helps to select effective antibiotics and to reduce the problems of drug resistance development towards commonly used antibiotics.