Prevalence and Antibiotic Resistance Profiles of Methicillin Resistant Staphylococcus aureus (MRSA) Isolated From Bovine mastitic Milk in Plateau State, Nigeria

Abstract

Mastitis is one of the major challenges of the dairy industry, culminating in the use of a lot of antibiotics which in most cases are often abused leading to resistance. One of the commonly resisted antibiotics is methicillin which is also referred to as Oxacillin. The prevalence of methicillin resistant Staphylococcus aureus (MRSA) and minimum inhibition concentration (MIC) of oxacillin 1μg/ml against, Oxacillin resistant Staphylococcus aureus (ORSA) from subclinical mastitic milk was investigated from 339 quarters of 85 cows, 105(30.9%) were found to be mastitic. One hundred and three (98%) Staphylococcus aureus were isolated from the mastitic quarters. Seventy three of the isolates tested against 12 antibiotics used in the study area, showed twenty six (35.6%) to be resistant to oxacillin and 10 other antibiotics. All the seventy three isolates were susceptible to vancomycin and resistant to penicillin, and also resistance to more than one antibiotic. The 26 ORSA were further confirmed by growth on ORSAB medium and the detection of the 23SrRNA specie specific fragment of S. aureus using PCR. PCR was also used to detect the gene mecA in 2(7.6%) of the 26 ORSA, and the blaZ gene in all the 26 ORSA. The MIC of oxacillin 1μg/ml for the mecA positive isolates was 2.4μg/ml to ≥ 10μg/ml higher than the non – mecA isolates 1.2μg/ml-2.5μg/ml. There is a need for urgent measure(s) to tackle the problem of antibiotic resistance.