Identification of Methicillin-resistant Staphylococcus aureus Isolated from Dairy Cow’s Milk in Tulungagung District, Indonesia

Background: Mastitis is one of the factors contributing to the health-related decreased milk production and quality for dairy cows. Mastitis in ruminants is a serious bacterial disease caused by Staphylococcus aureus. Staphylococcal bacteria are becoming increasingly resistant to many classes of antibiotics, particularly β-lactam families like the MRSA strain. Laboratory tests are required to determine the level of bacterial resistance and to identify MRSA isolates sourced from dairy cows in Tulungagung District. Methods: 110 milk samples were isolated on MSA media followed by Gram’s staining and biochemical tests. Kirby-bauer diffusion test-based assessment of antibiotic sensitivity. The S. aureus isolates that underwent the MRSA identification test were S. aureus isolates that had developed a resistance to β-lactam antibiotics. Result: A total 81 samples of the 110 isolated milk samples were determined to be positive for S. aureus. Out of total isolates, 25 isolates of S. aureus had the highest level of oxacillin resistance. As many as 4 isolates were confirmed to be MultiDrug Resistance (MDR) and 17 MRSA isolates were discovered from 100 samples of dairy cows. Early diagnosis of MRSA infection is crucial since it can be challenging to treat because this type of bacteria is known to be resistant to several drugs and spreads readily.