Prevalence and antibiotic resistance of Staphylococcus aureus and Escherichia coli isolated from raw milk in East Java, Indonesia

BACKGROUND AND AIM: Raw milk can be a source of food-borne disease transmission and a medium for spreading antibiotic-resistant bacteria. Staphylococcus aureus and Escherichia coli are bacteria that have the pathogenic ability to attack host cells and are capable of harboring antibiotic-resistant genes. This study estimated the prevalence and antibiotic resistance of S. aureus and E. coli isolated from raw milk in East Java, Indonesia. MATERIALS AND METHODS: Two hundred and fifty raw milk samples were collected from five dairy farms in East Java. S. aureus and E. coli were isolated using their respective selective media, whereas antibiotic susceptibility testing was performed using the Kirby–Bauer disk diffusion method. The methicillin-resistant S. aureus (MRSA) was confirmed using the oxacillin resistance screen agar test, and extended-spectrum beta-lactamase (ESBL)-producing E. coli was determined using the double-disk synergy test. The presence of mecA and blaTEM genes were screened by the polymerase chain reaction method. RESULTS: Results indicated that the prevalence of S. aureus was 138 (55.2%) and that E. coli was 176 (70.4%). Of the 138 S. aureus isolated, 27 (19.6%) were MRSA, and among the 176 E. coli isolates identified, 3 (1.7%) were ESBL producers. The mecA gene was observed in 2 (7.4%) MRSA and all 3 (100%) ESBL-producing E. coli isolated harbored blaTEM genes. CONCLUSION: The presence of MRSA and ESBL-producing E. coli in raw milk is a serious public health threat, and public awareness should be raised about the dangers posed by these pathogenic organisms.