Abstract

The objective of this study was to analyze the occurrence of methicillin-resistantStaphylococcus aureus (MRSA) from cattle with subclinical mastitis in two dairy herds in the northwest of Serbia. All quarters reacting positive in the California Mastitis Test were sampled for bacteriological analysis. Nasal and vaginal swabs from MRSA positive cattle, and nasal swabs from humans working on farms were also collected. From 1026 cows, 212 (20.7%) suffered from subclinical mastitis. S. aureus was detected in milk samples from 84 (39.6%) cows with subclinical mastitis. Among them, MRSA were isolated from 5 (5.9%) cows. Three out of five positive cows harboured MRSA in their nose and 1 cow harboured MRSA in the vagina. No MRSA was found in human nasal swabs. Seven out of 10 MRSA isolates in farm A, and two MRSA isolates in farm B, were resistant to gentamicin and tobramycin and exhibited SCCmec type IV. The three other isolates in farm A were resistant to tetracycline and carried SCCmec elements of type V. To our knowledge, this is the first description of MRSA from bovine subclinical mastitis in Serbia. The results of our study herald the emergence of MRSA in dairy farms in Serbia, so continued surveillance is recommended.

Key words: Methicillin-resistant Staphylococcus aureus, staphylococcal cassette chromosome mec typing, dairy cattle.