Prevalence and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) among subjects working on bovine dairy farms.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of healthcare-associated infections worldwide and has recently been identified as an emerging pathogen in livestock and companion animals. Livestock-associated MRSA (LA-MRSA) may be responsible for increased rates of colonization and/or infection among people working on farms. We evaluated the prevalence and molecular characteristics of MRSA among dairy farmers in the province of Ragusa, South-Eastern Sicily, their animals and bulk tank milk samples. A surprisingly high number of samples tested positive for MRSA: 36% of human nasal swabs, 61% of bovine nasal swabs and 44% of bulk tank milk samples. MRSA carrier prevalence in humans significantly correlated with the percentage of positive cows on the farm, the number of livestock units and the presence of consensual positive bulk tank milk samples. Prospective studies are needed to investigate MRSA transmission between animals and humans and implement preventive strategies.