Interspecific epidemiology of MRSA in pig farming

The populations of MRSA are classified in relation to their origin, distinguishing S. aureus Healthcare-Acquired aureus (HA), Community-Acquired (CA) and Livestock-Acquired (LA). For LA-MRSA livestock animals have an important epidemiological role. This has raised the suspicion that the intensive husbandry may be, for the frequency and intensity of use of antibacterial treatments, an elective field of clonal selection of antibiotic resistance. The presence of LA- MRSA in pig production is sure in many countries and the pig is considered a reservoir for transmission to humans and other animals. In fact, farmers and production workers have a higher rate of colonization than the rest of the population. This work reports the presence of MRSA in slaughter pigs (2.3% positivity of the tonsils), sows (10% positivity of nasal swabs) and veterinarians employed in pig production (25% of nasal carriers). Many of the isolates from pigs and man belong to the same genomic patterns.