Swine workers: An emerging risk group for community-associated methicillin-resistant Staphylococcus aureus (MRSA)

Over the past decade, the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) has undergone significant changes. Once primarily a hospital-based pathogen, MRSA is now found increasingly in the community, and this bacterium has caused serious infections in individuals with no history of hospitalization. Recent research has also shown that swine and swine farmers are colonized with MRSA at high levels in the Netherlands and Canada. With Iowa raising 16 million hogs a year in a $4 billion a year industry, we set out to examine the prevalence of MRSA in swine from Iowa and Illinois. Therefore, we collected samples from swine on 10 different farms (7 confinement, 3 organic/antibiotic free) in Iowa and Illinois. To date, no MRSA has been found on organic farms in Iowa. Nasal swabs were taken from 474 swine. Overall MRSA prevalence in swine was found to be 32% (151/474). MRSA prevalence in confinement swine was 40% (151/382). These results show that colonization of swine by MRSA is very common on the farm system we examined in the Midwestern U.S., adding to the concern about domestic animal species as a reservoir of this bacterium. In addition to swine, nasal and pharyngeal swabs were taken from humans. Overall MRSA prevalence in humans was 42% (20/48). Humans working in confinement operations had a prevalence of 63% (20/32). Individuals exposed to swine, especially in confinement operations, are risk for MRSA carriage. Additional studies are ongoing to examine the carriage rates of MRSA in rural Iowa.