A little over a year ago I put a post up documenting research out of Canada which found methicillin-resistant Staphylococcus aureus (MRSA) in Canadian pigs. This had also been seen in Europe (with a lot of research coming out of the Netherlands). What I didn’t note at the time was that we were gearing up to start some sampling of our own on area swine farms. Some of you saw that we presented the results of that research last year at ICEID and ASM; now the paper is out describing our pilot project in PLoS ONE. (Note: the paper was available earlier, but now they seem to have removed it…keep an eye on that link).
For this research, we swabbed pigs and humans from 2 large swine farming companies in the area. The first (“production system A”, PSA) had about 60,000 pigs at any one time; the second (PSB) was smaller, with about 27,000 pigs. These were distributed over several different farms in the area (with several thousand animals on each farm) and are typically age-segregated.
We didn’t find any MRSA on PSB, in either the pigs or the people. However, we found quite a lot on PSA, in roughly similar percentages of people and pigs (70% of PSA’s pigs, 64% of PSA’s people). We carried out molecular typing on all of the human isolates and a subset of the swine, and all that we tested were found to be ST398, the so-called “piggy” MRSA. To our knowledge, this is the first publication of this strain in the US.
I don’t want to just repeat what we wrote in the discussion (and hey, the paper’s freely available, so just read it!) but suffice it to say, we’re busy carrying out a lot of follow-up studies looking at various aspects of zoonotic S. aureus, including lots more studies in pigs but also other animals. A recent publication showed MRSA in a variety of meat products, so while pigs have been a focus, they’re obviously not the only potential problem out there.
Tara C. Smith, Michael J. Male, Abby L. Harper, Jennifer S. Kroeger, Gregory P. Tinkler, Erin D. Moritz, Ana W. Capuano, Loreen A. Herwaldt, Daniel J. Diekema (2008). Methicillin-Resistant Staphylococcus aureus (MRSA) Strain ST398 Is Present in Midwestern U.S. Swine and Swine Workers PLoS ONE, 4 (1) DOI: 10.1371/journal.pone.0004258
E DEBOER, J ZWARTKRUISNAHUIS, B WIT, X HUIJSDENS, A DENEELING, T BOSCH, R VANOOSTEROM, A VILA, A HEUVELINK (2008). Prevalence of methicillin-resistant Staphylococcus aureus in meat International Journal of Food Microbiology DOI: 10.1016/j.ijfoodmicro.2008.12.007