In a four-month study ending in January 2007, researchers
collected nasal and rectal swabs from 285 pigs of three
different age groups from 20 different farms. Nasal swabs
were collected from farm personnel and a brief questionnaire
was also administered. Nine out of 20 farms studied, or 45 per cent, were positive
for MRSA. Prevalence in pigs was 24.9 per cent with no
difference in colonization between age groups. Twenty per
cent of pig farmers tested positive for MRSA and researchers
found a correlation between the presence of MRSA in pigs
and humans on farms. The study’s senior author, Dr. Scott Weese of the
Department of Pathobiology, Ontario Veterinary College,
University of Guelph, says that the study left researchers
with a number of unanswered questions. “We need to find
out how broad this is,” Weese says. “We need to find out
how representative southern Ontario is compared to the
rest of North America.” One of the interesting findings in Weese’s study is that
one of the farms with the highest rate of MRSA was an
antibiotic-free farm. “I think it’s overly simplistic to say that antibiotic use in pigs is the sole reason this has emerged.
There’s gotta be something else going on.”