Earlier this year, at least 152 people in Washington state were infected with multidrug-resistant Salmonella I 4,[5],12:i:- linked to pork produced by Kapowsin Meats. According to federal estimates, pork is the source of about 8 percent of Salmonella illnesses in the U.S.
Scientists interested in finding ways to control Salmonella in pigs first want to know what might predispose the animals to carry the pathogen and cause them shed higher levels of it.
Researchers at the University of Minnesota’s Department of Veterinary and Biomedical Sciences are looking into the connections between Salmonella and Lawsonia intracellularis, the cause of a common diarrheal disease in pigs called porcine proliferative enteritis.
In the first part of their study, Minnesota professor Richard Isaacson and his colleagues experimentally challenged pigs with Lawsonia, Salmonella, or both, and followed their secretion of Salmonella over time.
What they found was that the animals infected with both pathogens had higher levels of Salmonella in their feces and over a longer period of time.
“It suggested to us that Lawsonia predisposes to this higher-level shedding and may cause what we’d like to call a ‘supershedder,’” Isaacson told Food Safety News.
People have found supershedders of E. coli O157 in cattle, but “people have looked for that in Salmonella and never has anyone actually been able to identify it as far as I’m aware,” he added.
The second part of the Minnesota study, which was published last month in the journal PLOS One, tracked changes in the microflora — the community of microorganisms living in the digestive tract — found in the pigs’ feces.
“People have said for a long time that normal flora of animals and people help protect us against pathogens coming in,” Isaacson said.
His team wanted to find out whether or not that was actually true. And the answer, according to their study, was that it’s not.
Both Lawsonia and Salmonella cause substantial changes to the composition of that microflora, and each one caused somewhat different changes, Isaacson explained. The researchers are now looking at how those changes might cause increased shedding of Salmonella.
In a further research that has just begun, the scientists aim to find out whether vaccinating pigs for Lawsonia would protect them from shedding Salmonella.
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