Lawsonia predisposes pigs to shed salmonella

Study to be basis of future research on vaccinating pigs for lawsonia as food safety measure.

A recent University of Minnesota College of Veterinary Medicine study shows that pigs infected with Lawsonia intracellularis, a bacterial pathogen that causes disease in pigs and horses, predisposes these animals to shed the foodborne pathogen Salmonella enterica.

S. enterica is responsible for 1.5 million cases of foodborne illness in the U.S. each year, according to the Centers for Disease Control & Prevention.

According to the university, the results of this study will be used as the basis for future research that is designed to show that vaccinating pigs for L. intracellularis could decrease shedding of S. enterica, potentially helping to reduce the number of foodborne illnesses attributed to this pathogen.

Pigs are frequent asymptomatic carriers of S. enterica, and pigs that carry the pathogen can result in contaminated pork products.

"Swine can act as a reservoir for the spread of S. enterica throughout the herd, within the packing plant and during processing to the finished product," the study noted.

Researchers in the College of Veterinary Medicine's department of veterinary and biomedical sciences — Drs. Klaudyna A. Borewicz, Hyeun Bum Kim, Randall Singer, Connie Gebhart, Srinand Sreevatsan, Timothy Johnson and Richard Isaacson — characterized the composition of the gut microbiome in pigs challenged with S. enterica serovar Typhimurium (a subspecies of S. enterica) and/or L. intracellularis and then compared it to the fecal microbiome of non-challenged control pigs.

The research analysis demonstrated that there was a disruption in the composition of the gut microbiome in pigs challenged with either pathogen. Moreover, the compositions of the microbiomes of pigs challenged with either L. intracellularis, S. enterica or both were similar to one another but differed from those of the non-challenged control animals, the announcement said. Significant increases in some other specific bacteria were also seen in the challenged pigs.

To determine whether the changes were specific to experimentally challenged pigs, the researchers also characterized the compositions of the fecal microbiomes of pigs naturally infected with S. enterica and found that similar changes in the gut microbiome were associated with carriage of S. enterica regardless of whether the pigs were experimentally challenged or acquired this pathogen naturally.

The study, "Changes in the Porcine Intestinal Microbiome in Response to Infection with Salmonella enterica and Lawsonia intracellularis," was published in the Oct. 13 issue of PLOS One, a peer-reviewed, open-access scientific journal published by the Public Library of Science (PLOS).

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