Treatment of diarrhea in pigs in the context of the antimicrobial resistance crisis

As antimicrobial resistance becomes a growing concern for animal and human health, Canadian swine researchers are looking for alternatives to antibiotics to treat diarrhea in finishing pigs, writes Kat Zens in a release from the University of Saskatchewan's Western College of Veterinary Medicine.

"The antimicrobial resistance pandemic is already here, and one way veterinarians can help address this problem is through the judicious use of antimicrobials (antibiotics) in animal treatment," says Mateus Costa, a swine veterinary medicine specialist and associate professor at the University of Saskatchewan. 

Costa, a faculty member at the Western College of Veterinary Medicine, is leading new research aimed at developing alternatives to antibiotics for the treatment and prevention of diarrhea in finishing pigs (large pigs weighing between 30 and 120 kilograms). These animals can develop diarrhea when exposed to pathogens (disease-causing organisms) or when experiencing stress.

Animals with diarrhea grow more slowly because they do not metabolize all the food they consume, resulting in economic losses and biosecurity issues, as diarrhea in pigs can be caused by Salmonella spp. or other zoonotic agents.

"It's cheaper to raise healthy pigs than sick ones. Given that pork is the world's primary source of animal protein, pig health is crucial for food security," says Costa. 

Under his leadership, a team of experts is searching for alternatives to antibiotics amid the global antimicrobial resistance crisis. Primarily, they are developing a vaccine against Brachyspira, a bacterium that is a common cause of diarrhea in pigs. 

"If we can create alternatives that either reduce or completely replace antimicrobial use, we will remove the selective pressure on pathogens and thereby prevent the growth of resistant bacteria," the scientist explains. 

As an alternative, researchers are using host defense peptides—small antimicrobial proteins naturally produced by pigs and other farm animals. Costa believes that commercial production of these peptides is feasible.

"When we start producing host defense peptides in a more specific and large-scale manner, we will be able to successfully control microbial populations without causing actual resistance, since the mechanism of action of these proteins is different from that of antibiotics," he says.

Costa's research team is conducting in vitro studies to determine whether alternative antimicrobials can protect cells from infection by pathogens that cause diarrhea in pigs. If these trials are successful, the scientists will begin testing them in live pigs, potentially leading to the commercialization of antimicrobial alternatives in livestock production.

Scientists are also looking for ways to block the pathway by which bacteria cause disease in pigs. Specifically, Costa's research group has identified molecular cascades (a series of reactions triggered by a single molecule) that bacterial pathogens use to cause disease. Experts are now investigating molecules to block these molecular cascades and prevent further disease progression. 

This research is jointly funded by the Government of Saskatchewan's Agricultural Development Fund and the Government of Alberta's Results-Based Agricultural Research Fund.