Global Food

Safely stamping out salmonella

Scientists have identified more than 250 different kinds of foodborne diseases, and while a case of food poisoning is an uncomfortable situation for most, an outbreak can be deadly for certain high-risk groups of people. 

Salmonella causes more hospitalizations in the United States than any other foodborne illness, and 94 percent of human cases come from food. So, when narrowing down which pathogen she wanted to focus on, Shijina Raj Manjankattil Rajan, DVM, a third-year PhD student in the College of Food, Agriculture and Natural Resource Sciences (CFANS), set her scope on salmonella. 

“Our focus is to eliminate salmonella from the food system without antibiotics,” Manjankattil Rajan says. That’s no easy task. There are more than 2,500 variations of salmonella, and every year, new variations emerge that are resistant to existing antibiotics, but very few alternatives exist. 

Part of the growing issue of antimicrobial resistance in bacteria is the widespread use of antibiotics in the animal food systems. For many years, low doses of antibiotics were used in animal feed as a preventative measure to control diseases.. But any time producers use antibiotics to keep bacteria at bay in animals, they risk helping a pathogen develop antibiotic resistance. Because animal health is closely tied to both environmental and human health, the issue of antibiotic-resistant pathogens impacts all parts of the One Health system.

“We see reports of antibiotic treatment failures in humans who are infected with salmonella that originated in poultry. We cannot continue the use of antibiotics in food production, so we need alternatives to fight against salmonella and other foodborne pathogens,” Manjankattil Rajan says.

Harnessing natural antibiotics 

With funding and support from the MnDRIVE Global Food Ventures Research Fellowship, Manjankattil Rajan is expanding on her master’s thesis work to help lessen the chances of antibiotic-resistant pathogens evolving in the first place. The research, which was presented at the 2019 Poultry Science Annual meeting in Montreal, investigated how natural compounds are able to reduce antibiotic use in chickens, while still ensuring meat and eggs as safe sources of protein for people. 

Manjankattil Rajan has zeroed in on caprylic acid, a fatty acid that naturally occurs in breast milk and coconut oil, which has natural antibacterial, antiviral, antifungal, and anti-inflammatory properties. So far, her work has shown the compound holds promising potential as a treatment for antibiotic-resistant salmonella in chickens. 

She first wanted to test whether or not adding caprylic acid to chicken feed could reduce the amount of salmonella living in the birds. While the bacteria doesn’t harm the animals, it can contaminate meat after a bird is harvested, and incorporating the natural antibacterialinto feed could reduce the chances of this happening. This research is completed and will be published later this year.

The next phase of research tested how effective caprylic acid can be at killing salmonella during the processing phase of food production. She tested whether or not caprylic acid could safely kill salmonella on meat that’s already contaminated. Manjankattil Rajan said the most important thing about this research is that her work in the lab has the potential to address a pressing health threat in the real world. 

“Chicken meat and eggs are one of the largest and economical sources of animal protein for the expanding world,” says Anup Kollanoor Johny, BVScAH, MVSc, PhD, an associate professor in CFANS and director of The Anup Johny Lab at the University of Minnesota, who advised the research. “The University of Minnesota is leading the effort to make food production more sustainable, not just for people but for the animals and the environment.”