Researchers in the U.K. have developed a new sequencing method to study simultaneously the survival of different salmonella serovars in cattle.
Salmonella is a pathogen that infects both cattle and humans. There are more than 2,600 types -- or serovars -- of salmonella, many of which can survive within the lymphatic system of cattle. Peripheral lymph nodes of cattle contaminated with salmonella can enter the food chain via ground beef products, and improper cooking of these foods can result in infections in people, the researchers said.
It is important to determine whether some salmonella serovars are better than others at surviving within cattle to determine if some serovars pose a greater threat to human health than others. This will enable researchers to develop appropriate vaccines and interventions to stop the transmission of salmonella to humans.
A study conducted by Dr. Prerna Vohra from The Roslin Institute in the U.K., under the supervision of professor Mark Stevens, used a novel whole-genome sequencing approach to investigate mixed-serovar infections of salmonella in cattle. Some salmonella genes naturally vary in sequence between different serovars. By using the variations in these genes as markers, it is possible to identify and quantify the serovars present in a mixed population.
The team determined the presence and abundance of serovars in various tissues of cattle challenged with a mixed-serovar population. Their results showed that all of the salmonella serovars were present in the peripheral lymph nodes, suggesting that they have similar zoonotic potentials and can all compromise food safety.
"This study helped further our understanding of salmonella infections in cattle, which can involve more than one serovar, and we can conclude that pan-serovar approaches are required to limit the transmission of salmonella from cattle to humans," Vohra said.
The method has the potential to be applied to other bacteria with naturally variable genes. It could also be used to test the efficacy of vaccines and control strategies against pathogens and for the routine surveillance of farms, food products and the environment, the announcement said.
"The method has the potential to reduce the number of animals required to understand the biology of different bacterial strains in animals," Stevens added. "It can be used not only to compare virulence but also to test the cross-protective efficacy of vaccines and other control strategies."
The study, funded by the U.K.'s Biotechnology & Biological Sciences Research Council and Zoetis, was published in Applied & Environmental Microbiology.