New Salmonella serotype identified

Research intended to find Salmonella organisms in certain organs included in some ground beef led to the discovery of a new serotype.

That serotype, Salmonella enterica Lubbock, was found in cattle peripheral lymph nodes, and it appears to be related to S Mbandaka and S Montevideo, said Dr. Guy Loneragan, a professor of food safety and public health at Texas Tech University. The serotype is named after the city where it was found, the home of Texas Tech’s main campus.

Further research will involve examining related strains in historical data sets, such as those held by veterinary diagnostic laboratories and the Centers for Disease Control and Prevention, to determine whether S Lubbock is present but unidentified in prior samples. Other research will involve work to understand why certain serotypes persist in niches such as peripheral lymph nodes and will re-examine methods and actions that transmit Salmonella organisms.

“Identification of a new serotype indicates that we still have quite a bit more to understand, in particular about the ecology of Salmonella and how it’s evolved or coevolved with cattle populations over time,” Dr. Loneragan said.

He said the discovery of S Lubbock is a testament to the brilliance of research assistant professor Marie Bugarel, PhD, who was a postdoctoral student when she noticed that the Salmonella strain recovered in the research did not match designated serotypes.

“Discovering this strain really represents the intellectual detective work that Marie Bugarel did, in that she identified that something just didn’t make sense and pursued it to the point that we have confirmation of a new serotype from the reference center at the Pasteur Institute in France,” he said.

Dr. Loneragan said the research began in 2010 out of concern that peripheral lymph nodes could harbor Salmonella organisms, which could be mixed into ground beef.

Dr. Bugarel said current work to characterize the Salmonella strain has shown that the serotype emerged recently, “confirming that Salmonella is a dynamic bacteria that is able to adapt to a host and to colonize and survive on it.” The work also will help improve understanding of bacteria-host interactions, selection pressure on bacteria, and features important for bacteria to persist in a bovine host.

By late February, the strain had been identified only in cattle.