Could identifying certain hypervirulent subtypes of Salmonella be a first step toward preventing food poisoning outbreaks caused by the bacteria?


An international research team, led by University of California Santa Barbara researchers Michael Mahan and Douglas Heithoff, thinks so and has detailed its findings in a paper titled “Intraspecies Variation in the Emergence of Hyperinfectious Bacterial Strains in Nature,” published in the journal PLoS Pathogens.

Salmonella infections in the U.S. have increased by 10 percent in recent years, according to the Centers for Disease Control and Prevention, and more than 1 million people in this country become ill from Salmonella each year. Salmonella infections account for about half of the hospitalizations and deaths among the nine foodborne illnesses the CDC tracks.

The federal public health agency also says the bacterium – which has many subtypes — is responsible for an estimated $365 million in direct medical costs each year in the United States. Control efforts to keep the pathogen out of the food supply are estimated to cost up to $14.6 billion annually.

Meats, eggs, produce and even processed foods can become contaminated with the pathogen, which is transmitted primarily through animal excrement. Contaminated foods that are undercooked or served raw are particularly risky.

The UCSB researchers said they found 14 hypervirulent isolates out of 184 Salmonella clinical isolates obtained from humans and animals, and discovered the powerfully infectious strains were restricted to certain serotypes, according to a news release. The scientists said they were aided by a special medium that helped them assess the bacteria’s virulence during infection, before the pathogens switched back to a less-virulent state in the lab.

Now that they know what to look for, the researchers said they are working on methods to rapidly detect the most harmful strains and design therapeutics to combat them.