Some Salmonella serotypes can permanently damage your DNA

While there are more than 2500 serotypes for Salmonella, the vast majority of foodborne illness is caused by fewer than 100 of them. The Center for Disease Control estimates that there are 1.2 million non-typhoidal Salmonella illnesses and about 450 deaths in the US annually, and there is no reason to assume that the statistics would be any better in Australia and New Zealand.

Most cases of Salmonella-caused food poisoning involve a few nasty days and a promise to be more vigilant about food hygiene and safety in the future. But now it seems that the effects of some serotypes may be much longer lasting. Cornell University food scientists have found that infection by some serotypes can permanently damage DNA.

Rachel Miller, a doctoral candidate in food science, and Martin Wiedmann, the Gellert Family Professor in Food Safety, examined multiple serotypes of Salmonella that encode for cytolethal distending toxin (S-CDT), a virulence component for serotype Typhi — the cause of typhoid fever. As it happens, the Salmonella serotypes called Javiana, Montevideo, Oranienburg and Mississippi — common culprits in the foodborne illness world — also carry the genetic material that encodes S-CDT, the researchers found.

In human cells grown in the lab, Salmonella strains with S-CDT were also found to lead to hallmark signatures that indicate the presence of DNA damage. The ability to cause DNA damage may contribute to long-term disease consequences, Miller said.

“Think about possible DNA damage this way: We apply sunscreen to keep the sun from damaging our skin. If you don’t apply sunscreen, you can get a sunburn — and possibly develop skin problems later in life,” said Miller. “While not the sun, Salmonella bacteria may work in a similar way. The more you expose your body’s cells to DNA damage, the more DNA damage that needs to be repaired, and there may one day be a chance that the DNA damage is not correctly repaired. We don’t really know right now the true permanent damage from these Salmonella infections.”

For a half-century, scientists have used Salmonella serotyping to track foodborne illness outbreaks and their sources.

“A person’s damaged DNA from Salmonella could lead to long-term health consequences after the infection subsides, such as longer bouts with foodborne illness,” said Wiedmann.

The research was shared in the journal mBio (November/December 2016), published by the American Society of Microbiology. The US Department of Agriculture provided funding.