Bacterium infects 50% of the population and you’ve never even heard of it

By Christopher Austin

There is a bacterium so common in the United States that about 20% of people below the age of 40, and 50% of people above 60, carry it. Across the globe, it lives inside roughly half of the population. Most experience no adverse side effect, but for a portion of those infected it has been linked with gastrointestinal diseases including ulcers and, more importantly, stomach cancer.

Helicobactor pylori (H. pylori), an unassuming spiral-shaped bacterium that lives in the stomach, is the only known bacteria linked to cancer. Treatments are available, but recent research suggests that the bacterium is adapting to be resistant.

Color enhanced electron micrographs of H. pylori. (Image Credit: of Dr. Lucy Thompson)

To combat this common killer, researchers at Uniformed Services University's (USU) Department of Microbiology & Immunology are stepping up research to better understand and defeat the pathogen; the ultimate goal being to block its ability to cause cancer.

They’ve discovered that, in high concentrations of salt, H. pylori in the stomach appears to undergo gene activity that makes it more deadly, which is linked with the chance of an infected person developing a severe gastric disease like cancer.

“Apparently [H. pylori] closely monitors the diets of those people whom it infects. Epidemiological evidence has long implied that there is a connection between H. pylori and the composition of the human diet. This is especially true for diets rich in salt,” said D. Scott Merrell, Ph.D., professor of Microbiology & Immunology at USU, who led the study that made this observation.

Part of what makes H. pylori so difficult to treat is that it can form a protective structure around itself, called a biofilm, when attaching to the stomach walls. This makes the bacteria particularly resistant to traditional antibiotics.

Color enhanced electron micrographs of H. pylori. (Image Credit: Dr. Nina Salama)

The USU researchers have discovered that the formation of the biofilm seems to be tied to the activity of a key regulatory system in H. pylori which senses the acidity of the environment. This way, it can tell when it has reached a surface in the stomach to adhere to and begin to form biofilms.

“Given that we have a target in this system, one can potentially design antibodies or therapeutics to block that target and potentially stop biofilm formation, which would hopefully help with treatment,” said Merrell.

Until such treatments exist, eating less smoked meats and pickled vegetables, and other foods that have a high salt content, can help protect against stomach cancer.