Ulcer bug linked to stroke. (Biomedicine).

What's bad for the gut may be bad for the brain. Potent strains of an ulcer-causing bacterium may also trigger strokes, according to a study in an upcoming Circulation.

Over the past several years, researchers have come to believe that low-grade inflammation, such as the body's response to a chronic infection, precedes heart disease and potentially stroke. But linking this inflammation to any specific infection has been tricky, says lead researcher Antonio Pietroiusti of Tor Vergata University in Rome.

Now, he and his colleagues have shown that a particularly virulent form of the bacterium Helicobacter pylori is associated with so-called large vessel stroke--an attack that's triggered when blood vessels to the brain are blocked by fatty plaques. This troublesome strain of H. pylori, designated as CagA-positive, produces potent toxins that are thought to attack plaque-lined blood vessels, causing inflammation.

In their study, the researchers found the strain turned up in 43 percent of 131 people with large-vessel stroke and in 20 percent of 61 patients with a stroke triggered by a blood dot from another part of the body. Overall, both groups were equally likely to be infected by some strain of H. pylori.

"A policy of selective eradication of virulent H. pylori strains might be the most appropriate approach for preventing [large-vessel strokes] in high-risk subjects," he says.