H. pylori is a type of bacterium that, unlike most bacteria, is able to survive and thrive in the highly acidic gastric (stomach) environment. It grows in the mucous barrier that protects the gastrointestinal lining from the digestive juices. H. pylori bacteria also produce large amounts of urease, an enzyme that breaks down to form ammonia. Ammonia neutralizes the acidity around the bacteria, further protecting them.

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), H. pylori bacteria are responsible for almost two-thirds of all peptic ulcers (open sores in the lining of the esophagus). H. pylori infection is also strongly associated with the development of stomach cancer.

Current methods to detect the bacteria are highly effective. However, they can be invasive, uncomfortable and expensive for patients. For example, H. pylori can be detected through an endoscopic gastric biopsy, which involves inserting a tiny camera attached to a thin tube through the patient's mouth and esophagus into the stomach. A tissue sample is then collected for laboratory analysis.

During the study, 35 subjects who complained of stomach problems and had previously undergone biopsies were instructed to swallow a capsule that contained an absorbent string. The string protruded from the capsule and was held outside the subjects' mouths. Researchers then retrieved the ingested string, recovering microbes from the digestive tract for analysis. H. pylori bacteria was found on the strings of 80 percent of the subjects who had received positive biopsy results, and no organisms were cultured from the strings of subjects who had received negative biopsy results.

"Our study shows that the string test, which is minimally invasive, inexpensive, and not dependent on sophisticated or costly equipment or radioactivity, allows culture of H. pylori from infected persons about 80 percent as efficiently as endoscopic gastric biopsies. We suggest that the H. pylori string test assays will be of increasing importance in a public health context," said the researchers in a recent press release.

The findings of the study appear in the March 2006 issue of the Journal of Clinical Microbiology.

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