Clinical Experiment of Helicobacter Pylori Transmission

The study proposes to test whether chronic infection with Helicobacter pylori protects individuals from symptomatic infection with enteropathogenic E. coli. The study will also evaluate the effect of gastric acidity in this relationship.

Because H. pylori is an enteric infection, its prevalence may be linked to exposure to other enteric pathogens. Results of observational studies on the association between H. pylori and gastroenteritis, however, have been conflicting. Some have shown increased incidence of diarrhea in children with H. pylori infection, with one study attributing 11% of diarrhea cases to H. pylori. Other studies found no association, and still others found a protective effect of H. pylori against gastroenteritis. Dissecting out confounding from true physiological associations can be difficult in observational studies. To better elucidate the association between H. pylori and gastroenteritis, we performed a direct challenge experiment with a well-characterized gastrointestinal pathogen, enteropathogenic Escherichia coli (EPEC). EPEC is a leading cause of infantile gastroenteritis in the world and has a long history of safe use in human experiments. It is also acid sensitive: in our laboratory less than 0.001% of inoculated EPEC organisms survived at pH 2.5. Our goal was to test the hypothesis that chronic infection with H. pylori increases the risk of diarrheal illness after direct challenge with EPEC.

Persons who tested negative for H. pylori by both serology and Urea breath test. All participants will receive the Biological intervention: Enteropathogenic E. coli.

Persons who tested positive for H. pylori by both serology and Urea breath test. All participants will receive the Biological intervention: Enteropathogenic E. coli.

Composite gastrointestinal symptom score was on a scale from 0 (no symptoms) to 15 (severe symptoms). This composite was the sum of 5 self-reported, symptom scores, each ranging from 0 (none) to 3 (severe). The self-reported symptoms that subjects scored were: malaise, headache, nausea, vomiting, and loose stool.

Inclusion Criteria:Healthy Exclusion Criteria:prior gastrointestinal disease prior treatment of H. pylori infection immune suppression or deficiency history of cancer, diabetes, or other co-morbidity