A reliable challenge model is needed to evaluate Helicobacter pylori vaccine candidates.
A team of researchers from the United States used a cag pathogenicity island negative, OipA positive, multiple antibiotic susceptible strain of H pylori to challenge 20 volunteers.
The volunteers received 40 mg of famotidine at bedtime and 104–1010 cfu of H. pylori in beef broth the next morning.
The researchers confirmed infection using 13C urea breath test, culture, and histology.
The subjects then received eradication therapy for 4 or 12 weeks post-challenge.
Eradication was confirmed by at least 2 separate urea breath tests, as well as culture and histology.
Of the 20 volunteers, 18 became infected.
The team found that mild to moderate dyspeptic symptoms occurred; these peaked between days 9 and 12, and resolved.
The team determined that vomitus from 1 subject contained >103 viable/ml H. pylori.
By two weeks post-challenge, the researchers found that gastric histology showed typical chronic H. pylori gastritis with intense acute and chronic inflammation.
They found that gastric mucosal interleukin 8 levels increased more than 20-fold by 2 weeks after the challenge.
The team established that the density of H. pylori was independent of the challenge dose, but was unable to identify a minimal infectious dose.
Dr Graham's team concluded, "Challenge reliably resulted in H. pylori infection".
"Infection was associated with typical H. pylori gastritis with intense polymorphonuclear cell infiltration and interleukin 8 induction in gastric mucosa, despite absence of the cag pathogenicity island".
"Experimental H. pylori infection is one of the viable approaches to evaluate vaccine candidates".