[CagA status and virulence of Helicobacter pylori strains. Results of a French multicentric prospective study]

Abstract

Previous experimental and epidemiological studies with few patients suggested that the presence of the cagA gene was a virulence factor for Helicobacter pylori (H. pylori).

Aim: To establish in this large epidemiological cohort study the relationship between the histological virulence of H. pylori infection and the cagA status of the bacteria.

Methods: This prospective cohort study (6 month follow-up) was conducted on adult patients undergoing endoscopy for upper gastrointestinal symptoms. The cagA status of H. pylori-positive patients was established using the polymerase chain reaction (PCR) method on an antral biopsy. A score of histological virulence (inflammation, activity) was recorded on the basis of the Sydney system (on antral, angular and fundic biopsies). Eradication treatment given was not imposed and a clinical follow-up was performed at 3 and 6 months. H. pylori eradication was verified by a 13C urea breath test at 3 months.

Results: Four hundred and twenty two centers recruited 652 patients (mean age: 51 +/- 15 years, 55% female). Upper GI endoscopy was abnormal in 80% of the patients of whom 68% had a gastritis aspect; 38% were infected by H. pylori, and among them 51% were cagA-positive. The histological virulence scores associated with the cagA-positive strains were significantly higher than those associated with the cagA-negative strains, globally (P = 0.0035), in the antrum (P = 0.0063), and in the angulus (P = 0.046), but not in the fundus (P = 0.05). The cagA status was correlated neither with the symptom severity at inclusion and at 6 months (P > 0.05), nor with the H. pylori eradication rate at 3 months (75% in cagA-positive and 70% in cagA-negative strains, P = 0.52).

Conclusion: This study on a large cohort of patients confirms the greater histological virulence of H. pylori cagA-positive strains. However, this virulence was not associated with more severe symptoms nor with an increase in resistance to H. pylori eradication treatment.