**Bacteria and culture conditions**

Biopsy samples were cultured on *Brucella* agar (Merck) supplemented with 7% fresh horse blood, vancomycin (6mg/L, Merck), trimethoprim (5mg/L, Merck) and amphotericin (2mg/L, Merck). For primary culture, plates were incubated at 37°C in a microaerophilic atmosphere (5% O2, 15% CO2, 80%N2) for 3 to 5 days. Strains were identified according to colony morphology, Gram staining and positive reactions with urease, catalase, and oxidase. The *ureC* gene (*glmM*) which encodes urease was used as a DNA target to confirm *H. pylori*  strain.
