VacA Genotyping Directly from Gastric Biopsy Specimens and Estimation of Mixed Helicobacter pylori Infections in Patients with Duodenal Ulcer and Gastritis

BACKGROUND: The vacA genotypes and the cagA gene status were investigated in 80 Helicobacter pylori-infected patients with duodenal ulcer (DU) and 49 with gastritis only. METHODS: Lysates of gastric biopsy specimens were used directly for polymerase chain reaction-based detection. RESULTS: The ml subtype was found in 36% and 31% and the m2 in 36% and 46% of specimens from patients with DU and gastritis, respectively (P > 0.05). In 15% of samples the midregion remained unclassified. The prevalence rate of s1 subtypes was higher in cases of DU (69%) than in gastritis (43%) (P < 0.0001); the opposite correlation was observed for s2. The cagA gene was detected in 80% of patients with DU and in 52% of those with gastritis (P < 0.0001). Infections with multiple H. pylori strains exceeded 50% in both groups. CONCLUSIONS: These results suggest that vacA s1 genotype and cagA+ status are associated with higher DU prevalence and that mixed H. pylori infections are very common in our geographic region.