vacA genotypes in Helicobacter pylori strains isolated from patients with and without duodenal ulcer in Bahrain.

Background: The vacuolating cytotoxin and the cytotoxinassociated protein, encoded by vacA and cagA, respectively, are important virulence determinants of Helicobacter pylori.

Objective: The aim of this study was to perform vacA genotyping and evaluate its association with cagA genotype and clinical outcome.

Methods: One hundred and twenty H. pylori strains were isolated from dyspeptic patients (29 with peptic ulcer, 91 with non-ulcer dyspepsia). Genotype was determined by PCR.

Results: Seventy-nine (66%) of 120 strains had the vacA signal sequence genotype s1 and 41 (34%) had the type s2. The vacA middle-region types m1 and m2 were detected in 56 (47%) and 64 (53%) strains, respectively. The combinations s1-m1 (n=56 [47%] and s2-m2 (41 [34%]) occurred more frequently than s1-m2 (23 [19.2%]; p=0.001). No strain with the combination s2-m1 was found. All patients with peptic ulcers harbored type s1 strains compared to 75 (82.4%) of 91 patients with non-ulcer dyspepsia (p=0.01). The vacA genotype s1 was associated with the presence of cagA (p <0.0001). The cagA gene was detectable in 38 (31.6%) of 120 isolates and present in all 29 patients with ulcer compared to nine of 91 with non-ulcer dyspepsia (p <0.001).

Conclusion: Helicobacter pylori strains of vacA type s1 and the combination of s1-m1 were associated with peptic ulceration and the presence of cagA gene.