Virulence markers of Helicobacter pylori in patients with diarrhoea-dominant irritable bowel syndrome.

Recent studies suggest that irritable bowel syndrome (IBS) is associated with low-grade inflammation. This study aims to determine the distribution of Helicobacter pylori cytotoxin-associated gene A (cagA) and vacuolating cytotoxin A (vacA) alleles (e.g., s1 and s2) in patients with diarrhoea-dominant IBS (IBS-D) as the latter causes vacuolation in colonic epithelial cells in vitro. One hundred and seventy patients meeting Rome III criteria for IBS-D (mean age: 40 +/- 15 years) were enrolled. Gastric biopsy was assessed histologically and DNA extraction was performed by polymerase chain reaction (PCR) for H. pylori genus 16S ribosomal DNA (16S rDNA), cagA and vacA allele s1 and s2. There was no age- or gender-related difference in H. pylori positivity in IBS-D compared to the control group. H. pylori was positive in 116 (68%) with IBS-D compared to 88 (55%) in the control group (P=0.01). cagA was positive in 73 (63%) with IBS-D compared to 42 (48%) in the control group (P=0.03). vacA s1 was positive in 61 (53%) with IBS-D compared to 32 (36%) in the control group (P=0.02). cagA s1 was positive in 39 (34%) with IBS-D compared to 13 (15%) in the control group (P=0.002).