THE SIGNIFICANCE OF CAGA AND VACA SUBTYPES OF HELICOBACTER-PYLORI IN THE PATHOGENESIS OF INFLAMMATION AND PEPTIC-ULCERATION

Aims-To assess the significance of cagA and vacA subtypes of Helicobac ter pylori in relation to inflammation and density of bacterial coloni sation in vivo within a dyspeptic UK population. Methods-Dyspeptic pat ients who were Helicobacter pylori positive had antral samples taken f or histology and culture. Gastroduodenal pathology was noted. The grad e of bacterial density and inflammation was assessed using the Sydney system. Bacterial DNA was extracted and the vacA alleles and the cagA gene typed using PCR. Results-120 patients were studied. There was hig h rate of cagA positive strains in this population. Bacterial density did not correlate with the presence of peptic ulceration. There was a significant association between cagA positive strains and increased in flammation and bacterial density. The vacA s1 type independently corre lated with extensive chronic inflammation but there was no association with bacterial density. The vacA m type did not correlate with extent of inflammation or bacterial density. Conclusions-The results suggest that cagA is important in the pathogenesis of inflammation and peptic ulceration. These findings are in keeping with the hypothesis that ca gA acts as a marker for a cag pathogenicity island which encodes sever al genes involved in inflammation. The vacA s1 allele correlates with inflammation independently of cagA, possibly through its enhanced abil ity to produce the vacuolating cytotoxin.