CLINICAL AND HISTOLOGICAL ASSOCIATIONS OF CAGA AND VACA GENOTYPES IN HELICOBACTER-PYLORI GASTRITIS

Aims-To determine the relation among the cytotoxin associated gene (ca gA) and vacuolating cytotoxin gene (vacA) status of Helicobacter pylor i isolates, the associated clinical diseases, and the severity and pat tern of chronic gastritis. Methods-Helicobacter pylori was cultured fr om gastric biopsies obtained from dyspeptic patients. DNA was extracte d from the isolates and the cagA and vacA status determined by the pol ymerase chain reaction (PCR). The prevalence of the different cagA and vacA genotypes in three clinical groups, duodenal ulcer, gastric ulce r, and non-ulcer dyspepsia was compared. The histological features in sections from two antral and two corpus biopsies were graded by one bl inded observer. The grades were compared with age and sex matched grou ps with different cagA and vacA genotypes, and with duodenal ulcers, o r non-ulcer dyspepsia. Results-Isolates from 161 patients were include d. One hundred and nine (68%) harboured a cagA+ strain and 143 (89%) h arboured a vacA sl strain. The prevalence of cagA+ strains in duodenal ulcer patients (94%) was highly significantly greater than in those w ith non-ulcer dyspepsia (56%). However, of the patients infected with a cagA+ strain, almost equal numbers had non-ulcer dyspepsia or peptic ulceration. Chronic inflammation, polymorph activity, surface epithel ial degeneration, atrophy, and intestinal metaplasia were all signific antly more severe in the cagA+ than in the cagA- group, whereas only c orpus epithelial degeneration was significantly more severe in the vac A sl group compared with the vacA s2 group. Patients infected with cag A+ strains were almost four times more Likely to have antral intestina l metaplasia than cagA- patients. An antral predominant gastritis was present in duodenal ulcer patients compared with matched nonulcer dysp epsia patients, but this was not attributable to cagA or vacA status. Conclusions-Helicobacter pylori strains showing cagA positivity and th e vacA sl genotype are associated with more severe gastritis but these virulence factors do not appear to determine the overall pattern. The pattern is closely linked to clinical disease. Therefore, it is likel y that the nature of the disease complicating chronic infection is det ermined by host and environmental factors, while bacterial factors det ermine the magnitude of the risk of developing such disease.