Helicobacter pylori cagA, vacA and iceA genotypes in northern Thai patients with gastric disease.

Helicobacterpylori, a common infectious bacterium, has been linked to chronic gastritis, peptic ulcer and gastric cancer. Gastric biopsy specimens were obtained from 58 northern Thai patients with gastritis, 28 with gastric ulcer, 45 with duodenal ulcer and 4 with gastric cancer. cagA, vacA s1 and iceA gene was found in 88, 98, and 89% of the specimens, respectively. For vacA, the frequency of subtype s1a, s1c and combined sla and s1c was 40, 16, and 41%, respectively. The frequency of subtype s1a/m1 and s1a/s1c/m1 was 27 and 20%, respectively. Fifty-three patients (39%) were infected with multiple vacA genotypes but there was no association with clinical outcome. cagA positive and mixed vacA s1a and s1c strains were found in significantly more cases of duodenal ulcer than gastritis (p < 0.05). For iceA, subtype iceA1 reached a frequency of 60%, whereas subtype iceA2 was only 24%.

Use of different PCR primers and gastric biopsy tissue from CLO test for the detection of Helicobacter pylori.

Four different DNA loci were assessed for the detection of H. pylori by PCR on gastric biopsy specimens. PCR, with a primer specific 860 bp DNA fragment, was the most sensitive, with a detection limit of 0.02 pg H. pylori DNA, corresponding to approximately 10 organisms. Nested-PCR of the 860-bp DNA fragment was 10-fold more sensitive than single-step PCR. The sensitivity and specificity of the four PCR methods, in comparison to the results obtained from histology and the urease test, are as follows: 80.7% and 76% for the hpaA gene; 100% and 76% for the 16S rRNA gene; 84.6% and 80.0% for the 860-bp DNA fragment; 61.5% and 84.0% for the ureC (glmM) gene, respectively. The sensitivity of nested-PCR for the 860-bp DNA fragment was 100%. This nested-PCR gave positive results for eight specimens which were negative by conventional methods. PCR can be performed on gastric biopsy specimens obtained from the CLO test.