Polymerase chain reaction based analysis of the cytotoxin associated gene pathogenicity island of Helicobacter pylori from saliva: an approach for rapid molecular genotyping in relation to disease status.

BACKGROUND AND AIMS: The genetic composition of the intricate cytotoxin associated gene pathogenicity island (cag PAI) of Helicobacter pylori is known to significantly influence the outcome of the disease. Hence, analysis of complete cag PAI of H. pylori isolated from saliva would be of immense importance in standardizing saliva as a reliable non-invasive diagnostic specimen and also to evaluate the type of H. pylori infection. The aim of the present study was to analyze the genes of cag PAI of H. pylori for their presence and correlating them with the disease status of the patients. METHODS: One hundred and twenty patients (55 duodenal ulcer [DU], 25 gastric ulcer and 40 non-ulcer dyspepsia [NUD]) were investigated for the present study. Eight pairs of oligonucleotide primers (cagA1, cagA2, cagAP1, cagAP2, cagE, cagT, LEC1 and LEC2) of five different loci; cagA, cagA promoter region, cagE which represents cagI region, cagT and LEC representing cagII were used to detect the presence of the cag PAI genes by polymerase chain reaction. RESULTS: The comprehensive analysis of the genes constituting cag PAI showed almost equivalent prevalence of all the genes between both the study groups (ulcer and NUD) included. Little significant difference was found in the percentage distribution in both the clinical groups. cagE and cagT were found in a larger proportion of the ulcer group (92.5% and 96.2%) compared with the NUD group (77.5% and 85%), respectively. CONCLUSION: Saliva could be efficiently used as a non-invasive source for H. pylori and cagT might be an important locus of the cag PAI, thus greatly influencing the disease condition of the subjects.