Direct determination of Helicobacter pylori vacA genotypes and cagA gene in gastric biopsies and relationship to gastrointestinal diseases

OBJECTIVE: Our aim was to detect Helicobacter pylori (H. pylori) from gastr ic biopsies of 248 patients using a novel, polymerase chain reaction (PCR)- based methodology, which simultaneously facilitates the determination of H. pylori vacA genotypes and cagA gene. METHODS: A simple methodology for sample preparation was established and PC R was performed with primer systems for the 16S rRNA, vacA, and cagA genes, thus circumventing the need to culture H. pylori and to extract DNA from b iopsy samples. RESULTS: Infection with H. pylori was detected in 147 (59.3%) of 248 patien ts. The vacA signal sequence genotype sl was present in 104 (81.3%) of 128 H. pylori-positive patients, and 24 (18.8%) patients had the genotype s2. T he vacA middle region types m1 and m2 were detected in 46 (35.9%) and 79 (6 1.7%) patients, respectively. The combinations s1/m2 (43%) and s1/m1 (35.9% ) were found more frequently than s2/m2 (18.8%). The cagA gene was detected in 75 (72.1%) of 104 H. pylori-positive biopsies with the vacA genotype s1 . All 24 biopsies with the type s2 were cagA negative. Strains of the type vacA s1 were found in 97% of H. pylori-positive patients with peptic ulcer disease and were associated with the presence of the cagA gene, whereas 96% of the strains of the type vacA s2 were detected in patients who only had nonulcer dyspepsia. CONCLUSIONS: Using a novel PCR-based methodology, H. pylori 16S rRNA gene, vacA genotypes, and cagA gene can now be rapidly detected directly in gastr ic biopsies with high accuracy. These data demonstrate that infection with H. pylori strains of the vacA s1 genotype and the cagA gene are more likely to result in peptic ulcer disease. Determination of vacA genotypes and cag A gene may contribute to the potential clinical identification of patients at different levels of risk. (Am J Gastroenterol 1999;94:1525-1531. (C) 199 9 by Am. Coll. of Gastroenterology).