Consensus and Variable Region PCR Analysis ofHelicobacter pylori 3′ Region of cagA Gene in Isolates from Individuals with or without Peptic Ulcer

摘要

The clinical outcome of Helicobacter pylori infection may be associated with the cagA bacterial genotype. To investigate the cagA status of H. pylori-infected patients and the relationship betweencagA and peptic ulcer disease, gastric biopsy specimens from 103 Caucasian patients in Brazil were analyzed by PCR. Since allelic variation in cagA exists and distinct H. pylori subgenotypes may circulate in different regions, PCR using primers for a variable 3′ region of the cagA gene according to a Japanese methodology and for a consensus cagA 3′ region used in Western methods was used for cagA detection.cagA was present in 53 (71%) of 75 H. pylori-positive cases when analyzed by the consensus region method and was associated with duodenal ulcer disease (P = 0.02), but not with gastric ulcer (P = 0.26), when compared to patients with duodenitis or gastritis. The variable region PCR method was able to detect 43 (57%) cagA-positive cases within the same group ofH. pylori-positive patients and showed three subtypes ofcagA (A, B/D, and C) that were not associated with clinical outcome. However, in 8 (18%) of the cases, more than one subtype was present, and an association between patients with multiple subtypes and disease outcome was observed when compared to patients with isolated subtypes (P = 0.048). cagA was a marker ofH. pylori strains for duodenal ulcer disease in our population, and in spite of the differences in the 3′ region of thecagA gene, the Japanese methodology was able to detect thecagA status in most cases. The presence of multiple subgenotypes of cagA was associated with gastric ulcer.