ABSTRACT
BACKGROUND: Helicobacter pylori infection is presumed to be the major causal agent of chronic active gastritis in humans. The persistent infection with this pathogen would be an important factor in the pathogenesis of peptic ulcer and also gastric cancer. METHODS: We investigated relationship between H. pylori characteristics in 42 patients with normal mucosa or gastritis with minor changes and 40 patients with mild and severe gastritis. Detection and typing of vacA and cagA genes were performed using a polymerase chain reaction method. RESULTS: The analysis of vacA prevalence and the type (S1 or S2) showed non-significant differences between the two groups studied (p > 0.05). However, cagA analysis showed highly significant differences between the groups classified as normal tissue-weak gastritis and mild-severe gastritis (p < 0.0001; OR = 8.4; CI = 3.1-22.8). CONCLUSIONS: cagA status is associated to the grade of gastritis, finding higher frequencies of H. pylori cagA+ in the moderate-severe gastritis group. These highly significant differences could make cagA status a genetic marker for disease progress.