Effect of cagA status on the sensitivity of enzyme immunoassay in diagnosing Helicobacter pylori-infected children

Background. The aims of our study were twofold. First, we sought to evaluat e in symptomatic children the influence of the Helicobacter pylori genotype on gastritis, abdominal pain, and circulating and-H. pylori Ige antibodies (anti-H. pylori IgG) or pepsinogen A (PGA) and C (PGC). Additionally, we s ought to assess anti-H. pylori IgG, PGA, and PGC patterns in a large cohort (N = 921) of asymptomatic children. Materials and Methods. In 183 symptomatic children, H. pylori infection and the presence of gastritis were evaluated by histology. In a subgroup of 20 H. pylori-positive children, the H. pylori genotype was evaluated also by polymerase chain reaction. Nine hundred and twenty-one asymptomatic childre n, aged 11 to 14 years, were studied by anti-H. pylori IgG, PGA, and PGC se rum determination. Results. The infection was found in 33 of 183 symptomatic children; among t he 20 H. pylori-positive children for which the I-I, pylori genotype was av ailable, cagA was present or absent in equal percentages. H, pylori infecti on was associated with more severe gastritis and higher serum levels of ant i-H. pylori IgG and PGC but not with abdominal pain. In infected children, higher levels of anti-II. pylori IgG and the presence of abdominal pain wer e associated with infections caused by caga-positive strains. In the cohort of 921 asymptomatic children, raised levels of anti-H. pylori IgG, PGA, an d PGC were found in approximately 5% of the cases. Conclusions. Infection with cagA-positive H. pylori strains can be associat ed with increased frequency of reported abdominal pain and higher circulati ng levels of anti-H. pylori IgG. The serological assessment of H. pylori Ig G using H. pylori antigens containing significant amounts of cagA protein m ay, therefore, underestimate the true prevalence of infection.