Relevance of CagA positivity to clinical course of Helicobacter pylori infection in children

A potential virulence determinant of Helicobacter pylori is the cagA gene p roduct. To determine the relevance of the expression of CagA to the clinica l picture and outcome of H. pylori infection in children, we examined 104 c onsecutive children diagnosed with H. pylori infection. Serum samples were collected to test for the presence of immunoglobulin G (IgG) anti-CagA anti bodies. Forty-five patients (43%) had antibodies to the CagA protein (group I), and 59 did not (group II). Seropositive patients had a longer prediagn ostic history of abdominal pain (P = 0.02), more severe abdominal pain (def ined as ulcer pain) (P = 0.05), a higher prevalence of duodenal ulcer (38 v ersus 7%; P < 0.01), more active chronic gastritis (82 versus 32%; P < 0.00 1), and a higher titer of serum IgG anti-fl. pylori antibodies (P < 0.001). Ninety percent of the patients were monitored for 27 +/- 18 months. On mul tivariate analysis, CagA-negative patients had a 3.8-fold-higher chance of achieving a disease-free state than CagA-positive patients (95% confidence interval, 1.5- to 9.5-fold). We conclude that infection with CagA-producing strains of H, pylori is a risk factor for severe clinical disease and ongo ing infection.