Serologic detection of CagA positive Helicobacter pylori infection in a northern Italian population: its association with peptic ulcer disease.

Background: About 60-70% of Helicobacter pylori strains possess cagA (cytotoxin associated gene A) gene and express its product CagA, a highly immunogenic 128-140 kD protein. Patients infected with CagA positive strains develop serum IgG anti-CagA. A serologic response to CagA has been detected in Helicobacter pylori infected patients with peptic ulcer more frequently than in those with gastritis alone. It is nuclear whether this finding is consistent in different geographical populations. We investigated the relationship between anti-CagA seropositivity and peptic ulcer disease in a Northern Italian population.
Materials and Methods: We studied 135 H. pylori infected patients: 65 with duodenal ulcer (DU), 28 with gastric ulcer (GU) and 42 with non ulcer dyspepsia (NUD). Sera from these patients were assayed by EIA (enzyme immunoassay) for anti-CagA IgG.
Results: A high prevalence of anti-CagA was found associated with DU (86.1%) and GU (96.4%), while NUD patients showed anti-CagA seropositivity of 52.4% (Odd ratio, 5.66; 95% confidence interval, 2.23 to 14.32; p < .001, DU vs. NUD; Odd ratio, 24.5; 95% confidence interval, 3.05 to 197.6; p = .003, GU vs. NUD). DU patients showed anti-CagA seropositivity titer (1.15 (0.61 OD, mean (SD) higher than that of NUD patients (0.78 (0.60 OD, mean (SD) (p < .05).
Conclusions: These data demonstrate in a Northern Italian population that anti-CagA seropositivity is strongly associated with peptic ulcer disease and suggest that CagA might play an important role in ulcer pathogenesis.