Immunoblotting and serology for diagnosis of Helicobacter pylori infection in children

Background. The easiest way to identify the presence of current or past Helicobacter pylori infection is to test for antibodies. The aim of this study was to compare an enzyme-linked immunosorbent assay (ELISA) technique based on the detection of IgG antibodies directed against a global antigenic preparation with immunoblotting based on the analysis of IgG antibody reactivity to separate proteins. Methods. Sera were collected from 80 children (mean age, 9.9 +/- 4.3 years). The reference tests were microbiologic and histologic examination of gastric biopsies obtained at upper endoscopy, Results. The immunoblotting was more sensitive (100%) and specific (88%) than ELISA (96 and 79%, respectively) in the evaluation of A. pylori infection in children. Its positive predictive value was 92%, and its negative predictive value was 100%. The best performance index of immunoreactive bands to detect antibodies was obtained with the 26-kDa (88.7%), 30-kDa (77.5%) and 19.5-kDa (70%) antigens. Antibodies by immunoblot technique against the CagA antigen were present in 43.1% of children. Conclusion, Immunoblotting is highly sensitive and more specific than ELISA in children and provides additional information about the full serologic profile. Immunoblotting may therefore be a useful complement to serology, particularly in cases with doubtful ELISA results.