Immunoblotting and serology for diagnosis of Helicobacter pylori infection in children

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Abstract
The easiest way to identify the presence of current or pastHelicobacter pyloriinfection 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. 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. The immunoblotting was more sensitive (100%) and specific (88%) than ELISA (96 and 79%, respectively) in the evaluation ofH. pyloriinfection 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. 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.