Diagnosis of Helicobacter pylori Infection in Children and Adult by Serological Test and Stool Antigen Test

Abstract

Background: Helicobacter pylori infection causes chronic gastritis that is related to duodenal ulcer, gastric ulcer, and possibly gastric adenocarcinoma. Noninvasive diagnostic tests consist of the urea breath test, serology, and stool antigen testing. Serodiagnosis of H.pylori infection is inaccurate for children. In order to investigate the immune response to H.pylori in children and adult, we compared anti-H pylori IgG and IgA antibodies with H. pylori antigen (HpSA) in the stool. Methods: Serum and stool samples were obtained from 218 children and adult patients with clinical symptom in the range of 4 to 77 years old. Paired results of H. pylori serology (IgG and IgA) and HpSA were analyzed by enzyme immunoassay methods. Results: There were 218 paired serology and HpSA results for 39 children (l17 years) and 179 adult (g18 years). The positivity rate of HpSA (45.8) was significantly lower (P<0.001) than those for H. pylori IgG (54.6) and IgA (28.9). Moreover in child patients specificity for serological test IgG and IgA were higher than adult. Conclusion: In this study, HpSA was sensitive and specific as a clinical and epidemiological tool to evaluate H. pylori infection. IgG correlated better with HpSA than IgA, and also IgG was much more specific in children than adults confirm the fact that adults are more possible to have been exposed to H. pylori in the past. Using HpSA as the gold standard, we found that the performances of IgG and IgA serology tests differ significantly by age because immature immune response or tolerance to H. pylori is present in childhood and serodiagnosis of H. pylori infection is less useful. Hence, we recommend that laboratories reevaluate reference serologic titers based on age and further clinical correlation is needed to establish the optimal ranges.