Stool Antigen Tests for the Detection of Helicobacter Pylori in Children

Objective: Reliable non-invasive methods for detection of Helicobacter pylori (H. pylori) infection are required to investigate the incidence, transmission, and clearance of infection in childhood.  Detecting bacterial antigens in stool offer an alternative noninvasive diagnostic test. However its accuracy in developing countries is not well established. The aim of this study was to evaluate the performance of stool antigen test for H pylori in Iranian children with recurrent abdominal pain necessitating endoscopy.
Methods: One hundred three children enrolled in this study. Endoscopy and biopsy was done on all patients providing a criterion standard for validation of the H. pylori stool antigen (HpSA) tests. The presence of H. pylori organisms in stool was determined by an enzyme-linked immunosorbent assay using a commercially available polyclonal antibody. HpSA sensitivity, specificity, and positive and negative likelihood ratios were determined with reference to the results of cultures of gastric biopsy.
Findings: Of the 103 children tested 41 (39.8%) and 39 (37.8%) were positive for H. pylori according to the results of cultures of gastric biopsy and HpSA, respectively. The sensitivity, specificity, and positive and negative likelihood ratios of HpSA were found to be 85%, 93%, 89.7%, and 90%, respectively.
Conclusion: In this pilot study, a low-cost and rapid diagnostic technique, stool antigen test proved to be highly sensitive and specific for detecting H pylori infection in children with recurrent abdominal pain. Our results are comparable to those reported elsewhere in children and demonstrate that the HpSA test can replace endoscopy and biopsy for detecting H. pylori infection.