Detection of Helicobacter pylori antigen in stools – an alternative method of verifying HP infection in children

Diagnosis of H. pylori (HP) infection in children presents a major problem. Serological tests cannot establish an active infection or eradication after therapy and repetition of endoscopy is an unacceptable method for children. A new method for the detection of HP antigen in stools has been recently developed in the USA and so far there have not been many studies in children. Therefore, the aims of this study were to investigate the sensitivity and specificity of this new method in children, by comparing HP antigen in stools to: i. HP isolation (culture and microscopy of biopsy samples); ii. urea-breath test (UBT). An enzyme immunoassay (Premier HpSA, Meridian Diagnostics, Inc.) was used to detect HP antigens directly in stool specimens. In our study HP infection was determined in 17 of 33 symptomatic children following upper GI endoscopy and HP isolation from biopsy samples. UBT was performed in 30 children to confirm diagnosis. Detection of HP in stool was compared with both of these methods - i.e. to i. isolation, and ii. to UBT. Sensitivity of 76.4% (13/17) and specificity of 100% (16/16) were found using culture and histology of biopsy specimens as the reference. Sensitivity of 77.2% (17/22) and specificity of 100% (3/3) were found when using UBT as the reference method. In conclusion, according to our results, a new diagnostic method for the detection of HP antigen in stools has proven to be a simple, non-invasive test of high (100%) specificity. However, its sensitivity is lower (76 and 77%) and therefore if the test is negative it may still be necessary to perform UBT. Since there have not been many validations of this method in children so far, further studies envolving higher numbers of patients are required for final conclusions.