Usefulness of Helicobacter pylori antigens detection in stools for infection diagnosis and confirming eradication

BACKGROUND: A new immunoassay to detect H. pylori antigen in stool (HpSA) h as been developed. We started this study to know the sensitivity and specif icity of this test as diagnostic tool of H. pyori infection and eradication control. PATIENTS AND METHODS: Forty patients were recruited to study H. pylori infe ction, At endoscopy, biopsy samples were taken for culture, histology and u rease test. Stool specimens were tested by HpSA and serum sample for serolo gy. Patients were defined as H. pylori positive if histology, urease test o r culture were positive. Forty-two patients treated with omeprazol based tr iple therapy were screened 8 weeks after treatent for eradication control u sing urea breath test, HpSa and serology, Patients with UBT negative were d efined as eradicated. RESULTS: As diagnostic tool: 34 out of 40 patients were infected (85%). HpS A was positive in 31 out of 34 patients, and achieve 3 false negative and 1 false positive (sensitivity: 91%, specificity: 84%). IgG anti-H. pylori wa s positive in 31 out of 34 infected patients, with 3 false positive and 3 f alse negative (sensitivity 91%, specificity 50%). In eradication control (n = 42), HpSA was negative in 33/38 successfully eradicated patients, and po sitive in all four noneradicated patients. Five patients eradicated showed positive HpSA (specificity 87%, positive predictive value: 87%, negative pr edictive value: 100%). IgG serology was negative in only a third of eradica ted patients. CONCLUSIONS: The stool assay was an accurate tool for diagnosis of H. pylor i infection and eradication control.