Diagnostic accuracy of a new non-invasive enzyme immunoassay for detecting Helicobacter pylori in stools after eradication therapy

Background: Helicobacterpylori (H pylori) eradication therapy has been commonly performedfor patients with peptic ulcer. An inexpensive, reliable, non-invasive test would be very useful for evaluation of the effectiveness of eradication therapy. In the course of investigations into techniques for detecting H pylori infection after eradication therapy, the diagnosticpotentialof a new non-invasive enzymeimmunoassay (HpSA)for H pylori antigen in stools was evaluated. Methods: One hundred and fifteen pepticulcerpatientswithH pylori infection(84 male,31 female; age range 22-81 years,mean54) receiveda courseof eradicationtherapy.Fourweeks after the end of the therapy, stool sampls were collectedfrom all patients and testedusing the HpSA.The diagnosticaccuracyof the HpSA EIA was evaluated in comparison with the the results of l3C-urea breath test (13C_ UBT). Results: After the eradication therapy, the H pylori status was negative in 106 (92%) cases and positive in 9 (8%), as assessed by 13C-UBT. On the other hand, HpSA stool test results were negativein 105 (91 %) cases and positive in 10 (9%). When the l3C-UBT was used as a gold-standard, the HpSA stool test showed 2 false positive and 1 false negative results, and the sensitivity and specificity were 89% and 98%, respectively, aftereradicationtherapy.The positiveand negativepredictive values of HpSA were 80% and 99%, respectively. Furthermore, a positive correlation (r=0.671, pstool test is potentiallyuseful for the diagnosisof H pylori infection4 weeksafter the end of eradicationtherapy. 2702