Diagnostic accuracy of a non-invasive test for the detection of Helicobacter pylori and resistance to clarithromycin in stool by Real-Time PCR Amplidiag® H. pylori + ClariR assay

Non-invasive detection of Helicobacter pylori and its resistance to clarithromycin could revolutionize the management of H. pylori-infected patients by tailoring eradication treatment without any need for endoscopy when histology is not necessary. If several real-time PCR tests performed on stools have been proposed, their performances were either poor or tested on too few patients to be properly evaluated. We have conducted a prospective, multicenter study including 1200 adult patients addressed for gastro-duodenal endoscopy with gastric biopsies and naive of eradication treatment in order to evaluate performances of the Amplidiag®H. pylori+ClariR assay recently developed by Mobidiag (Espoo, Finland). The results of the Amplidiag®H. pylori+ClariR assay performed on DNA stools (automatic extraction, EasyMag bioMerieux) were compared with those of the culture/E-test and quadriplex real-time PCRs performed on two gastric biopsies (antral and corpus) so as to detect H. pylori glmM gene and mutations in the 23S rRNA genes conferring clarithromycin resistance. Sensitivity and specificity of the detection of H. pylori were 96.3% (CI 92-98) and 98.7% (CI 97-99) respectively. Positive and Negative Predictive Value were evaluated at 92.2% (CI 92-98) and 99.3% (CI 98-99) respectively. In this cohort, 160 patients (14.7%) were found to be infected (positive in culture and/or PCR). Sensitivity and specificity for detecting resistance to clarithromycin were 100% (CI 88-100) and 98.4% (94-99), respectively.