Real-time PCR for Helicobacter pylori diagnosis. The best tools available

Abstract

Background: Knowledge of antimicrobial susceptibility, especially to macrolides, has become crucial for the management of Helicobacter pylori infection. Our aim was to evaluate two new PCR kits able to detect H. pylori in gastric biopsies as well as the mutations associated with macrolide resistance.

Materials and methods: Two hundred successive biopsies (received from gastroenterologists all over France) were used. The two new kits tested were Amplidiag H. pylori+Clari^R from Mobidiag Espoo, Finland, and RIDA^® GENE H. pylori from R-Biopharm, Darmstadt, Germany. Culture and a validated in-house real-time PCR were also performed, and in the case of a positive culture, Etest for clarithromycin was carried out. Discrepancies were solved by looking at the pathologic data.

Results: Culture was positive in 68 cases (34%), and with our in-house real-time PCR in these 68 cases plus 5 others (N = 73, 36%). All were also detected by the two new kits. In addition, RIDA^® GENE H. pylori detected one more positive also detected by Amplidiag H. pylori+Clari^R , and Amplidiag detected two other positives. Of these three additional cases, pathology confirmed the positivity for two. Only one case diagnosed by Amplidiag could be considered as a false positive. With regard to clarithromycin resistance, 22 cases were detected. The corresponding mutations (A2142/43G) were all identified with the three PCRs.

Conclusions: These two new kits which have an excellent sensitivity and specificity are convenient to use, adaptable to different thermocyclers, provide quick results, and deserve to be used in H. pylori diagnosis for a better choice of treatment regimen.

Keywords: antimicrobial susceptibility testing; clarithromycin; culture.