Molecular diagnosis of Helicobacter pylori infection in gastric biopsies: Evaluation of the Amplidiag H. pylori + ClariR assay.

BACKGROUND

Adapted treatments for Helicobacter pylori infection, guided by determining antimicrobial resistance, are associated with high eradication rates. We evaluated the performance of the Amplidiag H. pylori + ClariR PCR assay (Amplidiag ) for detecting H. pylori and its clarithromycin resistance from gastric biopsies taken during endoscopy in comparison to culture and our "in-house" PCR.

MATERIALS AND METHODS

A total of 127 gastric biopsies were analyzed (98 adults; 29 children). Culture, PCR Amplidiag , and in-house PCR were performed in parallel. The in-house PCR combined amplification and sequencing of a 267-bp fragment of the H. pylori 23S rRNA gene. Discrepancies were controlled by amplification of glmM gene.

RESULTS

For detection of H. pylori, Amplidiag and the in-house PCR were concordant in 118 of 127 of cases: 66 negative and 52 positive. Discrepancies were observed in nine cases, all with low bacterial load: Amplidiag did not detect seven biopsies positive on in-house PCR but detected two positive biopsies that were negative on in-house PCR. Among the 19 of 52 (36%) H. pylori cases resistant to clarithromycin, only four biopsies with mixed populations exhibited discordant results between the two PCR methods. The A2142T mutation was not detected by Amplidiag . With the in-house PCR and amplified glmM gene as the reference method, the sensitivity and specificity of Amplidiag was 88.5% (95% confidence interval 83-94.1) and 100%.

CONCLUSION

This study demonstrated the high sensitivity of the PCR-based Amplidiag H. pylori test, especially with low H. pylori load, and the probability of its clarithromycin resistance analysis. For clinical use, a well-designed trial with a large scale of samples may still be needed.