Real-Time Assessment of H. pylori Infection to Guide Molecular Antibiotic Resistance Testing: A Combined Endoscopy-Gastric Juice Analysis Approach

Background

Helicobacter pylori antibiotic resistance is the most relevant cause of treatment failure. Antibiotic susceptibility testing (AST) allows for selecting the appropriate eradication regimen.

Aims

To assess the diagnostic accuracy of gastric aspirate-based genotypic AST (G-AST) for detecting clarithromycin and levofloxacin resistance compared with conventional phenotypic AST (P-AST).

Methods

We recruited 461 consecutive patients scheduled for endoscopy. H. pylori was detected intraprocedurally using Endofaster, a novel method combining endoscopy with gastric juice analysis. For H. pylori-positive patients, we collected gastric aspirates and biopsies. G-AST was performed using DNA extracted from aspirates, with Sanger sequencing to detect polymorphisms in the 23S rRNA and gyrA genes associated, respectively, with resistance to macrolides and fluoroquinolones. P-AST was performed on H. pylori isolated from biopsies using ETEST.

Results

One hundred and seventy-eight (40.4%) patients tested positive for H. pylori during endoscopy. Paired gastric biopsies and aspirates were available from 152 H. pylori-positive patients. By P-AST, resistance rates were 15.1% (23/152) for clarithromycin and 18.4% (28/152) for levofloxacin. G-AST showed a high level of agreement with P-AST for clarithromycin (kappa 0.86) and levofloxacin (kappa 0.81) resistance and diagnostic accuracy of 97% and 95%, respectively.

Conclusions

The novel method combining endoscopy with immediate intraprocedural gastric juice analysis for the detection of H. pylori, followed by AST in case of a positive finding, is valid and practical for tailoring eradication regimens for H. pylori infection. Genotypic AST from gastric aspirates is highly accurate for detecting clarithromycin and levofloxacin resistances.