Molecular Detection of Clarithromycin Resistance: Is It Predictive of Treatment Success?: 1200

Introduction: Clarithromycin is a commonly used antibiotic in PPI Triple therapy (PPI TT). However, significant (and increasing) treatment failure rates occur in the range of 10—30% with PPI TT. Eradication failure is thought to be primarily driven by resistance to clarithromycin which is reported to be up to 30%. The purpose of this study was to investigate if clarithromycin resistance, as determined by PCR detection of 23S mutations, predicted a heightened risk of Helicobacter pylori (Hp) eradication failure using clarithromycin—based PPI TT.1200 Figure 1 No Caption available.Methods: This study is designed as a prospective blinded cohort study. At 6 endoscopy centers, patients >18 y/o who previously had an esophagogastroduodenoscopy and were CLO test positive were included if they were treated with at least 10 days of PPI TT with clarithromycin. Evaluation of eradication was determined using a stool antigen test (HpSAg) at least 4 weeks after completion of PPI TT and off of all acid suppression. Clarithromycin resistance was evaluated using organisms isolated from the pretreatment CLO test biopsies via amplification and detection of 23S mutations using real—time PCR and melt curve analysis. CLO test tissue biopsies were stored at 4°C for up to 1 yr before extraction; amplifiable 23S target was obtained in all but 4 samples. Results: See Table 1. PCR testing was able to detect Hp DNA in 68/73 (93.1%) of stored CLO test samples. Using the PCR assay, clarithromycin resistance was 33.8% (23/68) in our population. Treatment emergent HpSAg results were compared to 23S testing and evaluated by Chi—square. There was no significant association between the 23S mutation for clarithromycin resistance and eradication after clarithromycin based treatment. Conclusion: Our study does not show a clinical correlation between molecular detection of clarithromycin resistance and clearance of H. pylori following PPI triple therapy. This may be due to a small sample size and high rate of eradication (68/73; 93.2%).