Impact of Helicobacter pylori antimicrobial resistance on the outcome of 1-week lansoprazole-based triple therapy.

Purpose: To determine the effect of Helicobacter pylori antimicrobial resistance on the efficacy of different proton pump inhibitor (PPI)-based triple therapies.
Methods: One-hundred and twelve dyspeptic patients with H. pylori infection, as demonstrated by positive histology and culture, were randomized to receive one of the three PPI-based triple therapies. The regimens included lansoprazole (L) plus any two of the following three antibiotics: amoxicillin (A), metronidazole (M), and clarithromycin (C); patients were allocated to ALC, MLC, and ALM subgroups. Six weeks after the start of triple therapy, the 13C-urea breath test (UBT) was performed to evaluate the success of H. pylori eradication. Patients with positive UBT results underwent endoscopy for H. pylori culture. The pre- and post-treatment H. pylori isolates were analyzed for initial and acquired resistance using the E-test.
Results: One hundred patients completed the study. The H. pylori eradication rates were 70% (21/30) in the ALM subgroups, 79% (26/33) in the MLC subgroup, and 89% (33/37) in the ALC subgroup. The frequencies of pretreatment H. pylori antimicrobial resistance were 0% for amoxicillin resistance (AR), 32% for metronidazole resistance (MR), and 6% for clarithromycin resistance (CR). For H. pylori isolates with initial MR, the eradication rates in the ALM (40%) and MLC (67%) subgroups were apparently lower than that in the ALC (92%) subgroup. In the ALM and MLC subgroups (i.e., patients who received metronidazole), the eradication failure rate was significantly higher for patients with MR isolates than for patients with metronidazole-susceptible isolates (47% vs 16%, p < 0.05). In the ALC and MLC subgroups (i.e., patients who received clarithromycin), the eradication failure rate was significantly higher for patients with CR isolates than for those with clarithromycin-susceptible isolates (100% vs 11%, p < 0.05).
Conclusions: The results indicate that H. pylori antimicrobial resistance is relevant to the success of eradication. The high MR but low CR and AR prevalence among H. pylori isolates in this study suggests that PPI-based triple therapy including amoxicillin and clarithromycin may achieve the most favorable eradication rate.