Rates of Antimicrobial Resistance in Helicobacter pylori Isolates From Clinical Trial Patients Across the US and...

Guidelines recommend that proton pump inhibitor-based triple regimens with clarithromycin not be used for Helicobacter pylori infection in areas where clarithromycin resistance is ≥15%, or in patients with prior macrolide use. Up-to-date information on local resistance patterns is limited, especially in the US. Here, we report resistance rates to antibiotics commonly used to treat H. pylori from a large study conducted in the US and Europe (pHalcon-HP).

Gastric mucosal biopsies were collected from adult participants with H. pylori infection during screening. Minimum inhibitory concentrations were determined via agar dilution for clarithromycin, amoxicillin, and metronidazole, with breakpoints ≥1 μg/mL, >0.125 μg/mL, and >8 μg/mL, respectively. Resistance rates were obtained for the US and Europe, and also for US subregions and participating European countries.

Resistance rates were established in isolates from 907 participants. Overall, 22.2% were resistant to clarithromycin, 1.2% to amoxicillin, and 69.2% to metronidazole. Resistance in the US and Europe was similar; metronidazole resistance was the most prevalent (50%-79%) and amoxicillin the least (≤5%). In all subregions, ≥15% of isolates were resistant to clarithromycin, except the UK (0/8 isolates). Among clarithromycin-resistant isolates, 75% were also metronidazole-resistant. Two US isolates were resistant to clarithromycin and amoxicillin; one of these was also metronidazole-resistant.

The resistance rates observed in this study argue against the continued empiric use of proton pump inhibitor-based triple therapy containing clarithromycin, per treatment guidelines, and highlight the need for antibiotic resistance surveillance and novel treatment strategies for H. pylori infection in the US and Europe.