# High Levels of Helicobacter pylori Antimicrobial Resistance in Ireland—A Multicentre Study

## TL;DR

This study found high levels of antibiotic resistance in Helicobacter pylori bacteria in Ireland, suggesting current treatment guidelines need updating.

## Contribution

The study provides the first comprehensive antimicrobial resistance data for H. pylori in Ireland and recommends against using clarithromycin-based therapy without prior testing.

## Key findings

- Primary resistance rates to metronidazole, clarithromycin, and levofloxacin were 44.3%, 36.5%, and 18.3%, respectively.
- Secondary resistance rates were significantly higher than primary resistance for several antibiotics.
- Female sex and older age were associated with increased risk of resistance.

## Abstract

Resistance surveillance programmes are essential for choosing the most appropriate eradication therapy for the stomach pathogen Helicobacter pylori. This study aimed to determine H. pylori antimicrobial resistance rates in Ireland. H. pylori was cultured from patients attending four gastroenterology clinics from 2018 to 2023. Antimicrobial susceptibility testing (AST) was performed using Etests for metronidazole, clarithromycin, levofloxacin, amoxicillin, tetracycline and rifampicin and resistance classified using EUCAST guidelines. Resistance rates were compared between H. pylori treatment-naïve and previously treated patients (primary and secondary resistance, respectively). Samples from 138 culture-positive patients (mean age 49.4 ± 15.7 years, 47.1% female) were analysed. A total of 28.7% of isolates from treatment-naïve patients were susceptible to all antimicrobials tested. Primary resistance rates to metronidazole, clarithromycin, levofloxacin, amoxicillin, tetracycline and rifampicin were 44.3%, 36.5%, 18.3%, 14.6%, 9.6% and 9.6%, respectively. Primary dual resistance to clarithromycin and metronidazole was 22.6% and primary multidrug resistance was 13.0%. Secondary resistance rates were significantly higher than primary resistance rates for clarithromycin, metronidazole, dual resistance to clarithromycin and either amoxicillin, metronidazole or levofloxacin, and multidrug resistance. Female sex and older age were associated with increased risk of resistance. H. pylori resistance rates were high in our cohort. Clarithromycin-based triple therapy should no longer be used in Ireland in the absence of pre-treatment AST. Resistance to amoxicillin, tetracycline and rifampicin should be monitored closely.