Antimicrobial resistance among Helicobacter pylori isolates in Alaska, 2000-2016

Abstract

Objectives: Alaska Natives experience a high burden of Helicobacter pylori infection and concomitant high rates of gastric cancer. Additionally, the prevalence of antimicrobial-resistant H. pylori has been shown to be high in Alaska. In this study, antimicrobial resistance over time among sentinel surveillance isolates was evaluated and risk factors for carrying antimicrobial-resistant H. pylori were assessed.

Methods: Through Alaska's H. pylori sentinel surveillance system, antral and fundal biopsies from Alaska Native patients undergoing esophagogastroduodenoscopy for clinical indications during 2000-2016 were collected and cultured. For positive cultures, minimum inhibitory concentrations (MICs) of metronidazole, amoxicillin, clarithromycin, tetracycline and levofloxacin were determined.

Results: A total of 800 H. pylori isolates obtained from 763 patients were tested. Resistance to metronidazole was most common (342/800; 42.8%), followed clarithromycin (238/800; 29.8%), both clarithromycin and metronidazole (128/800; 16.0%) and levofloxacin (113/800; 14.1%). Low proportions of isolates were resistant to amoxicillin and tetracycline. Levofloxacin resistance increased between 2000 and 2016 (P<0.001), but resistance to other antimicrobials did not change over time. Metronidazole and clarithromycin resistance were more common among women (P<0.001 for both), whilst levofloxacin resistance was more common among those with an urban residence (P=0.003). Metronidazole and levofloxacin resistance were more common among older patients (P<0.05).

Conclusion: Between 2000 and 2016, a large percentage of H. pylori isolates received by the Alaska Sentinel Surveillance System demonstrated resistance to common antimicrobials. The surveillance system provides valuable information for clinicians to make informed treatment choices for patient with H. pylori.

Keywords: Antimicrobial resistance; Epidemiology; Helicobacter pylori.