High Antibiotic Resistance ofHelicobacter pyloriand Its Associated Novel Gene Mutations among the Mongolian Population

Mongolia has a high prevalence ofHelicobacter pyloriinfection and the second highest incidence of gastric cancer worldwide. Thus, investigating the prevalence of antibiotic resistance and its underlying genetic mechanism is necessary. We isolated 361H. pyloristrains throughout Mongolia. Agar dilution assays were used to determine the minimum inhibitory concentrations of five antibiotics; amoxicillin, clarithromycin, metronidazole, levofloxacin, and minocycline. The genetic determinants of antibiotic resistance were identified with next-generation sequencing (NGS) and the CLC Genomics Workbench. The resistance to metronidazole, levofloxacin, clarithromycin, amoxicillin, and minocycline was 78.7%, 41.3%, 29.9%, 11.9% and 0.28%, respectively. Multidrug resistance was identified in 51.3% of the isolates investigated which were further delineated into 9 antimicrobial resistance profiles. A number of known antibiotic resistance mutations were identified includingrdxA,frxA(missense, frameshift),gyrA(N87K, A88P, D91G/N/Y), 23S rRNA (A2143G),pbp1A(N562Y), and 16S rRNA (A928C). Furthermore, we detected previously unreported mutations inpbp1A(L610*) and the 23S rRNA gene (A1410G, C1707T, A2167G, C2248T, and C2922T). The degree of antibiotic resistance was high, indicating the insufficiency of standard triple therapy in Mongolia.