Objective: (1) To determine the prevalence of Helicobacter pylori strains resistant to clarithromycin in Peking. (2) To determine the genetic mutation in relation to clarithromycin resistance.
Methods: Helicobacter pylori were cultured from gastric biopsies obtained from 89 patients during upper endoscopy. Minimal inhibitory concentrations of clarithromycin were determined by Etest method. Genomic DNA was prepared by the hexadecyltrimethylammonium bromide (CTAB)-phenol extraction method. Mutations in clarithromycin-resistant strains were identified by polymerase chain reaction and restrictions analysis.
Results: (1) The prevalence of Helicobacter pylori strains resistant to clarithromycin was 13.5% in Beijing. (2) All twelve clarithromycin-resistant strains had the new BsaI site which is characteristic of the A2143G point mutation in 23S rRNA gene, none of the tested twenty-four susceptible strains had the A2142G or A2143G mutation.
Conclusion: The prevalence of clarithromycin-resistant strains was not rare in Beijing. Mutations in 23S rRNA are associated with clarithromycin resistance in Helicobacter pylori.