Formation of A2143G Mutation of 23S rRNA in Progression of Clarithromycin Resistance in Helicobacter pylori 26695

The aim of this work was to investigate the link between 23S rRNA mutation and clarithromycin (CLR)–resistant Helicobacter pylori (H. pylori). CLR-resistant (CLR^r) H. pylori strains were selected from the parent strain, H. pylori 26695, using medium containing CLR. Point mutations of 23S rRNA were analyzed by denaturing high-performance liquid chromatography and sequencing and restriction fragment length polymorphism (RFLP). Protein profiles of these strains were obtained by surface-enhanced laser/desorption ionization time-of-flight mass spectrometry technology. Two phenotype-stable L-CLRr resistant strains (MIC 8, 10 µg/ml) and two subsequent CLR^r strains (MIC 32 µg/ml) were obtained. An A2143G mutation of 23S rRNA was detectable in two CLR^r strains, but in neither the CLR^s parent strain nor the L-CLR^r strains. Four clinical CLR^r H. pylori strains were obtained from 41 Chinese H. pylori isolates. The A2143G mutation was observed in all four CLR^r isolates, but not in the six analyzed CLR^s ones. Protein profiling showed that the pattern of protein expression was changed from the CLR^s parent strain to the L-CLR^r strains and then to the CLR^r strains progressively. The formation of A2143G mutations of 23S rRNA might be a late event in the development of CLR-resistance of H. pylori 26695. Early events related to alteration of the pattern of protein expression might be involved in the development of CLR-resistance too.