title: New mutation points in 23S rRNA gene associated with Helicobacter pylori resistance to clarithromycin in northeast China.
abstract: OBJECTIVE
  To investigate the resistance rate of Helicobacter pylori (H pylori ) to clarithromycin, metronidazole, amoxicillin and tetracycline to guide clinical practice, and to study the mechanism of H pylori resistant to clarithromycin.
  
  
  METHODS
  Thirty H pylori strains were isolated from the mucosa of peptic ulcer, gastric tumor and chronic gastritis patients, then the minimal inhibitory concentration (MIC) to clarithromycin, metronidazole, amoxicillin and tetracycline was evaluated by E-test method. The sequence analysis of PCR fragments was conducted in 23S rRNA gene of H pylori resistant to clarithromycin to get the resistance mechanism of the bacteria.
  
  
  RESULTS
  Among 30 H pylori strains, 7 cases were resistant to clarithromycin, 12 to metronidazole, 2 to tetracycline and no strain was found to be resistant to amoxicillin. The resistance rates were 23.3%, 40%, 6.7% and 0%, respectively. Three new mutation points were found to be related to the clarithromycin resistance in H pylori isolates, which were G2224A, C2245T and T2289C.
  
  
  CONCLUSIONS
  In northeast China, H pylori shows high resistance to metronidazole, while sensitive to amoxicillin. The mechanism of resistance to clarithromycin may be related to the mutation of G2224A, C2245T and T2289C in the 23S rRNA gene.
authors.affiliation: Department of Gastroenterology, the 2nd Affiliated Hospital, China Medical University, Shenyang 110004, Liaoning Province, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Hao
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Zhi-Jie
authors.initials: ZJ
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.forename: Hong
authors.initials: H
authors.lastname: Gao
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002681:China; D017291:Clarithromycin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D016480:Helicobacter pylori / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D012338:RNA, Ribosomal, 23S / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D012338:RNA, Ribosomal, 23S; D017291:Clarithromycin