title: Mutations in the 23S rRNA gene are associated with clarithromycin resistance in Helicobacter pylori isolates in Brazil.
abstract: BACKGROUND
  Resistance of Helicobacter pylori to clarithromycin has been associated with A2142G and A2143G point mutations in the 23S rRNA gene. Thus, the purpose of the present study was to determine the prevalence of each mutation in 52 clarithromycin-resistant H. pylori strains and to characterize the influence each type of mutation on the MIC.
  
  
  METHODS
  The MIC for clarithromycin was determined by the agar dilution method, and the point mutations of H. pylori were detected by PCR followed by restriction fragment length polymorphism.
  
  
  RESULTS
  Clarithromycin MICs ranged from 2 to >256 microgram ml-1 among the 52 strains included in this study. Both the A2142G and the A2143G mutations were present in 94.2% of clarithromycin-resistant H. pylori strains examined. A relationship was observed between the presence of the A2142G mutation and the highest MIC values (p = 0.01).
  
  
  CONCLUSIONS
  In an H. pylori-infected population, the A2142G mutation may incur to a greater probability of treatment failure if clarithromycin is used.
authors: Clinical Pharmacology and Gastroenterology Unit, São Francisco University Medical School, Bragança Paulista, SP, Brazil. pedrazzoli@saofrancisco.edu.br
authors: Marcelo L
authors: ML
authors: Ribeiro
authors: Lea
authors: L
authors: Vitiello
authors: Maira C B
authors: MC
authors: Miranda
authors: Yune H B
authors: YH
authors: Benvengo
authors: Anita P O
authors: AP
authors: Godoy
authors: Sergio
authors: S
authors: Mendonca
authors: José
authors: J
authors: Pedrazzoli