title: Identification of a 23S rRNA gene mutation in clarithromycin-resistant Helicobacter pylori.
abstract: BACKGROUND
  Transition mutations (A-G) at residue 2143, cognate to position 2058 in the Escherichia coli 23S rRNA gene, have been shown to confer resistance to macrolides in Helicobacter pylori. This study reports the finding that transversion mutations (A-C) can occur at 2143 as well.
  
  
  METHODS
  Three clarithromycin-resistant H. pylori isolated from three different patients after treatment with clarithromycin were analyzed for point mutations by cycle sequencing of a 163-bp amplified region surrounding residue 2143 within the conserved loop of the 23S rRNA gene.
  
  
  RESULTS
  Nucleotide sequence comparisons of a 163-bp amplified product revealed that A-C transversion mutations occurred at position 2143. H. pylori isolated from the patients prior to treatment were susceptible to clarithromycin and displayed no polymorphism at 2143.
  
  
  CONCLUSIONS
  This is the first report to show that A-C transversion mutations at position 2143 can confer resistance to clarithromycin in H. pylori and further support the role that mutations at position 2143 play in conferring macrolide resistance in H. pylori.
authors.affiliation: Anti-infective Research Division, Abbott Laboratories, Abbott Park, IL 60064, USA.
authors.forename: G G
authors.initials: GG
authors.lastname: Stone
authors.forename: D
authors.initials: D
authors.lastname: Shortridge
authors.forename: R K
authors.initials: RK
authors.lastname: Flamm
authors.forename: J
authors.initials: J
authors.lastname: Versalovic
authors.forename: J
authors.initials: J
authors.lastname: Beyer
authors.forename: K
authors.initials: K
authors.lastname: Idler
authors.forename: L
authors.initials: L
authors.lastname: Zulawinski
authors.forename: S K
authors.initials: SK
authors.lastname: Tanaka
mesh_terms: D017291:Clarithromycin / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D004352:Drug Resistance, Microbial / Q000235:genetics; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D012329:RNA, Bacterial / Q000235:genetics*; D012338:RNA, Ribosomal, 23S / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S; D017291:Clarithromycin