title: Identification of a novel mutation affecting domain V of the 23S rRNA gene in Helicobacter pylori.
abstract: BACKGROUND
  This study analyzes clarithromycin resistance status and 23S rRNA gene mutations in Helicobacter pylori strains from Central Italian patients.
  
  
  METHODS
  H. pylori strains from 235 dyspeptic patients (205 with no history of clarithromycin exposure and 30 referred for failure of eradication therapy) were tested for clarithromycin resistance by screening agar method and E-test. Resistant strains were analyzed for mutations of the 23S rRNA gene by PCR-RFLP and sequencing.
  
  
  RESULTS
  Primary resistance was observed in strains from 43/205 (21%) patients with no history of clarithromycin exposure and secondary resistance in 30/30 (100%) strains from previously treated patients. A single mutant strain was detected in 54/73 (74%) cases, a mixture of one or more mutant(s) plus the wild type in the remaining 19/73 (26%) cases. One 23S rRNA gene mutation (A-->T transversion at nucleotide 2144) in the peptidyltransferase region of domain V was novel.
  
  
  CONCLUSIONS
  This study shows: (a) a high prevalence of H. pylori strains with primary or secondary clarithromycin resistance in an urban area of Central Italy; (b) colonization by both mutant and wild-type H. pylori in the same patient; (c) a novel variant of the H. pylori 23S rRNA gene.
authors.affiliation: Department of Medicine and Aging (Internal Medicine Unit), University G. D'Annunzio, Chieti-Pescara, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Toracchio
authors.forename: Gitana M
authors.initials: GM
authors.lastname: Aceto
authors.forename: Renato
authors.initials: R
authors.lastname: Mariani-Costantini
authors.forename: Pasquale
authors.initials: P
authors.lastname: Battista
authors.forename: Leonardo
authors.initials: L
authors.lastname: Marzio
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D017291:Clarithromycin / Q000627:therapeutic use; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D014644:Genetic Variation; D016481:Helicobacter Infections / Q000188:drug therapy / Q000453:epidemiology*; D016480:Helicobacter pylori / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D007558:Italy / Q000453:epidemiology; D009154:Mutation; D009690:Nucleic Acid Conformation; D010458:Peptidyl Transferases / Q000235:genetics / Q000378:metabolism; D015995:Prevalence; D012329:RNA, Bacterial / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics* / Q000378:metabolism; D014505:Urban Population
chemical_list: D000900:Anti-Bacterial Agents; D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S; D010458:Peptidyl Transferases; D017291:Clarithromycin