title: Clarithromycin-resistant Helicobacter pylori in Recife, Brazil, directly identified from gastric biopsies by polymerase chain reaction.
abstract: BACKGROUND
  Clarithromycin is the most effective drug used in the eradication of infection by Helicobacter pylori. Due to worldwide increase in resistance, pre-treatment susceptibility testing for clarithromycin is recommended.
  
  
  OBJECTIVE
  To evaluate the prevalence of clarithromycin resistance of H. pylori in Recife, a city in Northeast Brazil.
  
  
  METHODS
  From January 2006 to December 2007, 114 gastric biopsy samples positive for H. pylori at culture were directly assayed by polymerase chain reaction (PCR) to detect the most frequent point mutations involved in clarithromycin resistance. Results were compared with those obtained by Etests.
  
  
  RESULTS
  Molecular and phenotypic methods showed 111 (97.4%) susceptible or resistant concordant results. PCR detected 3 (2.6%) biopsy specimens with H. pylori-resistant genotypes, which were misdiagnosed as susceptible by Etests. In Recife, based on PCR results, primary clarithromycin resistance was found in 15 (16.5%) patients, prevalence close to that observed in Southeast Brazil. Resistance increased to 52% among previously treated patients. The point mutation A2143G was present in 20 (71.4%) of specimens and A2142G, in 8 (28.6%) of specimens. A2142C was not found.
  
  
  CONCLUSIONS
  In Recife, the prevalence of primary clarithromycin resistance, 16.5%, showed the need for pretreatment susceptibility testing in H. pylori infections.
authors.affiliation: Universidade de Pernambuco, Brazil. akellylins@gmail.com
authors.forename: Ana Kelly
authors.initials: AK
authors.lastname: Lins
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Lima
authors.forename: Marcelo
authors.initials: M
authors.lastname: Magalhães
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001706:Biopsy; D001938:Brazil; D017291:Clarithromycin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D016481:Helicobacter Infections / Q000382:microbiology / Q000473:pathology*; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008297:Male; D010641:Phenotype; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D013270:Stomach / Q000382:microbiology / Q000473:pathology*
chemical_list: D000900:Anti-Bacterial Agents; D017291:Clarithromycin