title: [Prevalence of metronidazole, clarithromycin and tetracycline resistance in Helicobacter pylori isolated from Chilean patients].
abstract: BACKGROUND
  Helicobacter pylori is a pathogenic bacterium that infects a significant number of individuals. At present, therapeutic strategies to eradicate this bacterium depend on our knowledge of its resistance to antimicrobials.
  
  
  OBJECTIVE
  To evaluate the primary resistance of H pylori to metronidazole (Mtz), clarithromycin (Cla), and tetracycline (Tet) in symptomatic out-patients.
  
  
  METHODS
  Fifty independent isolates of H pylori were obtained by endoscopy-assisted gastric biopsy from patients attending the University of Chile Clinical Hospital, that previously had not been treated with an eradication regime against this bacterium. The minimal inhibitory concentration of each antimicrobial was determined by agar dilution method.
  
  
  RESULTS
  Forty five and 27% of the isolates were found to be resistant to Mtz and Tet, respectively; the majority of these resistant isolates were from patients older than 21 years. Twenty percent of isolates were resistant to Cla; these were distributed evenly among different ages. Thirty two percent of the isolates were resistant to two or more of the antimicrobials.
  
  
  CONCLUSIONS
  The high frequency of naturally occurring, antimicrobial-resistant strains of H pylori poses a national and world-wide problem for public health.
authors.affiliation: Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
authors.forename: Cristian
authors.initials: C
authors.lastname: Vallejos
authors.forename: Leonardo
authors.initials: L
authors.lastname: Garrido
authors.forename: Dante
authors.initials: D
authors.lastname: Cáceres
authors.forename: Ana María
authors.initials: AM
authors.lastname: Madrid
authors.forename: Claudia
authors.initials: C
authors.lastname: Defilippi
authors.forename: Carlos
authors.initials: C
authors.lastname: Defilippi
authors.forename: Héctor
authors.initials: H
authors.lastname: Toledo
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D002677:Chile; D017291:Clarithromycin / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D013752:Tetracycline / Q000494:pharmacology*; D013753:Tetracycline Resistance / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D008795:Metronidazole; D013752:Tetracycline; D017291:Clarithromycin