title: Resistance to antibiotics and characterization of Helicobacter pylori strains isolated from antrum and body from adults in Mexico.
abstract: OBJECTIVE
  Resistance to antibiotics is common in patients with Helicobacter pylori infection in more than one anatomic stomach site. We assessed whether the antibiotic resistance varies according to virulence factors of the bacteria as well as to the age and gender of individuals infected in two anatomic sites.
  
  
  METHODS
  H. pylori strains were isolated from an antral and corpus biopsy from 90 patients with gastric ambulatory who had not received any previous therapy. Susceptibility to metronidazole and clarithromycin was assessed by E-test, and vacA and cagA genotypes were determined by polymerase chain reaction.
  
  
  RESULTS
  Dual resistance to metronidazole and clarithromycin was 3.3% in antrum and 4.4% in the corpus; heteroresistance was 19% and 5.5% for metronidazole and clarithromycin, respectively. Clarithromycin resistance significantly increased with age. Women showed a twofold increased risk for metronidazole-resistant strains in antrum (odds ratio = 2.85, 95% confidence interval 1.09 to 7.42). Virulence factors were not associated with antimicrobial resistance.
  
  
  CONCLUSIONS
  Prevalence of resistance to clarithromycin may be increasing in this country. Antimicrobial susceptibility tests from different biopsy sites deserve attention.
authors.affiliation: Instituto Nacional de Salud Pública, SSA, Cuernavaca, Morelos, Mexico.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Ayala
authors.forename: Marcia
authors.initials: M
authors.lastname: Galván-Portillo
authors.forename: Lilia
authors.initials: L
authors.lastname: Chihu
authors.forename: Geny
authors.initials: G
authors.lastname: Fierros
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sánchez
authors.forename: Berta
authors.initials: B
authors.lastname: Carrillo
authors.forename: Adolfo
authors.initials: A
authors.lastname: Román
authors.forename: Lizbeth
authors.initials: L
authors.lastname: López-Carrillo
authors.forename: Jesús
authors.initials: J
authors.lastname: Silva-Sánchez
mesh_terms: D000328:Adult; D000367:Age Factors; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000942:Antigens, Bacterial / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D001706:Biopsy / Q000379:methods*; D017291:Clarithromycin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D016480:Helicobacter pylori / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000494:pharmacology; D008800:Mexico; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D015995:Prevalence; D012737:Sex Factors; D013270:Stomach / Q000187:drug effects / Q000382:microbiology* / Q000473:pathology
chemical_list: D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori; D008795:Metronidazole; D017291:Clarithromycin