title: Cephalosporin and azithromycin susceptibility in Neisseria gonorrhoeae isolates by site of infection, British Columbia, 2006 to 2011.
abstract: BACKGROUND
  Widespread resistance of Neisseria gonorrhoeae to penicillin, tetracycline, and fluoroquinolones has challenged effective treatment and control; recent international case reports of cefixime, ceftriaxone, and azithromycin resistance suggest that the remaining treatment options are now additionally threatened. To explore trends in antimicrobial susceptibility of N. gonorrhoeae, we reviewed provincial laboratory data from British Columbia, 2006 to 2011.
  
  
  METHODS
  Susceptibility testing was performed for all N. gonorrhoeae isolates detected in-house or forwarded to the reference laboratory. Resistance or intermediate resistance (nonsusceptibility) was defined by standard breakpoints for penicillin, tetracycline, ciprofloxacin, and spectinomycin. Elevated minimum inhibitory concentrations (MICs) at serial dilutions of 0.064 μg/mL or greater were explored for cefixime/ceftriaxone and 0.5 μg/mL or greater for azithromycin. Nonsusceptibility/elevated MIC was compared by year, site of infection, sex, and age.
  
  
  RESULTS
  A total of 1837 isolates representing 22% of all reported gonorrhea cases were analyzed. Nonsusceptibility to penicillin was established at baseline. Nonsusceptibility to tetracycline and ciprofloxacin increased over the study period, reaching 96% and 36%, respectively, in 2011. Sixteen isolates (1%) had a cefixime MIC of 0.25 μg/mL (none ≥0.5), none had a ceftriaxone MIC of 0.25 μg/mL or greater, and 15 (1%) had an azithromycin MIC of 2.0 μg/mL or greater. Elevated MIC of these agents showed an increasing trend over time. Nonsusceptibility and elevated MIC were consistently highest at the rectal and pharyngeal sites and higher in isolates from males, including when stratified to the pharyngeal site.
  
  
  CONCLUSIONS
  Increases in elevated MIC of cefixime/ceftriaxone/azithromycin were superimposed on a background of established resistance to penicillin, tetracycline, and ciprofloxacin and may signal impending gonococcal resistance to first-line treatments. Ongoing surveillance will inform timely shifts in treatment recommendations.
authors.affiliation: British Columbia Centre for Disease Control, Vancouver, Canada.
authors.forename: Travis S
authors.initials: TS
authors.lastname: Hottes
authors.forename: Richard T
authors.initials: RT
authors.lastname: Lester
authors.forename: Linda M N
authors.initials: LM
authors.lastname: Hoang
authors.forename: Rachel
authors.initials: R
authors.lastname: McKay
authors.forename: Miguel
authors.initials: M
authors.lastname: Imperial
authors.forename: Mark
authors.initials: M
authors.lastname: Gilbert
authors.forename: David
authors.initials: D
authors.lastname: Patrick
authors.forename: Tom
authors.initials: T
authors.lastname: Wong
authors.forename: Irene
authors.initials: I
authors.lastname: Martin
authors.forename: Gina
authors.initials: G
authors.lastname: Ogilvie
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D017963:Azithromycin / Q000494:pharmacology* / Q000627:therapeutic use; D001955:British Columbia / Q000453:epidemiology; D002511:Cephalosporins / Q000494:pharmacology* / Q000627:therapeutic use; D002584:Cervix Uteri / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D005260:Female; D006069:Gonorrhea / Q000188:drug therapy* / Q000453:epidemiology; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000302:isolation & purification; D010614:Pharynx / Q000382:microbiology; D012007:Rectum / Q000382:microbiology; D014521:Urethra / Q000382:microbiology; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D017963:Azithromycin