title: Resistance to azithromycin of Neisseria gonorrhoeae isolates from 2 cities in China.
abstract: BACKGROUND
  Antimicrobial resistance in Neisseria gonorrhoeae (NG) is a public health concern globally, and azithromycin-resistant NG isolates have been identified in many countries. This study aimed to investigate azithromycin susceptibility in NG and to genetically characterize the azithromycin-resistant isolates identified in 2 cities in China.
  
  
  METHODS
  NG isolates (n = 318) were cultured from patients attending 2 sexually transmitted infection clinics in Nanjing and Chongqing, China, between 2008 and 2009. Minimum inhibitory concentration (MIC) of azithromycin, tetracycline, ciprofloxacin, spectinomycin and ceftriaxone was determined using the agar dilution method. NG strains ATCC 49226 and WHO G, J, L, and P were used for quality control. Azithromycin-resistant isolates were defined as having an MIC value equal to or greater than that of strain WHO P, which is internationally recognized as azithromycin-resistant (MIC = 2 mg/L), and genotyped using NG multiantigen sequence typing.
  
  
  RESULTS
  The MIC values of strain WHO P for azithromycin were 2 to 4 mg/L in all runs, which showed that the method provided consistent and reliable MIC values. Seventeen isolates (5.3%) showed resistance to azithromycin. Among these isolates (n = 17), 11 sequence types (STs) were identified by NG multiantigen sequence typing, of which 5 were novel. The most common ST was ST3356, represented by 6 isolates. ST1866 was represented by 2 isolates, which were isolated from patients with an unknown relationship, and both isolates were highly resistant to azithromycin, i.e., displayed an MIC of >64 mg/L.
  
  
  CONCLUSIONS
  A relatively high prevalence of azithromycin-resistant NG strains implies that azithromycin should not be recommended for the treatment of gonococcal urethritis or cervicitis in China.
authors.affiliation: National Center for STD Control, Chinese Academy of Medical Sciences and Peking Union Medical College Institute of Dermatology, Nanjing, China.
authors.forename: Liu-Feng
authors.initials: LF
authors.lastname: Yuan
authors.forename: Yue-Ping
authors.initials: YP
authors.lastname: Yin
authors.forename: Xiu-Qin
authors.initials: XQ
authors.lastname: Dai
authors.forename: Rachel V
authors.initials: RV
authors.lastname: Pearline
authors.forename: Zhi
authors.initials: Z
authors.lastname: Xiang
authors.forename: Magnus
authors.initials: M
authors.lastname: Unemo
authors.forename: Xiang-Sheng
authors.initials: XS
authors.lastname: Chen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017963:Azithromycin / Q000494:pharmacology*; D002443:Ceftriaxone / Q000494:pharmacology; D002681:China / Q000453:epidemiology; D002939:Ciprofloxacin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000235:genetics; D005260:Female; D006069:Gonorrhea / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D000198:Spectinomycin / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D014505:Urban Population / Q000706:statistics & numerical data
chemical_list: D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D002443:Ceftriaxone; D017963:Azithromycin; D000198:Spectinomycin; D013752:Tetracycline