title: Antimicrobial resistance, genetic resistance determinants for ceftriaxone and molecular epidemiology of Neisseria gonorrhoeae isolates in Nanjing, China.
abstract: OBJECTIVE
  Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major problem worldwide. This study investigated the AMR, genetic ceftriaxone resistance determinants and molecular epidemiology of N. gonorrhoeae in Nanjing, China.
  
  
  METHODS
  N. gonorrhoeae isolates were collected in 2007 (n = 198) and 2012 (n = 80). The susceptibility to ceftriaxone, spectinomycin, ciprofloxacin and tetracycline was determined using an agar-dilution method. The ceftriaxone resistance determinants penA, mtrR and penB were examined using sequencing. N. gonorrhoeae multi-antigen sequence typing (NG-MAST) was performed for molecular epidemiology.
  
  
  RESULTS
  All isolates were resistant to ciprofloxacin, 42.4% produced β-lactamase and 34.9% showed high-level resistance to tetracycline (MIC ≥16 mg/L). In total, 5.4% of isolates were resistant to ceftriaxone; however, all of these isolates were obtained in 2007 and the susceptibility to ceftriaxone appeared to have increased. All isolates were susceptible to spectinomycin. No penA mosaic alleles were found. Non-mosaic penA alleles with A501T and G542S alterations, an H105Y alteration in mtrR and an A102D/N alteration in porB1b were statistically associated with decreased susceptibility or resistance to ceftriaxone. The most prevalent NG-MAST sequence types (STs) were ST568 (n = 13), ST270 (n = 9) and ST421 (n = 7). ST270 was the most common ST in isolates with decreased susceptibility or resistance to ceftriaxone.
  
  
  CONCLUSIONS
  Ceftriaxone, ideally 500 mg and together with azithromycin (1-2 g), should be recommended for treatment of gonorrhoea in Nanjing, China. However, N. gonorrhoeae strains with resistance to ceftriaxone have been found in Nanjing. NG-MAST and ceftriaxone resistance determinant analysis can be valuable to supplement the antimicrobial resistance surveillance in China, which needs to be further strengthened.
authors.affiliation: National Center for STD Control, Chinese Center for Disease Control and Prevention, and Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, and Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing, China.
authors.forename: Shao-Chun
authors.initials: SC
authors.lastname: Chen
authors.affiliation: National Center for STD Control, Chinese Center for Disease Control and Prevention, and Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, and Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing, China yinyp@ncstdlc.org.
authors.forename: Yue-Ping
authors.initials: YP
authors.lastname: Yin
authors.affiliation: National Center for STD Control, Chinese Center for Disease Control and Prevention, and Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, and Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing, China.
authors.forename: Xiu-Qin
authors.initials: XQ
authors.lastname: Dai
authors.affiliation: WHO Collaborating Centre for Gonorrhoea and Other STIs, Department of Laboratory Medicine, Microbiology, Örebro University Hospital, Örebro, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Unemo
authors.affiliation: National Center for STD Control, Chinese Center for Disease Control and Prevention, and Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, and Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing, China.
authors.forename: Xiang-Sheng
authors.initials: XS
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology; D002443:Ceftriaxone / Q000494:pharmacology*; D002681:China / Q000453:epidemiology; D024881:Drug Resistance, Bacterial / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D009344:Neisseria gonorrhoeae / Q000235:genetics* / Q000302:isolation & purification*; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D002443:Ceftriaxone
keywords: NG-MAST; gonorrhoea; mtrR; penA; porB; treatment