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Molecular epidemiology of Neisseria gonorrhoeae isolates from Saskatchewan, Canada: utility of NG-MAST in predicting antimicrobial susceptibility regionally
  1. Sidharath D Thakur1,
  2. Paul N Levett2,
  3. Gregory B Horsman2,
  4. Jo-Anne R Dillon1,3
  1. 1Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
  2. 2Saskatchewan Disease Control Laboratory, Regina, Saskatchewan, Canada
  3. 3Vaccine and Infectious Disease Organization-International Vaccine Centre, University of Saskatchewan, Saskatchewan, Canada
  1. Correspondence to Professor Jo-Anne R Dillon, Department of Microbiology and Immunology, College of Medicine, University of Saskatchewan, c/o 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada; j.dillon{at}


Objectives To investigate the molecular epidemiology of isolates of Neisseria gonorrhoeae from Saskatchewan, Canada, using Neisseria gonorrhoeae multi antigen sequence typing (NG-MAST), and to assess associations between antimicrobial susceptibility (AMS) and specific strain types (STs).

Methods 320 consecutive gonococcal isolates, collected between 2003 and 2008, were typed by NG-MAST. STs were grouped if one of their alleles was common and the other differed by ≤1% in DNA sequence. AMS was determined by agar dilution (CLSI) to seven antibiotics.

Results N gonorrhoeae isolates were resolved into 82 individual NG-MAST STs and 18 NG-MAST ST groups with groups 25, 3655, 921, 3654, 3657 and 3656 comprising 53.4% (171/320) of the isolates. N gonorrhoeae isolates susceptible to all the tested antimicrobials were significantly (p<0.05) associated with ST 25 (87%). Other significant associations between ST and AMS included: ST 3654 and isolates with minimum inhibitory concentrations of ≥0.03 mg/L to third generation cephalosporins; ST 3711 (100%) and TRNG; and ST/group 3654 (43%) and chromosomal resistance to penicillin and tetracycline. Several NG-MAST STs/groups were significantly associated with isolates with chromosomal resistance to tetracycline. Isolates resistant to ciprofloxacin (n=5) and azithromycin (n=2) appeared as individual STs. Significant associations were observed among individual STs, sex and age of the patient, and regional and temporal distributions.

Conclusions Associations between N gonorrhoeae AMS and NG-MAST STs were identified and may be useful in predicting AMS regionally. Because STs in different countries vary considerably, the use of NG-MAST for the prediction of AMS globally requires further study.

  • Antibiotic Sensitivity
  • Neisseria Gonorrhoea
  • Molecular Epidemiology
  • Molecular Typing

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