title: Mixed gonococcal infections in a high-risk population, Sydney, Australia 2015: implications for antimicrobial resistance surveillance?
abstract: Previous studies have shown that mixed-strain gonococcal infections can occur. However, it remains unclear whether such infections impact upon the reliability of Neisseria gonorrhoeae antimicrobial resistance (AMR) surveillance. In this study, we aimed to resolve this question by intensively sampling isolates from gonorrhoea-positive specimens in a high-risk population in Sydney, Australia.
  
  
  
  A total of 615 N. gonorrhoeae isolates, originating from 63 clinical samples (31 rectal swabs and 32 throat swabs), were characterized. All isolates were subject to N. gonorrhoeae identification, antimicrobial susceptibility testing and genotyping by SNP-based MLST.
  
  
  
  Only 2 of the 63 (3.2%) samples provided evidence of mixed-strain infections. These comprised two rectal swabs that harboured isolates of different SNP-based MLST genotypes; however, the AMR susceptibility profiles of the different genotypes from these samples were indistinguishable. Within-sample differences in the AMR susceptibility profiles were observed for a further seven samples; however, the differences were not considered significant; MIC values were typically within a 2-fold difference or were close to test breakpoints.
  
  
  
  Results of this study provide further evidence that mixed-strain gonococcal infections do occur, although at low prevalence. Our data indicate that at a population level such infections are unlikely to impact significantly upon N. gonorrhoeae AMR surveillance.
authors.affiliation: WHO Collaborating Centre for Sexually Transmitted Diseases, Sydney, Department of Microbiology, South Eastern Area Laboratory Services, Prince of Wales Hospital, Randwick, New South Wales 2031, Australia namraj.goire@uqconnect.edu.au.|Sydney Medical School Nepean, The University of Sydney, Nepean Hospital, Penrith, New South Wales 2747, Australia.
authors.forename: Namraj
authors.initials: N
authors.lastname: Goire
authors.affiliation: WHO Collaborating Centre for Sexually Transmitted Diseases, Sydney, Department of Microbiology, South Eastern Area Laboratory Services, Prince of Wales Hospital, Randwick, New South Wales 2031, Australia.
authors.forename: Ratan
authors.initials: R
authors.lastname: Kundu
authors.affiliation: The University of Queensland Centre for Clinical Research, Royal Brisbane and Women's Hospital Campus, Herston, Queensland 4029, Australia.
authors.forename: Ella
authors.initials: E
authors.lastname: Trembizki
authors.affiliation: The University of Queensland Centre for Clinical Research, Royal Brisbane and Women's Hospital Campus, Herston, Queensland 4029, Australia.
authors.forename: Cameron
authors.initials: C
authors.lastname: Buckley
authors.affiliation: WHO Collaborating Centre for Sexually Transmitted Diseases, Sydney, Department of Microbiology, South Eastern Area Laboratory Services, Prince of Wales Hospital, Randwick, New South Wales 2031, Australia.
authors.forename: Tiffany R
authors.initials: TR
authors.lastname: Hogan
authors.affiliation: Western Sydney Sexual Health Centre, Parramatta, New South Wales 2150, Australia.|Marie Bashir Institute for Infectious Diseases and Biosecurity & Sydney Medical School-Westmead, University of Sydney, New South Wales 2006, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Lewis
authors.affiliation: Sydney Medical School Nepean, The University of Sydney, Nepean Hospital, Penrith, New South Wales 2747, Australia.
authors.forename: James M
authors.initials: JM
authors.lastname: Branley
authors.affiliation: The University of Queensland Centre for Clinical Research, Royal Brisbane and Women's Hospital Campus, Herston, Queensland 4029, Australia.|Pathology Queensland Central Laboratory, Brisbane, Queensland 4029, Australia.
authors.forename: David M
authors.initials: DM
authors.lastname: Whiley
authors.affiliation: WHO Collaborating Centre for Sexually Transmitted Diseases, Sydney, Department of Microbiology, South Eastern Area Laboratory Services, Prince of Wales Hospital, Randwick, New South Wales 2031, Australia.|School of Medical Sciences, Faculty of Medicine, The University of New South Wales, Kensington, New South Wales 2033, Australia.
authors.forename: Monica M
authors.initials: MM
authors.lastname: Lahra
mesh_terms: D001315:Australia / Q000453:epidemiology; D060085:Coinfection / Q000453:epidemiology / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D062665:Epidemiological Monitoring; D005260:Female; D006069:Gonorrhea / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D009344:Neisseria gonorrhoeae / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*