title: The influence of target population on nonculture-based detection of markers of Neisseria gonorrhoeae antimicrobial resistance.
abstract: BACKGROUND
  With treatment options for gonorrhoea (Neisseria gonorrhoeae) diminishing, strengthening antimicrobial resistance (AMR) surveillance is paramount.
  
  
  METHODS
  In this study, we investigated polymerase chain reaction (PCR) based methods, in parallel with N. gonorrhoeae multi-antigen sequence typing (NG-MAST), for direct detection of four N. gonorrhoeae chromosomal mechanisms associated with emerging resistance to extended spectrum cephalosporins using noncultured samples: an adenine deletion in the mtrR promoter, a mosaic penicillin-binding protein (PBP) 2, an A501V PBP2 mutation, and alterations at positions 120 and 121 of the porB protein. The PCR assays were validated using a panel of characterised N. gonorrhoeae isolates (n=107) and commensal Neisseria (n=100) species. These PCR assays with NG-MAST were then applied to noncultured clinical specimens from distinct populations in Australia with differing levels of N. gonorrhoeae AMR: the Northern Territory (NT), where resistance has a low population prevalence, and Queensland (Qld), with higher AMR prevalence.
  
  
  RESULTS
  The real-time PCR assays proved highly sensitive and specific. When applied to the noncultured samples, only 1 out of 50 (2%) samples from NT harboured a resistant mechanism, whereas the Qld samples (n=129) collected over different periods showed progressive acquisition of resistant mechanisms, and these were associated with specific NG-MAST types, including Type 225.
  
  
  CONCLUSIONS
  The results suggest that our PCR-based methods could be used to rapidly pinpoint incursion of resistant strains into previously unaffected populations. Likewise, our results show that for molecular AMR surveillance, the population being investigated is as important as the genetic mechanisms being targeted.
authors.affiliation: Queensland Paediatric Infectious Diseases Laboratory, Queensland Children's Medical Research Institute, Brisbane, Australia. namraj.goire@uqconnect.edu.au
authors.forename: Namraj
authors.initials: N
authors.lastname: Goire
authors.forename: Kevin
authors.initials: K
authors.lastname: Freeman
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Lambert
authors.forename: Graeme R
authors.initials: GR
authors.lastname: Nimmo
authors.forename: Athena E
authors.initials: AE
authors.lastname: Limnios
authors.forename: Monica M
authors.initials: MM
authors.lastname: Lahra
authors.forename: Michael D
authors.initials: MD
authors.lastname: Nissen
authors.forename: Theo P
authors.initials: TP
authors.lastname: Sloots
authors.forename: David M
authors.initials: DM
authors.lastname: Whiley
mesh_terms: D000225:Adenine; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001426:Bacterial Proteins / Q000235:genetics*; D002511:Cephalosporins / Q000627:therapeutic use*; D002872:Chromosome Deletion; D025063:Chromosome Disorders / Q000235:genetics; D004252:DNA Mutational Analysis; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D006069:Gonorrhea / Q000188:drug therapy* / Q000382:microbiology*; D006801:Humans; D009030:Mosaicism; D058885:Multilocus Sequence Typing; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000235:genetics*; D015876:Northern Territory; D010403:Penicillin Resistance / Q000235:genetics; D046915:Penicillin-Binding Proteins / Q000235:genetics; D018272:Porins / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011793:Queensland; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012097:Repressor Proteins / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D046915:Penicillin-Binding Proteins; D018272:Porins; D012097:Repressor Proteins; C057699:porin protein, Neisseria; C087450:mtrR protein, Neisseria gonorrhoeae; D000225:Adenine