title: Estimating the prevalence of mixed-type gonococcal infections in Queensland, Australia.
abstract: Background Mixed gonococcal infections within the one anatomical site have been recognised but questions remain over how often they occur. In this study, the aim was to estimate the prevalence of mixed gonococcal infections using novel real-time polymerase chain reaction (PCR) methods that were developed and validated, targeting the gonococcal porB gene.
  
  
  METHODS
  Neisseria gonorrhoeae strains were categorised into three different porB groups, based on sequence data derived from N. gonorrhoeae multi-antigen sequence typing (NG-MAST) analyses of local isolates. Specific PCR methods for each group were then developed and these PCR methods were used to test clinical samples (n=350) that were positive for gonorrhoea as determined by nucleic acid amplification test (NAAT) diagnostic screening.
  
  
  RESULTS
  Initial validation using isolates showed the group PCR methods proved 100% sensitive and 100% specific for their respective porB groups. When applied to the clinical specimens, 298/350 (85%) provided positive results by the group PCR methods. Of these, four specimens showed evidence of mixed infections, supported by subsequent DNA sequencing of the PCR products.
  
  
  CONCLUSIONS
  The data provide further evidence of mixed gonococcal infections at the same anatomical site, but show that such infections may be relatively infrequent (1.3%; 95% confidence interval 0.01-2.6%) in a general screening population.
authors.affiliation: Queensland Paediatric Infectious Diseases Laboratory, Queensland Children's Health Services, Block 28, Royal Children's Hospital, Herston Road, Herston, Qld 4029, Australia.
authors.forename: Ella
authors.initials: E
authors.lastname: Trembizki
authors.affiliation: Public Health Microbiology, Queensland Health Forensic and Scientific Services, Archerfield, Qld 4108, Australia.
authors.forename: Christine
authors.initials: C
authors.lastname: Doyle
authors.affiliation: Queensland Paediatric Infectious Diseases Laboratory, Queensland Children's Health Services, Block 28, Royal Children's Hospital, Herston Road, Herston, Qld 4029, Australia.
authors.forename: Cameron
authors.initials: C
authors.lastname: Buckley
authors.affiliation: Public Health Microbiology, Queensland Health Forensic and Scientific Services, Archerfield, Qld 4108, Australia.
authors.forename: Amy
authors.initials: A
authors.lastname: Jennison
authors.affiliation: Public Health Microbiology, Queensland Health Forensic and Scientific Services, Archerfield, Qld 4108, Australia.
authors.forename: Helen
authors.initials: H
authors.lastname: Smith
authors.affiliation: Public Health Microbiology, Queensland Health Forensic and Scientific Services, Archerfield, Qld 4108, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Bates
authors.affiliation: Queensland Paediatric Infectious Diseases Laboratory, Queensland Children's Health Services, Block 28, Royal Children's Hospital, Herston Road, Herston, Qld 4029, Australia.
authors.forename: Theo
authors.initials: T
authors.lastname: Sloots
authors.affiliation: Queensland Paediatric Infectious Diseases Laboratory, Queensland Children's Health Services, Block 28, Royal Children's Hospital, Herston Road, Herston, Qld 4029, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Nissen
authors.affiliation: WHO Collaborating Centre for STD, Microbiology Department, South Eastern Area Laboratory Services, Prince of Wales Hospital, Sydney, NSW 2031, Australia.
authors.forename: Monica M
authors.initials: MM
authors.lastname: Lahra
authors.affiliation: Queensland Paediatric Infectious Diseases Laboratory, Queensland Children's Health Services, Block 28, Royal Children's Hospital, Herston Road, Herston, Qld 4029, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Whiley