Table 1

Detailed description of PCR false negative porA mutant Neisseria gonorrhoeae isolates identified in England, and comparison to previously reported porA mutant isolates from Sweden, Scotland and Australia.

porA mutant gonococcal isolates (country)
356 (England)088 (England)Variant (Sweden)*GC1 (Scotland)*GC3 (Scotland)*Variant (Australia)*
Screening and confirmatory tests
porA pseudogene PCR†NegativeNegativeNegativeNegativeNegativeNegative
 Culture‡N gonorrhoeaeN gonorrhoeaeN gonorrhoeaeN gonorrhoeaeN gonorrhoeaeN gonorrhoeae
 Gen-Probe APTIMAN gonorrhoeaeN gonorrhoeaeN gonorrhoeaeN gonorrhoeaeN gonorrhoeae§
 16s rDNA (100% ID)N gonorrhoeaeN gonorrhoeaeN gonorrhoeae§§§
 MALDI-TOF-MSN gonorrhoeaeN gonorrhoeaeN gonorrhoeae§§N gonorrhoeae
porA gene sequencing
porA GenBank BLAST98% identity to MC 27898% identity to MC 27892% identity to MC 278¶99% identity to MC 278¶99% identity to MC 278¶99% identity to MC 278¶
 Meningococcal porA genosubtypeP1.22-New,14-5,36-2P1.22-New,14-5,36-2P1.21-6,2-48,35-1P1.¶,14-5,36-2P1.¶,23-13,36-2P1.¶,14-5,36-2
Molecular epidemiological typing
Antimicrobial susceptibility, MIC (mg/l)
 Anatomical siteUrethralUrethralPharyngealRectalUrethralRectal, pharyngeal
 Sexual orientationNot knownNot knownHeterosexualMSMMSMMSM
  • *Previously published isolates.13–15

  • porA pseudogene PCR,11 ,12 and/or dual-target PCR (porA and opa genes).18

  • ‡Including species confirmation using selective culture, rapid oxidase production, microscopy after Gram staining, sugar utilisation test, API NH (bioMérieux, Marcy l'Etoile, France) and Phadebact GC Monoclonal Test (Bactus AB, Uppsala, Sweden).

  • §Analysis not performed.

  • ¶Performed in this study on available full-length or partial porA gene sequences. Variable region 1 in the meningococcal porA genosubtyping was not possible to determine due to the lack of full-length porA sequence in previously published papers from Scotland and Australia.13 ,14

  • **MIC data not available.

  • MALDI-TOF-MS, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry; MC 278, Neisseria meningitidis strain 278 (GenBank accession no. GQ173789); MLST, multilocus sequence typing; MIC, minimum inhibitory concentration; MSM, men who have sex with men; NG-MAST, Neisseria gonorrhoeae multi-antigen sequence typing.