Real-time PCR detection of Neisseria gonorrhoeae susceptibility to penicillin

Cameron Buckley, Ella Trembizki, Basil Donovan, Marcus Chen, Kevin Freeman, Rebecca Guy, Monica M. Lahra, Ratan L. Kundu, David G. Regan, Helen V. Smith, David M Whiley, John Kaldor, Handan Wand, James Ward, Christopher Fairley, Nathan Ryder, Jiunn Yih Su

    Research output: Contribution to journalArticlepeer-review


    Objectives: The objective of this study was to develop a real-time PCR assay targeting the gonococcal porB gene (PorB-PCR) for predicting susceptibility of Neisseria gonorrhoeae to penicillin. This complements a previously described PCR assay for detecting penicillinase-producing N. gonorrhoeae (PPNG) developed by our laboratory (PPNG-PCR). 

    Methods: The PorB-PCR assay was designed using six probes to characterize various combinations of amino acids at positions 101 and 102 of the PorB1b class protein, including the WT G101/A102 and mutant G101K/A102D, G101K/A102N and G101K/A102G sequences, as well as the PorB1a sequence. The ability of these sequences to predict penicillin susceptibility was initially assessed using 2307 N. gonorrhoeae isolates from throughout Australia for which phenotypic susceptibility data were available. The assay was then applied to N. gonorrhoeae-positive clinical specimens (n = 70). Specificity was assessed by testing commensal Neisseria strains (n = 75) and N. gonorrhoeae-negative clinical specimens (n = 171). 

    Results: Testing of the 2307 N. gonorrhoeae isolates using PorB-PCR to detect G101/A102 and PorB1a sequences identified a total of 78.4% (61.2% and 17.2%, respectively) of penicillin-susceptible isolates with specificities of 97.4% and 99.3% and positive predictive values of 98.8% and 98.9%, where PPNG strains were simultaneously identified and excluded. Similar performance data were obtained when the PorB-PCR assay was applied to the N. gonorrhoeae-positive clinical specimens. No false-positive results were observed for the N. gonorrhoeae-negative samples and no cross-reactions were observed with the non-gonococcal species. 

    Conclusions: When used in parallel with the previously described PPNG-PCR, the PorB-PCR approach has the potential to facilitate individualized treatment of gonorrhoea using penicillin.

    Original languageEnglish
    Article numberdkw291
    Pages (from-to)3090-3095
    Number of pages6
    JournalJournal of Antimicrobial Chemotherapy
    Issue number11
    Publication statusPublished - 1 Nov 2016


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