Phenotypic and genetic characterization of the 2008 WHO Neisseria gonorrhoeae reference strain panel intended for global quality assurance and quality control of gonococcal antimicrobial resistance surveillance for public health purposes

Emergence and spread of antimicrobial resistance (AMR) in Neisseria gonorrhoeae remain a major global problem and expanded, but valid, AMR surveillance is crucial for public health purposes. The World Health Organization (WHO) Collaborating Centre in Sydney, Australia, continually evaluates N. gonorrhoeae strains used in quality control and assurance aspects of the national, WHO regional and international programmes for AMR surveillance it conducts. Here we phenotypically and genetically characterized the 2008 WHO N. gonorrhoeae reference panel, widely used under existing WHO AMR surveillance protocols. The eight N. gonorrhoeae WHO reference strains were phenotypically characterized by antibiogram, auxotype, serovar and prolyliminopeptidase screening; and genetically with regard to resistance plasmid types, polymorphisms in divergent genetic resistance-mediating loci (n = 9), porB sequencing and N. gonorrhoeae multi-antigen sequence typing. The 2008 WHO reference strains represented all the important susceptible and resistant phenotypes, including corresponding resistance genotypes, and the range of resistances currently seen for relevant antimicrobials. Several pertinent additional phenotypic and genotypic markers, for example, epidemiological markers, were also determined. The 2008 WHO N. gonorrhoeae reference strain panel was extensively characterized, which is crucial for the expansion of gonococcal AMR surveillance nationally and internationally. The panel is available through WHO sources for quality assurance and quality control aspects of current phenotypic testing protocols, to allow valid comparison of AMR data derived by divergent methods, and also for the control of present and future molecular assays for AMR detection. Additional WHO reference strains can be included as required by the emergence of additional resistant phenotypes and/or genotypes.