Gonococcal Antimicrobial Surveillance Program — Canada (GASP-Canada): Molecular typing:

On this page

• Multi-Antigen sequence typing
• Why we monitor NG-MAST
• NG-MAST publications
• Sequence typing for AMR
• NG-STAR publications

Multi-antigen sequence typing

The N. gonorrhoeae multi-antigen sequence typing (NG-MAST)^{Footnote 1} is a valuable tool to characterize different strains of gonorrhea. This method involves sequencing 2 genes:

• porinB (porB)
• transferrin-binding protein B (tbpB)

Together, these genes constitute the sequence type. We determine sequence type using Public databases for molecular typing (PubMLST).

Why we monitor NG-MAST

Monitoring sequence types helps us understand which strains are circulating in regions of Canada. It also supports investigations into outbreaks and treatment failures. Gonorrhoea strains with the same sequence type also have similar or identical AMR profiles. This makes the NG-MAST typing scheme a useful characterization tool for gonorrhoea.

Figure 1. NG-MAST distribution of the most common sequence types in Canada in

NG-MAST publications

• Rapid Sequence-Based Identification of Gonococcal Transmission Clusters in a Large Metropolitan Area
• Increasing Azithromycin Resistance in Neisseria gonorrhoeae due to NG-MAST 12302 clonal spread in Canada, 2015 to 2018
• Non-cultural detection and molecular genotyping of Neisseria gonorrhoeae from a piece of clothing

Sequence typing for AMR

We also use gonorrhea sequence typing for antimicrobial resistance (NG-STAR)^{Footnote 2}. It is a novel sequence-based molecular antimicrobial resistance scheme. It was developed by the National Microbiology Laboratory (NML) to track the global spread of N. gonorrhoeae strains.

This method classifies 7 well-characterized genes in N. gonorrhoeae (penA, mtrR, porB, ponA, gyrA and 23S rRNA). These genes are associated with AMR to 3 classes of antibiotics (cephalosporins, macrolides, fluoroquinolones). For each strain of gonorrhoea, an allele number is assigned to each gene. The combination of these allele numbers constitutes the sequence type.

NG-STAR web application

Figure 3. Annual NG-STAR Type distribution in Canada in Year

NG-STAR publications

• NG-STAR genotypes are associated with MDR in Neisseria gonorrhoeae isolates collected in 2017 in Shanghai
• Emergence and spread of Neisseria gonorrhoeae clinical isolates harboring mosaic-like structure of penicillin-binding protein 2 in central Japan
• Mutations in gyrA, gyrB, parC, and parE in quinolone-resistant strains of Neisseria gonorrhoeae
• Mutation in 23S rRNA associated with macrolide resistance in Neisseria gonorrhoeae
• Characterization of ciprofloxacin resistance in Neisseria gonorrhoeae isolates in Canada
• Rapid sequence-based identification of gonococcal transmission clusters in a large metropolitan area
• Multidrug-resistant strains of Neisseria gonorrhoeae in Greece
• Mutations in ponA, the gene encoding penicillin-binding protein 1, and a novel locus, penC, are required for high-level chromosomally mediated penicillin resistance in Neisseria gonorrhoeae

References