Genetic Characterization and Enhanced Surveillance of Ceftriaxone-Resistant Neisseria gonorrhoeae Strain, Alberta, Canada, 2018

Abstract

In July 2018, a case of Neisseria gonorrhoeae associated with ceftriaxone treatment failure was identified in Alberta, Canada. We identified the isolate and nucleic acid amplification testing (NAAT) specimen as the ceftriaxone-resistant strain multilocus sequence type 1903/NG-MAST 3435/NG-STAR 233, originally identified in Japan (FC428), with the same penA 60.001 mosaic allele and genetic resistance determinants. Core single-nucleotide variant (SNV) analysis identified 13 SNVs between this isolate and FC428. Culture-independent surveillance by PCR for the A311V mutation in the penA allele and N. gonorrhoeae multiantigen sequence typing directly from NAAT transport media positive for N. gonorrhoeae by NAAT did not detect spread of the strain. We identified multiple sequence types not previously detected in Alberta by routine surveillance. This case demonstrates the benefit of using culture-independent methods to enhance detection, public health investigations, and surveillance to address this global threat.

Keywords: Alberta; Canada; Neisseria gonorrhoeae; antimicrobial resistance; azithromycin; bacteria; cefixime; ceftriaxone; cephalosporin; drug resistance; gonorrhea; molecular epidemiology; molecular typing; penicillin binding protein 2; treatment failure.

Figure

Core single-nucleotide variant (SNV) phylogenetic tree of ceftriaxone-resistant Neisseria gonorrhoeae identified from enhanced surveillance in Alberta, Canada (bold), and reference isolates. The maximum-likelihood phylogenetic tree is rooted on the reference genome of N. gonorrhoeae FA1090 (GenBank accession no. NC_002946.2). Scale bar represents the estimated evolutionary divergence between isolates on the basis of average genetic distance between strains (estimated number of substitutions in the sample/total number of high-quality SNVs). Strains F89 (WHO-Y), A8806 (WHO-Z), and H041 (WHO-X), A7536, 47707, A7846, FC460, and FC428 are previously reported ceftriaxone-resistant reference strains (4). MLST, multilocus sequence typing; NG-MAST, N. gonorrhoeae multiantigen sequence typing; NG-STAR, N. gonorrhoeae sequence typing for antimicrobial resistance.