Time Required for Nanopore Whole-Genome Sequencing of Neisseria gonorrhoeae for Identification of Phylogenetic Relationships

BACKGROUND: Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a global health challenge. Limitations to AMR surveillance reporting, alongside reduction in culture-based susceptibility testing, has resulted in a need for rapid diagnostics and strain detection. We investigated Nanopore sequencing time, and depth, to accurately identify closely related N. gonorrhoeae isolates, compared to Illumina sequencing. METHODS: N. gonorrhoeae strains collected from a London sexual health clinic were cultured and sequenced with MiSeq and MinION sequencing platforms. Accuracy was determined by comparing variant calls at 68 nucleotide positions (37 resistance-associated markers). Accuracy at varying MinION sequencing depths was determined through retrospective time-stamped read analysis. RESULTS: Of 22 MinION-MiSeq pairs reaching sufficient sequencing depth, agreement of variant call positions passing quality control criteria was 185/185 (100%; 95% confidence interval [CI], 98.0%–100.0%), 502/503 (99.8%; 95% CI, 98.9%–99.9%), and 564/565 (99.8%; 95% CI, 99.0%–100.0%) at 10x, 30x, and 40x MinION depth, respectively. Isolates identified as closely related by MiSeq, within one yearly evolutionary distance of ≤5 single nucleotide polymorphisms, were accurately identified via MinION. CONCLUSIONS: Nanopore sequencing shows utility as a rapid surveillance tool, identifying closely related N. gonorrhoeae strains, with just 10x sequencing depth, taking a median time of 29 minutes. This highlights its potential for tracking local transmission and AMR markers.