Neisseria gonorrhoeae Sequence Typing for Antimicrobial Resistance (NG-STAR): a novel antimicrobial resistance multilocus typing scheme for tracking the global dissemination of N. gonorrhoeae strains.

Demczuk W1, Sidhu S1, Unemo M2, Whiley DM3, Allen VG4, Dillon JR5, Cole M6, Seah C4, Trembizki E3, Trees DL7, Kersh EN7, Abrams AJ7, de Vries HJ8,9,10, van Dam AP11,12, Medina I1, Bharat A1, Mulvey MR1, Van Domselaar G1, Martin I13.

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Abstract

A curated web-based user-friendly sequence typing tool based on antimicrobial resistance determinants in Neisseria gonorrhoeae was developed and is publicly accessible at https://ngstar.canada.ca The N. gonorrhoeae Sequence Typing for Antimicrobial Resistance (NG-STAR) molecular typing scheme uses the DNA sequences of 7 genes (penA, mtrR, porB, ponA, gyrA, parC, 23S rRNA) associated with resistance to β-lactam antimicrobials, macrolides, or fluoroquinolones. NG-STAR uses the entire penA sequence combining the historical nomenclature for penA types I-XXXVIII with novel nucleotide sequence designations; the full mtrR sequence and a portion of its promoter region; portions of ponA, porB, gyrA and parC; and 23S rRNA sequences. NG-STAR grouped 768 isolates into 139 sequence types (STs) (n=660) consisting of 29 CCs having a maximum of a single locus variation; and 76 NG-STAR STs (n=109) were identified as unrelated singletons. NG-STAR had a high Simpson's diversity index of 96.5% (CI 95%=0.959-0.969). The most common STs were NG-STAR: ST-90 (n=100, 13.0%), ST-42 and ST-91 (n=45, 5.9%), ST-64 (n=44, 5.72%), and ST-139 (n=42, 5.5%). Decreased susceptibility to azithromycin was associated with NG-STAR ST-58, ST-61, ST-64, ST-79, ST-91 and ST-139(n=156, 92.3%); decreased susceptibility to cephalosporins with NG-STAR ST-90, ST-91 and ST-97 (n=162, 94.2%); and ciprofloxacin resistance with NG-STAR ST-26, ST-90, ST-91, ST-97, ST-150 and ST-158 (n=196, 98.0%). All isolates of NG-STAR ST-42, ST-43, ST-63, ST-81, and ST-160 (n=106) were susceptible to all four antimicrobials. The standardization of nomenclature associated with antimicrobial resistance determinants through an internationally available database will facilitate the monitoring of the global dissemination of antimicrobial resistant N. gonorrhoeae strains.