Species discordant Neisseria gonorrhoeae (Ng) isolates detected at Milwaukee

Routine surveillance through the Gonococcal Isolate Surveillance Project (GISP) and Strengthening the U.S. Response to Resistant Gonorrhea (SURRG) detected six concerning urogenital Neisseria isolates with contradicting species identification in Milwaukee (MIL). While all six isolates were positive for Neisseria gonorrhoeae (Ng) using nucleic acid amplification testing and MALDI-ToF identified the isolates as Ng, two biochemical tests, Gonochek and API NH, classified them as Neisseria meningitidis (Nm). Whole genome sequencing revealed that putative recombination event in all MIL isolates within the Gamma-glutamyl transpeptidase (ggt) gene replacing the Ng pseudogenes ggt1 and ggt2 with active Nm ggt gene, a key component in the biochemical tests used to differentiate between Nm and Ng. Further analysis identified Nm as the source of HGT event.