Background:
Neisseria meningitidis (Nm), which typically colonizes the nasopharyngeal mucosa, is primarily associated with asymptomatic carriage but can lead to invasive meningococcal disease (IMD). Nm urethritis clade can also colonize urogenital and rectal mucosal surfaces, potentially resulting in disease. IMD is chiefly linked to six meningococcal serogroups (NmA, NmB, NmC, NmW, NmX, and NmY). Nongroupable (NmNG) strains that do not appear to produce capsular polysaccharide are less likely to cause IMD; however, urethrotropic NmNG strains were recently identified in the United States (U.S. NmNG urethritis clade).
Aim/Methods:
Nm isolates collected over three years (2017–2019) from oral, urethral, rectal, and endocervical swabs taken at 12 sexually transmitted disease (STD) clinics across 10 U.S. states via the Enhanced Gonococcal Isolates Surveillance Project (eGISP), were characterized. The isolates represented patients with urethritis/cervicitis or asymptomatic sexual contacts of patients with urethritis/cervicitis. Whole-genome sequencing (WGS) was conducted using the Illumina platform, with data analyzed using the Bacterial Meningitis Genome Annotation Platform for species identification, genogroup (i.e., serogroup-associated gene) confirmation, and molecular typing. Additionally, phylogenetic analysis was conducted to compare genetic characteristics between these isolates and a collection of isolates belonging to the U.S. NmNG urethritis clade.
Results:
Of 1,593 isolates recovered, WGS confirmed that 1,471 (92.34%) were Nm: 1,341 (91.16%) from oral, 104 (7.07%) from urethral, 25 (1.7%) from rectal, and 1 (0.07%) from endocervical specimens. Most isolates were NmNG (1,037/1,471, 70.5%), followed by NmB (338/1,471, 22.98%), NmY (49/1,471, 3.33%), NmC (29/1,471, 1.97%), NmX (9/1,471, 0.61%), NmZ (6/1,471, 0.41%), and NmW (3/1,471, 0.20%). Among NmNG isolates, 89/1,037 (8.48%) were part of the U.S. NmNG urethritis clade: 20 oral, 67 urethral, and 2 rectal isolates. Clonal complexes (CCs) with >5% prevalence included CC41/44, CC32, CC4821, CC11, CC198 and CC53. Phylogenetic analysis revealed that all 89 NmNG isolates characterized in this study belonging to the U.S. NmNG urethritis clade shared a common ancestor dating back to at least 2011.
Conclusions:
The NmNG urethritis clade continues to circulate and cause disease in the U.S. Continued genomic surveillance will enhance understanding of meningococcal urethritis in the U.S.