Tracking changes in antimicrobial resistance and clone replacement of Neisseria gonorrhoeae in Rio de Janeiro from...

Neisseria gonorrhoeae poses a significant global public health challenge due to its ability to rapidly evolve antimicrobial resistance. In this study, we analyzed 141 isolates of N. gonorrhoeae obtained between 2015 and 2022 from clinical laboratories in the metropolitan region of Rio de Janeiro. Antimicrobial susceptibility, resistance mechanisms, and clonal diversity were investigated. Whole-genome sequencing and multilocus sequence typing (MLST) revealed the circulation of internationally relevant sequence types (STs) such as ST-1901, ST-7363, and ST-9363. While non-susceptibility rates to penicillin (98 %) and ciprofloxacin (73 %) remained stable compared to earlier data, tetracycline resistance decreased from 67 % (in 2015-2016) to 20 % (in 2019-2020), likely due to the reduced prevalence of ST-1588. However, mainly after 2020, tetM plasmids were detected in ST-7822 and the emerging ST-7363, suggesting the concern of a rising occurrence of these determinants in the near future. Azithromycin non-susceptibility varied between 15 and 33 % in the different time frames, associated with mutations in the mtrR promoter and rrl gene, affecting isolates across eleven STs. While no ceftriaxone non-susceptibility was identified, ST-1901 and ST-7363 isolates harbored unique mosaic penA 34 alleles, and ST-1580/ST-17526 carried semi-mosaic 93 alleles. These findings underscore the persistence of resistance to older antimicrobials, the spread of plasmid-mediated resistance in key clones, and the growing threat of azithromycin resistance, which could compromise the treatment of gonorrhea in patients allergic to beta-lactams.