Emerging epidemic of the predominant clusters of FC428-like Neisseria gonorrhoeae in Guangdong, China.

Objectives: This study aimed to investigate the molecular characteristics of predominant epidemic clusters of FC428-like N. gonorrhoeae in Guangdong, China in 2022.

Methods: Minimum inhibitory concentrations (MICs) were determined for N. gonorrhoeae isolates collected from the Guangdong Gonococcal Antimicrobial Surveillance Program. N. gonorrhoeae multiantigen sequence typing (NG-MAST), antimicrobial resistance sequence typing (NG-STAR), multilocus sequence typing (MLST) sequence types (STs), and penA alleles were determined by whole-genome sequencing. The isolates were further characterized by phylogenetic analysis.

Results: A total of 537 N. gonorrhoeae isolates were analyzed, molecular analysis revealed that 7.8% of the isolates carried penA 60.001 allele, which was highly resistant to ceftriaxone (88.1%) and cefixime (100.0%). The predominant STs in penA 60.001 isolates were MLST ST1903 (23,54.8%), ST7365 (11,26.2%), NG-STAR ST1143 (13,31.0%), ST233 (4,9.5%), ST1133 (4,9.5%), and NG-MAST ST22261 (10,23.8%). Among 537 isolates, of which 11.2% were resistant to ceftriaxone and 19.6% to cefixime. In western Guangdong, resistance to ceftriaxone and cefixime reached 17.3% and 26.9%, respectively. The most predominant types among ceftriaxone-resistant isolates are genetically closer to FC428 isolates, and differ from those among cefixime-resistant isolates. Phylogenetic analysis revealed that the Guangdong FC428-like isolates from 2021 to 2022 spread across the whole phylogenetic tree, but the majority were clustered within a distinct evolutionary clade.

Conclusions: FC428-like isolates in Guangdong formed a unique evolutionary clade with high cephalosporin resistance. These findings highlight the need to revise national gonorrhea treatment guidelines and prioritize the development of new antimicrobials.