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 characterised by phylogenetic analysis.

RESULTS

A total of 537 N. gonorrhoeae isolates were analysed, 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 prioritise the development of new antimicrobials.