Clonal Expansion of penA-60.001 in Cephalosporin-Resistant Neisseria gonorrhoeae: A Molecular Epidemiology Study in Meizhou, China, 2020-2024.

BACKGROUND

Rising Neisseria gonorrhoeae cephalosporin resistance worldwide is compromising first-line therapy, yet data from underrepresented regions of China are lacking. This study provided a comprehensive analysis of antimicrobial susceptibility and the molecular epidemiology of cephalosporin-resistant strains from Meizhou.

METHODS

Neisseria gonorrhoeae isolates were collected from Meizhou People's Hospital between September 2020 and December 2024. The minimum inhibitory concentrations (MICs) were determined by the broth microdilution method. Isolates with ceftriaxone or cefixime MIC > 0.125 mg/L were genotyped by Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST), multilocus sequence typing (MLST), and Neisseria gonorrhoeae sequence typing for antimicrobial resistance (NG-STAR).

RESULTS

A total of 195 Neisseria gonorrhoeae isolates were collected. Among them, 48 (24.6%) showed cephalosporin resistance (ceftriaxone or cefixime MIC > 0.125 mg/L). Over the study period, ceftriaxone resistance rose from 0% (0/14) in 2020 to 24.1% (7/29) in 2024, while cefixime resistance declined from 28.9% (4/14) in 2020 to 6.3% (2/32) in 2023 and then rebounded to 24.1% (7/29) in 2024. Genotypic analysis of the 48 cephalosporin-resistant isolates identified three predominant penA types: XXXIV, LX, and XIII. Typing by MLST, NG‑MAST, and NG‑STAR revealed a diverse population with multiple sequence types. Initially, penA-XXXIV and penA-XIII were predominant. However, since 2022, penA-LX (NG-STAR penA-60.001) strains underwent significant clonal expansion and became the dominant resistant lineage. Using goeBURST, MLST ST7363 was placed at the center of the minimum spanning tree, with ST1903 and ST1901 as single- and double-locus variants, respectively. Subsequent NG-MAST phylogeny confirmed penA-specific clustering, indicating the emergence of distinct genotypic groups associated with these allelic changes.

CONCLUSION

This study reveals a clonal succession in Meizhou, where penA-60.001 strains became more prevalent than pre-existing cephalosporin-resistant lineages. This shift highlights the persistent threat of evolving resistance in Neisseria gonorrhoeae and emphasizes the need for sustained genomic surveillance to guide targeted interventions.