Global concerns, local challenges: the alarming spread of FC428-related gonococcal strains in Nanchang City, 2021.

OBJECTIVES

Antimicrobial resistance (AMR) in N. gonorrhoeae is a major global health issue, with most ceftriaxone treatment failures linked to Asian strains, especially FC428-related strains. Since 2019, Nanchang City has participated in World Health Organization’s surveillance program, but local AMR assessments were lacking. This study aimed to examine the AMR profiles and molecular traits of N gonorrhoeae from Nanchang in 2021.

METHODS

We used antibiotic susceptibility testing and whole genome sequencing for AMR surveillance, genotyping, resistance gene identification, and evolutionary analysis.

RESULTS

In 2021, Nanchang reported resistance rates of 68.5% for penicillin, 81.5% for tetracycline, 100% for ciprofloxacin, 5.6% for azithromycin, 0% for spectinomycin, 13% for ceftriaxone and 20.4% for cefixime. Decreased susceptibility was 16.7% for ceftriaxone. Twelve strains exhibited cephalosporins MICs ≥ 0.125 mg/L, with single-nucleotide polymorphisms in genes like porB, tbpB, penA, mtrR, ponA, gyrA and parC being key contributors to different NG-MAST and NG-STAR genotypes. For MLST, the predominant genotypes were MLST-7365 (n = 5) and MLST-8123 (n = 2), with additional genotypes including MLST-1580, MLST-1903, MLST-7367, MLST-8126, and MLST-15278. Resistance markers like penA mosaic mutations, blaTEM-1, and blaTEM-135 plasmids were detected in cephalosporins and penicillin high-level resistant strains. Among above cephalosporins decreased-susceptible isolates, six strains with penA-60.001 mosaic mutation were found to be related to global FC428-related clones previously, particularly those originating from domestic strains.

CONCLUSIONS

The study highlights high AMR rates in N. gonorrhoeae in Nanchang, China, in 2021, particularly strains with decreased cephalosporin susceptibility, threatening their effectiveness as a first-line treatment, likely due to the spread of FC428 subclones.