Abstract
BACKGROUND: The global dissemination of ceftriaxone-resistant Neisseria gonorrhoeae, primarily associated with mosaic penA alleles, threatens the efficacy of ceftriaxone therapy. While the FC428 clone and its associated penA allele 60.001 are well-documented, data on other emerging resistance-conferring alleles in high-burden regions remain limited. This study characterizes the penA alleles associated with ceftriaxone resistance in Cambodia, China, and Vietnam. METHODS: Publicly available and novel genomes of N. gonorrhoeae isolates from Cambodia, China, and Vietnam with decreased ceftriaxone susceptibility (minimum inhibitory concentration [MIC] ≥ 0.125 mg/L) were analyzed. Multi-locus sequence types and penA alleles were assigned using PubMLST and BIGSdb and a core-genome neighbor-joining phylogenetic tree was constructed. To address selection bias, all isolates with reduced susceptibility from Hangzhou, China (2015-2022), were also analyzed for penA alleles using the NG-STAR method. RESULTS: Analysis of 236 genomes revealed that ceftriaxone resistance (MIC > 0.125 mg/L) was predominantly associated with penA alleles 60.001 (n = 145) and 237.001 (n = 70), which formed 2 major phylogenetic clades. All resistance-conferring alleles contained the A311 V polymorphism. PenA 60.001 was linked to multiple sequence types (STs), including FC428-associated ST1903 and endemic STs like ST8123 and ST8130. PenA 237.001 was almost exclusively found in Vietnam, primarily in ST1901. Analysis of the unbiased Hangzhou dataset (n = 132) confirmed that high-level resistance (MIC = 0.5-1 mg/L) was exclusively linked to penA 60.001. CONCLUSIONS: Ceftriaxone resistance in the Asia Pacific region is primarily driven by penA 60.001 and 237.001 along with related alleles harboring the A311 V polymorphism. The concerning acquisition of these alleles by successful endemic lineages enhances their potential for local and international spread.