Background: Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is an urgent global health issue. The prevalence of AMR is highest in the Western Pacific Region. Patients in HIV pre-exposure prophylaxis (PrEP) programs have higher rates of N. gonorrhoeae infections and AMR. Our study investigated AMR in N. gonorrhoeae among participants in an HIV PrEP program in Hanoi, Vietnam.
Methods: Starting in January 2022, patients in the HIV PrEP program at Hanoi Medical University were enrolled into the study. Swabs for N. gonorrhoeae culture were collected from those with signs or symptoms of infection and those found to have N. gonorrhoeae infection by nucleic-acid amplification testing (NAAT). Culture was performed on Modified Thayer-Martin media. Antibiotic susceptibility testing (AST) was done using Etests (BioMerieux) and minimum inhibitory concentrations (MICs) were interpreted by Clinical and Laboratory Standards Institute breakpoints. Whole genome sequencing (WGS) was performed on extracted DNA using MiSeq (Illumina). Genomic analysis was performed using PathogenWatch.
Results: In total, 17 N. gonorrhoeae isolates were cultured from 16 male participants. There were 7 urethral, 6 rectal, and 4 pharyngeal isolates. Two isolates (11.7%) were non-susceptible to azithromycin. Two isolates (11.7%) were non-susceptible to both cefixime (MIC=1.5 ug/mL) and ceftriaxone (MIC=0.38 ug/mL). The ceftriaxone non-susceptible isolates were both rectal isolates identified in November and December 2022. One patient reported rectal symptoms of discharge and diarrhea while the other was asymptomatic. Both patients received ceftriaxone 500mg intramuscularly; neither presented for test-of-cure, but both had negative NAATs 3 months after their initial infections. Genomic analysis of the two ceftriaxone non-susceptible isolates show they belonged to MLST 13871, a sub-clone of FC428, containing the mosaic penA-60 allele with A311V, G545S, I312M, and T483S penA mutations.
Conclusions: Routine culturing for N. gonorrhoeae within a PrEP program in Vietnam identified two ceftriaxone non-susceptible isolates containing the penA-60 allele. The penA-60 allele is emerging as an allele of international concern and associated with reports of treatment failure in Europe, typically associated with travel to Asia. Integrating N. gonorrhoeae culture, AST and WGS in HIV PrEP programs can improve AMR surveillance, particularly in regions with a high prevalence of AMR.
