Antimicrobial resistance in Neisseria gonorrhoeae isolates at the Bangrak STIs Center, Bangkok, Thailand and WGS of antimicrobial-resistant isolates, 2018-23.

OBJECTIVES

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a global public health concern, particularly due to increasing resistance to the last remaining monotherapy, ceftriaxone, in several Asian countries. We examined the AMR of gonococcal isolates obtained at the Bangrak STIs Center, Bangkok, Thailand in 2018-23, and used WGS on isolates resistant to ceftriaxone, cefixime and/or azithromycin.

METHODS

Genital and extragenital swabs from males, females and transgender women were cultured. Etest (five antimicrobials) and EUCAST breakpoints (v16.0), or disc diffusion method (ciprofloxacin) were used to determine AMR. WGS was performed using Illumina NextSeq 550.

RESULTS

In 2018-23, 765 gonococcal isolates from 739 patients were cultured. Resistance to ceftriaxone, cefixime, azithromycin, tetracycline and ciprofloxacin was 0.5%, 0.8%, 1.7%, 83.7% and 95.7%, respectively. Ceftriaxone-resistant isolates, all resistant also to cefixime, were first detected in 2023 (n = 3, 1.2%). Additional cefixime-resistant isolates were found in 2022 (n = 2, 1.4%). Azithromycin-resistant isolates first emerged in 2020 (n = 1, 0.9%) and increased to nine (3.7%) isolates in 2023. All ceftriaxone-resistant isolates contained penA-60.001, but cefixime resistance was additionally caused by penA-34.019 and penA-10.001. All azithromycin-resistant isolates had 23S rRNA mutations and/or mosaic/semi-mosaic MtrD (subunit of the MtrCDE efflux pump).

CONCLUSIONS

Resistance to ceftriaxone, cefixime and azithromycin has emerged in gonococcal strains circulating in Bangkok, Thailand, and resistance appears to be increasing. Resistance to these last options for monotherapy or dual therapy emphasize the need for strengthened national culture-based and genomic surveillance to prevent the spread of MDR and XDR strains in Thailand and globally, and implementation of the novel oral treatments, i.e. zoliflodacin and gepotidacin.