Flashtalk 25th International Pathogenic Neisseria Conference 2026

Increased Neisseria gonorrhoeae antimicrobial resistance trends in Thailand and emergence of XDR isolates (#097)

Adriana Le Van 1 2 , Evan Greengraw 1 , Gilda Bocco 1 2 , Reuel Sandy 1 2 , Krit Harncharoenkul 3 , Anjali Sapre 4 , Melissa Martin 5 , Eric Garges 1 3 , Ann E Jerse 1
  1. Uniformed Services University, Bethesda, MARYLAND, United States
  2. Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc, Bethesda, MD, USA
  3. Walter Reed Army Institute of Research, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand., Bangkok, Thailand
  4. Multidrug Resistant Organism Repository and Surveillance Network, Walter Reed Army Institute of Research, Silver Spring, MD, USA
  5. Multidrug Resistant Organism Repository and Surveillance Network, Walter Reed Army Institute of Research, Silver Spring, MD, USA

Background: Neisseria gonorrhoeae (NG) infections are responsible for a high global disease burden and are the second most common reportable infection in the United States. This study analyzes trends in antibiotic resistance in recently collected NG isolates from Thailand and the genomic determinants as part of the U.S. Department of War Global Emerging Infections Surveillance Program (GEIS). 

Methods: Urogenital, rectal and pharyngeal samples (n = 340) were collected from subjects enrolled in clinical care or public health surveillance activities from FY2023 to FY2025 including military populations, civilians, and high-risk populations. Isolates were tested for susceptibility to seven different antibiotics using ETEST. Whole genome sequencing was performed to define the prevalence of specific antimicrobial resistance determinants in different geographic regions.

Results: Phenotypic AMR data for all 340 isolates showed multi-drug resistance was common amongst all study sites.  AMR data showed a shift in the number of isolates with resistance to the tetracycline, ciprofloxacin, azithromycin, ceftriaxone, cefixime and gentamicin with higher MIC levels in FY2025 compared to previous years. This observed increase was statistically significant as measured by Pearson chi2(4) = 22.0459.  Four isolates showed resistance to both extended spectrum cephalosporins. Two of these isolates were XDR displaying resistance to tetracycline, ciprofloxacin, cefixime, ceftriaxone and high-level resistance to azithromycin. They harbored mosaic penA allele 60.001 and the 23S RNA A2059G mutation.

Conclusion: NG isolates collected through the GEIS program displayed a high frequency of resistance to penicillin, tetracycline, and ciprofloxacin, and an increasing number of resistant isolates to current treatments such as cefixime and gentamicin. The four ceftriaxone resistant isolates are alarming; and may reflect the rapid emergence of ceftriaxone resistance reported in other south Asian countries. Continued surveillance of AMR NG is needed to identify genetic determinants of AMR and inform appropriate treatment recommendations.