Early Release – Emergence of Ceftriaxone-Resistant Neisseria gonorrhoeae penA-60–Carrying Strains, Thailand, 2025 – Volume 32, Number 6—June 2026 – Emerging Infectious Diseases journal

During January–April 2025, we identified 5 ceftriaxone-resistant gonococcal isolates among 272 isolates collected through the National Gonococcal Antimicrobial Resistance program in Thailand. The 5 isolates had been obtained from 5 male patients, 16–55 years of age, who sought care for dysuria at STI clinics in Thailand’s eastern region (4 patients in Pattaya, Chonburi Province) and southern region (1 patient in Phuket Province) of Thailand. Our case investigations were conducted by authorized public health officers according to the Communicable Disease Act in Thailand. Case identification information was confidential.

Figure 2

Figure 2. Number of Neisseria gonorrhoeaebacteria isolates examined and percentages of isolates with resistance to azithromycin, cefixime, and ceftriaxone in national surveillance system (National Gonococcal Antimicrobial Resistance program and World…

The patients were from Thailand (n = 3), Russia (n = 1), and China (n = 1) (Table 1). All 5 patients were men who have sex with women, and 4 of them reported recent sexual contact with a casual partner, including a 1-night-stand partner and a female sex worker. Four patients reported self-treatment with oral antimicrobial drugs (mostly azithromycin 1 g) obtained from pharmacies in Pattaya Province before any visit to an STI clinic; however, because of persisting symptoms, they all subsequently visited an STI clinic. Gram-stained microscopic examination of urethral discharge from all 5 patients revealed gram-negative intracellular diplococci, and culture on modified Thayer-Martin medium confirmed the presence of gonococci. On the basis of European Committee on Antimicrobial Susceptibility Testing resistance breakpoints (10), we determined that all 5 gonococcal isolates were resistant to ceftriaxone (MIC >0.125 μg/mL) and cefixime (MIC >0.125 μg/mL), and 3 isolates showed high-level resistance to azithromycin (Table 1). Three of the 5 isolates also were nonsusceptible to ceftriaxone based on the Clinical Laboratory and Standards Institute clinical breakpoint (MIC >0.5 μg/mL) (11) (Table 2; Figure 2). All 5 isolates contained the penA-60 allele, which is associated with ceftriaxone resistance in N. gonorrhoeae bacteria (2–7,12,13).

On the same day results of the gram-stained microscopic examination of urethral discharge were available, all 5 patients were treated with intramuscular ceftriaxone (1 g) (n = 1) or intramuscular ceftriaxone (1 g) plus oral azithromycin (1 g) or a 7-day regimen of oral doxycycline (n = 4) in accordance with current gonorrhea management guidelines in Thailand (14). All 3 Thailand patients returned for test-of-cure 1–2 weeks after treatment; results of culture and the Xpert CT/NG assay (Cepheid, https://www.cepheid.com) from urethral and oropharyngeal sites were negative, and all 5 patients were asymptomatic. The 2 patients of foreign nationality did not return for test-of-cure. Only the first Thailand case-patient, who had a regular female partner, could bring his sexual partner to the STI clinic for examination and treatment. An Xpert CT/NG assay of pooled cervical and oropharyngeal specimens detected N. gonorrhoeae bacteria, whereas cervical and oropharyngeal cultures were negative. The woman was treated with intramuscular ceftriaxone (1 g) but did not return for test-of-cure.

Increasing clinicians’ awareness of ceftriaxone-resistance is essential. Ceftriaxone is the last remaining gonorrhea treatment option and has acquired high levels of resistance in several countries in Asia, especially Cambodia, China, and Vietnam (2,3,9,12,13). Data from the National Gonococcal Antimicrobial Resistance program and EGASP in Thailand for 2015–2023 have shown that antimicrobial-resistant N. gonorrhoeae also is an emerging major concern in Thailand, particularly resistance to oral antimicrobial drugs such as ciprofloxacin (which exhibits >90% resistance), azithromycin, and (since 2017) cefixime, all of which are commonly available without a prescription at pharmacies in Thailand. However, before 2025, only 2 ceftriaxone-resistant gonococcal isolates had been confirmed in national surveillance of gonococcal antimicrobial resistance (6,8,9).

We report 5 ceftriaxone-resistant isolates detected during January–April 2025 in Thailand. Most of the patients with ceftriaxone-resistant gonorrhea were initially self-treating with antimicrobial drugs instead of seeking care at STI clinics, and their sexual encounters involved 1-night stand partners and female sex workers, behaviors that are associated with further rapid transmission of the ceftriaxone-resistant gonococcal strains and substantial health risks and can complicate sexual contact tracing efforts. In Thailand, STIs have also become 1 of the top 5 conditions for which persons seek treatment at pharmacies (15), and the resulting widespread use of oral antimicrobial drugs probably has contributed to the increase in gonococcal antimicrobial resistance. Of note, we detected 3 additional ceftriaxone-resistant isolates during October–December 2025, which are undergoing further investigation.

One limitation of our study is the lack of whole-genome sequencing of all the ceftriaxone-resistant isolates. However, we plan to conduct whole-genome sequencing in 2026.

The emergence of ceftriaxone-resistant gonorrhea cases in Thailand poses a serious public health challenge, and treatment of all gonorrhea cases with ceftriaxone, consistent with the updated gonorrhea management guidelines in Thailand, is critical (14). The increasing practice of self-treatment by purchase of antimicrobial drugs without a prescription at pharmacies (15), often resulting in inappropriate and failing treatment and further driving antimicrobial resistance, is a major concern.

The spread of ceftriaxone-resistant gonococcal strains in Thailand and other countries in Asia (2,3,9,12,13) underscores the urgent need to promote safer sex practices and ensure access to professional medical care (diagnostics, treatment, and follow-up of patients and sexual contacts). In a promising development, novel drugs such as zoliflodacin and gepotidacin have been approved by the US Food and Drug Administration (2,3). However, encouraging responsible antimicrobial use and stewardship remains critical to protect health. Among the cases we describe, the 2 foreign male patients with ceftriaxone-resistant gonorrhea, who were subsequently lost to follow-up, underscore major gaps in continuity of care and highlight the urgent need to strengthen global gonococcal antimicrobial resistance surveillance and enhance coordinated international efforts to address gonococcal antimicrobial resistance.