Australian Gonococcal Surveillance Programme Annual Report, 2025

Abstract

The Australian Gonococcal Surveillance Programme (AGSP) has continuously monitored antimicrobial resistance in Neisseria gonorrhoeae (NG) for more than 45 years through the system of jurisdictional Neisseria reference laboratories, the National Neisseria Network (NNN). In 2025, a total of 10,204 isolates across Australia, from public and private sectors, were tested for in vitro antimicrobial susceptibility by standardised methods. In 2025, the AGSP captured antimicrobial susceptibility data for 23.9% of all gonococcal infection notifications nationally. The current treatment recommendation for gonorrhoea, for the majority of Australia, continues to be dual therapy with ceftriaxone and azithromycin.

In 2025, of NG isolates tested, 0.73% (74/10,204) met the World Health Organization (WHO) criterion for decreased susceptibility (DS) to ceftriaxone, defined as a minimum inhibitory concentration (MIC) ≥ 0.125 mg/L. This proportion of isolates meeting the ceftriaxone DS criterion was greater than that reported in 2024 (0.51%), with the majority from New South Wales and Victoria. Genomic analysis indicated that 64.9% of these isolates (48/74) possessed the mosaic penA 60.001 allele, the key target associated with ceftriaxone resistance.

Resistance to azithromycin was reported in 7.1% of NG isolates nationally, increasing from being proportionally stable (3.9% to 4.7%) since 2019. Of NG isolates tested, 0.20% (20/10,204) exhibited high-level resistance to azithromycin (MIC value ≥ 256 mg/L), with cases reported across Australia, predominantly in New South Wales, Victoria and non-remote Western Australia.

There were ten isolates detected in 2025 that had an extensively drug-resistant (XDR) phenotype: i.e., displaying both high-level resistance to azithromycin and decreased susceptibility to ceftriaxone (MIC ≥ 0.125 mg/L). When added to the 14 XDR isolates reported during 2022–2024, this brings the total to 24 XDR NG isolates reported in Australia since 2022. Genomic analyses of the ten XDR isolates reported in 2025 indicated all harboured the mosaic penA 60.001 allele, with several differing sequence types (ST) identified. By contrast, during 2022 and 2024, XDR NG sequence types were limited to ST-16406, consistent with reports from Europe and England. Travel information, where available, indicates infections in 2025 were associated with travel to Southeast Asia but also arose where no travel was involved.

In 2025, penicillin resistance was found in 23.4% of gonococcal isolates, and ciprofloxacin resistance in 59.3% of isolates where tested, although there was variation by jurisdiction particularly in remote settings, where acquisition of cultures for antimicrobial susceptibility testing is low.

Tetracycline resistance has been included in surveillance in the AGSP in recent years, coincident with increasing use of doxycycline post-exposure prophylaxis for syphilis and chlamydia. Nationally 36.2% of NG isolates in 2025 were tetracycline resistant, with variation by jurisdiction. No isolates were resistant to spectinomycin; data for gentamicin, whilst no breakpoints are defined, are reported by the AGSP as these data are reportable to the WHO Global Antimicrobial Resistance and Use Surveillance System (GLASS). The emergence of antimicrobial resistant NG in Australia has largely occurred through importation, spread and local transmission. In 2025, in Australia and overseas, increased detection of drug-resistant NG isolates is of significant concern as the threat for the future of the current recommended therapeutic agents is increasingly evident, and no ideal alternate therapeutic agent has been identified. Disease prevention strategies under investigation for the future have included the MenB-4C vaccine, designed to protect against meningococcal disease. Despite early promise, recent results from a large Australian trial indicate the MenB-4C vaccine is not effective at preventing gonorrhoea in men who are at high risk of infection. The AGSP continues to monitor antimicrobial resistance and to identify emerging resistant clones by enhanced surveillance approaches, to inform strategies for disease management and treatment of gonorrhoea in Australia.