This study examined temporal trends in antimicrobial resistance in Neisseria gonorrhoeae isolates collected from men who have sex with men (MSM) attending a single sexual health service over a 10-year period (2015–2024). The analysis focused on commonly used agents for gonorrhea management and considered implications for doxycycline post-exposure prophylaxis (doxyPEP).
All MSM with an N. gonorrhoeae isolate at Melbourne Sexual Health Centre (MSHC) between 2015 and 2024 were included in the analysis. The dataset comprised 11,334 isolates obtained from 6,611 individual MSM. The cohort encompassed persons with varying HIV and pre-exposure prophylaxis (PrEP) status; the investigators performed stratified analyses by HIV and PrEP, though specific stratified outcome details were not presented in the excerpt provided.
Resistance was defined using the 2025 EUCAST breakpoints and epidemiological cutoff values. The authors identified acquired resistance mechanisms for azithromycin and applied standard breakpoints to classify resistance for ciprofloxacin, tetracycline, and ceftriaxone. The exact laboratory methods for susceptibility testing (for example, culture conditions, MIC methods, or molecular assays) were referenced in the full article but are not detailed in the provided abstract.
Temporal trends were evaluated with the Cochran-Armitage test for trend. The comparison of tetracycline resistance between doxyPEP users and non-users was performed using the chi-square test. Other specific statistical model details, adjustment for confounders, or subgroup statistical approaches were not reported in the available excerpt.
A total of 11,334 isolates from 6,611 MSM were analyzed across the 2015–2024 period.
Ceftriaxone resistance was very uncommon: 3 of 11,334 isolates (0.03%). This indicates continued low prevalence of ceftriaxone resistance in this service population during the study interval.
The proportion of isolates with acquired azithromycin resistance mechanisms increased over time, from 0.9% (8 of 940 isolates) in 2015 to 6.4% (102 of 1,584 isolates) in 2024. The trend was statistically significant (P trend < 0.001). The 6.4% level in 2024 exceeds the World Health Organization’s 5% threshold at which an antimicrobial is considered no longer appropriate for empirical treatment.
Ciprofloxacin resistance rose substantially during the observation period. Reported values increased from 18.5% (170 of 920 isolates) in 2015 to 55.2% (875 of 1,584 isolates) in 2024. The abstract truncates at this point and does not present further numerical context, confidence intervals, or P values for this increase in the excerpt supplied.
The authors specifically assessed tetracycline resistance in relation to reported doxyPEP use, comparing resistance proportions between doxyPEP users and non-users using chi-square testing. The provided abstract does not include the observed tetracycline resistance frequencies, the number of doxyPEP users versus non-users, or the statistical comparison results. Therefore, the outcome of that comparison and its statistical significance are not available in the excerpt.
Within the limits of the abstract, the study identifies rising resistance to azithromycin and ciprofloxacin among MSM isolates over a decade, while ceftriaxone resistance remained rare. The increase in acquired azithromycin resistance to above 5% in 2024 has direct relevance for empirical treatment choices, given WHO guidance to avoid empirical use of antimicrobials when resistance exceeds that threshold.
The study’s planned comparison of tetracycline resistance according to doxyPEP use addresses an important clinical and public health question: whether doxycycline post-exposure prophylaxis is associated with increased tetracycline resistance in circulating N. gonorrhoeae strains. However, the abstract provided here does not include those results, so no source-supported conclusion about doxyPEP’s impact on tetracycline resistance can be drawn from this excerpt.
Note: all data and statements above are drawn from the provided PubMed/NCBI abstract. Details not present in that excerpt are explicitly reported as not available in the source.