The STI prevention vs antimicrobial resistance debate

UNSW masters students go head-to-head over evidence, equity and ethics in public health.

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A recent debate, published in Sexual Health last month, examined whether the health benefits of doxycycline post-exposure prophylaxis (Doxy-PEP) among gay, bisexual and other men who have sex with men (GBMSM) outweighed its potential to accelerate antimicrobial resistance (AMR).

Working with Associate Professor Bridget Haire, senior research fellow at the Kirby Institute, UNSW masters students outlined their arguments – Sam Templeman argued for the use of Doxy-PEP and Shreyas Iyer argued against.

The resurgence of syphilis is a global public health concern, particularly in Australia where notifications have more than tripled per 100,000 between 2012 and 2021, they explained.

They noted that disease burden is significantly higher among Aboriginal and Torres Strait Islander peoples than the non-Indigenous population, along with rising rates of congenital syphilis, but that these populations have been underrepresented in Doxy-PEP studies.

The risk of expanding antibiotic use has prompted some experts to advocate withholding doxycycline post-exposure prophylaxis until further research is done, they said.

So, let’s break down the arguments.

Yes to Doxy-PEP

1. While Doxy-PEP is effective against several bacterial STIs, its key value is preventing syphilis. Reducing disease burden, treatment costs, antibiotic use and rates of congenital syphilis are important public health measures. Syphilis is often missed and untreated infection can cause serious harm, making prevention critical.
2. While recent studies have found Doxy-PEP use may slightly increase tetracycline-resistant gonorrhoea, it is not used to treat gonorrhoea in Australia and resistance has not been observed for syphilis or chlamydia.
3. Trials show it’s highly effective in GBMSM, and modelling suggests that if 50% of GBMSM in Australia used an antibiotic prophylaxis that is 70% effective against syphilis, national notifications could drop by half within a year.
4. The extent of the risk AMR poses is uncertain and may not be clinically significant, so why should this outweigh the known benefits of syphilis prevention?
5. Withholding Doxy-PEP is placing the burden of AMR risk onto vulnerable populations when there are other ways to minimise AMR.

No to Doxy-PEP

1. AMR is a major global public health threat which is estimated to be associated with nearly 5 million deaths in 2019. Multiple studies have linked Doxy-PEP use to increases in resistance genes, raising concerns that its use could conflict with the principles of antibiotic stewardship.
2. There is emerging evidence that Doxy-PEP can fuel resistance in major pathogens like S. aureus and K. pneumoniae, two of the leading causes of AMR-related deaths worldwide. Doxycycline exposure may drive resistance to tetracyclines and key drugs like methicillin and cephalosporins, potentially limiting treatment for deadly infections – harms which could outweigh its short-term STI prevention benefits.
3. While withholding Doxy-PEP challenges patient autonomy, the rights of future patients reliant on effective antibiotics must be weighed. Under Rawls’ “Veil of Ignorance,” most would prioritise preserving antibiotic efficacy over individual choice, especially when alternative STI prevention methods are available.
4. Condoms remain a proven preventive option, though social and structural barriers limit use. As such, frequent testing and timely treatment, as outlined in national guidelines, remain the most viable alternative.
5. From a justice perspective, while GBMSM face higher STI risks, resistant S. aureus disproportionately affects vulnerable groups, including Aboriginal and Torres Strait Islander peoples. Broad Doxy-PEP use could worsen these health inequities by adding to their disease burden.

While Doxy-PEP has a clear public health goal and strong evidence of efficacy, concerns about accelerating AMR, particularly in pathogens of global concern, cannot be ignored.

Yet the uncertainty around these risks, alongside the goal of reducing health disparities and protecting vulnerable populations, suggests Doxy-PEP should be offered to GBMSM in Australia, with ongoing monitoring and parallel research in Aboriginal and Torres Strait Islander communities to guide equitable implementation.

Argument for: Sexual Health, 22 July 2025Argument against: Sexual Health, 22 July 2025