^{Florent Jouinot from Swiss AIDS Federation reports on AFRAVIH 2026 in Lausanne.}

The “test and treat” approach reaches its limits

STI screening is based on three key objectives: reducing prevalence, lowering transmission rates and preventing complications. However, for asymptomatic gonorrhoea and chlamydia among men who have sex with men (MSM), these benefits have not been demonstrated.

As Thibaut Vanbaelen pointed out, the natural history of these infections is often more complex than one might imagine. Following exposure, infection does not occur systematically. When it does occur, it often remains asymptomatic, then resolves spontaneously in a significant proportion of cases, usually within a few weeks.

However, observational studies, randomised trials, ecological studies and mathematical models all point to the same conclusion: regular screening for asymptomatic gonorrhoea and chlamydia among MSM reduces neither their prevalence nor their incidence. On the other hand, it mechanically increases the number of diagnoses and therefore the use of antibiotics.

In other words: we detect more, we treat more, but we do not control the epidemic any better.

The hidden cost: antimicrobial resistance

This situation would already be problematic were it not for a major collective cost: antibiotic resistance.

MSM on PrEP are now among the groups receiving the highest number of prescriptions for certain antibiotics, notably macrolides, fluoroquinolones, third-generation cephalosporins and tetracyclines. A significant proportion of these treatments are for asymptomatic infections detected during routine screening in the absence of symptoms.

The problem is not merely individual. Antibiotic treatment does not in itself “create” resistance, but it alters the bacterial ecosystem, eliminates susceptible bacteria and promotes the selection and establishment of microorganisms that are already resistant.

The expected risks of routine screening are therefore already apparent: resistance is rising rapidly, and MSM are among the first to be affected.

When resistance itself becomes sexually transmissible

Laure Surgers’ presentation broadened the scope further. STIs are no longer limited to infections historically classified as such. Enteric, cutaneous or environmental bacteria can also be transmitted during sexual intercourse, particularly within certain MSM networks.

This is the case with ESBL-producing Enterobacteriaceae, which are capable of resisting numerous antibiotics. Their sexual transmission is now well documented, with particularly high prevalence rates among MSM (10%), even higher among MSM on PrEP (16%) and especially among those engaging in chemsex (24%).

Certain multi-drug-resistant bacterial strains appear to circulate specifically within these sexual networks. They establish themselves in the gut microbiota, sometimes for the long term, and can subsequently cause infections that are difficult to treat.

The issue therefore goes beyond gonorrhoea or chlamydia. Repeated antibiotic treatments for these asymptomatic STIs may contribute to a broader transformation of the bacterial ecology of the most at-risk communities and, by extension, the entire population.

Sexual health must include the microbiota

This shift in perspective is significant. The effects of repeated treatments do not concern only the resistance of the targeted pathogen. They can also affect other microorganisms, particularly enteric ones, and alter the microbiota.

These impacts remain poorly understood. But they call for a more comprehensive approach to infections transmitted through sexual contact.

The question is no longer simply: “Should we screen for and/or treat this infection?”

It becomes: “What is the real benefit of this screening and/or treatment, for the individual, for their community and for public health, given the potential individual and collective effects?”

This is a major shift for prevention.

Not all STIs are the same

The speakers, however, emphasised a key point: this does not mean abandoning STI screening.

HIV and syphilis remain clear examples where regular screening of at-risk groups, particularly MSM, continues to have proven value. In the event of a diagnosis, treatment must be systematic, as rapid and as effective as possible.

For Mycoplasma genitalium, by contrast, asymptomatic screening is of no benefit and may promote resistance that is difficult to manage.

For asymptomatic gonorrhoea and chlamydia, the debate is now open, particularly among cisgender MSM, especially those regularly monitored for preventive or therapeutic HIV treatment. The available data suggest that reducing asymptomatic screening could decrease antibiotic use without increasing the prevalence and incidence of symptomatic cases.

The case of Togo: caution and contextualisation

The ANRS-12400/DepIST-H cohort study conducted among MSM in Lomé, however, serves as a reminder that strategies must remain context-specific. The incidence of anal chlamydia and gonococcal infections is high there, in a context where access to PrEP, regular follow-up and appropriate services remains more limited.

The presentation also highlights specific challenges: participant mobility, loss to follow-up, low actual uptake of PrEP despite its availability, and the need for new prevention strategies.

Post-exposure doxycycline appears to be a promising avenue, but its implementation in an African context requires rigorous evaluation, particularly in light of resistance concerns.

This point is central: European debates on scaling back asymptomatic screening cannot be mechanically applied everywhere. But everywhere, the use of antibiotics must be approached with caution.

What lessons for Switzerland?

For Switzerland, these presentations call for a re-examination of screening practices in sexual health services, PrEP follow-up consultations and care for people living with HIV, as well as community-based services.

The aim is not to provide less care, but to provide better care.

This involves:

distinguishing between symptomatic and asymptomatic infections;

• maintaining regular screening for HIV and syphilis;
• avoiding unnecessary testing, particularly for Mycoplasma genitalium;
• reviewing the frequency and locations of gonorrhoea/chlamydia testing among asymptomatic MSM;
• integrating gut microbiota health and enteric infections into sexual health;
• integrating the prevention of antibiotic resistance into sexual health;
• informing those affected without making them feel guilty.

For Swiss AIDS Aid, the issue is also a community one: supporting these changes without giving the impression that prevention is being scaled back. The discussion must be transparent: 

it is not a question of saving money by reducing testing, but of reducing unnecessary treatments and safeguarding the future effectiveness of antibiotics.

Moving from a reflexive approach to a reasoned one

The message from these sessions is clear: “test and treat” must not become an automatic response applied indiscriminately to all infections and all situations.

For HIV and syphilis, screening and treatment save lives and prevent transmission. For certain asymptomatic bacterial STIs, the individual and collective benefits are much less clear, whilst the risks associated with resistance are becoming increasingly real.

Sexual health is thus entering a new phase: one of more refined, nuanced prevention, capable of taking into account not only visible infections, but also microbial ecosystems, resistance and the long-term consequences of the strategies implemented.

Treating better does not always mean treating more.