DoxyPEP to Zoliflodacin: Recent STI Advances for SCE

Sexual health is in the middle of its most exciting period of change in decades. After years of relying on the same antibiotics and the same prevention messages, the field now has a genuinely new prevention tool (doxyPEP), two first-in-class oral treatments for gonorrhoea in the pipeline or approved, and early signs that a vaccine against gonorrhoea may be possible. For SCE candidates in sexual health and genitourinary medicine, this is exactly the territory examiners love: recent, guideline-shifting, and clinically nuanced. This guide brings you up to date with what you actually need to know.

Why This Topic Matters for the SCE

The Specialty Certificate Examination does not just test recall of guidelines — it tests whether you can apply current evidence to real clinical dilemmas. Recent advances in STI prevention and management hit that sweet spot because they combine:

• Antimicrobial resistance (AMR) — a core theme across the SCE

• Novel drug classes with new mechanisms examiners find attractive

• Shared decision-making — who qualifies for doxyPEP and who does not

• Population-specific evidence — a lesson in not extrapolating trial results

The Backdrop: Rising STIs and the AMR Crisis

Before diving into the advances, remember the context that makes them necessary:

• The WHO estimates approximately 1 million curable STIs (chlamydia, gonorrhoea, syphilis, trichomoniasis) are acquired every day worldwide.

• Diagnoses of gonorrhoea and infectious syphilis have risen sharply in the UK over the last decade, with gonorrhoea diagnoses reaching record levels in recent years.

• Neisseria gonorrhoeae has developed resistance to nearly every class of antibiotic used against it — penicillins, tetracyclines, fluoroquinolones, macrolides — and is a WHO priority pathogen. Ceftriaxone is effectively the last available first-line agent, with extended-spectrum cephalosporin resistance and treatment failures now reported internationally.

Exam pearl: Know that current first-line treatment for uncomplicated anogenital gonorrhoea in UK and US guidelines is ceftriaxone 1 g IM as monotherapy — azithromycin has been dropped due to macrolide resistance. UK guidance now also recommends test of cure with NAAT around 2 weeks after treatment.

DoxyPEP: Post-Exposure Prophylaxis for Bacterial STIs

What It Is

DoxyPEP = a single 200 mg dose of doxycycline taken within 72 hours (ideally within 24 hours) of condomless sex, with no more than one dose per 24 hours.

The Evidence

Guideline Positions

• CDC (2025 STI Treatment Guidelines) now include doxyPEP as a prevention option for cisgender men and transgender women with a history of bacterial STIs, particularly those living with HIV or taking PrEP, using shared decision-making.

• UK (UKHSA/BASHH) remains more cautious: UK bodies have reviewed the evidence and highlighted ongoing uncertainty about antimicrobial resistance selection and the lack of efficacy in cisgender women. Routine commissioning has not followed the US.

The SCE-Level Nuance: The Resistance Debate

This is where high-scoring candidates separate themselves. Concerns include:

• Selection of tetracycline resistance in N. gonorrhoeae and commensal Neisseria species (which can pass resistance genes to gonococci)

• Changes in nasal S. aureus carriage and potential selection of resistant E. coli

• The French trial's failure against gonorrhoea is a real-world illustration of the resistance problem

• Balancing individual benefit (genuine reductions in syphilis and chlamydia) against population-level antimicrobial stewardship — a classic SCE ethics-of-public-health tension

Practical Counselling Points (Consultation Gold)

• Explain that protection is strongest for chlamydia and syphilis; gonorrhoea protection is inconsistent

• Side effects: GI upset, photosensitivity, pill oesophagitis (take upright with water)

• It is an addition to, not a replacement for, condoms, vaccination (Hep A/B, HPV), HIV PrEP and regular testing

• Evidence does not currently support use in cisgender women

• DoxyPrEP (scheduled pre-exposure dosing) remains under investigation — know the term, don't oversell the evidence

New Drugs for Gonorrhoea: The Oral Revolution

Gepotidacin (Blujepa)

• First-in-class triazaacenaphthylene antibiotic — a novel topoisomerase type II inhibitor (bacterial DNA replication target)

• FDA-approved in 2025 for uncomplicated urogenital gonorrhoea in patients aged 12 years and over — one of the first genuinely new anti-gonococcal agents in decades

• The EAGLE-1 phase 3 trial showed oral gepotidacin was non-inferior to ceftriaxone plus azithromycin for urogenital infection

• Post-marketing surveillance continues, including monitoring of hypersensitivity reactions — a reminder that approval is the start, not the end, of the safety story

Zoliflodacin

• A spiropyrimidinetrione with a novel mechanism of action (also targeting DNA gyrase/topoisomerase)

• Single-dose oral therapy, developed with the Global Antibiotic R&D Partnership (GARDP) specifically to address AMR and improve global access

• Phase 3 results (reported 2023): roughly 90% microbiological cure at urogenital sites, non-inferior to ceftriaxone-based therapy — but lower cure rates at pharyngeal and rectal sites (approximately 70–80%)

Exam pearl: Both agents are oral, single-dose, first-in-class compounds developed explicitly in response to cephalosporin resistance. If an SCE question asks which new oral agents address AMR in gonorrhoea, these are your answers. Remember the site-of-infection caveat — pharyngeal gonorrhoea remains the hardest to treat.

A Gonorrhoea Vaccine? The 4CMenB Story

One of the most surprising recent developments in sexual health:

• Observational data from New Zealand (the MeNZB vaccine) suggested roughly 30% effectiveness against gonorrhoea — the first human evidence that vaccination against gonorrhoea is even possible

• Australian data (South Australia programme using 4CMenB/Bexsero) supported a similar ~one-third reduction

• Randomised trial data (e.g., the Australian STRIVE study in men who have sex with men) have been emerging but have not yet delivered a definitive signal

• WHO has acknowledged that the potential benefits of off-label use may outweigh risks in high-burden settings, but no routine gonorrhoea vaccination programme exists yet

• Meanwhile, dedicated gonococcal vaccine candidates (protein-based and mRNA platforms) are in early-phase trials, alongside early work on chlamydia and syphilis vaccines

Exam pearl: Even partial (~30%) vaccine effectiveness matters at population scale for gonorrhoea — because of the huge burden, reinfection and ongoing transmission. This is the concept of vaccines as public health tools even when individual protection is modest.

Putting It Together: The Prevention Toolkit for 2025

Modern sexual health consultations now combine:

1. HIV prevention: condoms, oral PrEP (emtricitabine/tenofovir), long-acting injectable cabotegravir PrEP, and treatment-as-prevention (U=U)

2. Vaccination: hepatitis A and B, HPV, and potentially 4CMenB in the future

3. Biomedical STI prophylaxis: doxyPEP (selected populations)

4. Routine testing: three-site NAAT testing, syphilis serology — with retesting intervals of ~3 months in high-risk groups

5. Partner notification and rapid re-treatment pathways

6. New therapeutics: ceftriaxone monotherapy now, gepotidacin/zoliflodacin next

High-Yield SCE Summary Table

How the SCE Might Test This

Expect question stems built around application, not recall:

• A man on PrEP with three episodes of rectal chlamydia in a year asks what else he can do — is doxyPEP appropriate, and what must you counsel him about?

• A patient treated for pharyngeal gonorrhoea with ceftriaxone asks about new oral options — what are gepotidacin and zoliflodacin, and why do pharyngeal cure rates matter?

• A public health vignette on rising tetracycline-resistant gonorrhoea — what are the stewardship arguments for and against population doxyPEP?

• An immunisation question linking meningococcal B vaccination with gonorrhoea incidence — what is the biological rationale and the evidence quality?

The candidates who score well will demonstrate three things: knowledge of the evidence, awareness of its limitations, and the judgement to apply it population-by-population.

Conclusion

From doxyPEP to zoliflodacin to vaccine possibility, sexual health is finally innovating at the pace the AMR crisis demands. For your SCE, treat this as a model topic: it tests evidence appraisal, guideline awareness, prescribing safety and consultation skills all at once. Learn the trials, respect their limitations, and practise articulating the uncertainties — because that is precisely what consultant-level sexual health practice, and the SCE, actually reward.

Keep checking current UKHSA, BASHH and CDC updates before your exam date — this is one area where the guidance genuinely moves.