PhD Defence: István Szondy (New Frontiers in the Prevention of Sexually Transmitted Infections)

Sexually transmitted infections (STIs) remain a major global public health challenge, with rising incidence and increasing antimicrobial resistance threatening current prevention and treatment strategies. In this PhD defence, István Szondy, medical doctor and PhD candidate in dermatology at Semmelweis University’s Centre for Translational Medicine, presents two complementary, evidence-based approaches aimed at preventing bacterial STIs in high-risk populations.

1) Doxycycline prophylaxis for STI prevention (DoxyPEP / DoxyPREP)
Through a systematic review and meta-analysis of randomized controlled trials, this project evaluates the effectiveness and safety of doxycycline used as post-exposure (DoxyPEP) or pre-exposure prophylaxis (DoxyPREP).
The analysis demonstrates a clinically meaningful reduction in bacterial STI incidence, particularly for chlamydia and syphilis, among men who have sex with men and transgender women—groups disproportionately affected by these infections. High adherence rates and few serious adverse events were observed, while antimicrobial resistance remains a key issue requiring ongoing surveillance.

2) Meningococcal vaccines and cross-protection against gonorrhea
The second project investigates whether outer membrane vesicle (OMV)–containing meningococcal vaccines can provide cross-protection against Neisseria gonorrhoeae. Based on a systematic review and meta-analysis of large cohorts, the findings show moderate but significant vaccine effectiveness against gonorrhea, with improved protection following full vaccination schedules.

Taken together, these studies suggest that combining doxycycline post-exposure prophylaxis with OMV meningococcal vaccination may offer a powerful, complementary strategy for STI prevention in the highest-risk groups—while emphasizing the importance of careful patient selection, shared decision-making, and antimicrobial stewardship.

This defence highlights how translational research can directly inform clinical guidelines, public health strategies, and everyday dermatological practice.