STI Prophylaxis and Emergence of Antimicrobial Resistance

Recruiting

• Conditions: Sexually Transmitted Infection (STI) Prevention; Antibiotic Prophylaxis; Antibiotic Resistance, Bacterial; Microbiome; Doxycycline

• Registration Number: NCT06778083
• Lead Sponsor: University College, London

Brief Summary

The goal of this observational study is to understand the risk of antibiotic resistance and changes in the human microbiome (bacteria that live inside and on us), if people use antibiotics to prevent sexually transmitted infections (STI prophylaxis, doxycycline post-exposure prophylaxis, or 'doxyPEP'). The study will assess how easy and acceptable it is to find antibiotic resistance and microbiome changes in the throats and guts of men-who-have-sex-with-men (MSM) who use STI prophylaxis.

The study will recruit 108 MSM who are using and not using STI prophylaxis. Participants will visit the clinic every 6 months. At each visit, they will provide a throat swab and stool sample, and complete a questionnaire. DNA of the bacteria from the samples will be analysed to identify the bacteria and look for antibiotic resistance.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2025-01-10
• Study First Submitted QC: 2025-01-10
• Study Start: 2025-02-10
• Status Verified: 2025-03
• Study First Posted: 2025-03-25
• Last Update Submitted: 2025-03-26
• Last Update Posted: 2025-03-27
• Primary Completion: 2027-04-30
• Study Completion: 2027-04-30

Recruitment & Eligibility

• Status: RECRUITING
• Sex: Male
• Target Recruitment: 108

Inclusion Criteria

• Aged ≥ 18 years.
• Identifies as a man (cis or trans).
• Has sex with men.
• Able to provide informed consent.

Exclusion Criteria

• Use of an antibiotic other than doxycycline in the 3 months prior to enrolment
• Currently being treated for an STI with doxycycline
• Use of doxycycline within the prior 3 months for an indication other than STI treatment or STI prevention.

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Detection of antimicrobial resistance genes of interest and characterisation of microbiome	From enrolment to 12 months	The successful detection of antimicrobial resistance genes of interest (tetracycline and other antibiotic classes) and identification of bacterial species (microbiome) and in the oropharynx and gastrointestinal tract.

Secondary Outcome Measures

Name	Time	Method
Detection of differences in prevalence of antimicrobial resistance genes of interest between people using and not using antibiotic STI prophylaxis.	From enrolment to 12 months
Detection of differences in microbiome between people using and not using antibiotic STI prophylaxis.	From enrolment to 12 months
Change over time in prevalence of antimicrobial resistance genes of interest between people using and not using antibiotic STI prophylaxis.	From enrolment to 12 months
Change over time in microbiome between people using and not using antibiotic STI prophylaxis.	From enrolment to 12 months

Trial Locations

Locations (1)

Central and North West London NHS Foundation Trust; 🇬🇧 London, United Kingdom