Project Summary
We are conducting a study on the impact of using an antibiotic called doxycycline to prevent sexually transmitted infections (STIs), known as STI prophylaxis or ‘DoxyPEP’. The study will investigate antibiotic resistance and the impact on normal bacteria (the microbiome) in the gut and throat of gay, bisexual, and other men who have sex with men. This will help us explain to people using or thinking about using DoxyPEP what the possible risks and benefits are, and help us develop the tools to monitor antibiotic resistance.
Who can take part?
- We are inviting gay, bisexual, and other men who have sex with men, over the age of 18 to take part, who:
- have used DoxyPEP in the last 3 months
- or been treated for an STI with doxycycline in the last 3 months
- or not had any antibiotics in the last 3 months
If you have had any other antibiotics in the last 3 months, you cannot take part in the study. Once those 3 months have passed, you may become eligible again.
What does the study involve?
We are aiming to recruit 108 GBMSM in total. Participants will attend 3 study visits over 12 months. Participants will receive a £30 voucher for each study visit. At each visit, participants will complete a 15-minute questionnaire, have a throat swab taken, and provide a stool (poo) sample. Bacterial DNA in the samples will be analysed to identify the bacteria and look for antibiotic resistance.
How do I take part?
If you are interested in taking part in SPEAR and think you might be eligible, please read the Participant Information Sheet (PIS) below, and email cnwl.spear@nhs.net.
Key Project Information
Dates: February 2025 - April 2027
Principal Investigator: Dr Manik Kohli
Partners: University of Oxford, Central and North West London NHS Foundation Trust, The Love Tank CIC
Location: UK
Funding: National Institute for Health and Care Research (NIHR), British HIV Association (BHIVA), British Infection Association (BIA)
Contact: cnwl.spear@nhs.net

Participant Information
If you are interested in taking part, please read our participant information sheet below.