Chlamydia Antimicrobial Resistance Among DoxyPEP users (CAMRAD)
Research type
Research Study
Full title
Does tetracycline resistance exist in Chlamydia trachomatis strains sourced from individuals using Doxycycline for STI prevention? A pilot study.
IRAS ID
368552
Contact name
Sarah Alexander
Contact email
Sponsor organisation
UK Health Security Agency
Duration of Study in the UK
2 years, 11 months, 31 days
Research summary
Chlamydia is a common sexually transmitted infection (STI) that can cause health problems if it is not treated, such as pain when urinating, rectal pain, and pelvic inflammatory disease. Chlamydia is treated with antibiotics. The bacteria that cause chlamydia (Chlamydia trachomatis) is one of the very few organisms for which true antimicrobial resistance (AMR) has not yet been seen in people. AMR happens when bacteria stop responding to antibiotics, meaning infections become harder to treat.
A new approach to preventing STIs has recently been introduced, called doxycycline post‑exposure prophylaxis (doxyPEP). DoxyPEP involves taking a dose of doxycycline shortly after sex to stop infection. Studies have shown that doxyPEP is very good at reducing new cases of chlamydia and syphilis. However, there are concerns that repeated use of doxycycline could encourage C. trachomatis to develop resistance. At present, no laboratories in the UK routinely test chlamydia for AMR, and there are no national systems to monitor whether treatment remains effective.
This study aims to find out whether C. trachomatis is showing early signs of AMR in people who are using doxyPEP. To do this, we will grow (culture) chlamydia from samples collected in sexual health clinics from individuals diagnosed with chlamydia including those use doxyPEP. Any chlamydia strains we are able to grow will be analysed to look for genetic markers linked to antibiotic resistance, especially resistance to doxycycline.
The study findings will help determine whether routine monitoring of chlamydia AMR would be valuable for clinicians and public health bodies in the future. This is an early, proof‑of‑concept study designed to provide the first evidence on whether doxyPEP could contribute to the development of antibiotic resistance in chlamydia.
REC name
London - Bloomsbury Research Ethics Committee
REC reference
26/LO/0336
Date of REC Opinion
23 Jun 2026
REC opinion
Further Information Favourable Opinion