Overview

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.

Eligibility

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.