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Choice of antibiotics for prophylaxis of bacterial STIs among individuals currently self-sourcing
  1. Manik Kohli1,2,
  2. David Reid1,3,
  3. Caisey V Pulford3,4,
  4. Alison Howarth1,3,
  5. Jack Brown1,3,
  6. Hamish Mohammed3,4,
  7. Gwenda Hughes3,4,
  8. Catherine H Mercer1,3,
  9. John Saunders1,4
  1. 1 Institute for Global Health, University College London, London, UK
  2. 2 Department of Sexual Health and HIV, Central and North West London NHS Foundation Trust, London, UK
  3. 3 The National Institute for Health Research Health Protection Research Unit in Blood Borne and Sexually Transmitted Infections at University College London in partnership with UK Health Security Agency, London, UK
  4. 4 Blood Safety, Hepatitis, STIs and HIV Division, National Infection Service, UK Health Security Agency, London, UK
  1. Correspondence to Dr Manik Kohli, Institute for Global Health, University College London, London WC1E 6JB, UK; m.kohli{at}

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As interest in antibiotic prophylaxis for bacterial STIs grows, there is a need to better understand the current landscape of antibiotic self-sourcing. STI prophylaxis is not currently recommended in routine practice: only two small studies demonstrated efficacy of pre-/post-exposure doxycycline prophylaxis for syphilis and chlamydia, and there are concerns about antimicrobial resistance (AMR).1 However, 2%–10% of HIV pre-exposure prophylaxis (PrEP) users self-source antibiotics for STI prophylaxis.1

During the COVID-19 pandemic, online surveys of men-who-have-sex-with-men(MSM) were carried out in the UK within the Reducing Inequalities and Improving Sexual Health Study.2 The second survey (23 November–12 December 2020) included questions on STI prophylaxis. The survey had 1522 respondents, of which 1520 completed the STI prophylaxis questions. The median age was 38 years (IQR 29–50), 96% were cis male, 82% identified as gay and 71% were white British.

Overall, 20% (308 of 1520) had heard of STI prophylaxis, 3.6% (55 of 1520) had ever used prophylaxis and 1.8% (28 of 1520) had used prophylaxis in the preceding 12 months. HIV-negative respondents not using HIV-PrEP had lower reported STI prophylaxis use than both respondents with HIV (1.9% (18 of 933) vs 6.9% (11 of 160); p<0.001) and HIV-PrEP users (1.9% (18 of 933) vs 6.2% (26 of 421); p<0.001). Respondents reporting STI prophylaxis use (n=55) were asked which antibiotic(s), being able to select more than one if appropriate: 56% reported using doxycycline, 18% azithromycin, 20% amoxicillin, 4% metronidazole and 16% were unsure.

This analysis corroborates available estimates of STI prophylaxis use among MSM, and for the first time estimates use among HIV-negative people not using HIV-PrEP and people with HIV. Participants reported using antibiotics that lack evidence of effectiveness at preventing STIs, such as macrolides and penicillins. Driving further AMR through use of these is particularly concerning for the management of enteric STIs and non-sexually acquired infections. Practical guidance on STI prophylaxis to support patient-centred care is needed.

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Ethics approval

This study involves human participants and was approved by UCL Research Ethics Committee (Ref: 9155/001). Participants gave informed consent to participate in the study before taking part.


The authors thank all the participants involved in this study. We acknowledge members of the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Blood Borne and Sexually Transmitted Infections (BBSTI) Steering Committee: Professor Caroline Sabin (HPRU Director), Dr John Saunders (UK HSA Lead), Professor Catherine Mercer, Professor Gwenda Hughes, Dr Hamish Mohammed, Professor Greta Rait, Dr Ruth Simmons, Professor William Rosenberg, Dr Tamyo Mbisa, Professor Rosalind Raine, Dr Sema Mandal, Dr Rosamund Yu, Dr Samreen Ijaz, Dr Fabiana Lorencatto, Dr Rachel Hunter, Dr Kirsty Foster and Dr Mamooma Tahir. The authors would like to thank Takudzwa Mukiwa and Ross Purves from Terrence Higgins Trust for their help with participant recruitment.



  • Handling editor Anna Maria Geretti

  • Twitter @saunders_j

  • Contributors MK carried out the analysis and wrote the first draft. All other authors provided comments and edits. The original study design, data collection and data management were carried out by AH, DR, CVP, GH, CHM and JMS.

  • Funding The original survey was funded by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Blood Borne and Sexually Transmitted Infections at University College London in partnership with UK Health Security Agency.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.