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Original research
Factors associated with reporting antibiotic use as STI prophylaxis among HIV PrEP users: findings from a cross-sectional online community survey, May–July 2019, UK
  1. Charlotte O'Halloran1,
  2. Sara Croxford1,
  3. Hamish Mohammed1,
  4. Owen Noel Gill1,
  5. Gwenda Hughes1,
  6. Helen Fifer1,
  7. Hester Allen1,
  8. Greg Owen2,
  9. Will Nutland3,
  10. Valerie Delpech1,
  11. John Michael Saunders1
  1. 1National Infection Service, Public Health England, London, UK
  2. 2iwantPrEPnow, London, UK
  3. 3PrEPster, London, UK
  1. Correspondence to Charlotte O'Halloran, National Infection Service, Public Health England Colindale, London, UK; char.ohalloran{at}


Objectives The use of antibiotics as pre-exposure or postexposure prophylaxis for sexually transmitted infection (STI) prevention (STI prophylaxis) is not currently recommended in the UK, but there is evidence that self-prescribing occurs among those at greatest risk. We present the prevalence and factors associated with STI prophylaxis among a community sample of HIV pre-exposure prophylaxis (PrEP) users.

Methods The 2019 online PrEP User Survey ran between 17 May and 1 July. Eligible participants included UK residents reporting HIV PrEP use or having tried to obtain HIV PrEP since January 2017. STI prophylaxis use was defined as reporting buying antibiotics to prevent STIs, either privately or through the internet; this question was only asked to HIV PrEP users. Factors associated with STI prophylaxis use were assessed using univariable and multivariable logistic regression.

Results Overall, 9% (167/1856) of HIV PrEP users reported STI prophylaxis use; 97% were gay or bisexual men, 84% reported white ethnicity, 55% resided in London and 69% were aged ≥35 years. Factors associated with STI prophylaxis included: reporting ≥5 compared with 1–4 condomless sex partners in the past 6 months (12% vs 5.6%, adjusted odds ratio (aOR)=1.80; 95% CI 1.22 to 2.64), reporting chemsex drug use compared with no sexualised drug use in the past 12 months (13% vs 6.0%, aOR=1.88; 95% CI 1.20 to 2.93) and reporting an STI diagnosis in the past 12 months (12% vs 6.6%, aOR=1.54; 95% CI 1.08 to 2.18). Variables not significant in multivariable analyses included: ethnicity, age, residence and HIV PrEP sourcing.

Conclusions Approximately 1 in 10 HIV PrEP users from this community sample reported self-prescribed STI prophylaxis. STI prophylaxis was associated with sexual behaviour known to facilitate STI transmission and with a history of recent STIs acquisition. Given the potential risk of antimicrobial resistance, sexual health clinicians should consider asking attendees, especially HIV PrEP users, about the use of antibiotics as STI prophylaxis, to inform appropriate counselling, testing and management.

  • antibiotics
  • antimicrobial resistance
  • bacterial infection
  • HIV pre-exposure prophylaxis
  • prophylaxis

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  • Handling editor Joseph D Tucker

  • Twitter @saunders_j

  • Contributors All authors were involved in shaping the research and interpretation of findings. All authors reviewed the manuscript, provided critical feedback on revisions and contributed to writing. JMS was the principal investigator for the subanalysis on STI prophylaxis. COH was responsible for carrying out data analyses, writing manuscript drafts, incorporating author comments and was responsible for final draft publication. SC and HM provided support with statistical analyses. JMS, HM, HF, HA and GH provided key epidemiological and clinical advice on STI treatment and surveillance. WN and GO provided valuable insight into STI prophylaxis and HIV PrEP use in the community. VD, ONG, COH, GO, WN and SC are part of the PrEP User Survey team and are responsible for the overall aims of the survey, design, recruitment, management and analysis of results.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The survey was approved by the PHE Research Ethics and Governance Group (reference number NR0118) in 2018.

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

  • Data availability statement No data are available. Data are collected by Public Health England and stored on secure servers that can only be accessed by the national HIV surveillance (HARS) team at PHE. No patient identifiable information (PII) was collected in the survey. The principles for accessing, storing and sharing data are given in PHE’s HIV and STI data sharing policy found here: The HARS team at PHE can be contacted by emailing

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