Objectives There is interest in doxycycline as prophylaxis against sexually transmitted infections (STIs), but concern about antimicrobial resistance (AMR). We conducted a systematic review (CRD42021273301) of the impact of oral tetracycline-class antibiotics on AMR in normal flora. Methods We searched MEDLINE, EMBASE, the Cochrane Library (1940–2021) and conference proceedings (2014–21) for randomized controlled trials in adults comparing daily oral tetracycline-class antibiotics to non-tetracycline controls. The primary outcome was AMR to tetracyclines; secondary outcomes included resistance to non-tetracyclines. Data were inappropriate for meta-analysis, so we analysed findings descriptively. Results Our search yielded 6265 abstracts of which 7 articles fulfilled inclusion criteria. Most were at moderate/high risk of bias, generally due to inadequate methodologic reporting. Studies used doxycycline, tetracycline, oxytetracycline or minocycline for 2–18 weeks. Most observed an increased burden of tetracycline resistance, including in subgingival (n = 3 studies), gastrointestinal (n = 2) and upper respiratory tract (n = 1) flora; one study of skin flora found no change in tetracycline-resistant Propionibacterium species after 18 weeks of oxytetracycline/minocycline. Four studies reassessed AMR at 2–50 weeks post-intervention and reported varying degrees of resistance. Three articles reported on the prevalence of non-tetracycline AMR after doxycycline prophylaxis, of which one found a transient increase among gastrointestinal Escherichia coli; the other two showed no difference from control. Conclusions Although the effects are modest and transient, limited data from small prospective studies may suggest that oral tetracyclines for 2–18 weeks increase resistance in subgingival, gastrointestinal and upper respiratory tract flora. STI prophylaxis trials should include AMR in commensal bacteria as study outcomes.

Background HIV Pre-exposure prophylaxis (PrEP) is an underutilized intervention to prevent HIV infection in Canada. Known barriers to PrEP uptake include lack of awareness, low HIV risk perception, side effects, PrEP not being publicly funded (which is the case in Ontario) and stigma. We aimed to identify barriers to PrEP use and actions that may facilitate PrEP uptake in Ontario and British Columbia. Methods Gay, bisexual and other men who have sex with men 19 years or older living in Ontario and British Columbia, Canada, answered a survey between July 2019 and August 2020. Participants who met Canadian PrEP guideline criteria for PrEP and not already using PrEP indicated which barriers were relevant to them and which actions would make them more likely to start PrEP. We used descriptive statistics and tested differences between Ontario and British Columbia using Chi-square tests for proportions and t-tests or Wilcoxon rank-sum tests for continuous variables. Results Of 1527 survey responses, 260 (184 in Ontario and 76 in British Columbia) who were never PrEP users and met criteria for PrEP were included. In Ontario, the most common barriers were affordability (43%) and concern about side effects (42%). In British Columbia, the most common reasons were concern about side effects (41%) and not feeling at high enough risk (36%). In Ontario, the actions that would most likely encourage the respondent to start PrEP were short waiting time (63%), the healthcare provider informing about their HIV risk being higher than perceived (62%) and a written step-by-step guide (60%). In British Columbia, the actions that would most likely encourage the respondent to start PrEP were short waiting time (68%), people speaking publicly about PrEP (68%) and their healthcare provider counselling about: their HIV risk being higher than perceived (64%), side effects of PrEP (64%) and about how PrEP works (62%). Table. Top reasons for not using PrEP and top actions that might influence the decision to start PrEP stratified by province. (n= 184 in Ontario, n= 76 in British Columbia). Conclusion Concern about side effects and not feeling at high enough risk were common barriers. Short waiting times may increase PrEP uptake. In Ontario, the findings suggested lack of affordability. In British Columbia, actions involving healthcare providers were valued. Disclosures Kevin Woodward, MD FRCPC, Gilead (Independent Contractor) Darrell Tan, MD PhD, Abbvie (Grant/Research Support)Gilead (Grant/Research Support)GlaxoSmithKline (Scientific Research Study Investigator)ViiV Healthcare (Grant/Research Support)