Pre-exposure prophylaxis and bacterial sexually transmitted infections (STIs) among gay and bisexual men.

While pre-exposure prophylaxis (PrEP) prevents HIV acquisition among gay, bisexual and other men who have sex with men (GBM), PrEP-using GBM may be more likely to engage in sexual behaviours associated with bacterial STIs. We examined associations between PrEP use, condomless anal sex (CAS), number of anal sex partners, oral sex and bacterial STI diagnoses among GBM living in Canada's three largest cities. Among HIV-negative/unknown-status GBM in the baseline of the Engage cohort study, we fit a structural equation model of the associations between any PrEP use, sexual behaviours and bacterial STI diagnosis. We estimated direct and indirect paths between PrEP use and STI via CAS, number of anal sex partners and oral sex. The sample included 2007 HIV-negative/unknown status GBM in Montreal, Toronto and Vancouver. There was a significant direct association between PrEP use and current STI diagnosis (β=0.181; 95% CI: 0.112 to 0.247; p<0.001), CAS (β=0.275; 95% CI: 0.189 to 0.361; p<0.001) and number of anal sex partners (β=0.193; 95% CI: 0.161 to 0.225; p<0.001). In the mediated model, the direct association between PrEP use and STIs was non-significant. However, the indirect paths from PrEP to CAS to STIs (β=0.064; 95% CI: 0.025 to 0.120; p=0.008), and from PrEP to greater number of anal sex partners to CAS to STIs were significant (β=0.059; 95% CI: 0.024 to 0.108; p=0.007). Our study adds to the growing awareness that PrEP use among GBM may be associated with bacterial STIs because PrEP users have more anal sex partners and are more likely to engage in CAS. The results underscore the importance of providing effective STI counselling and regular testing to PrEP users, adapting PrEP care and related STI testing to individual needs, and the need for effective prevention strategies for bacterial STIs.

Hart TA ，Noor SW ，Berlin GW ，Skakoon-Sparling S ，Tavangar F ，Tan D ，Lambert G ，Grace D ，Lachowsky NJ ，Jollimore J ，Sang J ，Parlette A ，Lal A ，Apelian H ，Moore D ，Cox J ，Engage Study ... -  《-》

Human Immunodeficiency Virus Treatment Attitudes and Bacterial Sexually Transmitted Infections Among Gay and Bisexual Men.

Positive attitudes toward human immunodeficiency virus (HIV) treatment, such as reduced concern about HIV transmissibility, are associated with sexual behaviors that may increase the risk of bacterial sexually transmitted infections (STIs) among gay, bisexual, and other men who have sex with men (GBM). We examined associations between HIV treatment attitudes and bacterial STI diagnoses among GBM in Canada's three largest cities. We fit a structural equation model between HIV treatment attitudes and bacterial STI diagnoses via sexual behaviors in the Engage study's baseline data. We estimated direct and indirect paths between scores on HIV treatment attitudes and STIs via number of male anal sex partners, condomless anal sex, and oral sex. We conducted sub-analyses with participants stratified by HIV serostatus. Among 2449 GBM recruited in 2017 to 2019, there was a direct association between HIV treatment attitudes and current STI diagnoses (β = 0.13; 95% CI, 0.07-0.19; P < 0.001). The mediated model revealed a positive total indirect effect through 2 pathways: (1) engaging in condomless anal sex and (2) number of male anal sex partners and condomless anal sex. These 2 indirect pathways remained in the stratified mediation models for both HIV negative GBM and for GBM living with HIV. The association between HIV treatment attitudes and diagnosed STIs is mediated through a higher number of male anal sex partners and condomless anal sex. The results highlight the importance of providers educating patients when providing effective STI counseling, testing, and prevention for GBM about how accurate HIV treatment attitudes may inadvertently be associated with the bacterial STI epidemic.

Hart TA ，Noor SW ，Tavangar F ，Zahran A ，Skakoon-Sparling S ，Tan DHS ，Lambert G ，Grace D ，Lachowsky N ，Sang JM ，Palma PA ，Zhang T ，Dvorakova M ，Cox J ，Moore DM ，Engage Study ... -  《-》

Factors Associated With Willingness to Use Daily Antibiotics as Sexually Transmitted Infection Prophylaxis Among HIV Preexposure Prophylaxis-Experienced Gay and Bisexual Men in Australia.

Gay and bisexual men (GBM) who use HIV preexposure prophylaxis (HIV-PrEP) have high rates of bacterial sexually transmitted infections (STIs). The use of daily antibiotics as STI preexposure prophylaxis (STI-PrEP) may be appealing to GBM who are using or have previously used HIV-PrEP (HIV-PrEP-experienced) for the prevention of bacterial STIs. We examined willingness to use daily STI-PrEP among a cross-sectional sample of HIV-PrEP-experienced GBM in Australia who participated in an observational online cohort study from August 2018 to March 2020. Factors associated with willingness to use daily STI-PrEP were determined using bivariate and multivariate logistic regression. Of the 1347 participants, half (54.3%) were willing to use daily STI-PrEP. Factors independently associated with greater willingness to use daily STI-PrEP included having >10 sexual partners in the last 6 months, using methamphetamine in the last 6 months, being more conscious about avoiding STIs, having a greater number of STIs since commencing HIV-PrEP, being willing to take HIV-PrEP for as long as they were at risk of acquiring HIV, and only using condoms when a sexual partner requested them. Conversely, factors associated with less willingness to use daily STI-PrEP included being university educated, using nondaily dosing regimens of HIV-PrEP, preferring event-driven HIV-PrEP, and being concerned about long-term HIV-PrEP adverse effects. Sexually transmitted infection PrEP is likely to be appealing to many HIV-PrEP-experienced GBM, especially those who engage in activities associated with a higher risk of STI transmission. However, they are less likely to be willing to use STI-PrEP unless it aligns with their HIV-PrEP dosing regimen, suggesting that research into the safety and efficacy of alternative STI prophylaxis dosing options should be prioritized.

Arapali T ，Grulich AE ，Heywood AE ，Chan C ，Fraser D ，Zablotska IB ，Holt M ，Vaccher SJ ，Bavinton BR ... -  《-》

Sexual behaviour and incidence of HIV and sexually transmitted infections among men who have sex with men using daily and event-driven pre-exposure prophylaxis in AMPrEP: 2 year results from a demonstration study.

Pre-exposure prophylaxis (PrEP) for HIV might induce risk compensation, defined as increased sexual risk behaviour leading to increased incidence of bacterial sexually transmitted infections (STIs). We examined the incidence of HIV, STIs, and sexual behaviour after initiating daily and event-driven PrEP. AMPrEP is a demonstration study that assessed the incidence of HIV and bacterial STIs and sexual behaviour among PrEP users at the STI clinic of the Public Health Service of Amsterdam (Amsterdam, the Netherlands). Eligible adults (aged ≥18 years) were HIV-negative men who have sex with men (MSM) and transgender people who had reported one or more of the following in the previous 6 months: condomless anal sex with casual partners, at least one bacterial STI, use of post-exposure prophylaxis after a sexual risk incident, or an HIV-positive sexual partner with detectable viral load. Participants were given a choice of daily PrEP or event-driven PrEP regimens. Participants were seen every 3 months for HIV and STI testing. Participants also completed self-administered questionnaires about sexual behaviour at each visit. Over the first 2 years, we assessed the number and incidence rate of HIV and chlamydia, gonorrhoea, and syphilis, including STIs diagnosed in between study visits and assessed changes in incidence over time using piecewise exponential survival models. The number of sexual acts and sexual partners were also analysed and changes over time were assessed using negative binomial regression models. This study is ongoing; the data cutoff for this analysis was June 30, 2018. Between Aug 3, 2015, and May 31, 2016, 376 participants were recruited, of whom nine participants were lost to follow-up, thus 367 participants were included in the analysis. Overall, 365 MSM and two transgender women were included, contributing 681·7 person-years of follow-up. At enrolment, 269 (73%) of 367 participants chose daily PrEP and 98 (27%) participants chose event-driven PrEP. Two individuals in the daily PrEP group became HIV-positive; overall HIV incidence rate was 0·30 per 100 person-years (95% CI 0·07-1·19). 253 participants were diagnosed with one or more STI during the first 2 years (incidence rate 90·4 per 100 person-years). STI incidence did not change over time (adjusted incidence rate ratio [aIRR] 1·00 per 3 month follow-up, 95% CI 0·93-1·07). More than a quarter of all STIs were diagnosed from tests done in between study visits. STI incidence was lower in the event-driven PrEP group than the daily PrEP group (aIRR 0·59, 95% CI 0·46-0·75). The number of condomless anal sex acts with casual partners per 3 months increased, but the number of partners and sex acts remained stable. Although the overall incidence of STIs did not change during 2 years of PrEP use, the incidence of STIs was higher among participants using daily PrEP than those using event-driven PrEP, which is likely a result of differences in sexual behaviour. This finding suggests the need to tailor STI prevention interventions according to behavioural profiles. ZonMw, H-TEAM, Internal GGD research funds, Aidsfonds, Stichting AmsterdamDiner Foundation, Gilead Sciences, Janssen Pharmaceutica, M A C AIDS Fund, and ViiV Healthcare.

Hoornenborg E ，Coyer L ，Achterbergh RCA ，Matser A ，Schim van der Loeff MF ，Boyd A ，van Duijnhoven YTHP ，Bruisten S ，Oostvogel P ，Davidovich U ，Hogewoning A ，Prins M ，de Vries HJC ，Amsterdam PrEP Project team in the HIV Transmission Elimination AMsterdam (H-TEAM) Initiative ... -  《Lancet HIV》

Trends in Sexual Behavior and Sexually Transmitted Infections After Initiating Human Immunodeficiency Virus Pre-Exposure Prophylaxis in Men Who Have Sex with Men from Amsterdam, the Netherlands: A Longitudinal Exposure-Matched Study.

Coyer L ，Prins M ，Davidovich U ，van Bilsen WPH ，Schim van der Loeff MF ，Hoornenborg E ，Matser A ，Boyd A ... -  《-》