Post-exposure prophylaxis with doxycycline to prevent sexually transmitted infections in men who have sex with men: an open-label randomised substudy of the ANRS IPERGAY trial

Syphilis vaccine development: Aligning vaccine design with manufacturing requirements

Syphilis, caused by Treponema pallidum subsp. pallidum, is a global health concern with increasing rates worldwide. Current prevention strategies, including screen-and-treat approaches, are not sufficient to resolve rising infection rates, emphasizing the need for a vaccine. Developing a syphilis vaccine necessitates a range of cross-disciplinary considerations, including essential disease-specific protection, technical requirements, economic feasibility, manufacturing constraints, public acceptance, equitable vaccine access, alignment with global public vaccination programs, and identification of essential populations to be vaccinated to achieve herd immunity. Central to syphilis vaccine development is prioritization of global vaccine availability, including access in low- to middle-income settings. Various vaccine platforms, including subunit, virus-like particle (VLP), mRNA, and outer membrane vesicle (OMV) vaccines, present both advantages and challenges. The proactive consideration of both manufacturing feasibility and efficacy throughout the pre-clinical research and development stages is essential for producing an efficacious, inexpensive, and scalable syphilis vaccine to address the growing global health burden caused by this disease.

IUSTI Europe position statement on use of DoxyPEP: June 2024

This position statement is aimed at front-line clinical practitioners and public health authorities in WHO European Region providing services for people wishing to reduce their risk of acquiring sexually transmitted infections (STIs), including HIV.

Sexually Transmitted Infections in Transgender and Gender-Diverse Individuals: Review of Screening and Treatment Recommendations

Transgender and gender-diverse individuals experience disproportionately high rates of sexually transmitted infections (STIs). In this review, the authors discuss the epidemiology, screening recommendations, and treatment guidelines for STIs in transgender and gender-diverse people.

Clinical considerations for sexual and gender minorities with prostate cancer

At every stage of the cancer continuum, the management of sexual and gender minorities with prostate cancer requires a thoughtful and multidisciplinary approach. For example, it is important to recognize that receptive anal intercourse, common among sexual minority men-i.e. gay and bisexual men-can potentially elevate prostate-specific antigen (PSA) leading to overdiagnosis and overtreatment. Additionally, it is important to understand that sexual minority men with prostate cancer might engage in insertive and/or receptive anal intercourse, as opposed to insertive vaginal intercourse, requiring a treatment conversation that expands beyond the usual discussion of sexual health in prostate cancer patients. For gender minorities-i.e. transgender women or trans feminine individuals (those recorded male at birth with feminine gender identities)-it is important to consider gender affirming hormones and pelvic surgeries as they can cause diagnostic and treatment challenges, including PSA suppression, more aggressive disease, and anatomical changes. Furthermore, it is essential to recognize that gender minorities are a diverse cohort and may or may not be on gender affirming hormone therapy and may or may not have received or intend to receive pelvic affirming surgery. In this seminar article, we highlight considerations for personalized management of prostate cancer in sexual and gender minorities to improve care for this understudied cohort and enhance health equity.

Effects of doxycycline post-exposure prophylaxis for prevention of sexually transmitted infections on gonorrhoea prevalence and antimicrobial resistance among men who have sex with men in the USA: a modelling study

BACKGROUND

Doxycycline post-exposure prophylaxis (PEP) has been shown to be efficacious for the prevention of bacterial sexually transmitted infections, but resistance implications for Neisseria gonorrhoeae remain unknown. We aimed to use a mathematical model to investigate the anticipated impact of doxycycline PEP on the burden of gonorrhoea and antimicrobial resistance dynamics in men who have sex with men (MSM) in the USA.

METHODS

Using a deterministic compartmental model, characterising gonorrhoea transmission in a US MSM population comprising three sexual activity groups defined by annual partner turnover rates, we introduced doxycycline PEP at various uptake levels (10-90%) among those with high sexual activity. Infections were stratified by symptom status and resistance profile (ie, susceptible, ceftriaxone-resistant, tetracycline-resistant, or dual-resistant), with ceftriaxone the treatment for active infection. As resistance to tetracycline, not doxycycline, is monitored and reported nationally, we used this as a proxy for doxycycline PEP resistance. We compared the 20-year prevalence, incidence rates, and cumulative incidence of gonococcal infection, resistance dynamics (time to 5% prevalence of ceftriaxone resistance, 5% prevalence of dual resistance, and 84% prevalence of tetracycline resistance), and antibiotic consumption with baseline (ie, no doxycycline PEP).

FINDINGS

Uptake of doxycycline PEP resulted in substantial reductions in the prevalence and incidence of gonorrhoea, but accelerated the spread of tetracycline resistance. The maximum reduction in prevalence over 20 years compared with no uptake ranged from 40·3% (IQR 15·3-83·4) with 10% doxycycline PEP uptake to 77·4% (68·4-84·9) with 90% uptake. Similarly, the maximum reduction in the incidence rate ranged from 38·6% (14·1-83·6) with 10% uptake to 77·6% (68·1-84·7) with 90% uptake. Cumulative gonococcal infections were reduced by a median of 14·5% (IQR 8·4-21·6) with 10% uptake and up to 46·2% (26·5-59·9) with 90% uptake after 5 years, and by 6·5% (3·4-13·0) with 10% uptake and 8·7% (4·3-36·2) with 90% uptake by 20 years. In almost all scenarios explored, doxycycline PEP lost clinical effectiveness (defined as 84% prevalence of tetracycline resistance) within the 20-year period, but its lifespan ranged from a median of 12·1 years (IQR 9·9-15·7) with 10% uptake to 1·6 years (1·3-1·9) with 90% uptake. Doxycycline PEP implementation had minimal impact on extending the clinical lifespan of ceftriaxone monotherapy (5·0 years [IQR 4·0-6·2]), with the median time to 5% prevalence of resistance ranging from 4·8 years (3·9-6·0) for 90% uptake to 5·0 years (4·1-6·2) for 10% uptake. Similarly, the median time to 5% prevalence of dual resistance to ceftriaxone and tetracycline ranged from 4·8 years (3·9-6·0) for 90% uptake to 5·8 years (4·8-7·4) for 10% uptake. Median decrease in ceftriaxone consumption for high doxycycline PEP uptake levels compared with baseline ranged from 41·7% (27·0-54·3) for 50% uptake to 50·2% (29·3-62·7) for 90% uptake at 5 years, but dropped to 11·8% (6·9-32·0) for 50% uptake and 12·1% (7·0-41·6) for 90% uptake after 20 years.

INTERPRETATION

Notwithstanding the clear benefits of doxycycline PEP for other sexually transmitted infections, for N gonorrhoeae, model findings suggest that doxycycline PEP is an effective but impermanent solution for reducing infection burden, given eventual selection for resistant strains. This finding presents a challenge for policy makers considering strategies for doxycycline PEP implementation and oversight: the need to balance the clear, short-term clinical benefits with the risk of harm via antimicrobial resistance.

FUNDING

US Centers for Disease Control and Prevention, National Institute of Allergy and Infectious Diseases.

Impact of doxycycline post-exposure prophylaxis for sexually transmitted infections on the gut microbiome and antimicrobial resistome

Doxycycline post-exposure prophylaxis (doxy-PEP) reduces bacterial sexually transmitted infections among men who have sex with men and transgender women. Although poised for widespread clinical implementation, the impact of doxy-PEP on antimicrobial resistance remains a primary concern as its effects on the gut microbiome and resistome, or the antimicrobial resistance genes (ARGs) present in the gut microbiome, are unknown. To investigate these effects, we studied participants from the DoxyPEP trial, a randomized clinical trial comparing doxy-PEP use, a one-time doxycycline 200-mg dose taken after condomless sex (DP arm, n = 100), to standard of care (SOC arm, n = 50) among men who have sex with men and transgender women. From self-collected rectal swabs at enrollment (day-0) and after 6 months (month-6), we performed metagenomic DNA sequencing (DNA-seq) or metatranscriptomic RNA sequencing (RNA-seq). DNA-seq data were analyzable from 127 samples derived from 89 participants, and RNA-seq data were analyzable from 86 samples derived from 70 participants. We compared the bacterial microbiome and resistome between the two study arms and over time. The median number of doxycycline doses taken since enrollment by participants with DNA-seq data was zero (interquartile range (IQR): 0-7 doses) for the SOC arm and 42 (IQR: 27-64 doses) for the DP arm. Tetracycline ARGs were detected in all day-0 DNA-seq samples and in 85% of day-0 RNA-seq samples. The proportional mass of tetracycline ARGs in the resistome increased between day-0 and month-6 in DP participants from 46% to 51% in the metagenome (P = 2.3 × 10-2) and from 4% to 15% in the metatranscriptome (P = 4.5 × 10-6), but no statistically significant increases in other ARG classes were observed. Exposure to a higher number of doxycycline doses correlated with proportional enrichment of tetracycline ARGs in the metagenome (Spearman's ρ = 0.23, P = 9.0 × 10-3) and metatranscriptome (Spearman's ρ = 0.55, P = 3.7 × 10-8). Bacterial microbiome alpha diversity, beta diversity and total bacterial mass did not differ between day-0 and month-6 samples from DP participants when assessed by either DNA-seq or RNA-seq. In an abundance-based correlation analysis, we observed an increase over time in the strength of the correlation between tetracycline ARGs and specific bacterial taxa, including some common human pathogens. In sum, doxy-PEP use over a 6-month period was associated with an increase in the proportion of tetracycline ARGs comprising the gut resistome and an increase in the expression of tetracycline ARGs. At 6 months of doxy-PEP use, no residual differences were observed in alpha and beta diversity or taxonomic composition of the gut microbiome. As doxy-PEP is implemented as a public health strategy, further studies and population-level surveillance of doxycycline-resistant pathogens are needed to understand the implications of these findings. ClinicalTrials.gov registration number: NCT03980223 .

Bacterial sexually transmitted infections among men who have sex with men and transgender women using oral pre-exposure prophylaxis in Latin America (ImPrEP): a secondary analysis of a prospective, open-label, multicentre study

BACKGROUND

The global burden of sexually transmitted infections (STIs) poses a challenge in the context of HIV pre-exposure prophylaxis (PrEP) programmes. We aimed to explore factors associated with prevalent, incident, and recurrent STIs in men who have sex with men (MSM) and transgender women on PrEP in Brazil, Mexico, and Peru.

METHODS

ImPrEP was a prospective, single-arm, open-label, multicentre study that enrolled MSM and transgender women in the context of the public health systems of Brazil (14 sites), Mexico (four sites), and Peru (ten sites) between February, 2018, and June, 2021. Eligibility criteria followed regional PrEP guidelines at the study start, including participants aged 18 years and older, not living with HIV, and reporting at least one of the following in the previous 6 months: condomless anal sex (CAS), anal sex with partner(s) living with HIV, any bacterial STI, or transactional sex. Eligible participants were screened and enrolled on the same day to receive daily oral PrEP (tenofovir disoproxil fumarate 300 mg and emtricitabine 200 mg). We assessed three outcomes: prevalent bacterial STIs, incident bacterial STIs, and recurrent bacterial STIs. Testing occurred at baseline and quarterly for syphilis, anorectal chlamydia, and anorectal gonorrhoea. Behavioural data were collected at baseline and quarterly. The study was registered with the Brazilian Registry of Clinical Trials, U1111-1217-6021.

FINDINGS

Among all 9509 participants included in the ImPrEP study (3928 [41·3%] in Brazil, 3288 [34·6%] in Mexico, and 2293 [24·1%] in Peru), 8525 (89·7%) had available STI results at baseline and were included in the prevalent STI analysis, and 7558 (79·5%) had available STI results during follow-up and were included in the incident and recurrent STI analyses. 2184 (25·6%) of 8525 participants had any bacterial STI at baseline. STI incidence during follow-up was 31·7 cases per 100 person-years (95% CI 30·7-32·7), with the highest rate for anorectal chlamydia (11·6 cases per 100 person-years, 95% CI 11·0-12·2), followed by syphilis (10·5 cases per 100 person-years, 9·9-11·1) and anorectal gonorrhoea (9·7 cases per 100 person-years, 9·2-10·3). Although only 2391 (31·6%) of 7558 participants had at least one STI during follow-up, 915 (12·1%) participants had recurrent diagnoses, representing 2328 (61·2%) of 3804 incident STI diagnoses. Characteristics associated with prevalent, incident, and recurrent STIs included younger age, multiple sex partners, receptive CAS, substance use, and previous STI diagnoses at baseline (incident or recurrent only).

INTERPRETATION

Our findings underscore the nuanced dynamics of STI transmission among MSM and transgender women across Latin America, highlighting an urgent need for tailored interventions to mitigate STI burden effectively, especially among the most susceptible individuals.

FUNDING

Unitaid, WHO, and ministries of health (Brazil, Mexico, and Peru).

TRANSLATIONS

For the Portuguese and Spanish translations of the abstract see Supplementary Materials section.

Syphilis testing, incidence, and reinfection among gay and bisexual men in Australia over a decade spanning HIV PrEP implementation: an analysis of surveillance data from 2012 to 2022

Background

Gay and bisexual men (GBM) remain overrepresented among syphilis diagnoses in Australia and globally. The extent to which changes in sexual networks associated with HIV pre-exposure prophylaxis (PrEP) and treatment as prevention (TasP) may have influenced syphilis transmission among GBM at the population-level is poorly understood. We describe trends in syphilis testing and incidence among GBM in Australia over eleven years spanning widespread uptake of HIV PrEP and TasP.

Methods

We analysed linked clinical data from GBM aged 16 years or older across a sentinel surveillance network in Australia from January 1, 2012, to December 31, 2022. Individuals with at least two clinic visits and with at least two syphilis tests during the observations period were included in testing and incidence analyses, respectively. Annual rates of testing and infectious syphilis incidence from 2012 to 2022 were disaggregated by HIV status and PrEP use (record of PrEP prescription; retrospectively categorised as ever or never-PrEP user). Cox regression explored associations between demographics, PrEP use and history of bacterial sexually transmissible infections (STIs) and infectious syphilis diagnosis.

Findings

Among 129,278 GBM (mean age, 34.6 years [SD, 12.2]) included in testing rate analyses, 7.4% were living with HIV at entry and 31.1% were prescribed PrEP at least once during the study period. Overall syphilis testing rate was 114.0/100 person-years (py) and highest among GBM with HIV (168.4/100 py). Syphilis testing increased from 72.8/100 py to 151.8/100 py; driven largely by increases among ever-PrEP users. Among 94,710 GBM included in incidence analyses, there were 14,710 syphilis infections diagnosed over 451,560 person-years (incidence rate = 3.3/100 py). Syphilis incidence was highest among GBM with HIV (6.5/100 py), followed by ever-PrEP users (3.5/100 py) and never-PrEP users (1.4/100 py). From 2012 to 2022, syphilis incidence increased among ever-PrEP users from 1.3/100 py to 5.1/100 py, and fluctuated between 5.4/100 py and 6.6/100 py among GBM with HIV. In multivariable Cox regression, previous syphilis diagnosis (adjusted hazard ratio [aHR] = 1.98, 95% CI = 1.83-2.14), living with HIV (aHR = 1.83, 95% CI = 1.12-1.25) and recent (past 12 m) prescription of PrEP (aHR = 1.78, 95% CI = 1.61-1.97) were associated with syphilis diagnosis.

Interpretation

Syphilis trends between GBM with HIV and GBM with evidence of PrEP use have converged over the past decade in Australia. Our findings recommend targeting emergent syphilis control strategies (e.g. doxycycline post-exposure prophylaxis) to GBM with prior syphilis diagnoses, using HIV PrEP or who are living with HIV.

Funding

Australian Department of Health and Aged Care, National Health and Medical Research Council.

Doxycycline prophylaxis for the prevention of sexually transmitted infections: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

To investigate the effects of doxycycline pre- and post-exposure prophylaxis (doxy-PrEP/PEP) on bacterial sexually transmitted infections (STIs) by conducting a systematic review and meta-analysis.

METHODS

PubMed, Embase, and CENTRAL were searched for randomized controlled trials (RCTs), including ongoing studies published until November 7, 2023. Our primary endpoint was the incidence of bacterial STIs measured as the number of visits with an STI per total number of visits. Random-effects model was used to estimate pooled effect sizes. The study was registered with PROSPERO, CRD42023478486.

RESULTS

We identified six eligible studies containing data from seven articles and four conference abstracts, enrolling men who have sex with men (MSM), transgender women (TGW), and cisgender women (CGW). The pooled analysis of 1,766 participants with 602 newly diagnosed STIs showed a 56% decrease in the overall STI incidence using doxy-PrEP/PEP (RR = 0.44; 95% CI: 0.30-0.65; I2 = 73%). For doxy-PEP, including MSM and TGW only, the RR observed for overall STI incidence was 0.40 (95% CI: 0.28-0.57; I² = 37%), 0.19 (95% CI: 0.08-0.44; I² = 39%) for chlamydia, 0.23 (0.14-0.36; I² = 0%) for syphilis and 0.55 (95% CI: 0.34-0.87; I² = 41%) for gonorrhea. No serious adverse events were reported in the studies. The certainty of evidence regarding the efficacy of doxy-PEP among MSM and TGW was graded as high.

CONCLUSION

Doxy-PEP significantly reduces the number of new cases of chlamydia and syphilis and is potentially effective against gonorrhea, influenced by local resistance patterns. Thus, it is a promising tool in the prevention of bacterial STIs among MSM and TGW.

Doxycycline prophylaxis and meningococcal group B vaccine to prevent bacterial sexually transmitted infections in France (ANRS 174 DOXYVAC): a multicentre, open-label, randomised trial with a 2 × 2 factorial design

BACKGROUND

Increased rates of sexually transmitted infections (STIs) are reported among men who have sex with men (MSM) and new interventions are needed. We aimed to assess whether post-exposure prophylaxis (PEP) with doxycycline could reduce the incidence of chlamydia or syphilis (or both) and whether the meningococcal group B vaccine (4CMenB) could reduce the incidence of gonorrhoea in this population.

METHODS

ANRS 174 DOXYVAC is a multicentre, open-label, randomised trial with a 2 × 2 factorial design conducted at ten hospital sites in Paris, France. Eligible participants were MSM aged 18 years or older, HIV negative, had a history of bacterial STIs within the 12 months before enrolment, and who were already included in the ANRS PREVENIR study (a cohort of MSM using pre-exposure prophylaxis with tenofovir and emtricitabine for HIV prevention). Participants were randomly assigned (2:1) to doxycycline PEP (two pills of 100 mg each orally within 72 h after condomless sex, with no more than three doses of 200 mg per week) or no PEP groups and were also randomly assigned (1:1) to the 4CMenB vaccine (GlaxoSmithKline, Paris, France; two intramuscular injections at enrolment and at 2 months) or no vaccine groups, using a computer-generated randomisation list with a permuted fixed block size of four. Follow-up occurred for at least 12 months (with visits every 3 months) up to 24 months. The coprimary outcomes were the risk of a first episode of chlamydia or syphilis (or both) after the enrolment visit at baseline for the doxycycline intervention and the risk of a first episode of gonorrhoea starting at month 3 (ie, 1 month after the second vaccine dose) for the vaccine intervention, analysed in the modified intention-to-treat population (defined as all randomly assigned participants who had at least one follow-up visit). This trial is registered with ClinicalTrials.gov, NCT04597424 (ongoing).

FINDINGS

Between Jan 19, 2021, and Sept 19, 2022, 556 participants were randomly assigned. 545 (98%) participants were included in the modified intention-to-treat analysis for the doxycycline PEP and no PEP groups and 544 (98%) were included for the 4CMenB vaccine and no vaccine groups. The median follow-up was 14 months (IQR 9-18). The median age was 40 years (34-48) and all 545 participants were male. There was no interaction between the two interventions (p≥0·1) for the primary outcome. The incidence of a first episode of chlamydia or syphilis (or both) was 8·8 per 100 person-years (35 events in 362 participants) in the doxycycline PEP group and 53·2 per 100 person-years (80 events in 183 participants) in the no PEP group (adjusted hazard ratio [aHR] 0·17 [95% CI 0·12-0·26]; p<0·0001). The incidence of a first episode of gonorrhoea, starting from month 3 was 58·3 per 100 person-years (103 events in 274 participants) in the 4CmenB vaccine group and 77·1 per 100 person-years (122 events in 270 participants) in the no vaccine group (aHR 0·78 [95% CI 0·60-1·01]; p=0·061). There were no deaths during the study. One drug-related serious adverse event (fixed-drug eruption) occurred in the doxycycline PEP group. Six (2%) participants in the doxycycline group discontinued doxycycline PEP because of gastrointestinal adverse events.

INTERPRETATION

Doxycycline PEP strongly reduced the incidence of chlamydia and syphilis in MSM, but we did not show efficacy of the 4CmenB vaccine for gonorrhoea. Doxycycline PEP should be assessed in other populations, such as heterosexual men and women, and its effect on antimicrobial resistance carefully monitored.

FUNDING

ANRS Maladies Infectieuses Emergentes.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

A novel pan-proteome array for high-throughput profiling of the humoral response to Treponema pallidum

Given the resurgence of syphilis, research endeavors to improve current assays for serological diagnosis and management of this disease are a priority. A proteome-scale platform for high-throughput profiling of the humoral response to Treponema pallidum (T. pallidum) proteins during infection could identify antigens suitable to ameliorate the performance and capabilities of treponemal tests for syphilis. Additionally, because infection-induced immunity is partially protective, profiling the response to T. pallidum outer membrane proteins (OMPs) could help select vaccine candidates. Therefore, we developed a pan-proteome array (PPA) based on the Nichols and SS14 strain complete proteomes and used it to define the immunoglobulin M (IgM) and IgG humoral response to T. pallidum proteins in sera collected longitudinally from long-term infected rabbits and from rabbits that were infected, treated, and re-infected. We identified antigens that could facilitate early diagnosis and immunity to a core set of OMP that could explain protection upon reinfection.

Behind Prep Decisions: Understanding User Patterns and Discontinuation Factors in Real-World

This study aimed to characterize the epidemiological aspects of PrEP use and barriers to accessing this prophylaxis. This cross-sectional study was conducted between January 2021 and April 2022, encompassing 140 PrEP users treated at the Testing and Counseling Center (CTA) in Campo Grande, Mato Grosso do Sul. Data on sociodemographic characteristics and factors associated with PrEP discontinuation were obtained using a standardized questionnaire. Most PrEP users were cisgender men (92.00%), predominantly white (51.00%), over 30 years of age (56.50%), homosexual-oriented (76.50%), and had a minimum of 12 years of education (77.50%). Approximately 60.00% admitted to inconsistent condom use in recent sexual encounters, primarily involving anal intercourse. Approximately 88.00% perceived themselves as at risk of contracting STIs in the upcoming year. Regarding new presentation forms, 54.00% indicated a willingness to use "on-demand PrEP," and 92.00% expressed interest in using "injectable PrEP." After 6 months of follow-up, 43.60% (95.00% CI: 35.50-52.00) discontinued PrEP use, primarily due to changes in sexual behavior (38.30%) and difficulties accessing healthcare services (21.28%). This study underscores the need to involve diverse key populations and highlights the significance of PrEP as an ongoing monitoring strategy for HIV/STI prevention in addition to the importance of incorporating new formulations such as daily oral PrEP into the Brazilian National Health System (SUS).

Sexually Transmitted Infections in People with Human Immunodeficiency Virus

Sexually transmitted infections (STIs) are more commonly seen in patients with human immunodeficiency virus (PWH). Routine sexual history taking and appropriate multisite screening practices support prompt identification and treatment of patients, which in turn reduces morbidity and spread of STIs including HIV. Nucleic acid amplification testing has high accuracy for diagnosing many of the major STIs. Diagnosis of syphilis remains complex, requiring 2 stage serologic testing, along with provider awareness of the myriad symptoms that can be attributable to this disease. Prevention through mechanisms such as vaccines and postexposure prophylaxis hold promise to reduce the burden of STIs in PWH.

Doxycycline post-exposure prophylaxis among men who have sex with men and transgender women in Belgium: awareness, use and antimicrobial resistance concerns in a cross-sectional online survey

OBJECTIVES

We aimed to assess the awareness, willingness to use and use of doxycycline post-exposure prophylaxis (doxyPEP) among men who have sex with men (MSM) and transgender women (TGW) in Belgium. Additionally, we aimed to identify factors associated with doxyPEP use and concerns regarding antimicrobial resistance (AMR).

METHODS

Cross-sectional online survey among MSM and TGW in Belgium in April 2024. Participants were recruited through sexual networking applications and social media of community-based organisations. Numerical variables were compared with Wilcoxon rank-sum test and categorical variables with χ2 or Fisher's exact tests. Factors associated with doxyPEP use were assessed using logistic regression. Willingness to use doxyPEP and concerns about side effects/AMR were assessed before and after presenting a brief paragraph on the potential effects of doxyPEP on AMR.

RESULTS

875 individuals initiated the survey. Almost all identified as men (860/875, 98.3%) with a median age of 40 years (IQR 32-48), 40.4% (n=352/875) had heard of doxyPEP and 9.4% (n=82/875) had used it, among whom the majority used it within the previous 6 months (70/81, 86.4%). In multivariable logistic regression, doxyPEP use was associated with reporting ≥1 sexually transmitted infection (STI) in the previous 12 months, engagement in chemsex, HIV status and pre-exposure prophylaxis use, and education level.About 80% of the participants initially reported being willing to use doxyPEP, and about 50% reported being concerned about side effects. After reading about the potential effects of doxyPEP on AMR, willingness to use decreased to 60% and concerns of side effects/AMR increased to around 70%.

CONCLUSIONS

Approximately 1 in 10 MSM in Belgium reported using doxyPEP. A recent history of STIs and STI risk factors were positively associated with doxyPEP use. Importantly, concerns about AMR and side effect influenced willingness to use doxyPEP. If doxyPEP is introduced, informing patients about doxyPEP benefits and risks is crucial to enable informed decision-making.

An updated molecular diagnostic for surveillance of tetM in Neisseria gonorrhoeae

Doxycycline post-exposure prophylaxis (doxy-PEP) for sexually transmitted bacterial infections reduces the risk of syphilis and chlamydia, but effectiveness against gonorrhea is variable, likely attributable to varying resistance rates. As doxy-PEP is incorporated into clinical practice, an urgent unanswered question is whether increased doxycycline use will drive tetracycline-class resistance in Neisseria gonorrhoeae. Here, we report an updated RT-PCR molecular diagnostic to detect the tetM gene that confers high-level tetracycline resistance in N. gonorrhoeae.

Early adopters of doxycycline as post-exposure prophylaxis to prevent bacterial sexually transmitted infections in a real-world clinical setting

OBJECTIVES

Doxycycline as post-exposure prophylaxis (DoxyPEP) is a novel prevention approach which has demonstrated efficacy in preventing bacterial sexually transmitted infections (STIs) in men who have sex with men (MSM) and transgender women (TGW) including people who are living with HIV and those on HIV pre-exposure prophylaxis (PrEP). We evaluated patient knowledge and interest in DoxyPEP, as well as early adopters of its use.

METHODS

In 2023, patients presenting for HIV and STI services at a primary care and sexual health clinic were asked about DoxyPEP knowledge, interest and use. Bivariate and multivariate analyses were used to evaluate demographics and behaviours associated with these outcomes.

RESULTS

A total of n=421 people presented for care. Of these, 314 were MSM/TGW. Fifteen percent were Black/African-American, and 21% were Hispanic/Latino. A total of 50% of MSM/TGW had heard of DoxyPEP, 49% were interested and 18% reported prior DoxyPEP use. Having a history of STI infection ever (adjusted OR (aOR) 5.95, 95% CI 2.69 to 13.13) and in the past 12 months (aOR 2.99, 95% CI 1.56 to 5.72) were both associated with DoxyPEP use. Individuals who had ever used HIV PrEP had nearly three times the odds of ever taking DoxyPEP (aOR 2.88, 95% CI 1.56 to 5.30). There was no association between the use of DoxyPEP and race, ethnicity or HIV status.

CONCLUSIONS

Among MSM and TGW, there is already significant awareness, interest and use of DoxyPEP to prevent bacterial STIs. Public health efforts should focus on improving access and delivery of this STI prevention intervention to MSM and TGW.

Epidemiological impact of Neisseria gonorrhoeae and Chlamydia trachomatis screening in men having sex with men: a modelling study

OBJECTIVES

The impact of the systematic screening of Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) in men having sex with men (MSM) on these pathogens' epidemiology remains unclear. We conducted a modelling study to analyse this impact in French MSM.

METHODS

We modelled NG and CT transmission using a site-specific deterministic compartmental model. We calibrated NG and CT prevalence at baseline using results from MSM enrolled in the Dat'AIDS cohort. The baseline scenario was based on 1 million MSM, 40 000 of whom were tested every 90 days and 960 000 every 200 days. Incidence rate ratios (IRRs) at steady state were simulated for NG, CT, NG and/or CT infections, for different combinations of tested sites, testing frequency and numbers of frequently tested patients.

RESULTS

The observed prevalence rate was 11.0%, 10.5% and 19.1% for NG, CT and NG and/or CT infections. The baseline incidence rate was estimated at 138.2 per year per 100 individuals (/100PY), 86.8/100PY and 225.0/100PY for NG, CT and NG and/or CT infections. Systematically testing anal, pharyngeal and urethral sites at the same time reduced incidence by 14%, 23% and 18% (IRR: 0.86, 0.77 and 0.82) for NG, CT and NG and/or CT infections. Reducing the screening interval to 60 days in frequently tested patients reduced incidence by 20%, 29% and 24% (IRR: 0.80, 0.71 and 0.76) for NG, CT and NG and/or CT infections. Increasing the number of frequently tested patients to 200 000 reduced incidence by 29%, 40% and 33% (IRR: 0.71, 0.60 and 0.67) for NG, CT and NG and/or CT infections. No realistic scenario could decrease pathogens' incidence by more than 50%.

CONCLUSIONS

To curb the epidemic of NG and CT in MSM, it would not only be necessary to drastically increase screening, but also to add other combined interventions.

Efficacy of postexposure prophylaxis with doxycycline (Doxy-PEP) in reducing sexually transmitted infections: a systematic review and meta-analysis

OBJECTIVES

This systematic review aimed to identify the efficacy, adherence, safety and impact on antimicrobial resistance of postexposure prophylaxis with doxycycline (Doxy-PEP) in different populations.

METHODS

We searched MEDLINE (via PubMed), Embase and Cochrane CENTRAL databases from inception to 29 May 2024. Two reviewers independently screened the studies and extracted data. We included randomised clinical trials that evaluated the efficacy of Doxy-PEP within 72 hours after condomless sex. A random-effects meta-analysis was conducted to compare the risk of bacterial sexually transmitted infections (STIs) between Doxy-PEP and no prophylaxis. The risk of bias was assessed with the risk-of-bias tool for randomized trials (RoB 2) and the certainty of evidence (CoE) with Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

Four studies were included in the systematic review, totalling 1727 participants. Studies were conducted between 2015 and 2022. Most participants (73%) were men who have sex with men, and the median age of participants varied from 24 to 43 years. Doxy-PEP reduced the risk of having any bacterial STI in different populations by 46% (hazard ratio (HR) 0.54; 95% CI 0.39 to 0.75; CoE moderate), the risk of chlamydia by 65% (relative risk (RR) 0.35; 95% CI 0.15 to 0.82; CoE low) and syphilis by 77% (RR 0.23; 95% CI 0.13 to 0.41; CoE high), without significant effect for risk of gonorrhoea infection (RR 0.90; 95% CI 0.64 to 1.26; CoE very low). The self-reported adherence rate of Doxy-PEP was approximately 80% and one drug-related serious adverse event was reported.

CONCLUSION

Doxy-PEP reduced the incidence of chlamydia and syphilis infections. No significant reduction in gonorrhoea infection was observed. This strategy seems promising for some high-risk groups; however, there is still a lack of information on the induction of bacterial resistance and long-term adverse events. PROSPERO REGISTRATION NUMBER.

Trends of Antimicrobial Susceptibility of Neisseria gonorrhoeae Isolates Between 2012 and 2023: Results From an Open Italian Cohort

BACKGROUND

Neisseria gonorrhoeae (Ng) is a public health priority because of the rapid evolution of antimicrobial resistance, the emergence of antibiotic resistance, and the absence of a vaccine against Ng. The aim of this study was to investigate trends in the minimum inhibitory concentration and resistance (R) or reduced susceptibility (DS) of Ng cases to ceftriaxone (CRO), azithromycin (AZM), tetracycline (TET), benzylpenicillin (PenG), and ciprofloxacin (CIP) during a 10-year period.

METHODS

We conducted a retrospective analysis on an open cohort of Ng cases diagnosed on rectal, urethral, and pharyngeal samples at San Raffaele Scientific Institute, between September 2012 and February 2023. Minimum inhibitory concentrations of antibiotics were determined by gradient-test strips. Bivariate linear regression models were applied on logarithmic minimum inhibitory concentrations values; Cochran-Armitage test was used to determine a linear trend in the proportions of resistant strains.

RESULTS

A total of 436 Ng isolates from 352 individuals were analyzed. Minimum inhibitory concentrations of CRO and PenG reduced over time ( P < 0.001, P = 0.030), AZM increased ( P = 0.001), and CIP and TET did not change ( P = 0.473, P = 0.272). The percentages of resistant strains were as follows: PenG, 89.9%; TET, 90.8%; CIP, 48.2%; AZM, and 4.4%. CRO-DS strains were 8.7%, and only 1 case of CRO-R was identified. The proportion of resistant strains increased over time for AZM ( P = 0.007), TET ( P = 0.001), and CIP ( P < 0.001), whereas it decreased for PenG ( P < 0.001) and CRO-DS/R strains ( P < 0.001).

CONCLUSIONS

Ng strains showed high susceptibility to CRO, although we identified cases of DS/R and observed high levels of susceptibility to AZM. Overall, the recommended primary regimen for Ng treatment was confirmed to be effective.

Could the effect of antimicrobials on antimicrobial resistance be saturated at high-antimicrobial consumption? A comparison of the MORDOR and ResistAZM studies

OBJECTIVES

Antimicrobial resistance poses a considerable threat in high-antimicrobial-consumption populations, such as men who have sex with men (MSM) taking HIV pre-exposure prophylaxis. While the ResistAZM trial found no increase in macrolide resistance genes in MSM with gonorrhea after azithromycin treatment, the MORDOR trial observed an increase in these genes after mass azithromycin distribution. We hypothesized that this could be due to saturation of the resistome. To test this hypothesis, we compared the abundance of macrolide resistance determinants in anorectal samples between the baselines of the two trials.

METHODS

Shotgun metagenome reads from the anorectal baseline samples from the ResistAZM (n = 42) and MORDOR (n = 30) trials were analyzed using AMRPlusPlus. Nonhost reads were mapped to the MEGARes database to detect antibiotic resistance genes (ARG). Antimicrobial resistance (AMR) was normalized using cumulative sum scaling, and ARG abundance was estimated.

RESULTS

Macrolide, lincosamides, and streptogramins determinants were approximately 10-fold more abundant in the ResistAZM than the MORDOR samples (P ≤ 0.001).

CONCLUSION

The findings are compatible with our hypothesis. Thus, in populations with high-antimicrobial use, the relationship between antimicrobial consumption and AMR may be diminished due to saturation. These findings are vital for future studies investigating the resistogencity of novel interventions, such as doxycycline post-exposure prophylaxis, in populations with high preceding consumption of antimicrobials.

The rising tide of HIV among young men who have sex with men in Brazil: insights from the Conectad@s study

Background

Young gay, bisexual, and other men who have sex with men (YMSM) in Latin America experience disproportionately high rates of HIV. While new case numbers have stabilised in other demographics, the incidence of HIV in this particular group continues to rise. We estimated the prevalence of HIV and sexually transmitted infections (STI) and identified correlates of new HIV diagnoses among YMSM in Brazil.

Methods

Conectad@s was a respondent-driven sampling-based study to recruit and engage YMSM in HIV prevention and treatment services in Rio de Janeiro, Brazil (November 2021-October 2022). Eligibility criteria were age 18-24 years and self-identification as MSM (cis/trans) or non-binary person who have sex with men. Participants underwent HIV/STI testing and completed a socio-behavioural questionnaire. We described baseline characteristics by HIV status and used logistic regression models to identify correlates of new HIV diagnoses. Trial ID: DERR1-10.2196/34885.

Findings

Among 409 participants, 370 (90.5%) self-identified as cisgender men, nine (2.2%) transgender men, and 30 (7.3%) non-binary. Median age was 21 years (IQR: 20-23), with 80 (19.6%) aged 18-19 years. Most self-identified as Black or Pardo (70.6%); 109 (26.7%) never tested for HIV. HIV prevalence was 9.8%; 50% (n = 20/40) were newly diagnosed with HIV. Only nine participants ever used PrEP and three were currently using it. Overall, 133 (32.5%) reported sexual violence in their lifetime and 102 (24.9%) reported a suicide attempt. Prevalence of active syphilis, chlamydia, and gonorrhoea were 14.4%, 15.9%, and 14.7%, respectively. New HIV diagnoses were positively associated with engaging in high-risk behaviour (aOR 4.88 [95% CI: 1.88-13.40]) and anxiety (aOR 2.67 [95% CI: 1.01-7.70]), and negatively associated with ever disclosing sexual orientation (aOR 0.19 [95% CI: 0.04-0.92]) and HIV knowledge (aOR 0.77 [95% CI: 0.59-1.01]).

Interpretation

High prevalence of HIV coupled with a high proportion of new HIV diagnoses underscore a potentially growing HIV epidemic among YMSM in Brazil.

Funding

National Institutes of Health (NIH), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Ministry of Health of Brazil.

A practice already in use: a snapshot survey on the use of doxycycline as a preventive strategy (Doxy-PEP and Doxy-PrEP) in the GBMSM population in Spain

PURPOSE

. While doxycycline shows promise as a preventative measure against certain STIs (post-exposure prophylaxis or PEP, and pre-exposure prophylaxis or PrEP), very few medical and scientific associations favor its community use. Nevertheless, sexual health organizations for gay, bisexual and other men who have sex with men (GBMSM) community have noticed an increase in requests of its use.

METHODS

. The sexual health organization "Stop Sida" in Spain launched an anonymous snapshot survey to evaluate the current use of doxycycline as prevention strategy (both PEP and PrEP) in Spain through its social networks and its support groups in telegram.

RESULTS

. 150 valid answers were obtained from different parts of Spain. 82 respondents (54,6% of total) had ever taken doxycycline, out of which 29 (35,4%) indicated the use as doxy-PEP and 7 (8,5%) as doxy-PrEP. The self-reported rate of STI diagnoses (mainly of syphilis and chlamydia) in the past 12 months was lower among those participants who reported having used doxy-PEP compared with those who did not report using doxy-PEP. The most common ways to obtain the doxycycline were telling a specialist that they have had a risky contact or by using leftover pills from a previous treatment.

CONCLUSION

The current study is the first study to describe the use of doxycycline as a preventive strategy among the GBMSM community in Spain, and the first designed, launched and analyzed entirely by an NGO dealing with sexual health for the GBMSM community. The results obtained are aligned with other studies in other parts of Europe, such as Germany.

Is doxycycline post-exposure prophylaxis being utilised in Germany? Insights from an online survey among German men who have sex with men

PURPOSE

Doxycycline post-exposure prophylaxis (Doxy-PEP) reduces the likelihood of Chlamydia and early syphilis by approximately two-thirds. Currently, data on the frequency of Doxy-PEP use in men who have sex with men (MSM) are limited. This study aimed to assess knowledge, attitude towards, and frequency of Doxy-PEP use among MSM in Germany.

METHODS

We conducted a national online survey in Germany from summer to fall 2023, recruiting MSM and transgender women. Participants were invited to complete the online survey through social media, online dating platforms, and print media advertisements with active recruitment and poster advertising in private practices, tertiary outpatient clinics, and MSM community events in Germany.

RESULTS

In total, 438 participants completed the survey and were included in the analysis, and 285 (65.1%) were living with the human immunodeficiency virus (HIV) or taking HIV-pre-exposure prophylaxis (PrEP). Overall, 170 participants (38.8%) had heard of Doxy-PEP, and 275 (62.8%) would consider taking it, but only 32 (7.3%) reported having ever taken Doxy-PEP. The most common reason for a negative attitude towards Doxy-PEP were apprehension about insufficient detailed information, and concerns about antibiotic resistance. Doxy-PEP users were more likely to be on HIV-PrEP, had a higher self-reported risk of bacterial sexually transmitted infections (STIs), and often had a history of bacterial STIs.

CONCLUSION

The study demonstrated high awareness and strong interest in Doxy-PEP among MSM in Germany, most of whom were living with HIV or taking HIV-PrEP; however, the actual usage of Doxy-PEP remains low in the summer and fall of 2023.

Combination of compound screening with an animal model identifies pentamidine to prevent Chlamydia trachomatis infection

Chlamydia trachomatis (Ct) is the most common cause for bacterial sexually transmitted infections (STIs) worldwide with a tremendous impact on public health. With the aim to unravel novel targets of the chlamydia life cycle, we screen a compound library and identify 28 agents to significantly reduce Ct growth. The known anti-infective agent pentamidine-one of the top candidates of the screen-shows anti-chlamydia activity in low concentrations by changing the metabolism of host cells impairing chlamydia growth. Furthermore, it effectively decreases the Ct burden upon local or systemic application in mice. Pentamidine also inhibits the growth of Neisseria gonorrhea (Ng), which is a common co-infection of Ct. The conducted compound screen is powerful in exploring antimicrobial compounds against Ct in a medium-throughput format. Following thorough in vitro and in vivo assessments, pentamidine emerges as a promising agent for topical prophylaxis or treatment against Ct and possibly other bacterial STIs.

Vaccine effectiveness and impact of meningococcal vaccines against gonococcal infections: A systematic review and meta-analysis

OBJECTIVES

To systematically review and synthesis the evidence of vaccine effectiveness (VE) and impact (VI) of meningococcal vaccines in preventing gonorrhoea.

METHODS

We systematically evaluated studies. Literature searches were conducted in PubMed, Embase, Cochrane Library, CINAHL, Google Scholar, clinical trial registries, and major health and immunisation conferences. Meta-analysis was performed with the DerSimonian-Laird random-effects model to estimate the pooled VE.

RESULTS

Twelve studies met the criteria for inclusion. VE of meningococcal B (MenB) outer membrane vesicle (OMV) vaccines was evaluated in nine studies, with one study evaluating a non-OMV vaccine, MenB-FHbp. The majority of studies targeted individuals aged 15-30 years. Adjusted VE for OMV vaccines against gonorrhoea ranged from 22% to 46%. MenB-FHbp did not show protection against gonorrhoea. The pooled VE estimates of OMV vaccines against any gonorrhoea infection following the full vaccine series were 33-34%. VI was assessed for 4CMenB in Canada and Australia, for VA-MENGOC-BC in Cuba; and for MenBvac in Norway. VI ranged from a 30% to 59% reduction in gonorrhoea incidence.

CONCLUSIONS

4CMenB and other MenB-OMV vaccines show moderate effectiveness against gonorrhoea. Further research is required to explore the factors associated with vaccine protection, informing more effective vaccination strategies for the management of gonococcal infections.

Assessing thresholds of resistance prevalence at which empiric treatment of gonorrhea should change among men who have sex with men in the US: A cost-effectiveness analysis

BACKGROUND

Since common diagnostic tests for gonorrhea do not provide information about susceptibility to antibiotics, treatment of gonorrhea remains empiric. Antibiotics used for empiric therapy are usually changed once resistance prevalence exceeds a certain threshold (e.g., 5%). A low switch threshold is intended to increase the probability that an infection is successfully treated with the first-line antibiotic, but it could also increase the pace at which recommendations are switched to newer antibiotics. Little is known about the impact of changing the switch threshold on the incidence of gonorrhea, the rate of treatment failure, and the overall cost and quality-adjusted life-years (QALYs) associated with gonorrhea.

METHODS AND FINDINGS

We developed a transmission model of gonococcal infection with multiple resistant strains to project gonorrhea-associated costs and loss in QALYs under different switch thresholds among men who have sex with men (MSM) in the United States. We accounted for the costs and disutilities associated with symptoms, diagnosis, treatment, and sequelae, and combined costs and QALYs in a measure of net health benefit (NHB). Our results suggest that under a scenario where 3 antibiotics are available over the next 50 years (2 suitable for the first-line therapy of gonorrhea and 1 suitable only for the retreatment of resistant infections), changing the switch threshold between 1% and 10% does not meaningfully impact the annual number of gonorrhea cases, total costs, or total QALY losses associated with gonorrhea. However, if a new antibiotic is to become available in the future, choosing a lower switch threshold could improve the population NHB. If in addition, drug-susceptibility testing (DST) is available to inform retreatment regimens after unsuccessful first-line therapy, setting the switch threshold at 1% to 2% is expected to maximize the population NHB. A limitation of our study is that our analysis only focuses on the MSM population and does not consider the influence of interventions such as vaccine and common use of rapid drugs susceptibility tests to inform first-line therapy.

CONCLUSIONS

Changing the switch threshold for first-line antibiotics may not substantially change the health and financial outcomes associated with gonorrhea. However, the switch threshold could be reduced when newer antibiotics are expected to become available soon or when in addition to future novel antibiotics, DST is also available to inform retreatment regimens.

Oral streptococcal susceptibility to azithromycin may be associated with doxycycline use: A post-hoc analysis with implications for doxycycline post exposure prophylaxis

OBJECTIVE

Tetracycline and macrolide resistance are frequently linked in streptococci and other species. We aimed to assess the association between doxycycline use and azithromycin MICs in oral streptococci.

METHODS

Linear regression was used to assess the association between doxycycline use in the prior year and the median MIC per participant of oral streptococcal colonies isolated at the baseline visit of the ResistAZM study. The analysis controlled for receipt of other antimicrobials as well as time since antimicrobial consumption.

RESULTS

Fifty-six individual colonies confirmed to be streptococci were isolated from 19 individuals at baseline. The azithromycin MICs of these isolates varied considerably between 0.25 mg/L and >256 mg/L (median 28 mg/L; IQR 1-192 mg/L). The consumption of doxycycline in the preceding 12 months was positively associated with median streptococcal azithromycin MIC (coef. 151.6 [95% CI 10.6-292.7]; p = .037).

CONCLUSION

This post-hoc analysis found that doxycycline use was associated with streptococcal azithromycin susceptibility. Numerous limitations of the study design mean that this study is best considered hypothesis generating. Prospective studies are required to assess if the use of doxycycline could select for macrolide resistance in oral streptococci.

Antimicrobial treatment and resistance in sexually transmitted bacterial infections

Sexually transmitted infections (STIs) have been part of human life since ancient times, and their symptoms affect quality of life, and sequelae are common. Socioeconomic and behavioural trends affect the prevalence of STIs, but the discovery of antimicrobials gave hope for treatment, control of the spread of infection and lower rates of sequelae. This has to some extent been achieved, but increasing antimicrobial resistance and increasing transmission in high-risk sexual networks threaten this progress. For Neisseria gonorrhoeae, the only remaining first-line treatment (with ceftriaxone) is at risk of becoming ineffective, and for Mycoplasma genitalium, for which fewer alternative antimicrobial classes are available, incurable infections have already been reported. For Chlamydia trachomatis, in vitro resistance to first-line tetracyclines and macrolides has never been confirmed despite decades of treatment of this highly prevalent STI. Similarly, Treponema pallidum, the cause of syphilis, has remained susceptible to first-line penicillin.

A behavioral economics approach to enhancing HIV preexposure and postexposure prophylaxis implementation

PURPOSE OF REVIEW

The 'PrEP cliff' phenomenon poses a critical challenge in global HIV PrEP implementation, marked by significant dropouts across the entire PrEP care continuum. This article reviews new strategies to address 'PrEP cliff'.

RECENT FINDINGS

Canadian clinicians have developed a service delivery model that offers presumptive PEP to patients in need and transits eligible PEP users to PrEP. Early findings are promising. This service model not only establishes a safety net for those who were not protected by PrEP, but it also leverages the immediate salience and perceived benefits of PEP as a natural nudge towards PrEP use. Aligning with Behavioral Economics, specifically the Salience Theory, this strategy holds potential in tackling PrEP implementation challenges.

SUMMARY

A natural pathway between PEP and PrEP has been widely observed. The Canadian service model exemplifies an innovative strategy that leverages this organic pathway and enhances the utility of both PEP and PrEP services. We offer theoretical insights into the reasons behind these PEP-PrEP transitions and evolve the Canadian model into a cohesive framework for implementation.

An update on drug-drug interactions in older adults living with human immunodeficiency virus (HIV)

INTRODUCTION

People with HIV are living longer due to advances in antiretroviral therapy. With improved life expectancy comes an increased lifetime risk of comorbid conditions - such as cardiovascular disease and cancer - and polypharmacy. Older adults, particularly those living with HIV, are more vulnerable to drug interactions and adverse effects, resulting in negative health outcomes.

AREA COVERED

Antiretrovirals are involved in many potential drug interactions with medications used to treat common comorbidities and geriatric conditions in an aging population of people with HIV. We review the mechanisms and management of significant drug-drug interactions involving antiretroviral medications and non-antiretroviral medications commonly used among older people living with HIV. The management of these interactions may require dose adjustments, medication switches to alternatives, enhanced monitoring, and considerations of patient- and disease-specific factors.

EXPERT OPINION

Clinicians managing comorbid conditions among older people with HIV must be particularly vigilant to side effect profiles, drug-drug interactions, pill burden, and cost when optimizing treatment. To support healthier aging among people living with HIV, there is a growing need for antiretroviral stewardship, multidisciplinary care models, and advances that promote insight into the correlations between an individual, their conditions, and their medications.

Long-term in vitro exposure of Treponema pallidum to sub-bactericidal doxycycline did not induce resistance: Implications for doxy-PEP and syphilis

Doxycycline post-exposure prophylaxis (doxy-PEP) could significantly reduce syphilis incidence. However, the increase in intermittent doxycycline usage might select resistant Treponema pallidum ( T. pallidum ) strains. To assess whether resistance to doxycycline could be induced in this pathogen, we exposed the SS14 strain in vitro both intermittently and continuously to a sub-bactericidal doxycycline concentration that still exerts antibiotic pressure. During and after each exposure experiment, we assessed the doxycycline minimal inhibitory concentration in test and control treponemes and performed whole genome sequencing, concluding that no resistance developed. This work suggests that doxycycline-resistant T. pallidum is not an immediate threat for doxy-PEP implementation.

Effect of mass treatment on the long-term prevalence of gonorrhoea, chlamydia and syphilis-a systematic review

BACKGROUND

Selective mass treatment of STIs may lead to a durable reduction in the prevalence of STIs or a temporary reduction associated with an increased probability of antimicrobial resistance emerging.

METHODS

We searched PubMed and Google Scholar for studies evaluating the impact of mass STI treatment on the long-term prevalence of chlamydia, gonorrhoea, syphilis and chancroid. The primary outcomes were the long term (≥3 months post the intervention) impact of the intervention on prevalence/incidence of the STI and on antimicrobial resistance.

RESULTS

Our search yielded 269 studies, of which 4 met the inclusion criteria. With the exception of the Carletonville study, where this was not assessed, three of the four studies found that intensive STI treatment was associated with a reduced prevalence of the targeted STI during or immediately after the intervention. In all four studies, there was no evidence that the intense treatment had a long-term effect on prevalence. In the only study where this was assessed, the intensive use of penicillin to reduce gonococcal prevalence was associated with the emergence of reduced susceptibility to penicillin in N. gonorrhoeae.

CONCLUSION

The available evidence suggests that mass treatment of chlamydia, gonorrhoea and syphilis in high prevalence populations is only associated with a temporary reduction in the prevalence of these infections and may select for antimicrobial resistance.

Pleasurable and problematic receptive anal intercourse and diseases of the colon, rectum and anus

The ability to experience pleasurable sexual activity is important for human health. Receptive anal intercourse (RAI) is a common, though frequently stigmatized, pleasurable sexual activity. Little is known about how diseases of the colon, rectum, and anus and their treatments affect RAI. Engaging in RAI with gastrointestinal disease can be difficult due to the unpredictability of symptoms and treatment-related toxic effects. Patients might experience sphincter hypertonicity, gastrointestinal symptom-specific anxiety, altered pelvic blood flow from structural disorders, decreased sensation from cancer-directed therapies or body image issues from stoma creation. These can result in problematic RAI - encompassing anodyspareunia (painful RAI), arousal dysfunction, orgasm dysfunction and decreased sexual desire. Therapeutic strategies for problematic RAI in patients living with gastrointestinal diseases and/or treatment-related dysfunction include pelvic floor muscle strengthening and stretching, psychological interventions, and restorative devices. Providing health-care professionals with a framework to discuss pleasurable RAI and diagnose problematic RAI can help improve patient outcomes. Normalizing RAI, affirming pleasure from RAI and acknowledging that the gastrointestinal system is involved in sexual pleasure, sexual function and sexual health will help transform the scientific paradigm of sexual health to one that is more just and equitable.

Frequent chlamydia and gonorrhoea but very infrequent syphilis among men who have sex with men using HIV pre-exposure prophylaxis in West Africa

OBJECTIVES

Although oral pre-exposure prophylaxis (PrEP) for HIV is being rolled out in West Africa, data on sexually transmitted infections (STIs) in PrEP users are scarce. We assessed the prevalence, incidence and determinants of bacterial STIs in men who have sex with men (MSM) taking PrEP in Burkina Faso, Côte d'Ivoire, Mali and Togo.

METHODS

A prospective cohort study among MSM initiating PrEP as part of a comprehensive HIV prevention package was conducted between 2017 and 2021 in community-based clinics in the four study countries. Molecular screening for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) was performed at months 0, 6 and 12. Serological testing for syphilis was performed every 3 months over the first year of follow-up. Determinants of CT and/or NG incidence were identified using Poisson generalised linear mixed models.

RESULTS

A total of 598 participants with a median age of 24.7 years were included. Prevalence of CT and/or NG was 24.4% (95% CI 21.0 to 28.1), 22.4% (95% CI 18.4 to 26.8) and 29.0% (95% CI 24.2 to 34.1) at months 0, 6 and 12, respectively. The prevalence of syphilis ranged from 0.2% (95% CI 0.0 to 0.9) at month 0 to 0.8% (95% CI 0.2 to 2.4) at month 12. Ninety incident CT and/or NG infections occurred during a total follow-up time of 280.6 person-years (incidence rate 32.1 per 100 person-years, 95% CI 25.8 to 39.4). Three incident syphilis infections were detected during a total follow-up time of 459.7 person-years (incidence rate 0.7 per 100 person-years, 95% CI 0.1 to 1.9). CT and/or NG incidence was associated with condomless insertive anal sex (adjusted incidence rate ratio 1.96, 95% CI 1.04 to 3.71, p=0.038).

CONCLUSIONS

CT and NG were frequent but syphilis was very infrequent in MSM using HIV PrEP in West Africa. HIV programme managers should integrate STI services into PrEP programmes.

Pre-exposure prophylaxis against HIV infection

Pre-exposure prophylaxis (PrEP) decreases the risk for HIV transmission in high-risk populations. PrEP has been available in Denmark since 2019 and consists of antiretroviral drugs in a combination tablet taken daily or on demand. The effect of this prophylaxis in Denmark is summarized in the review. PrEP is indicated in men and transgender persons with unprotected anal intercourse with multiple male partners in the latest 12 weeks or recent diagnoses of syphilis, chlamydia, or gonorrhoea. PrEP is provided by infectious disease specialists. Continued implementation could significantly reduce HIV transmission and potentially end the epidemic in Denmark.

The impact of socio-environmental factors on doxycycline post-exposure prophylaxis awareness in the US: a cross-sectional study

Background We investigated awareness and use of doxycycline post-exposure prophylaxis (doxyPEP) in the US. DoxyPEP has preventative benefits for bacterial STIs among people assigned male at birth. We considered how individual, interpersonal and social determinants of health, such as state-level LGBTQ equality, impact doxyPEP awareness. Methods We conducted an online snapshot cross-sectional survey in June 2023. Survey questions included demographics, sexual and substance use behaviours, and socio-environmental factors, and provided a short explanation of doxyPEP, with questions regarding prior awareness and use. Results Among a racially diverse sample of 196 participants (median age 33 years), 94% identified as cisgender men, 26% were aware of doxyPEP, whereas only 14 (7%) had ever used it. Factors significantly associated with awareness included being college educated (OR 2.50, 95% CI 1.09-5.74), a past year bacterial STI (OR 4.20, 95% CI 1.97-8.89), having discussed HIV pre-exposure prophylaxis with a health care provider (OR 3.88, 95% CI 1.99-7.57) and having taken HIV pre-exposure prophylaxis (OR 2.29, 95% CI 1.11-4.70). Socio-environmental factors associated with doxyPEP awareness included living in a large urban city (OR 2.14, 95% CI 1.12-4.10) and living in a state with higher levels of LGBTQ policy equality (OR 2.18, 95% CI 1.07-4.44). Conclusions Considering the disproportionate impact of bacterial STIs on men who have sex with men, especially those living in lower LGBTQ equality regions, such as the Southern US, our study emphasises how socio-environmental factors may limit awareness and uptake of novel biomedical approaches that have the potential to prevent morbidity and enhance sexual health.

Phase transforming in situ gels for sustained and controlled transmucosal drug delivery via the intravaginal route

Direct, reliable, controlled, and sustained drug delivery to female reproductive tract (FRT) remains elusive, with conventional dosage forms falling way short of the mark, leading to premature leakage, erratic drug delivery, and loss of compliance. Historically, the intravaginal route remains underserved by the pharmaceutical sector. To comprehensively address this, we turned our focus to phase-transforming sol-gels, using poloxamers, a thermosensitive polymer and, doxycycline (as hyclate salt, DOXH) as our model agent given its potential use in sexually transmitted infections (STIs). We further enhanced mucoadhesiveness through screening of differing viscosity grade hydroxypropyl methyl celluloses (HPMCs). The optimised sol-gels remained gelled at body temperature (<37 °C) and were prepared in buffer aligned to vaginal cavity pH and osmolality. Lead formulations were progressed based on their ability to retain key rheological properties, and acidic pH in the presence of simulated vaginal fluid (SVF). From a shelf-life perspective, DOXH stability, gelation temperature (Tsol-gel), and pH to three months (2-8 °C) was attained. In summary, the meticulously engineered, phase-transforming sol-gels provided sustained mucoretention despite dilution by vaginal fluid, paving the way for localised antimicrobial drug delivery at concentrations that potentially far exceed the minimum inhibitory concentration (MIC) for target STI-causing bacteria of the FRT.

Doxycycline post-exposure prophylaxis for sexually transmitted infections impacts the gut antimicrobial resistome

Doxycycline post-exposure prophylaxis (doxy-PEP) reduces bacterial sexually transmitted infections (STIs) among men who have sex with men and transgender women. While poised for widespread clinical implementation, the impact of doxy-PEP on antimicrobial resistance remains a primary concern as its effects on the gut microbiome and resistome, or the antimicrobial resistance genes (ARGs) present in the gut microbiome, are unknown. To investigate these effects, we studied participants from a randomized clinical trial who either received doxy-PEP as a one-time doxycycline 200 mg taken after condomless sex (DP arm, n = 100) or standard of care treatment (SOC arm, n = 50). From self-collected rectal swabs at enrollment (day-0) and after 6 months (month-6), we performed metagenomic DNA sequencing (DNA-seq) or metatranscriptomic RNA sequencing (RNA-seq). DNA-seq data was analyzable from 127 samples derived from 89 participants, and RNA-seq data from 86 samples derived from 70 participants. We compared the bacterial microbiome and resistome between the two study arms and over time. Tetracycline ARGs were detected in all day-0 DNA-seq samples and 85% of day-0 RNA-seq samples. The proportional mass of tetracycline ARGs in the resistome increased between day-0 and month-6 in DP participants from 46-51% in the metagenome (p = 0.02) and 4-15% in the metatranscriptome (p < 0.01), but no changes in other ARG classes were observed. Exposure to a higher number of doxycycline doses correlated with proportional enrichment of tetracycline ARGs in the metagenome (Spearman's ρ = 0.23, p < 0.01) and metatranscriptome (Spearman's ρ = 0.55, p < 0.01). Bacterial microbiome alpha diversity, beta diversity, and total bacterial mass did not differ between day-0 and month-6 samples from DP participants when assessed by either DNA-seq or RNA-seq. In an abundance-based correlation analysis, we observed an increase over time in the strength of the correlation between tetracycline ARGs and specific bacterial taxa, including some common human pathogens. In sum, doxy-PEP use over a 6-month period was associated with an increase in the proportion of tetracycline ARGs comprising the gut resistome, and an increase in the expression of tetracycline ARGs. Notably, doxy-PEP did not significantly alter alpha diversity or taxonomic composition of the gut microbiome, and did not demonstrate significant increases in non-tetracycline ARG classes. Further studies and population level surveillance are needed to understand the implications of these findings as doxy-PEP is implemented as a public health strategy.

Four recent insights suggest the need for more refined methods to assess the resistogenicity of doxycycline post exposure prophylaxis

Two recently published randomized trials of doxycycline post exposure prophylaxis (PEP) have concluded that this intervention is highly effective at reducing the incidence of bacterial sexually transmitted infections (STIs) and has little or no risk of promoting the spread of antimicrobial resistance (AMR). In this perspective piece, we review four types of evidence that suggest that the risk of promoting AMR has been inadequately assessed in these studies. 1) The studies have all used proportion resistant as the outcome measure. This is a less sensitive measure of resistogenicity than MIC distribution. 2) These RCTs have not considered population-level pathways of AMR selection. 3) In populations with very high antimicrobial consumption such as PrEP cohorts, the relationship between antimicrobial consumption and resistance may be saturated. 4) Genetic linkage of AMR means that increased tetracycline use may select for AMR to not only tetracyclines but also other antimicrobials in STIs and other bacterial species. We recommend novel study designs to more adequately assess the AMR-inducing risk of doxycycline PEP.

45 years of tetracycline post exposure prophylaxis for STIs and the risk of tetracycline resistance: a systematic review and meta-analysis

There is considerable interest in the use of doxycycline post exposure prophylaxis (PEP) to reduce the incidence of bacterial sexually transmitted infections (STIs). An important concern is that this could select for tetracycline resistance in these STIs and other species. We searched PubMed and Google Scholar, (1948-2023) for randomized controlled trials comparing tetracycline PEP with non-tetracycline controls. The primary outcome was antimicrobial resistance (AMR) to tetracyclines in all bacterial species with available data. Our search yielded 140 studies, of which three met the inclusion criteria. Tetracycline PEP was associated with an increasedprevalence of tetracycline resistance in Neisseria gonorrhoeae, but this effect was not statistically significant (Pooled OR 2.3, 95% CI 0.9-3.4). PEP had a marked effect on the N. gonorrhoeae tetracycline MIC distribution in the one study where this was assessed. Prophylactic efficacy was 100% at low MICs and 0% at high MICs. In the one study where this was assessed, PEP resulted in a significant increase in tetracycline resistance in commensal Neisseria species compared to the control group (OR 2.9, 95% CI 1.5-5.5) but no significant effect on the prevalence of tetracycline resistance in Staphylococcus aureus. The available evidence suggests that PEP with tetracyclines could be associated with selecting tetracycline resistance in N. gonorrhoeae and commensal Neisseria species.

Position statement of the German STI Society on the prophylactic use of doxycycline to prevent STIs (Doxy-PEP, Doxy-PrEP)

Over the past two decades, there has been a rise in the incidence of syphilis, particularly among men who have sex with men (MSM). This has sparked interest in studying the prophylactic use of doxycycline to prevent syphilis and other sexually transmitted infections (STIs), commonly referred to as Doxycycline Pre- or Post-Exposure Prophylaxis (Doxy-PrEP, Doxy-PEP). At the same time, demand from potential users for this preventive measure is increasing. Several randomized controlled trials have demonstrated that the prophylactic use of doxycycline in MSM and trans women using HIV pre-exposure prophylaxis (HIV-PrEP) or living with an HIV infection effectively reduces the risk of syphilis and chlamydia infections. At present, however, unresolved questions remain, particularly regarding implications of a broad implementation of prophylactic doxycycline to prevent STIs on tetracycline and other antimicrobial resistance in bacterial STIs, non-STI-related bacterial pathogens, and the microbiome. In response to the increasing demand and the challenge of balancing effectiveness, safety, and the risk of promoting antibiotic resistance, the German STI Society (DSTIG) has issued a position statement, providing specific recommendations regarding potential indications, criteria, and occasions for the use of doxycycline in STI prevention. These recommendations are based on current evidence and expert opinion.