Doxycycline post-exposure prophylaxis for prevention of sexually transmitted infections among Kenyan women using HIV pre-exposure prophylaxis: study protocol for an open-label randomized trial

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.

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.

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.

Pharmacokinetics of single dose doxycycline in the rectum, vagina, and urethra: implications for prevention of bacterial sexually transmitted infections

BACKGROUND

Clinical trials showed a single oral dose of doxycycline taken after sex protects against STIs among men who have sex with men (MSM) but not women. Pharmacokinetic data at vaginal, rectal and penile sites of STI exposure are lacking. We examined vaginal, rectal and urethral doxycycline concentrations in men and women to better inform STI prevention.

METHODS

Doxycycline pharmacokinetics in male and female participants 18-59 years of age were evaluated in blood and urine and on rectal and vaginal swabs collected at 1, 2, 4, 8, 24, 48, 72, 96 and 168 h after receiving a 200 mg oral doxycycline dose in a non-randomised single dose open label single centre study in Atlanta, Georgia. Rectal, vaginal, and cervical biopsies and male urethral swabs were collected 24 h after dosing (Trial registration: NCT04860505). Doxycycline was measured by liquid chromatography-mass spectrometry.

FINDINGS

Eleven male and nine female participants participated in the study. Doxycycline concentrations on rectal and vaginal swabs collected up to 96 h after dosing were approximately twice those of plasma and remained above minimum inhibitory concentrations (MICs) for at least four, three, and two days for Chlamydia trachomatis, Treponema pallidum, and tetracycline-sensitive Neisseria gonorrhoeae, respectively. Geometric mean doxycycline concentrations in male urethral secretions (1.166 μg/mL; 95% CI 0.568-2.394 μg/mL), male rectal (0.596 μg/g; 0.442-0.803 μg/g), vaginal (0.261 μg/g; 0.098-0.696 μg/g) and cervical tissue (0.410 μg/g; 0.193-0.870 μg/g) in biopsies collected 24 h after dosing exceeded MICs. Plasma and urine doxycycline levels defined adherence markers up to four and seven days postdosing, respectively. No adverse events were reported in this study.

INTERPRETATION

Doxycycline efficiently distributes to the rectum, vagina and urethra. Findings can help explain efficacy of STI prevention by doxycycline.

FUNDING

Funded by CDC intramural funds, CDC contract HCVJCG-2020-45044 (to CFK).

Stellungnahme der Deutschen STI-Gesellschaft zur antibiotischen STI-Prophylaxe mit Doxycyclin (Doxy-PEP, Doxy-PrEP): Position Statement of the German STI Society on the Prophylactic Use of Doxycycline to Prevent STIs (Doxy-PEP, Doxy-PrEP)

Seit etwa zwei Jahrzehnten ist eine Zunahme der Syphilisinzidenz zu beobachten, insbesondere unter Männern, die Sex mit Männern haben (MSM). Diese Entwicklung hat zu einem wachsenden Interesse an Studien zur prophylaktischen Anwendung des Antibiotikums Doxycyclin zur Vermeidung von Syphilisinfektionen und anderen sexuell übertragbaren Infektionen (STI), international meist als Doxycyclin‐Prä‐ beziehungsweise Post‐Expositionsprophylaxe (Doxy‐PrEP, Doxy‐PEP) bezeichnet, geführt. Zugleich steigt die Nachfrage seitens potenzieller Nutzer nach dieser präventiven Maßnahme.

Mehrere randomisierte kontrollierte Studien haben gezeigt, dass die prophylaktische Anwendung von Doxycyclin bei MSM und Trans‐Frauen mit HIV‐PrEP‐Gebrauch oder bekannter HIV‐Infektion das Risiko einer Syphilis‐ und Chlamydien‐Infektion wirksam reduziert. Zum gegenwärtigen Zeitpunkt bestehen jedoch noch offene Fragen, insbesondere hinsichtlich der möglichen Auswirkungen einer breiten Anwendung der antibiotischen STI‐Prophylaxe mit Doxycyclin auf Tetrazyklin‐ und andere antimikrobielle Resistenzen bei bakteriellen STI, anderen bakteriellen Pathogenen und Bakterien des Mikrobioms.

Angesichts der steigenden Nachfrage und der Herausforderung, eine Abwägung zwischen Wirksamkeit, Sicherheit und dem Risiko der Förderung von Antibiotikaresistenzen vorzunehmen, hat die Deutsche STI‐Gesellschaft (DSTIG) die vorliegende Stellungnahme erarbeitet. Diese enthält spezifische Empfehlungen zu potenziellen Indikationen, Kriterien und Anlässen für den Einsatz von Doxycyclin zur Prävention von STI. Die Empfehlungen basieren auf aktuellen Studienergebnissen und der Meinung von Fachpersonen.

Modelling of doxycycline-based prevention of bacterial sexually transmitted infections in comparison to condom-based and test-based prevention

Background

Doxycycline-based prevention of bacterial sexually transmitted infections (STIs) has been assessed in various studies and has been recommended by the European AIDS Clinical Society to be proposed to persons with repeated STIs on a case-by-case basis. However, while good preventive effects could be shown for Chlamydia trachomatis and Treponema pallidum in Europe, no reliable prevention against doxycycline resistance-affected bacterial causes of STIs like Neisseria gonorrhoeae and Mycoplasma genitalium was confirmed.

Methods

In a modelling-approach, we assessed potential beneficial effects even against the latter microorganisms in case of optimized adherence with doxycycline prevention. These effects were modelled for Germany in comparison to traditional prevention schemes like condom-based STI-prevention and testing-as-prevention.

Results

With estimated risk reduction in the ranges of 86% for N. gonorrhoeae and of 82% for Mycoplasma genitalium, expectable preventive efficacy similar to alternative preventive approaches could be calculated in case of optimized adherence with doxycycline prevention. In case of repeated risk exposure, the preventive potential of condom-based prevention was decreased compared to both optimized doxycycline prevention and testing-as-prevention.

Conclusions

As suggested by the applied modelling, the preventive effect of optimized doxycycline prevention against bacterial STIs is in a similar range, like other common prevention strategies.

Doxycycline Prophylaxis to Prevent Sexually Transmitted Infections in Women

BACKGROUND

Doxycycline postexposure prophylaxis (PEP) has been shown to prevent sexually transmitted infections (STIs) among cisgender men and transgender women, but data from trials involving cisgender women are lacking.

METHODS

We conducted a randomized, open-label trial comparing doxycycline PEP (doxycycline hyclate, 200 mg taken within 72 hours after condomless sex) with standard care among Kenyan women 18 to 30 years of age who were receiving preexposure prophylaxis against human immunodeficiency virus (HIV). The primary end point was any incident infection with Chlamydia trachomatis, Neisseria gonorrhoeae, or Treponema pallidum. Hair samples were collected quarterly for objective assessment of doxycycline use.

RESULTS

A total of 449 participants underwent randomization; 224 were assigned to the doxycycline-PEP group and 225 to the standard-care group. Participants were followed quarterly over 12 months. A total of 109 incident STIs occurred (50 in the doxycycline-PEP group [25.1 per 100 person-years] and 59 in the standard-care group [29.0 per 100 person-years]), with no significant between-group difference in incidence (relative risk, 0.88; 95% confidence interval [CI], 0.60 to 1.29; P = 0.51). Among the 109 incident STIs, chlamydia accounted for 85 (78.0%) (35 in the doxycycline-PEP group and 50 in the standard-care group; relative risk, 0.73; 95% CI, 0.47 to 1.13). No serious adverse events were considered by the trial investigators to be related to doxycycline, and there were no incident HIV infections. Among 50 randomly selected participants in the doxycycline-PEP group, doxycycline was detected in 58 of 200 hair samples (29.0%). All N. gonorrhoeae-positive isolates were resistant to doxycycline.

CONCLUSIONS

Among cisgender women, the incidence of STIs was not significantly lower with doxycycline PEP than with standard care. According to hair-sample analysis, the use of doxycycline PEP among those assigned to receive it was low. (Funded by the National Institutes of Health; dPEP ClinicalTrials.gov number, NCT04050540.).

A patient with secondary syphilis following incomplete treatment of primary infection

Syphilis is a bacterial infection caused by Treponema pallidum and is primarily transmitted via skin-to-skin or mucosal contact during sexual encounters, or through vertical transmission during pregnancy. Cases continue to rise globally across various demographic groups despite effective treatment and prevention interventions. We discuss the case of a 28-year-old cisgender man who presented with secondary syphilis 1 month after being inadequately treated for primary syphilis. Individuals can present with symptoms and signs of syphilis to clinicians of various subspecialties due to diverse clinical presentation. All health-care providers should be able to identify the common and less common manifestations of this infection, and adequate treatment and follow-up are crucial to preventing serious sequelae. Novel biomedical prevention interventions, such as doxycycline post-exposure prophylaxis, are on the horizon.

Challenges and Solutions to STI Control in the Era of HIV and STI Prophylaxis

PURPOSE OF REVIEW

This article reviews current efforts to control bacterial sexually transmitted infections (STIs) among HIV pre-exposure prophylaxis (PrEP) users and outlines the opportunities and challenges to controlling STIs within HIV PrEP programs.

RECENT FINDINGS

The incidence of STIs continues to rise globally especially among HIV PrEP users, with an estimated 1 in 4 PrEP users having a curable bacterial STI. STIs and HIV comprise a syndemic needing dual interventions. The majority of STIs are asymptomatic, and when testing is available, many STIs occur in extragenital sites that are missed when relying on urine testing or genital swabs. Optimal testing and treatment, including testing for antimicrobial resistance, pose difficulties in high income countries and is essentially non-existent in most low- and middle-income countries. Novel STI primary prevention strategies, like doxycycline post-exposure prophylaxis (PEP) for STI prevention, have proven to be highly efficacious in some populations. A few jurisdictions have issued normative guidelines and position statements for doxycycline PEP; however, clinical standards for implementation and data on public health impact are limited. STI incidence rates are high and rising in sexually active populations. Sexual health programs should leverage the expansion of HIV PrEP delivery services to integrate STI testing, surveillance, and novel STI prevention services.

Doxycycline PEP can induce doxycycline resistance in Klebsiella pneumoniae in a Galleria mellonella model of PEP

Background

Four randomized controlled trials have now established that doxycycline post exposure (sex) prophylaxis (PEP) can reduce the incidence of chlamydia and syphilis in men who have sex with men. These studies have concluded that the risk of selecting for antimicrobial resistance is low. We evaluated this risk in vitro and in vivo using a Galleria mellonella infection model.

Methods

We evaluated how long it took for doxycycline resistance to emerge during passage on doxycycline containing agar plates in 4 species - Escherichia coli, Klebsiella pneumoniae, Neisseria gonorrhoeae and Neisseria subflava. We then assessed if K. pneumoniae could acquire resistance to doxycycline (and cross resistance to other antimicrobials) during intermittent exposure to doxycycline in a Galleria mellonella model of doxycycline PEP.

Results

In our passage experiments, we found that resistance first emerged in K. pneumoniae. By day 7 the K. pneumoniae MIC had increased from 2 mg/L to a median of 96 mg/L (IQR 64-96). Under various simulations of doxycycline PEP in the G. mellonella model, the doxycycline MIC of K. pneumoniae increased from 2 mg/L to 48 mg/L (IQR 48-84). Ceftriaxone and ciprofloxacin MICs increased over ten-fold. Whole genome sequencing revealed acquired mutations in ramR which regulates the expression of the AcrAB-TolC efflux pump.

Conclusion

Doxycycline PEP can select for doxycycline, ceftriaxone and ciprofloxacin resistance in K. pneumoniae in a G. mellonella model. The emergent ramR mutations were similar to those seen in circulating strains of K. pneumoniae. These findings suggest that we need to assess the effect of doxycycline PEP on resistance induction on a broader range of bacterial species than has hitherto been the case.

Predominance of High-Level Tetracycline-Resistant Neisseria gonorrhoeae in Kenya: Implications for Global Implementation of Doxycycline Postexposure Prophylaxis for Prevention of Sexually Transmitted Infections

ABSTRACT

Using archived Neisseria gonorrhoeae samples from 2008 to 2012, the prevalence of tet (M) genemediating high-level tetracycline resistance in N. gonorrhoeae was 96% among 50 Kenyan women. Determining the local and national prevalence of gonococcal tetracycline resistance and surveillance of gonococcal antimicrobial resistance can inform the implementation of doxycycline postexposure prophylaxis for STI prevention.

Sexually Transmitted Infections in Older Adults: Increasing Tide and How to Stem It

Sexually transmitted infections (STIs) have been increasing in older adults. Sexual health remains an important part of overall health care at any age. There are several barriers and facilitators to addressing sexual health in this population. Changes attributable to normal physiologic aging as well as sexual dysfunction can affect sexuality in older adults. When it comes to preventing STIs, combination prevention strategies remain applicable in older adults. Addressing sexual health using a tailored approach is critical to stem the tide of increasing STIs rates in older adults.

Acceptability and feasibility of leveraging community-based HIV counselling and testing platforms for same-day oral PrEP initiation among adolescent girls and young women in Eastern Cape, South Africa

INTRODUCTION

Community-based delivery of HIV pre-exposure prophylaxis (PrEP) to South African adolescent girls and young women's (AGYW) could increase access but needs evaluation. We integrated PrEP services via home-based services and pop-up tents into existing community-based HIV testing services (CB-HTS) in Eastern Cape Province, South Africa.

METHODS

After accessing CB-HTS via a "pop-up" tent or home-based services, HIV-negative AGYW aged 16-25 years were invited to complete a baseline questionnaire and referred for PrEP services at a community-based PrEP site co-located with pop-up HTS tents. A 30-day supply of PrEP was dispensed. PrEP uptake, time-to-initiation, cohort characteristics and first medication refill within 90 days were measured using descriptive statistics.

RESULTS

Of the 1164 AGYW who tested for HIV, 825 (74.3%) completed a questionnaire and 806 (97.7%) were referred for community-based PrEP. Of those, 624 (77.4%) presented for PrEP (482/483 [99.8%] from pop-up HTS and 142/323 [44.0%] from home-based HTS), of which 603 (96.6%) initiated PrEP. Of those initiating PrEP following home-based HTS, 59.1% initiated within 0-3 days, 25.6% within 4-14 days and 15.3% took ≥15 days to initiate; 100% of AGYW who used pop-up HTS initiated PrEP the same day. Among AGWY initiating PrEP, 37.5% had a detectable sexually transmitted infection (STI). Although AGYW reported a low self-perception of HIV risk, post-hoc application of HIV risk assessment measures to available data classified most study participants as high risk for HIV acquisition. Cumulatively, 329 (54.6%) AGYW presented for a first medication refill within 90 days of accepting their first bottle of PrEP.

CONCLUSIONS

Leveraging CB-HTS platforms to provide same-day PrEP initiation and refill services was acceptable to AGYW. A higher proportion of AGYW initiated PrEP when co-located with CB-HTS sites compared to those referred following home-based HTS, suggesting that proximity of CB-HTS and PrEP services facilitates PrEP uptake among AGYW. The high prevalence of STIs among those initiating PrEP necessitates the integration of STI and HIV prevention programs for AGYW. Eligibility for PrEP initiation should not be required among AHYW in high HIV burden communities. Community-based service delivery will be crucial to maintaining access to PrEP services during the COVID-19 pandemic and future health and humanitarian emergencies.