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

Efficacy of Doxycycline as Preexposure and/or Postexposure Prophylaxis to Prevent Sexually Transmitted Diseases: A Systematic Review and Meta-Analysis

INTRODUCTION

Bacterial sexually transmitted infections (STIs), specifically infection by Chlamydia trachomatis , Neisseria gonorrhoeae , and Treponema pallidum , have an important burden worldwide. The use of doxycycline as preexposure prophylaxis (PREP or doxy-PREP) or postexposure prophylaxis (PEP or doxy-PEP) might be effective as prophylaxis because it is effective against C. trachomatis and T. pallidum .

AIMS

Our objective was to evaluate the efficacy of doxycycline as PREP or PEP against bacterial STIs ( C. trachomatis , N. gonorrhoeae , and T. pallidum ).

METHODS

A systematic review and meta-analysis of randomized clinical trials of a high-risk group of individuals was conducted to evaluate whether doxycycline is as effective as PREP or PEP in preventing bacterial STIs. The PubMed-MEDLINE (MEDlars online), Cohrane, Scientific Electronic Library Online (SciELO), and Latin America and the Caribbean Literature on Health Sciences ( Literatura Latino-Americana e do Caribe em Ciências da Saúde -LILACS) databases were searched for randomized clinical trials published up to March 2024. Data were extracted from published reports. Hazard ratios (HRs) and risk ratios (RRs) with 95% confidence interval (CI) were pooled across trials.

MAIN OUTCOME MEASURE

The primary end points were any incidence of bacterial STIs and individual STI infections.

RESULTS

A total of 4 studies were included in the analysis, 3 of which evaluated doxy-PEP and 1 evaluated doxy-PREP. In the doxy-PEP group, a total of 1182 participants were evaluated. In the pooled analysis of doxy-PEP studies, the incidence of the first STI was lower in the doxy-PEP group (HR, 0.538 [95% CI, 0.337-0.859]; I2 = 77%; P < 0.05). Regarding individual infections, only 2 studies were included. In the doxy-PEP group, the incidence of individual infection of C. trachomatis was lower compared with controls (RR, 0.291 [95% CI, 0.093-0.911]) ( I2 = 89%; P < 0.05). Because only one study evaluated doxy-PREP, it was not possible to calculate a meta-analysis index; however, the use of doxycycline as PREP was associated with a decrease in the rate of any STI.

CONCLUSIONS

The use of doxy-PEP might reduce the first STI, mainly C. trachomatis , if used within 72 hours after condomless sex. The use of doxy-PREP might also decrease the chance of any STI; however, only 1 study was evaluated.

Review of doxycycline for prophylaxis of sexually transmitted infections

The surging rates of STIs necessitate medical practitioners in the appropriate specialties to focus on rapid recognition, treatment and prevention of these conditions. Through both pre- and post-exposure prophylaxis with doxycycline, dermatologists can provide up-to-date treatment in the field of venereology. Herein, we review the results of clinical trials in the available literature that investigate doxycycline prophylaxis in the prevention of bacterial STIs. A search was performed using the PubMED and Scopus databases which yielded six clinical trials for our review. Based on the results of these clinical trials, doxycycline prophylaxis offers significant reductions in bacterial STIs, specifically in men who have sex with men (MSM). Additional research is needed in other high-risk groups, including females. Moreover, additional research is needed to determine the effects of doxycycline prophylaxis on tetracycline resistance in STI-causing bacteria. As the utilization of doxycycline prophylaxis for STIs becomes more common, it is important that dermatologists become familiar with the data surrounding this prevention regimen and patient populations who may seek to know more about it. More research is needed to determine benefits in other subpopulations, antimicrobial resistance and cost effectiveness.

Doxycycline Post-Exposure Prophylaxis for Bacterial Sexually Transmitted Infections: The Current Landscape and Future Directions

PURPOSE OF REVIEW

The incidence of bacterial sexually transmitted infections (STI) continues to rise particularly among men who have sex with men (MSM). Doxycycline post-exposure prophylaxis (doxy-PEP) has emerged as a promising biomedical prevention strategy. This review aims to summarize the results of recent studies, highlight the current normative guidance on the use of doxy-PEP, and discuss remaining questions.

RECENT FINDINGS

In the past decade, there have been four randomized controlled trials and three real-world analyses of doxy-PEP, which consistently demonstrated a reduction in Chlamydia trachomatis and Treponema pallidum infections among MSM. Questions remain regarding the efficacy of doxy-PEP for Neisseria gonorrhoeae infection and among cisgender women. Possible detrimental impacts include an increase in antimicrobial resistance as well as alterations to the gut microbiome Doxy-PEP is an effective strategy for preventing Chlamydia trachomatis and Treponema pallidum among MSM. Further work is needed to investigate the benefits among other populations, as well as to monitor for adverse effects.

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.

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.

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).

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.).

Doxycycline postexposure prophylaxis for prevention of sexually transmitted infections

Doxycycline postexposure prophylaxis (doxy-PEP) is a novel strategy now demonstrated in several clinical trials to dramatically reduce incidence rates of gonorrhea, chlamydia, and syphilis in some key populations at high risk of sexually transmitted infections. Even so, much remains unknown about the long-term consequences of doxy-PEP, and several concerns, including the potential for the development of antibiotic resistance and disturbances to the microbiome, balance the benefits. This review highlights the history of antibiotic prophylaxis for sexually transmitted infections, and the rationale, current evidence, and future directions for doxy-PEP.

A Genomic Perspective on the Near-term Impact of Doxycycline Post-exposure Prophylaxis on Neisseria gonorrhoeae Antimicrobial Resistance

Pre-existing tetracycline resistance in Neisseria gonorrhoeae limits the effectiveness of post-exposure prophylaxis (PEP) with doxycycline against gonorrhea, and selection for tetracycline resistance may influence prevalence of multi-drug resistant strains. Using genomic and antimicrobial susceptibility data from N. gonorrhoeae, we assessed the near-term impact of doxycycline PEP on N. gonorrhoeae resistance.

Resistance and prevalence implications of doxycycline post-exposure prophylaxis for gonorrhea prevention in men who have sex with men: a modeling study

Background

Doxycycline post-exposure prophylaxis (DoxyPEP) has demonstrated efficacy for prevention of bacterial sexually transmitted infections. To inform policy decisions on the use of DoxyPEP for gonorrhea prevention, we used a mathematical model to investigate its impact on resistance dynamics and the burden of infection in men who have sex with men (MSM).

Methods and Findings

Using a deterministic compartmental model of gonorrhea transmission in an MSM population, we introduced DoxyPEP at various uptake levels (10-75%) and compared 20-year prevalence and resistance dynamics relative to those at baseline (i.e., no DoxyPEP introduction). Uptake of DoxyPEP resulted in initial drops in the prevalence and incidence of gonorrhea infection, but also accelerated the spread of doxycycline resistance, with increasing DoxyPEP use driving steeper initial declines followed by faster spread of resistance. This resulted in the total loss of DoxyPEP's clinical efficacy within 1-2 decades in almost all scenarios explored. The magnitude by which DoxyPEP initially reduced the prevalence of infection was constrained by the extent of pre-existing doxycycline resistant strains in the population. De novo emergence of doxycycline resistance did not influence these dynamics. Additionally, the implementation of DoxyPEP had minimal impact on extending the clinically useful lifespan of ceftriaxone monotherapy.

Conclusions

Model findings suggest DoxyPEP can be an effective but short-term solution for reducing the burden of gonorrhea infection, as its selection for doxycycline-resistant strains results in loss of its prophylaxis benefit. Increasing levels of DoxyPEP uptake and higher starting prevalence of doxycycline resistance resulted in faster loss of its efficacy and had little change on extending the clinical lifespan of ceftriaxone for treatment of N. gonorrhoeae infections.

A genomic perspective on the near-term impact of doxycycline post-exposure prophylaxis on Neisseria gonorrhoeae antimicrobial resistance

Post-exposure prophylaxis with doxycycline (doxyPEP) is being introduced to prevent bacterial sexually transmitted infections (STIs). Pre-existing tetracycline resistance in Neisseria gonorrhoeae limits doxyPEP effectiveness against gonorrhea, and selection for tetracycline resistant lineages may influence prevalence of resistance to other antimicrobials via selection for multi-drug resistant strains. Using genomic and antimicrobial susceptibility data from 5,644 clinical isolates of N. gonorrhoeae , we assessed the near-term impact of doxyPEP on N. gonorrhoeae antimicrobial resistance. We found that the impact on antimicrobial resistance is likely to be influenced by the strength of selection for plasmid-encoded and chromosomally-encoded tetracycline resistance, as isolates with high-level, plasmid-encoded resistance had lower minimum inhibitory concentrations to other antimicrobials compared to isolates with low-level tetracycline resistance. The impact of doxyPEP may differ across demographic groups and geographic regions within the United States due to variation in pre-existing tetracycline resistance.