Treatment efficacy of azithromycin 1 g single dose versus doxycycline 100 mg twice daily for 7 days for the treatment of rectal chlamydia among men who have sex with men - a double-blind randomised controlled trial protocol

Effectiveness of doxycycline 100 mg twice daily for 7 days and azithromycin 1 g single dose for the treatment of rectal Chlamydia trachomatis infection among men who have sex with men

OBJECTIVES

To compare the effectiveness of doxycycline 100 mg twice daily for 7 days and azithromycin 1 g single dose for the treatment of rectal Chlamydia trachomatis infection among MSM in a real clinical setting.

METHODS

A prospective study was performed to compare the effectiveness of doxycycline and azithromycin for the treatment of rectal C. trachomatis among MSM in Tokyo, Japan. Subjects diagnosed with rectal C. trachomatis infection were treated and test-of-cure examination (TOC) was performed at least 3 weeks after the treatment. Treatment of rectal C. trachomatis infection was decided prospectively in a time-dependent manner; in the period between January 2017 and October 2018, azithromycin was administered to all subjects, whereas from October 2018 through March 2020, doxycycline was administered to all subjects. Effectiveness of these treatments was calculated by the number of rectal C. trachomatis-negative subjects at TOC divided by the number of subjects treated.

RESULTS

Two hundred and ninety-six MSM with rectal C. trachomatis infection were treated with azithromycin (80 patients) and doxycycline (216 patients) in a time-dependent manner. Of the 296 MSM, 274 (92.6%) were treated successfully [67 (83.7%, 95% CI = 79.6%-87.9%) in the azithromycin group versus 207 (95.8%, 95% CI = 94.5%-97.2%) in the doxycycline group, P < 0.001]. To evaluate factors associated with treatment failure, we performed logistic regression analysis. In univariate and multivariate analysis, only doxycycline treatment was inversely associated with treatment failure (OR = 0.29, 95% CI = 0.084-0.976, P = 0.046).

CONCLUSIONS

The treatment with doxycycline 100 mg twice daily for 7 days was superior to that with azithromycin 1 g single dose for rectal C. trachomatis among MSM in a real-world setting.

Azithromycin or Doxycycline for Asymptomatic Rectal Chlamydia trachomatis

BACKGROUND

Rectal chlamydia is a common bacterial sexually transmissible infection among men who have sex with men. Data from randomized, controlled trials are needed to guide treatment.

METHODS

In this double-blind trial conducted at five sexual health clinics in Australia, we randomly assigned men who have sex with men and who had asymptomatic rectal chlamydia to receive doxycycline (100 mg twice daily for 7 days) or azithromycin (1-g single dose). Asymptomatic chlamydia was selected as the trial focus because more than 85% of men with rectal chlamydia infection are asymptomatic, and clinical guidelines recommend a longer treatment course for symptomatic infection. The primary outcome was a negative nucleic acid amplification test for rectal chlamydia (microbiologic cure) at 4 weeks.

RESULTS

From August 2016 through August 2019, we enrolled 625 men (314 in the doxycycline group and 311 in the azithromycin group). Primary outcome data were available for 290 men (92.4%) in the doxycycline group and 297 (95.5%) in the azithromycin group. In the modified intention-to-treat population, a microbiologic cure occurred in 281 of 290 men (96.9%; 95% confidence interval [CI], 94.9 to 98.9) in the doxycycline group and in 227 of 297 (76.4%; 95% CI, 73.8 to 79.1) in the azithromycin group, for an adjusted risk difference of 19.9 percentage points (95% CI, 14.6 to 25.3; P<0.001). Adverse events that included nausea, diarrhea, and vomiting were reported in 98 men (33.8%) in the doxycycline group and in 134 (45.1%) in the azithromycin group (risk difference, -11.3 percentage points; 95% CI, -19.5 to -3.2).

CONCLUSIONS

A 7-day course of doxycycline was superior to single-dose azithromycin in the treatment of rectal chlamydia infection among men who have sex with men. (Funded by the National Health and Medical Research Council; RTS Australian New Zealand Clinical Trials Registry number, ACTRN12614001125617.).

Factors Associated With Early Resumption of Condomless Anal Sex Among Men Who Have Sex With Men After Rectal Chlamydia Treatment

BACKGROUND

The resumption of sexual activity shortly after commencing treatment for sexually transmitted infections (STIs) is poorly described despite contributing to onward transmission. With azithromycin remaining an option for rectal Chlamydia trachomatis, resuming sex too early after treatment may contribute to antimicrobial resistance because of exposure of newly acquired STIs to subinhibitory concentrations.

METHODS

Clinical and sexual behavioral data were collected from men participating in a trial assessing treatment efficacy for rectal chlamydia. Data were collected at recruitment and weekly for 3 weeks after commencing treatment. Outcome measures were resumption of any sexual activity or condomless receptive anal sex within 1, 2, or 3 weeks after commencing treatment. Generalized linear regression was used to calculate adjusted risk ratios (aRR) to identify associated factors.

RESULTS

Almost 1 in 10 men (9.5%; 95% confidence interval [CI], 7.2-12.1) resumed condomless receptive anal sex within 1 week of commencing treatment. This was associated with current preexposure prophylaxis use (aRR, 3.4; 95% CI, 2.5-4.8]) and having 9 or more sexual partners in the last 3 months (aRR, 3.2; 95% CI, 1.6-5.0). Most men (75.0%; 95% CI, 71.3-78.5) resumed any sexual activity within 3 weeks; this was associated with a greater number of sexual partners (4-8 partners; aRR, 1.2; 95% CI, 1.1-1.5; ≥9 partners; aRR, 1.5; 95% CI, 1.3-1.7).

CONCLUSIONS

Resuming condomless receptive anal sex early after treatment may facilitate onward transmission and promote antimicrobial resistance for STIs. Although azithromycin remains a treatment option, this analysis highlights the need for new health promotion messages regarding early resumption of sex and continued surveillance for antimicrobial resistance.

Doxycycline Versus Azithromycin for the Treatment of Rectal Chlamydia in Men Who Have Sex With Men: A Randomized Controlled Trial

BACKGROUND

Azithromycin and doxycycline are both recommended treatments for rectal Chlamydia trachomatis (CT) infection, but observational studies suggest that doxycycline may be more effective.

METHODS

This randomized, double-blind, placebo-controlled trial compared azithromycin (single one-gram dose) vs. doxycycline (100mg twice daily for seven days) for the treatment of rectal CT in men who have sex with men (MSM) in Seattle and Boston. Participants were enrolled after a diagnosis of rectal CT in clinical care and underwent repeated collection of rectal swabs for nucleic acid amplification testing (NAAT) at study enrollment, two weeks, and four weeks post-enrollment. The primary outcome was microbiologic cure (CT-negative NAAT) at four weeks. The complete case (CC) population included participants with a CT-positive NAAT at enrollment and a follow-up NAAT result; the intention-to-treat (ITT) population included all randomized participants.

RESULTS

Among 177 participants enrolled, 135 (76%) met CC population criteria for the four-week follow-up visit. Thirty-three participants (19%) were excluded because the CT NAAT repeated at enrollment was negative. Microbiologic cure was higher with doxycycline than azithromycin in both the CC population [100% (70 of 70) vs. 74% (48 of 65); absolute difference 26% (95% CI: 16-36%; p<0.001)] and the ITT population [91% (80 of 88) vs. 71% (63 of 89); absolute difference 20% (95% CI: 9-31%; p<0.001)].

CONCLUSIONS

A one-week course of doxycycline was significantly more effective than a single dose of azithromycin for the treatment of rectal CT in MSM. (Funded by National Institute of Allergy & Infectious Diseases contract HHSN272201300014I, Protocol 17-0092).

Azithromycin in the treatment of rectogenital Chlamydia trachomatis infections: end of an era?

INTRODUCTION

Azithromycin was recommended as the first-line therapeutic regimen for treatment of genital infections in men and women by the Centers for Disease Control in 1998. A series of studies of azithromycin for treatment of rectal chlamydial infection in men who have sex with men (MSM) found that azithromycin was significantly less effective than doxycycline.

AREAS COVERED

Literature on treatment of rectal C. trachomatis from 2000 through May 2020 was searched using PubMed. Retrospective and observational studies were identified documenting the frequency and treatment of rectal chlamydial infection in MSM, heterosexual men and women that reported lower efficacy of single-dose azithromycin compared to doxycycline. Literature on possible reasons for the lower efficacy were also reviewed including studies of antibiotic resistance, impact of organism load, and persistent infection in rectal specimens and pharmacokinetics and pharmacodynamics of azithromycin in rectal tissue.

EXPERT OPINION

The available data suggests that single-dose azithromycin is not as effective as azithromycin for the treatment of rectal infection in MSM and women. Most of these data have been retrospective or from observational studies. Final recommendations will depend on the outcome of prospective, randomized, treatment studies. We may also need to examine other dosage regimens for azithromycin.

Treatment Effectiveness of Azithromycin and Doxycycline in Uncomplicated Rectal and Vaginal Chlamydia trachomatis Infections in Women: A Multicenter Observational Study (FemCure)

Background

Rectal infections with Chlamydia trachomatis (CT) are prevalent in women visiting a sexually transmitted infection outpatient clinic, but it remains unclear what the most effective treatment is. We assessed the effectiveness of doxycycline and azithromycin for the treatment of rectal and vaginal chlamydia in women.

Methods

This study is part of a prospective multicenter cohort study (FemCure). Treatment consisted of doxycycline (100 mg twice daily for 7 days) in rectal CT–positive women, and of azithromycin (1 g single dose) in vaginally positive women who were rectally untested or rectally negative. Participants self-collected rectal and vaginal samples at enrollment (treatment time-point) and during 4 weeks of follow-up. The endpoint was microbiological cure by a negative nucleic acid amplification test at 4 weeks. Differences between cure proportions and 95% confidence intervals (CIs) were calculated.

Results

We analyzed 416 patients, of whom 319 had both rectal and vaginal chlamydia at enrollment, 22 had rectal chlamydia only, and 75 had vaginal chlamydia only. In 341 rectal infections, microbiological cure in azithromycin-treated women was 78.5% (95% CI, 72.6%–83.7%; n = 164/209) and 95.5% (95% CI, 91.0%–98.2%; n = 126/132) in doxycycline-treated women (difference, 17.0% [95% CI, 9.6%–24.7%]; P < .001). In 394 vaginal infections, cure was 93.5% (95% CI, 90.1%–96.1%; n = 246/263) in azithromycin-treated women and 95.4% (95% CI, 90.9%–98.2%; n = 125/131) in doxycycline-treated women (difference, 1.9% [95% CI, –3.6% to 6.7%]; P = .504).

Conclusions

The effectiveness of doxycycline is high and exceeds that of azithromycin for the treatment of rectal CT infections in women.

Clinical Trials Registration

NCT02694497.

High prevalence of coinfection of azithromycin-resistant Mycoplasma genitalium with other STIs: a prospective observational study of London-based symptomatic and STI-contact clinic attendees

OBJECTIVES

Azithromycin treatment of Chlamydia trachomatis (CT) may not be adequate to treat concomitant Mycoplasma genitalium (MG) infection, and particularly if MG has macrolide resistance-associated mutations (MG-MRAMs). We estimated prevalence of coinfections of CT with MG carrying MRAM, and risk factors for MG-MRAM among a sexual health clinic population.

STUDY DESIGN AND SETTING

Among symptomatic and STI-contact clinic attendees in London, prevalence of CT-MG coinfection and MG-MRAM were estimated using nucleic acid amplification testing and Sanger sequencing, respectively, and their associated risk factors analysed using logistic regression.

RESULTS

MG prevalence was 7.5% (23/307), 17.3% (30/173), and 11.4% (8/70) in females, men who have sex with women (MSW) and men who have sex with men (MSM), respectively; MG coinfection in CT-infected participants represented 28.0% (7/25), 13.5% (5/37), 0.0% (0/0), respectively. Presence of MG-MRAM was 39.1% (9/23) in female swabs, 70.0% (21/30) in MSW urine and 83.3% (5/6) in MSM rectal swabs. In multivariate analyses, coinfection with another STI was strongly associated with MG-MRAM (OR: 7.19; 95% CI: 2.4 to 21.5).

CONCLUSION

A significant proportion of participants in our study of symptomatic patients and STI contacts were infected with macrolide-resistant MG, suggesting that testing for MG and MRAM, for MG positives, might be clinically useful. The findings also suggest services explore potential benefits of testing CT positive samples for MG in these patient groups. Where MG testing is not available, potential high rates of MG coinfection should be borne in mind when considering azithromycin in the treatment of CT among STI contacts and symptomatic patients.

Outcomes of Resistance-guided Sequential Treatment of Mycoplasma genitalium Infections: A Prospective Evaluation

Background

Rising macrolide and quinolone resistance in Mycoplasma genitalium necessitate new treatment approaches. We evaluated outcomes of sequential antimicrobial therapy for M. genitalium guided by a macrolide-resistance assay.

Methods

In mid-2016, Melbourne Sexual Health Centre switched from azithromycin to doxycycline (100 mg twice daily for 7 days) for nongonococcal urethritis, cervicitis, and proctitis. Cases were tested for M. genitalium and macrolide-resistance mutations (MRMs) by polymerase chain reaction. Directly after doxycycline, MRM-negative infections received 2.5 g azithromycin (1 g, then 500 mg daily for 3 days), and MRM-positive infections received sitafloxacin (100 mg twice daily for 7 days). Assessment of test of cure and reinfection risk occurred 14-90 days after the second antibiotic.

Results

Of 244 evaluable M. genitalium infections (52 women, 68 heterosexual men, 124 men who have sex with men) diagnosed from 20 June 2016 to 15 May 2017, MRMs were detected in 167 (68.4% [95% confidence interval {CI}, 62.2%-74.2%]). Treatment with doxycycline decreased bacterial load by a mean 2.60 log10 (n = 56; P < .0001). Microbiologic cure occurred in 73 of 77 MRM-negative infections (94.8% [95% CI, 87.2%-98.6%]) and in 154 of 167 MRM-positive infections (92.2% [95% CI, 87.1%-95.8%]). Selection of macrolide resistance occurred in only 2 of 76 (2.6% [95% CI, .3%-9.2%]) macrolide-susceptible infections.

Conclusions

In the context of high levels of antimicrobial resistance, switching from azithromycin to doxycycline for presumptive treatment of M. genitalium, followed by resistance-guided therapy, cured ≥92% of infections, with infrequent selection of macrolide resistance.

Chlamydiae from Down Under: The Curious Cases of Chlamydial Infections in Australia

In Australia, the most researched and perhaps the most successful chlamydial species are the human pathogen Chlamydia trachomatis, animal pathogens Chlamydia pecorum and Chlamydia psittaci. C. trachomatis remains the leading cause of sexually transmitted infections in Australians and trachoma in Australian Indigenous populations. C. pecorum is globally recognised as the infamous koala and widespread livestock pathogen, whilst the avian C. psittaci is emerging as a horse pathogen posing zoonotic risks to humans. Certainly not innocuous, the human infections with Chlamydia pneumoniae seem to be less prevalent that other human chlamydial pathogens (namely C. trachomatis). Interestingly, the complete host range for C. pecorum and C. psittaci remains unknown, and infections by other chlamydial organisms in Australian domesticated and wildlife animals are understudied. Considering that chlamydial organisms can be encountered by either host at the human/animal interface, I review the most recent findings of chlamydial organisms infecting Australians, domesticated animals and native wildlife. Furthermore, I also provide commentary from leading Australian Chlamydia experts on challenges and future directions in the Chlamydia research field.

The efficacy of azithromycin and doxycycline treatment for rectal chlamydial infection: a retrospective cohort study in South Australia

BACKGROUND

There are ongoing concerns about treatment failure with azithromycin for the treatment of rectal chlamydia.

AIM

To investigate treatment efficacy of two treatments for rectal chlamydial infection.

METHODS

We performed a retrospective analysis of all patients diagnosed with rectal chlamydial infection between 2009 and 2015 in Adelaide, Australia. Patients were treated with either azithromycin (1 g single dose) or doxycycline (100 mg twice a day for 10 days) and returned for repeat testing 14-180 days after treatment commenced. Log-binomial models were used to estimate the relative risk (RR) of recurrent rectal chlamydia associated with the treatment with azithromycin versus doxycycline.

RESULTS

In men, rectal chlamydia prevalence was 6.7%, and in women, it was 8.1%. Of the 526 patients diagnosed with rectal chlamydial infections, 419 (79.7%), 93 (17.7%) and 14 (2.6%) patients were treated with doxycycline, azithromycin or other medication respectively. Of these patients, 173 (41.3%) of 419 doxycycline-treated patients and 31 (33.3%) of 93 azithromycin-treated patients were retested between 14 and 180 days after treatment commenced (P = 0.16). Among these patients, the repeat rectal chlamydia test was less commonly positive in those treated with doxycycline (5.8%; 95% confidence interval (CI) 0.03-0.10) compared with those treated with azithromycin (19.4%; 95% CI 0.09-0.36) and (P = 0.01). In the multivariate analysis, azithromycin-treated patients had a significantly higher risk of a positive test in the 14 and 180 days after treatment commenced (adjusted relative risk (aRR) 2.96, 95% CI 1.16-7.57).

CONCLUSION

The findings suggest that doxycycline may be more effective than azithromycin in treating rectal chlamydial infections.

Review of Chlamydia trachomatis viability methods: assessing the clinical diagnostic impact of NAAT positive results

INTRODUCTION

Chlamydia trachomatis (chlamydia) is the most commonly diagnosed bacterial sexually transmitted infection (STI) worldwide. The advancement of molecular techniques has made chlamydia diagnostics infinitely easier. However, molecular techniques lack the information on chlamydia viability. Where in routine diagnostics the detection of chlamydia DNA or RNA might suffice, in other patient scenarios, information on the viability of chlamydia might be essential. Areas covered: In this review, the authors discuss the specific strengths and limitations of currently available methods to evaluate chlamydia viability: conventional cell culture, messenger RNA (mRNA) detection and viability-PCR (V-PCR). PubMed and Google Scholar were searched with the following terms: Chlamydia trachomatis, Treatment failure, Anal chlamydia, Microbial viability, Culture, Viability-PCR, Messenger RNA, and Molecular diagnostics Expert commentary: Several techniques are currently available to determine chlamydia viability and thus the clinical relevance of a positive test result in clinical samples. Depending on the underlying research question, all three discussed techniques have their merits when testing for viability. However, mRNA methods show the most promise in determining the presence of a true infection, in case the chlamydia reticulate body can be specifically detected. Further research is needed to understand how to best apply viability testing in current chlamydia diagnostics.