Abstract
BackgroundRectal infection with Chlamydia trachomatis is one of the most common bacterial sexually transmissible infections among men who have sex with men (MSM) with diagnosis rates continuing to rise. Current treatment guidelines recommend either azithromycin 1 g single dose or doxycycline 100 mg twice daily for 7 days. However, there are increasing concerns about treatment failure with azithromycin. We are conducting the first randomised controlled trial (RCT) to compare treatment efficacy of azithromycin versus doxycycline for the treatment of rectal chlamydia in MSM.Methods/DesignThe Rectal Treatment Study will recruit 700 MSM attending Australian sexual health clinics for the treatment of rectal chlamydia. Participants will be asked to provide rectal swabs and will be randomised to either azithromycin 1 g single dose or doxycycline 100 mg twice daily for 7 days. Participants will be asked to complete questionnaires about adverse drug reactions, sexual behaviour and drug adherence via short message service and online survey. The primary outcome is the treatment efficacy as determined by a negative chlamydia nucleic acid amplification test at 4 weeks post treatment. Secondary outcomes will utilise whole genome sequencing and mRNA assay to differentiate between treatment failure, reinfection or false positive results.DiscussionRectal chlamydia is an increasing public health concern as use of pre-exposure prophylaxis against HIV becomes commonplace. Optimal, evidence-based treatment is critical to halting ongoing transmission. This study will provide the first RCT evidence comparing azithromycin and doxycycline for the treatment of rectal chlamydia. The results of this trial will establish which treatment is more efficacious and inform international management guidelines.Trial registrationAustralian New Zealand Clinical Trials Registry ACTRN12614001125617.
Highlights
Rectal infection with Chlamydia trachomatis is one of the most common bacterial sexually transmissible infections among men who have sex with men (MSM) with diagnosis rates continuing to rise
We examined the side-effect data from treatment trials for urethral/cervical chlamydia and found that among 17 trials, there was no difference in side-effects (24.0% for azithromycin vs 23.0% for doxycycline, p = 0.45) [36]
Genotype determination Identification of each chlamydia strain including Lymphogranuloma venereum (LGV) will be determined by qPCR assays using serovarspecific probes as we have described previously [41]
Summary
Given rectal chlamydia is highly prevalent among MSM and is likely to increase, it is vital that the most efficacious treatment is used. Azithromycin is delivered to the site of infection by phagocytic cells released during the immune response to infection [52] whereas doxycycline is highly lipid soluble and rapidly absorbed into the tissues [53] Data from both human studies [54] and mice models [55] suggest that chlamydia down-regulates the immune response in the gastrointestinal tract, and may reduce the number of phagocytic cells available to deliver the azithromycin. We will collect comprehensive sexual practice data to identify men at risk of re-infection using SMS This trial must be done to ensure STI management guidelines internationally are evidence-based and recommend the most efficacious treatment for rectal chlamydia so that ongoing transmission is minimised
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