Azithromycin or Doxycycline for Asymptomatic Rectal Chlamydia trachomatis

Abstract

BACKGROUNDRectal 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. METHODSIn 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. RESULTSFrom 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). CONCLUSIONSA 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.

Controversies and evidence on Chlamydia testing and treatment in asymptomatic women and men who have sex with men: a narrative review

“…75% and 100%). Another randomized, double-blind, double-dummy controlled trial in MSM in Australia showed 76% (227/297; 95% CI 74–79) for azithromycin and 97% (281/290; 95% CI 95–99) for doxycycline [ 127 ]. The results from the first controlled trial in women, the are underway [ 128 ].…”

“…In assessing factors that could predict azithromycin treatment failure, it was consistently shown that a higher baseline rectal CT load was associated with azithromycin treatment failure in MSM and in women [ 116 , 127 , 131 , 132 ]. In women, it was additionally shown that baseline viable rectal CT was key to later viable CT treatment failure [ 129 ].…”

“…In women, it was additionally shown that baseline viable rectal CT was key to later viable CT treatment failure [ 129 ]. Failure is not associated with sex, baseline report of anal symptoms or anal sex, or other factors that could be useful to guide treatment choice [ 116 , 126 , 127 ]. It is unknown whether antibiotic concentrations are sufficient to cure high pretreatment CT loads, and it is posited that larger or longer doses of azithromycin may be more effective at clearing higher load rectal infections.…”

“…Another systematic review found that the risk of side effects was lower in azithromycin in a mixed population of men and women, but no difference was noted in studies that only included men [ 3 ]. A study on MSM demonstrated that diarrhoea occurred more often with azithromycin (40%) than with doxycycline (26%) use [ 127 ]. Taken together, while doxycycline might not be indicated in all situations or in all patients, overall doxycycline use should be considered widely applicable in women and in MSM.…”

Incident urogenital and anorectal Chlamydia trachomatis in women: the role of sexual exposure and autoinoculation: a multicentre observational study (FemCure)

“…Both treatments are highly effective in urogenital CT 10. Two randomised controlled trials in Men who have sex with men (MSM) demonstrate substantial lower effectiveness of azithromycin in anorectal CT 11 12. An observational study in women (FemCure spin-off) showed similar findings13 and moreover demonstrated that CT treatment failures frequently (in 75%) represented viable CT 4.…”