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.