Comparison of the efficacy of azithromycin and doxycycline for Chlamydia trachomatis infection in the rectum and urinary tract

[Objective] The purpose of this study was to compare the efficacy of azithromycin and doxycycline in the treatment of Chlamydia trachomatis infection in the rectum and urinary tract. [Methods] From November 2019 to April 2023, male volunteers who had sex with men (MSM) were recruited for Chlamydia trachomatis testing of the rectum and urinary tract. Patients diagnosed with Chlamydia trachomatis infection were treated orally with either azithromycin or doxycycline. Azithromycin was given orally at a dose of 1 g on the first day, and 0.5 g on the second and third days, or 100 mg of oral doxycycline was given twice daily, for 7 consecutive days. Nucleic acid testing for Chlamydia trachomatis was conducted to compare the microbial clearance rates three weeks after the therapy. [Results] A total of 1 596 MSM were recruited, including 125 cases of Chlamydia trachomatis rectal infection and 59 cases of urethral infection. After excluding individuals who did not undergo follow-up examinations and those having high-risk behaviors during the study period, 152 cases of Chlamydia trachomatis infection were included in this study. Azithromycin was given to 97 cases, including 72 cases of rectal infection and 25 cases of urethral infection. Doxycycline was given to 55 cases, including 30 cases of rectal infection and 25 cases of urethral infection. Three weeks after the therapy, all cases in the azithromycin group were negative for Chlamydia trachomatis, while in the doxycycline group, 5 cases of rectal infection and 2 cases of urethral infection were positive for Chlamydia trachomatis, resulting in a microbial clearance rate of 87.27% (48/55). The total microbial clearance rate in the azithromycin group was significantly higher than that in the doxycycline group (χ2=12.94, P<0.001). Following azithromycin therapy, all Chlamydia trachomatis positive cases in the doxycycline group became negative. [Conclusions] Azithromycin at a dose of 2 g can be used as a first-line treatment option for simple Chlamydia trachomatis infection in the rectum and urinary tract.