Centers for Disease Control and Prevention guidelines recommend azithromycin or doxycycline for treatment of rectal chlamydial infection.
We created a retrospective cohort of male patients diagnosed as having rectal chlamydia between 1993 and 2012 at a sexually transmitted disease clinic in Seattle, Washington. Men were included in the analysis if they were treated with azithromycin (1 g single dose) or doxycycline (100 mg twice a day × 7 days) within 60 days of chlamydia diagnosis and returned for repeat testing 14 to 180 days after treatment. We compared the risk of persistent/recurrent rectal chlamydial infection among recipients of the 2 drug regimens using 4 follow-up testing time intervals (14–30, 60, 90, and 180 days).
Of 1835 cases of rectal chlamydia diagnosed in the study period, 1480 (81%) were treated with azithromycin or doxycycline without a second drug active against Chlamydia trachomatis. Of these, 407 (33%) of 1231 azithromycin-treated men and 95 (38%) of 249 doxycycline-treated men were retested 14 to 180 days after treatment (P = 0.12); 88 (22%) and 8 (8%), respectively, had persistent/recurrent infection (P = 0.002). Persistent/recurrent infection was higher among men treated with azithromycin compared with doxycycline at 14 to 30 days (4/53 [8%] vs. 0/20 [0%]), 14 to 60 days (23/136 [17%] vs. 0/36 [0%]), and 14 to 90 days (50/230 [22%] vs. 2/56 [4%]). In multivariate analysis, azithromycin-treated men had a significantly higher risk of persistent/recurrent infection in the 14 to 90 days (adjusted relative risk, 5.2; 95% confidence interval, 1.3–21.0) and 14 to 180 days (adjusted relative risk, 2.4; 95% confidence interval, 1.2–4.8) after treatment.
These data suggest that doxycycline may be more effective than azithromycin in the treatment of rectal chlamydial infections.
Among male sexually transmitted disease clinic patients with rectal chlamydial infection, treatment with azithromycin was associated with a significantly higher risk of persistent/recurrent rectal chlamydia compared with treatment with doxycycline.
From the Departments of *Epidemiology and †Medicine, University of Washington, Seattle, WA; ‡Public Health–Seattle & King County HIV/STD Program, Seattle, WA; and §Department of Global Health, University of Washington, Seattle, WA
Acknowledgments: The authors thank the Public Health–Seattle & King County STD staff, clinicians, and disease investigation specialists.
Conflict of interests: M.R.G. has received research support from Cempra Pharmaceuticals, Bio-rad Diagnostics, and Genprobe Diagnostics. All other authors report no conflict of interests.
Funding: This work was supported by Public Health–Seattle & King County, the National Institutes of Health (NIH; Grant Nos. K23MH090923 to J.C.D. and T32 AI07140 to L.A.B.), and the University of Washington Center for AIDS Research, an NIH-funded program (Grant No. P30 AI027757), which is supported by the following NIH institutes and centers: National Institute of Allergy and Infectious Diseases; National Career Institute; National Institutes of Mental Health; National Institute on Drug Abuse; National Institute of Child Health and Human Development; National Heart, Lung, and Blood Institute; and National Institute on Aging.
Correspondence: Christine M. Khosropour, MPH, Department of Epidemiology, Harborview Medical Center, Box 359777, 325 Ninth Ave, Seattle, WA 98104. E-mail: firstname.lastname@example.org.
Received for publication September 11, 2013, and accepted December 2, 2013.