Clinical Edge

Summaries of Must-Read Clinical Literature, Guidelines, and FDA Actions

Treating Urogenital Chlamydia Infection

Is doxycycline superior to azithromycin?

The efficacy of both azithromycin and doxycycline was high for the treatment of urogenital chlamydia infection among adolescents in youth correctional facilities, with the noninferiority of azithromycin to doxycycline not established. This according to a study of 567 participants where 284 were randomly assigned to receive azithromycin, and 283 were randomly assigned to receive doxycycline. Researchers found:

• There were no treatment failures in the doxycycline group.

• Treatment failure occurred in 5 participants (3.2%) in the azithromycin group.

• The efficacy of both types of treatment was high (97% vs 100%) with the noninferiority of azithromycin not established in the study setting.

Citation: Geisler WM, Uniyal A, Lee JY. Azithromycin versus doxycycline for urogenital chlamydia trachomatis infection. N Engl J Med 2015;373:2512-21. doi: 10.1056/NEJMoa1502599.

Commentary: In this study, both doxycycline and azithromycin had very high efficacy for treating chlamydia. It is important to distinguish here between efficacy and effectiveness. Efficacy looks at how well an intervention does under ideal circumstances. Effectiveness looks at how well an intervention does under the usual conditions in which it is carried out. Since doxycycline needs to actually be taken for 7 full days, it is likely that under real life circumstances, not everyone given a prescription for 7 days of doxycycline actually take a full 7 days, which likely interferes with its effectiveness in real life. The current STD Guidelines recommend either azithromycin 1 gram in a single dose or doxycycline 100mg twice a day for 7 days as first line treatment for chlamydia.1Neil Skolnik, MD

1. Centers for Disease Control and Prevention Web site. STD treatment guidelines 2015 at