Treatment options
Prompt treatment of C trachomatis infection is essential to decrease the risk of disease sequelae. Nonpregnant adults can be treated with oral doxycycline 100 mg twice daily for 7 days.
In a head-to-head study performed in a controlled environment that ensured treatment adherence, 97% efficacy was achieved with one oral dose of azithromycin (1 g) compared with 100% efficacy with doxycycline.10 However, in the real-world setting, imperfect adherence to the multi-day doxycycline regimen is associated with treatment failures. Thus, a single dose of azithromycin is preferable for patients with questionable compliance.11
In obstetric patients, azithromycin and amoxicillin are preferred as first-line agents for treatment of C trachomatis due to their improved safety profile in this demographic. Amoxicillin 500 mg orally 3 times daily for 7 days has 95% efficacy.2
Women allergic to these agents may be treated with an alternative regimen of erythromycin base, 500 mg orally 4 times daily for 7 days, or erythromycin ethylsuccinate, 800 mg orally 4 times daily for 7 days. Erythromycin should be reserved for second-line therapy because of its lower efficacy (64%) and frequent gastrointestinal adverse effects.2 Doxycycline is contraindicated in pregnancy because of possible teratogenic effects on the teeth and bone of the fetus.