A Controlled Trial of a Single Dose of Azithromycin for the Treatment of Chlamydial Urethritis and Cervicitis

Currently, there is no single-dose therapy that is effective in the treatment of urethral or endocervical infections with Chlamydia trachomatis. Azithromycin is a new azalide antibiotic that has substantial activity against C. trachomatis, is concentrated intracellularly, and has a long half-life in serum and tissue. We conducted a trial in which 299 female patients and 158 male patients with uncomplicated genital infection and a positive C. trachomatis antigen test were randomly assigned to receive either azithromycin (1 g once orally) or doxycycline (100 mg orally twice daily for seven days). Only patients subsequently determined to have a culture positive for C. trachomatis at base line were included in the evaluation of efficacy. Among the patients who could be evaluated, 5 of the 141 patients (4 percent) treated with azithromycin did not respond to treatment, as compared with 3 of the 125 patients (2 percent) treated with doxycycline (difference between groups, 2 percent; 95 percent confidence interval, 0 to 6 percent). Of the patients evaluated 21 to 35 days after treatment, none of 112 treated with azithromycin and 1 of 102 treated with doxycycline had a positive culture. The rates of bacteriologic cure were similar for the 98 female patients (97 percent) and the 43 male patients (95 percent) treated with azithromycin. Seventeen percent of the patients who received azithromycin and 20 percent of those treated with doxycycline had mild-to-moderate drug-related side effects, mainly gastrointestinal symptoms. A single 1-g dose of azithromycin is as effective for the treatment of uncomplicated genital chlamydial infections as a standard seven-day course of doxycycline. (N Engl J Med 1992;327:921–5.), IN the United States, Chlamydia trachomatis is the most common sexually transmitted pathogen. Several million cases of chlamydial infection occur in the United States every year.¹ C. trachomatis causes substantial morbidity in men, women, and infants. The most common presentations of chlamydial infection in sexually active adults are urethritis and cervicitis. Chlamydial infection is also responsible for many cases of epididymitis, endometritis, acute salpingitis, ectopic pregnancy, and obstructive infertility in women.^{2 , 3} Infected pregnant women can also transmit the infection to their infants at birth, resulting in neonatal conjunctivitis and chlamydial pneumonia.⁴ The complex life cycle and relatively slow replication of…