Double-blind randomized study comparing amoxicillin and erythromycin for the treatment of Chlamydia trachomatis in...

To compare the efficacy and patient tolerance of amoxicillin to that of erythromycin in the treatment of lower genital tract chlamydia infections during pregnancy.

A double-blind, randomized study was conducted comparing oral amoxicillin 500 mg three times daily versus oral erythromycin 500 mg four times daily for 7 days. One hundred forty-three women with positive cervical cultures for chlamydia at less than 36 weeks' gestation were enrolled. A test-of-cure culture was obtained 4 weeks after entry into the study and side effects were assessed. Success of the regimen was defined as completing the course of medication and having a negative test-of-cure culture.

Thirty of the 65 women in the erythromycin group (46.1%) developed symptoms while taking the medication and 15 of them were unable to continue treatment (23.1%). In contrast, five of the 65 women (7.7%) in the amoxicillin group became symptomatic, with only one of these patients intolerant of the side effects (1.5%) (P < .001). Of the 50 patients in the erythromycin group who were able to complete their course of medication, only three had a positive test of cure (6.0%). In comparison, nine of the 64 patients (14.1%) taking amoxicillin who completed their course had positive cultures at test of cure. This difference was not statistically significant (P = .14). Forty-seven of the 65 patients (72.3%) in the erythromycin group successfully completed their regimen, compared to 55 of the 65 women (84.6%) in the amoxicillin group. This difference was not statistically significant.

These findings suggest that amoxicillin is a reasonable alternative for the treatment of chlamydia in pregnant patients intolerant to erythromycin. The incidence of side effects and intolerance to therapy for amoxicillin are less than those for erythromycin.