Objective: The purpose of this study was to compare the efficacy and side effects of erythromycin,
amoxicillin, and clindamycin in eradicating Chlamydia trachomatis from the lower genital tract of
Methods: A total of 174 women at <36 weeks gestation with positive cervical cultures for C.
trachomatis were enrolled. Patients were assigned in a randomized prospective fashion to either
erythromycin (500 mg q.i.d, for 7 days), amoxicillin (500 mg t.i.d, for 7 days), or clindamycin (600 mg
t.i.d, for 10 days). Six women elected not to participate and 8 patients were lost to follow-up, leaving
53 patients in the erythromycin group, 55 patients in the amoxicillin group, and 52 patients in the
clindamycin group. All sexual partners of the enrolled women were offered doxycycline (100 mg
b.i.d. for 7 days) and patients were instructed to use barrier contraception until treatment was
Results: All 3 medications were effective agents for the treatment of antenatal C. trachomatis
infection with treatment efficacies of 96%, 94%, and 98% for the erythromycin, amoxicillin, and
clindamycin groups, respectively. When the antibiotic groups were compared, no statistically significant
differences were noted in intolerance. However, the differences in the incidence of gastrointestinal
symptoms between erythromycin and amoxicillin and/or clindamycin were significant
(P < 0.05).
Conclusions: These findings suggest that 1) all 3 antibiotic regimens are efficacious, 2) erythromycin
has a higher incidence of side effects, and 3) amoxicillin or clindamycin are reasonable alternatives
for the treatment of C. trachomatis in pregnant patients unable to tolerate erythromycin.