A randomized, prospective trial comparing amoxicillin and erythromycin for the treatment of Chlamydia trachomatis in pregnancy

Am J Obstet Gynecol. 1994 Mar;170(3):829-32. doi: 10.1016/s0002-9378(94)70292-6.


Objective: Our purpose was to evaluate the efficacy of amoxicillin as an alternative therapy to erythromycin for the treatment of cervical chlamydial infections during pregnancy.

Study design: A randomized, prospective trial of two treatment regimens for Chlamydia trachomatis was performed in a cohort of pregnant women enrolled for care in an inner-city, university-based prenatal clinic, with an alternate-therapy crossover arm for primary treatment failures. Pregnant women diagnosed with chlamydial infection by McCoy cell culture of cervical swabs were assigned to receive either 500 mg of amoxicillin three times daily or 500 mg of erythromycin four times daily for 7 days. Patients' partners were treated with doxycycline. Compliance information was obtained by a standardized questionnaire at a posttherapy follow-up visit. Patients with positive follow-up cultures were crossed over into the alternate treatment arm and recultured at a later visit.

Results: During the study period 74 women consented to participate in this trial; 36 were treated with amoxicillin and 38 with erythromycin. Initial cure rates of 82.3% (28/34) for the amoxicillin group and 84.6% (27/32) for erythromycin were obtained before crossover (p = 0.91); four patients in each group were lost to follow-up. Overall cure rates after crossover were 84.6% (33/39) for amoxicillin and 84.2% (32/38) for erythromycin (p = 0.83). In the amoxicillin group 12.8% of patients reported side effects compared with 31.6% treated with erythromycin (p = 0.09), although seven erythromycin-treated patients compared with none of those in the amoxicillin arm stopped therapy because of side effects (p = 0.02).

Conclusion: Amoxicillin offers a reasonable alternative to erythromycin for the treatment of Chlamydia trachomatis in pregnancy, on the basis of both cure rates and patient compliance.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Amoxicillin / adverse effects
  • Amoxicillin / therapeutic use*
  • Chlamydia Infections / drug therapy*
  • Chlamydia trachomatis*
  • Erythromycin / adverse effects
  • Erythromycin / therapeutic use*
  • Female
  • Humans
  • Pregnancy
  • Pregnancy Complications, Infectious / drug therapy*
  • Prospective Studies
  • Treatment Outcome


  • Erythromycin
  • Amoxicillin