Oral metronidazole vs. clindamycin to treat bacterial vaginosis in pregnancies at risk for preterm labour.

OBJECTIVES

Bacterial vaginosis (BV) and abnormal vaginal flora (AVF) are associated with maternal discomfort and preterm labour. Oral metronidazole and clindamycin are acceptable treatments during pregnancy for their eradication; however, direct comparative data between them during pregnancy are lacking. We compared the efficacy of metronidazole and clindamycin in eradicating BV/AVF among women at high risk for preterm labour.

METHODS

In this multicentre randomized controlled trial, pregnant women at high risk for preterm labour were screened for BV/AVF using the Nugent criteria on vaginal smears. BV/AVF were defined as Nugent scores ≥4. Women diagnosed with BV/AVF were randomly allocated to receive either oral metronidazole 500 mg twice daily or oral clindamycin 300 mg twice daily for 1 week. After treatment, a repeat vaginal smear was obtained. If BV/AVF persisted, the alternative treatment was administered for an additional week, after which eradication was reassessed by vaginal smear. The primary outcome was the rate of BV/AVF eradication after first-line treatment.

RESULTS

Of the 914 women screened, 170 (19%) tested positive for BV/AVF, and 82 and 84 women were analysed in the metronidazole and clindamycin groups, respectively. There were no significant differences between the metronidazole and clindamycin groups in the rate of BV/AVF eradication after first-line treatment (48 [60%] vs. 47 [56%]), total eradication rate after second-line treatment (63 [77%] vs. 63 [79%]), or the rate of preterm delivery/late miscarriage (30% vs. 24%), respectively. Among women who received metronidazole or clindamycin (as first- or second-line treatment), adverse effects were reported in 36 of 115 (31%) and 31 of 117 (26%), respectively, and treatment discontinuation because of adverse effects occurred in only 3% and 5%, respectively (p >0.05 for all comparisons).

CONCLUSIONS

In pregnant women at high risk for preterm labour, oral metronidazole and clindamycin for the treatment of BV/AVF demonstrated similar efficacy, adverse effect profiles, and preterm delivery rates.