Treat Group B Strep During The Late Third Trimester

ST. PETERSBURG, FLA. -- Using penicillin G to treat a patient colonized with group B streptococcus during the late third trimester can eradicate her bacterial load when it comes time for her to deliver, according to results of a small prospective trial.

The Centers for Disease Control and Prevention currently recommends that women colonized with group B streptococcus (GBS) should receive intrapartum treatment with penicillin or ampicillin for at least 4 hours before delivery. However, up to 15% of women with GBS are delivered before that time and therefore receive inadequate treatment, Dr. Mark Bland said at the South Atlantic Association for Obstetricians and Gynecologists.

The study enrolled 78 expectant mothers who had a positive GBS culture between 34 and 38 weeks' gestation. Of these, 28 received 4.8 million U of intramuscular penicillin G while the remaining 50 patients received no treatment. The mean time from treatment to delivery was 19 days in the treatment group. Upon admission for delivery all the women were recultured for GBS and given the standard intrapartum prophylaxis.

The women in the two groups were similar with respect to age, parity insurance status, and gestational age at delivery.

At delivery, 75% of the treated women had no evidence of GBS colonization, compared with 20% of women in the observation arm, a significant difference. None of the women with persistent GBS in the treatment group had a heavy colonization pattern, whereas more than 60% of women in the observation arm did.

"Penicillin G administration in the late third trimester may provide adequate therapy for those GBS-positive mothers at risk for receiving inadequate intrapartum prophylaxis," said Dr. Bland, an ob.gyn resident at the Medical College of South Carolina in Charleston.

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