Group B streptococcus and preterm rupture of membranes.

The effect of cervical group B streptococcus on the conservative management of preterm premature rupture of membranes was examined in 140 consecutive patients. Upon the patient's admission, we obtained cervical cultures for group B streptococcus, genital mycoplasmas, and chlamydia. Patients with and without group B streptococcus were compared. Group B streptococcus patients had earlier rupture of membranes (30.7 versus 31.6 weeks) and shorter latent periods (76.8 versus 138.5 hours). Intra-amniotic infection (six of 16 versus 26 of 120) and endometritis (four of ten versus three of 94) were significantly more common in group B streptococcus patients. Neonates of mothers positive for group B streptococcus were smaller (1749 +/- 844 versus 2100 +/- 779 g) and more likely to have infectious complications (eight of 16 versus 29 of 120; P less than .01). Control for the presence of mycoplasmas, chlamydia, listeria, or gonorrhea failed to change the significance of these results. The usual policy was to use intrapartum ampicillin prophylaxis in asymptomatic group B streptococcus patients. However, only four of 16 remained asymptomatic and had latent periods long enough for the results of cultures obtained on admission to be available. We conclude that group B streptococcus significantly complicates the conservative management of preterm premature rupture of membranes and that the effectiveness of intrapartum prophylactic ampicillin may be compromised by awaiting the results of conventional cultures to define colonized patients.