Bacterial infection (Figure 42.1)
Group B streptococcus
- Incidence. In developed countries, neonatal group B streptococcus (GBS) sepsis complicates 1.8/1,000 live births.
- Maternal signs/symptoms. Of all pregnant women 20% are asymptomatically colonized in the vaginal or perianal region.
- Fetal/neonatal effects. Two clinically distinct neonatal GBS infections have been identified:
1 Early onset, neonatal GBS infection (80%) results from transmission during labor or delivery. Signs of serious infection (respiratory distress, septic shock) usually develop within 6–12 hours of birth. The mortality rate is 25% and surviving infants frequently exhibit neurologic sequelae.
2 Late-onset GBS infection (20%) is a nosocomial or community-acquired infection. It presents more than a week after birth, usually as meningitis. The mortality rate is lower than for early onset disease, but neurologic sequelae are equally common.
- Prevention. Strategies to prevent early onset neonatal GBS infection vary. In the UK, a risk factor-based protocol is used. Patients are treated in labor if one of the following risk factors is present: a prior affected infant (not GBS positive in a prior pregnancy), GBS urinary tract infection (UTI) in index pregnancy, preterm labor, fever, or rupture of membranes ≥18 hours. This protocol results in the treatment of 15–20% of pregnant women and prevents 65–70% of early onset GBS sepsis. US practice favors a universal screening protocol. All women are screened for GBS carrier status at 35–37 weeks. Women who are GBS carriers receive intrapartum antibiotics. The latter protocol results in the treatment of 25–30% of pregnant women and prevents 85–90% of cases of early onset GBS sepsis. Patients with unknown GBS carrier status in labor should be treated according to the risk factor-based protocol.
- Treatment. Intrapartum penicillin (second-generation cephalosporin, erythromycin, or clindamycin if penicillin allergy and sensitivities available; vancomycin if penicillin allergy and no sensitivities available).
Chorioamnionitis
- Incidence. One to ten percent of pregnancies.
- Maternal signs/symptoms.
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