Group B Streptococcus - Infectious Diseases in Pregnancy

GROUP B STREPTOCOCCUS

Group B streptococcus (GBS) (orStreptococcus agalac-tiae) is an important cause of perinatal infections. Asymptomatic lower genital tract colonization occurs in up to 30% of pregnant women, but cultures may be posi-tive only intermittently, even in the same patient. Approximately 50% of infants exposed to the organism in the lower genital tract will become colonized. For most of these infants, such colonization is of no consequence, but without treatment, GBS sepsis occurs in approximately 0.2 infants per 1000 live births annually.

There are two manifestations of clinical infection of the newborn, termed early-onset and late-onset, occur-ring at roughly equal frequency. Early-onset infection manifests as septicemia and septic shock, pneumonia, or meningitis and occurs during the first week of life. Early-onset infection is much more common in preterm infants than in term infants. Late-onset infection occurs later, after delivery, and has been reported beyond 3 months (late-late onset infection) in very low–birth-weight pre-term neonates. GBS disease in newborns may occur as a result of vertical transmission or nosocomial or community-acquired infection.

With prevention strategies, current rates of early-onset GBS disease of the newborn have decreased to approxi-mately 0.3 per 1000 live births. Currently, the Centers for Disease Control and Prevention (CDC) and the American College of Obstetricians and Gynecologists (ACOG) rec-ommend universal screening for GBS between 35 to 37 weeks of gestation.

All women who are GBS positive by rectovaginal culture should receive antibiotic prophylaxis in labor or with rupture of membranes.

If a patient’s culture status is unknown, then prophylaxis should be given if any of the following conditions exists:

·  Preterm labor (less than 37 weeks of gestation)

·              Preterm premature rupture of membranes (PROM) (less than 37 weeks of gestation)

·      Rupture of membranes 18 hours or longer

·      Maternal fever during labor (at or above 38°C [100.4°F])

Women with GBS bacteriuria during their current preg-nancy, or women who have previously given birth to an infant with early-onset GBS disease also are candidates for intrapartum antibiotic prophylaxis. When culture results are not available, intrapartum prophylaxis should be of-fered only on the basis of the presence of intrapartum risk factors for early-onset GMS disease. CDC Guidelines include recommended medication regimens.

In the mother, significant postpartum fever may indi-cate postpartum endometritis, sepsis, and, rarely, meningi-tis, which may be caused by infection with GBS. With endometritis, the onset is often sudden and within 24 hours of delivery. Significant fever and tachycardia are typically present; sepsis may follow.