Group B Streptococcal Disease in the Era of Intrapartum Antibiotic Prophylaxis

Both pregnant women and newborn infants are vulnerable to group B streptococcal (GBS) infection, but many cases in neonates may be preventable through intrapartum antibiotic prophylaxis. Consensus guidelines established in 1996 proposed using either a risk-based or a screening-based approach to determine who should receive prophylaxis. This study examined trends in GBS disease in the years 1993 to 1998. Population-based surveillance was conducted in designated counties of eight states, where project personnel communicated at least twice a month with contacts in participating microbiology laboratories that served acute-care hospitals. GBS infection was diagnosed when the organism was isolated from a nominally sterile site. The criterion age for late-onset neonatal disease was 7 days; for child disease, 90 days; and for adult disease, 15 years. Race-specific incidence rates were estimated using census and live-birth data, and national projections were adjusted for race.A total of 7867 cases of invasive GBS disease were identified in the surveillance areas; 84 percent of isolated were in the blood. Infants less than 3 months of age were affected in 28 percent of cases, and more than two-thirds of these were less than 1 week of age. The proportion of early onset cases identified on the day of birth decreased from 76 percent in 1993 to 71 percent in 1998, not a significant change. Four of five infants with early onset GBS disease presented with bacteremia, another 6 percent with meningitis, and 7 percent with pneumonia. The same case fatality rate of 4 percent was associated with each presentation. Preterm infants (gestational age