Group B streptococcal disease in the era of intrapartum antibiotic prophylaxis

Background: Group B streptococcal infections are a leading cause of neonata l mortality, and they also affect pregnant women and the elderly. Many case s of the disease in newborns can be prevented by the administration of prop hylactic intrapartum antibiotics. In the 1990s, prevention efforts increase d. In 1996, consensus guidelines recommended use of either a risk-based or a screening-based approach to identify candidates for intrapartum antibioti cs. To assess the effects of the preventive efforts, we analyzed trends in the incidence of group B streptococcal disease from 1993 to 1998. Methods: Active, population-based surveillance was conducted in selected co unties of eight states. A case was defined by the isolation of group B stre ptococci from a normally sterile site. Census and live-birth data were used to calculate the race-specific incidence of disease; national projections were adjusted for race. Results: Disease in infants less than seven days old accounted for 20 perce nt of all 7867 group B streptococcal infections. The incidence of early-ons et neonatal infections decreased by 65 percent, from 1.7 per 1000 live birt hs in 1993 to 0.6 per 1000 in 1998. The excess incidence of early-onset dis ease in black infants, as compared with white infants, decreased by 75 perc ent. Projecting our findings to the entire United States, we estimate that 3900 early-onset infections and 200 neonatal deaths were prevented in 1998 by the use of intrapartum antibiotics. Among pregnant girls and women, the incidence of invasive group B streptococcal disease declined by 21 percent. The incidence among nonpregnant adults did not decline. Conclusions: Over a six-year period, there has been a substantial decline i n the incidence of group B streptococcal disease in newborns, including a m ajor reduction in the excess incidence of these infections in black infants . These improvements coincide with the efforts to prevent perinatal disease by the wider use of prophylactic intrapartum antibiotics. (N Engl J Med 20 00;342:15-20.).