Perinatal Group B Streptococcal Infections: Past, Present, and Future

Abstract

After completing this article, readers should be able to: 1. Differentiate early-onset from late-onset group B streptococcal (GBS) disease. 2. Describe the current literature on patient outcome and surveillance studies regarding GBS disease. 3. Compare and contrast the screening-based and risk factor-based strategies. 4. Delineate the adverse consequences of widespread use of intrapartum antibiotics. 5. Discuss the need to revise the 1996 perinatal GBS prevention guidelines based on newly available data. Group B Streptococcus (GBS) remains the leading cause of neonatal bacterial infections in the United States. Prior to using intrapartum antibiotic prophylaxis in the 1990s, an average of 8,000 cases of early-onset GBS infection occurred in the United States annually (approximately 2 cases per 1,000 live births). Approximately 4% to 6% of affected newborns died. Some surviving infants had disabilities such as mental retardation, hearing loss, or vision loss. Not only were infants affected, but parturient women also developed clinical infection with GBS, accounting for more than 50,000 maternal infections each year, including bacteremia, postpartum endometritis, chorioamnionitis, and urinary tract infections. Other adverse outcomes of pregnancy associated with GBS colonization include early fetal loss, premature rupture of membranes, and preterm delivery of low-birthweight infants. Intrapartum prophylaxis has decreased the incidence of early-onset GBS sepsis by 70% and narrowed the gap between affected African-American and Caucasian infants by 75%. However, 1999 Centers for Disease Control and Prevention (CDC) surveillance data estimated that 1,600 infants still become infected each year. Therefore, effective GBS screening, improved compliance, and vigilance must prevail until an effective vaccine becomes available. Moreover, continued surveillance of patient outcome is imperative to minimize unintended consequences of widespread intrapartum antibiotic prophylaxis, such as the emergence of resistant GBS and nonGBS organisms. Beta-hemolytic streptococci of the Lancefield Group B classification ( S agalactiae ) were considered commensal organisms until the late 1930s, when severe infections affected both …