Prevention of neonatal group B streptococcal disease: intrapartum detection and chemoprophylaxis of heavily colonized parturients. Prevention of early-onset neonatal group B streptococcal disease with selective intrapartum chemoprophylaxis.
Parturients with heavy vaginal colonization of group B streptococci were selected randomly to receive either penicillin or no antibiotic. A simple and fast latex agglutination test, applied in 8977 consecutive parturients, detected 412 women with heavy colonization with group B streptococcus, 199 of whom were eligible for the study. The offspring of penicillin-treated women had a lower incidence of early-onset group B streptococcal disease (1.1%; 95% confidence interval 0-3.4%) than the controls (9.0%; 95% confidence interval 3.6--14.4%) (P less than .01). Among the offspring of streptolatex-negative parturients, the incidence of streptococcal disease was very low (0.07%). Thus, antibiotic prophylaxis of latex agglutination test-positive parturients would reduce the total incidence of group B streptococcal disease in the newborn by 25-80%. Most cases of neonatal group B streptococcal disease with early onset have an intrapartum pathogenesis. Attack rates are increased substantially in infants born to mothers with prenatal group B streptococcal colonization and various perinatal risk factors (premature labor, prolonged membrane rupture, or intrapartum fever). In a randomized controlled trial, we studied the effect of selective intrapartum prophylaxis with ampicillin in 160 such high-risk women. In infants born to mothers who received intravenous ampicillin during labor, as compared with controls who received no treatment, neonatal colonization with group B streptococci was present in 8 of 85 (9 percent) versus 40 of 79 (51 percent; P less than 0.001), colonization at multiple (greater than or equal to 3) sites was observed in 3 of 85 (4 percent) versus 24 of 79 (30 percent; P less than 0.001), and bacteremia occurred in none of 85 versus 5 of 79 (6 percent; P = 0.024). The side effects of ampicillin were limited to a single episode of urticaria in a mother who had no history of penicillin allergy. We conclude that intrapartum ampicillin prophylaxis in women with positive prenatal cultures for group B streptococci who have certain perinatal risk factors can prevent early-onset neonatal group B streptococcal disease.
Intrapartum antibiotic prophylaxis appeared to reduce EOGBSD, but this result may well be a result of bias as we found a high risk of bias for one or more key domains in the study methodology and execution. There is lack of evidence from well designed and conducted trials to recommend IAP to reduce neonatal EOGBSD.
Ideally the effectiveness of IAP to reduce neonatal GBS infections should be studied in adequately sized double-blind controlled trials. The opportunity to conduct such trials has likely been lost, as practice guidelines (albeit without good evidence) have been introduced in many jurisdictions.