Prevention of neonatal group B streptococcal sepsis by the use of a rapid screening test and selective intrapartum chemoprophylaxis.

A randomized 18-month study was conducted to determine the effect of intrapartum chemotherapy in the prevention of neonatal group B streptococcal disease. Twelve hundred seven indigent patients at term were screened weekly for group B streptococci antenatally with a rapid test based on coagglutination methods and at the time of admission in labor, 263 (22%) were confirmed to have colonization, 67 of which had heavy colonization. One hundred thirty-five of these mothers were randomized to a group treated with 1 gm of ampicillin intravenously every 6 hours until delivery. The remaining 128 mothers were not treated. None of the infants born to the treated mothers had colonization with group B streptococci at surface culture sites. Fifty-nine (46%) of the infants born to untreated mothers, including 24 of 30 (80%) from mothers with heavy colonization, had colonization. Ampicillin treatment administered during labor to pregnant patients with heavy colonization significantly reduced vertical transmission of group B streptococci.