"Streptococcus agalactiae, or Group B Streptococcus, is a gram-positive coccus in chains with beta-hemolytic colonies. Group B streptococci are subdivided from other beta-hemolytic streptococci by differences in the antigenicity of their cell-wall carbohydrate. S. agalactiae is catalase negative and bacitracin resistant. It causes neonatal meningitis and sepsis. Its habitat is the human vagina, and transmission occurs during birth. It is a pyogenic organism, and no exotoxins have been identified. Predisposing factors to neonatal infection include rupture of membranes more than 18 hours before delivery, labor before 37 weeks, absence of maternal antibody, and heavy colonization of the genital tract by the organism. Diagnosis is made by Gram-stained smear and culture. On blood agar, colonies are beta-hemolytic and resistant to bacitracin. The organisms hydrolyze hippurate and are CAMP-test positive. Penicillin G is used. There is no vaccine. Penicillin or ampicillin should be given to mothers if prolonged rupture of membranes occurs, if the mother has a fever, or if the neonate is premature."