Laboratory detection of group B Streptococcus for prevention of perinatal disease

Group B Streptococcus (GBS) or Streptococcus agalactiae emerged in the 1970s as the leading cause of neonatal morbidity and mortality. Today, GBS remains one of the leading causes of sepsis and meningitis in newborns despite important prevention efforts, including the issuance of recommendations for prevention of perinatal GBS disease by the American College of Obstetricians and Gynecologists, the Centers for Disease Control and Prevention, and the American Academy of Pediatrics in 1996/1997. The gastrointestinal tract is the natural human reservoir for GBS and is the likely source of vaginal colonization. GBS disease in newborns usually results from ascending spread of GBS into the amniotic fluid, which leads to neonatal colonization and to invasive disease in some infants. This review analyzes the various laboratory methods available for the detection of GBS from clinical samples collected from pregnant women and will discuss their impact in the prevention of neonatal GBS infections and in the rationalization of antibiotic use. The recent commercial availability of a rapid and highly sensitive real-time polymerase chain reaction assay suitable for the specific detection of GBS from vagino-rectal samples obtained from pregnant women during delivery, which is approved by the US Food and Drug Administration, provides improvements in the accuracy and rapidity of GBS colonization screening compared to the standard culture-based method using the recommended selective enrichment broth.