Perinatal Group B streptococcal disease: clinical-microbiological aspects and prevention

Abstract

Lancefield group B streptococci (GBS, or Streptococcus agalactiae) are Gram-positive bacterial components of the resident microbiota of human mucous membranes, chiefly colonizing the gut and the urogenital tract. Vertical perinatal transmission, from colonized women, is known to occur both as intrauterine infection or through contamination during labor. The worldwide prevalence of GBS-colonized pregnant women ranges from 3% to 41%. Neonatal infection may lead chiefly to sepsis and pneumonia, with less frequent occurrences of meningitis, celullitis, osteomyelitis and septic arthritis. The first guidelines for prevention of the vertical transmission of perinatal streptococcal disease were issued in 1996. Routine investigation of the S. agalactiae colonization status, through selective-medium culture of vaginal and rectal secretions at the term of pregnancy, and intrapartum antimicrobial prophylaxis were established in 2002. A significant decrease in the incidence of perinatal infection was seen in the countries that adopted the prophylactic measures. Although neonatal mortality in Brazil is a serious public health issue, no preventive or treatment strategies targeting GBS-neonatal infection have been adopted. Because of the high cost and serious consequences of perinatal streptococcal disease, health policies aiming at reducing vertical transmission are clearly called for.