Group B Streptococcal Disease
المؤلف:
Mary Louise Turgeon
المصدر:
Immunology & Serology in Laboratory Medicine
الجزء والصفحة:
5th E, P228
2025-08-17
585
Group B Streptococcus agalactiae infections causes substantial morbidity and mortality in adults and neonates.
Epidemiology
Fatality rate ranges from 26% to 70% among men and non-pregnant women with group B streptococcus (GBS) disease. Despite substantial progress in the prevention of perinatal GBS disease since the 1990s, GBS remains the leading cause of early-onset neonatal sepsis in the United States. Universal screening at 35 to 37 weeks’ gestation for maternal GBS colonization and the use of intrapartum antibiotic prophylaxis has resulted in substantial reductions in the burden of early-onset GBS disease in newborns. Although early-onset GBS disease has become relatively uncommon in recent years, the rates of maternal GBS colonization (and therefore the risk for early onset GBS disease in the absence of intrapartum antibiotic prophylaxis) remain unchanged since the 1970s. GBS disease remains the leading infectious cause of morbidity and mortality in newborns in the United States.
Etiology
GBS, or S. agalactiae, is a gram-positive bacterium that causes invasive disease primarily in infants, pregnant or postpartum women, and older adults, with the highest incidence among young infants.
Laboratory Data
Group B streptococci are most frequently isolated from blood, although cerebrospinal fluid (CSF) can also be tested. Serologic identification using latex agglutination with group B streptococcal antisera is available. In addition, more rapid techniques for identifying GBS directly from enrichment broth or after subculture have been developed, including DNA probes and nucleic acid amplification tests (NAATs), such as polymerase chain reaction (PCR) assays.
Signs and Symptoms
The most common clinical finding is skin and soft tissue infec tion. Early-onset infections are acquired vertically through exposure to GBS from the vagina of a colonized woman. Neo natal infection occurs primarily when GBS ascends from the vagina to the amniotic fluid after the onset of labor or rupture of membranes, although GBS also can invade through intact membranes. Infants also can become infected with GBS during passage through the birth canal; infants who are exposed to the organism through this route can become colonized at mucous membrane sites in the gastrointestinal or respiratory tracts, but these colonized infants usually remain healthy.
Future Directions
Because of the gravity of GBS disease, especially in those who are older and those with chronic diseases, the development of a vaccine is being pursued. Determining the incidence of adult disease and groups at greatest risk helps focus prevention efforts. Intrapartum antibiotics can prevent early-onset neonatal GBS disease but have not been widely used.
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