From the Guidelines
Group B Streptococcus (GBS) is a significant cause of early-onset neonatal sepsis in the United States, and its prevention is crucial to reduce morbidity and mortality in newborns. The bacterium commonly colonizes the gastrointestinal and genital tracts in adults, particularly in pregnant women. According to the Centers for Disease Control and Prevention (CDC) guidelines updated in 2010 1, universal screening at 35–37 weeks’ gestation for maternal GBS colonization and use of intrapartum antibiotic prophylaxis has resulted in substantial reductions in the burden of early-onset GBS disease among newborns.
Key Points
- The American Academy of Pediatrics recommends identification of maternal colonization through universal, culture-based screening with intrapartum antibiotic prophylaxis (IAP) for women with positive screening results 1.
- Women who are identified as being GBS-colonized through culture-based screening are more than 25 times more likely to deliver an infant with early-onset infection than are women with negative prenatal cultures 1.
- The standard regimen for intrapartum antibiotic prophylaxis is intravenous penicillin G, 5 million units initially, then 2.5-3 million units every 4 hours until delivery.
- For penicillin-allergic patients without anaphylaxis risk, cefazolin 2g initially followed by 1g every 8 hours is recommended.
- If there's high anaphylaxis risk, clindamycin 900mg IV every 8 hours or vancomycin 20mg/kg every 8 hours can be used.
Prevention and Treatment
In non-pregnant adults, GBS can cause urinary tract infections, skin and soft tissue infections, bacteremia, and occasionally endocarditis or meningitis. Treatment typically involves beta-lactam antibiotics for 10-14 days, with penicillin or ampicillin being first-line choices. GBS infections require prompt treatment as they can progress rapidly, especially in immunocompromised individuals, the elderly, and neonates. The bacterium's polysaccharide capsule is a key virulence factor that helps it evade host immune responses.
Recommendations
Intrapartum antibiotic prophylaxis is recommended for all pregnant women who test positive for GBS to prevent transmission to the newborn during delivery. Continued efforts are needed to sustain and improve on the progress achieved in the prevention of GBS disease, and to monitor for potential adverse consequences of intrapartum antibiotic prophylaxis 1.
From the Research
Significance of Beta-hemolytic Streptococcus (BHS) Group B
- Group B Streptococcus (GBS) is a leading cause of neonatal sepsis in the United States, with a significant decrease in early-onset GBS disease due to intrapartum antibiotic prophylaxis 2.
- GBS can cause chorioamnionitis, endometritis, and urinary tract infections in pregnant women, and can be transmitted to newborns, resulting in early-onset or late-onset neonatal disease 3.
- The screening-based strategy for preventing GBS disease involves universal screening of pregnant women at 35-37 weeks' gestation, with intrapartum antibiotic prophylaxis recommended for GBS carriers 2, 3.
Antibiotic Resistance and Treatment
- Beta-lactam antibiotics, such as penicillin, are the drugs of choice for preventing vertical infection of GBS, with macrolides and lincosamides as second-line options 4.
- There is a growing concern about antibiotic resistance in GBS, with reports of reduced susceptibility to beta-lactams and high resistance rates to second-line antibiotics such as erythromycin and clindamycin 4, 5.
- Vancomycin is used as a last resort antibiotic in cases of penicillin allergy, but there have been documented cases of vancomycin resistance in GBS 5.
Prevention and Management
- The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists recommend maternal intrapartum antibiotic prophylaxis based on antenatal screening for GBS colonization to prevent perinatal GBS disease 6.
- Pregnant women with a history of penicillin allergy are recommended to undergo skin testing to confirm or delabel the allergy, and empiric antibiotics are recommended for infants at high risk for GBS early-onset disease 6.
- Currently, there is no approach for the prevention of GBS late-onset disease, and rates of late-onset disease and stillbirths associated with GBS infections remain unchanged despite intrapartum antibiotic prophylaxis 5.