From the Guidelines
Group B Streptococcus (GBS) positive pregnant women should receive intravenous antibiotics during labor to prevent transmission to the newborn, with the recommended treatment being penicillin G, given as a 5 million unit initial dose, followed by 2.5-3 million units every 4 hours until delivery 1.
Key Considerations
- For women with penicillin allergy but low risk of anaphylaxis, cefazolin 2g initial dose followed by 1g every 8 hours is appropriate 1.
- Those with high risk of anaphylaxis can receive clindamycin 900mg every 8 hours or vancomycin 20mg/kg every 8 hours (if the GBS is susceptible) 1.
- Antibiotics should ideally be started at least 4 hours before delivery for maximum effectiveness 1.
- No treatment is needed before labor unless there's GBS bacteriuria or a previous infant with GBS disease 1.
Rationale
- GBS can cause serious infections in newborns, including sepsis, pneumonia, and meningitis 1.
- The bacteria, present in the vagina or rectum of about 25% of pregnant women, can be transmitted during vaginal delivery, and intrapartum antibiotics significantly reduce this risk 1.
Special Cases
- Women with GBS bacteriuria in any concentration during their current pregnancy or who previously gave birth to an infant with GBS disease should receive intrapartum antimicrobial prophylaxis 1.
- Women with threatened preterm (<37 weeks' gestation) delivery should be assessed for need for intrapartum prophylaxis to prevent perinatal GBS disease 1.
From the Research
Treatment of GBS Positive Pregnant Women
- The primary approach to prevent perinatal GBS disease is maternal intrapartum antibiotic prophylaxis based on antenatal screening for GBS colonization 2, 3.
- Universal screening for GBS among women at 35 to 37 weeks of gestation is more effective than administration of intrapartum antibiotics based on risk factors 2.
- Women with GBS bacteriuria in the current pregnancy and those who previously delivered a GBS-septic newborn are not screened but automatically receive intrapartum antibiotics 2.
- Intrapartum chemoprophylaxis is selected based on maternal allergy history and susceptibility of GBS isolates 2, 4.
Antibiotic Regimens
- Intravenous penicillin G is the preferred antibiotic, with ampicillin as an alternative 2, 3.
- Penicillin G should be administered at least four hours before delivery for maximum effectiveness 2, 4.
- Cefazolin is recommended in women allergic to penicillin who are at low risk of anaphylaxis 2, 3.
- Clindamycin and erythromycin are options for women at high risk for anaphylaxis, and vancomycin should be used in women allergic to penicillin and whose cultures indicate resistance to clindamycin and erythromycin or when susceptibility is unknown 2, 5.
Management of Newborns
- Asymptomatic neonates born to GBS-colonized mothers should be observed for at least 24 hours for signs of sepsis 2.
- Newborns who appear septic should have diagnostic work-up including blood culture followed by initiation of ampicillin and gentamicin 2.
- Empiric antibiotics are recommended for infants at high risk for GBS early-onset disease 3.