Do we treat Group B Streptococcus (GBS) in a pregnant woman without symptoms?

Treatment of Asymptomatic Group B Streptococcus in Pregnancy

Asymptomatic Group B Streptococcus (GBS) colonization in pregnant women should not be treated with antibiotics during pregnancy, but requires intrapartum antibiotic prophylaxis (IAP) during labor to prevent early-onset neonatal GBS disease. 1, 2

Screening and Management Protocol

Screening Recommendations

• All pregnant women should be screened for GBS colonization at 36 0/7 to 37 6/7 weeks' gestation with vaginal-rectal cultures 2
• The culture swab should be inserted 2 cm into the vagina and 1 cm into the anus for proper specimen collection 3

Management Based on GBS Status

When NOT to Treat During Pregnancy:

• Asymptomatic GBS colonization detected on routine screening does not require antibiotic treatment during pregnancy 1
• Antimicrobial agents should not be used before the intrapartum period to eradicate GBS genitorectal colonization, as such treatment is ineffective in eliminating GBS colonization long-term 1

When Treatment IS Required:

• GBS bacteriuria at any concentration during pregnancy:
  • Requires appropriate antibiotic treatment if symptomatic (7-14 days course) 2
  • All women with GBS bacteriuria during pregnancy will need intrapartum antibiotic prophylaxis regardless of whether they received treatment earlier in pregnancy 2

Intrapartum Antibiotic Prophylaxis (IAP) Indications

IAP is indicated for women with:

• Positive GBS vaginal-rectal screening culture in current pregnancy
• GBS bacteriuria during any trimester of current pregnancy
• Previous infant with invasive GBS disease
• Unknown GBS status at labor onset with any of these risk factors:
  • Delivery at <37 weeks' gestation
  • Amniotic membrane rupture ≥18 hours
  • Intrapartum temperature ≥100.4°F (≥38.0°C) 1, 2

IAP Recommendations

First-line Treatment:

• Penicillin G: 5 million units IV initial dose, then 2.5-3.0 million units IV every 4 hours until delivery 2

Alternatives:

• Ampicillin: 2 g IV initial dose, then 1 g IV every 4 hours until delivery
• For penicillin allergy: Cefazolin, clindamycin, or vancomycin based on sensitivity testing 2

Special Considerations

• Patients who are GBS-positive with preterm premature rupture of membranes after 34 weeks are not candidates for expectant management due to higher rates of neonatal infectious complications 2, 3
• Cesarean delivery performed before onset of labor on a woman with intact amniotic membranes does not require IAP, regardless of GBS colonization status 1
• GBS colonization in a previous pregnancy without colonization in the current pregnancy does not require IAP 1

Clinical Importance

• GBS remains a significant cause of neonatal sepsis, morbidity, and mortality despite preventive efforts 3
• The incidence of early-onset GBS disease is approximately 6.06 per 1000 births 4
• IAP has been shown to be highly effective in preventing early-onset GBS disease in newborns 4

Common Pitfalls to Avoid

• Not performing screening at the correct gestational age (36 0/7 to 37 6/7 weeks)
• Treating asymptomatic colonization during pregnancy rather than reserving antibiotics for intrapartum prophylaxis
• Failing to provide IAP to women with GBS bacteriuria during pregnancy, regardless of whether they received treatment earlier
• Not recognizing that GBS in urine at any concentration is an indication for both treatment (if symptomatic) and subsequent IAP during labor
• Inadequate or incomplete IAP administration, which has been associated with cases of early-onset disease 4