What is the management for a pregnant patient who is Group B Streptococcus (GBS) positive?

Management of GBS-Positive Pregnancy

All pregnant women who test positive for Group B Streptococcus (GBS) on vaginal-rectal screening at 35-37 weeks gestation must receive intravenous antibiotic prophylaxis during labor to prevent early-onset neonatal GBS disease. 1

Universal Screening Protocol

• Screen all pregnant women at 35-37 weeks' gestation (updated recommendation now specifies 36 0/7 to 37 6/7 weeks) with vaginal and rectal swab cultures 1, 2
• Collect specimens by swabbing the lower vagina first, then inserting the same swab through the anal sphincter into the rectum to maximize GBS detection 3
• Women with GBS bacteriuria at any concentration during any trimester of the current pregnancy automatically qualify for intrapartum prophylaxis and do not need third trimester screening 1, 3
• Women with a previous infant with invasive GBS disease should receive intrapartum prophylaxis without screening 1

Intrapartum Antibiotic Prophylaxis Regimens

First-Line Treatment (No Penicillin Allergy)

• Penicillin G: 5 million units IV initially, then 2.5-3.0 million units IV every 4 hours until delivery (preferred agent due to narrow spectrum and universal GBS susceptibility) 1, 3, 2
• Ampicillin: 2 g IV initially, then 1 g IV every 4 hours until delivery (acceptable alternative with broader spectrum) 1, 3

Penicillin-Allergic Patients

For patients NOT at high risk for anaphylaxis:

• Cefazolin: 2 g IV initially, then 1 g IV every 8 hours until delivery 1, 3, 4
• Note that approximately 10% of penicillin-allergic patients cross-react with cephalosporins 3, 4

For patients at HIGH RISK for anaphylaxis (history of anaphylaxis, angioedema, urticaria, or asthma):

• Clindamycin: 900 mg IV every 8 hours until delivery (ONLY if isolate confirmed susceptible) 1, 3, 5
• Vancomycin: 1 g IV every 12 hours until delivery (if isolate resistant to clindamycin or susceptibility unknown) 1, 3
• Susceptibility testing for clindamycin and erythromycin is mandatory for prenatal GBS isolates from penicillin-allergic women at high risk for anaphylaxis, as clindamycin resistance ranges from 3-15% 3, 5

Critical Timing Considerations

• Administer antibiotics ≥4 hours before delivery for maximum effectiveness (78% reduction in early-onset neonatal GBS disease) 1, 3, 2
• Although 4+ hours is optimal, even 2 hours of antibiotic exposure reduces GBS vaginal colony counts and decreases clinical neonatal sepsis 2
• Do not delay necessary obstetric interventions solely to achieve 4 hours of antibiotic administration 2

When Prophylaxis is NOT Indicated

• Cesarean delivery performed before onset of labor with intact amniotic membranes (regardless of GBS status or gestational age) 1, 6
• Negative vaginal-rectal GBS screening culture in late gestation during current pregnancy, regardless of intrapartum risk factors 1
• GBS colonization during a previous pregnancy (unless current pregnancy has indication) 1

Management When GBS Status Unknown at Labor

Administer intrapartum prophylaxis if ANY of the following risk factors present: 1, 6

• Delivery at <37 weeks and 0 days' gestation
• Duration of membrane rupture ≥18 hours
• Intrapartum temperature ≥100.4°F (≥38.0°C)
• Positive intrapartum nucleic acid amplification test (NAAT) for GBS (if available)

Special Clinical Scenarios

Preterm Labor (<37 weeks)

• Women admitted with signs/symptoms of preterm labor should be screened for GBS at hospital admission unless screened within preceding 5 weeks 1
• Start GBS prophylaxis immediately at admission for women with unknown GBS status or positive screen within 5 weeks 1, 3
• Discontinue prophylaxis if preterm labor resolves and patient not delivering 1
• Continue prophylaxis until delivery if patient enters true labor 1

GBS Bacteriuria During Pregnancy

• Any concentration of GBS in urine during any trimester requires immediate treatment of the UTI AND mandatory intrapartum prophylaxis during labor 1, 3
• Treating the UTI does NOT eliminate GBS colonization—recolonization after oral antibiotics is typical, which is why intrapartum IV prophylaxis remains mandatory 3
• Women with GBS bacteriuria should not be re-screened at 35-37 weeks as they are presumed heavily colonized 3

Preterm Premature Rupture of Membranes (PPROM)

• For PPROM at ≥24 weeks with expectant management: Ampicillin 2 g IV once, followed by 1 g IV every 6 hours for at least 48 hours (adequate for both latency prolongation and GBS prophylaxis) 3

Critical Pitfalls to Avoid

• NEVER use oral or IV antibiotics before the intrapartum period to eradicate GBS colonization—this is completely ineffective at eliminating carriage, promotes antibiotic resistance, and may cause adverse consequences 1, 3, 4, 6
• Do not assume treating a GBS UTI earlier in pregnancy eliminates the need for intrapartum prophylaxis—this is a common and dangerous error 3
• Do not use ciprofloxacin or other fluoroquinolones for GBS prophylaxis—they are not validated for this indication 4
• Do not use clindamycin without confirmed susceptibility testing in penicillin-allergic patients, as resistance is significant and can lead to prophylaxis failure 3, 5
• Verify penicillin allergy history carefully, as many reported allergies are not true IgE-mediated reactions 3, 4
• Do not rely on GBS screening results from previous pregnancies for current pregnancy management 6

Coordination with Pediatric Care

• Inform women of their GBS screening results and recommended interventions 1
• Ensure laboratory reports of GBS bacteriuria are communicated to both the anticipated site of delivery and the ordering provider 3
• Coordinate with neonatal care providers regarding maternal GBS status and adequacy of intrapartum prophylaxis received 1