Prevention and Treatment of Group B Streptococcus in Pregnancy and Newborns

Universal Screening and Indications for Prophylaxis

The Centers for Disease Control and Prevention recommends that all pregnant women should be screened at 35-37 weeks' gestation for vaginal and rectal GBS colonization, and intrapartum antibiotic prophylaxis should be given to all women identified as GBS carriers to prevent early-onset GBS disease 1, 2
Pregnant women should undergo universal screening for GBS colonization between 35-37 weeks' gestation with both vaginal and rectal specimens 1, 2
Women with GBS isolated from urine at any concentration during the current pregnancy should receive intrapartum antibiotic prophylaxis without need for additional screening 2, 3
Women who previously gave birth to an infant with invasive GBS disease should receive intrapartum prophylaxis without additional screening 1, 2
If GBS status is unknown at labor onset, intrapartum prophylaxis should be administered to women with any of these risk factors: gestation <37 weeks, membrane rupture ≥18 hours, or temperature ≥100.4°F (≥38.0°C) 1, 2

The Centers for Disease Control and Prevention recommends that collection should involve swabbing the lower vagina and rectum (through the anal sphincter) 1
Specimens should be placed in nonnutritive transport medium and clearly labeled for GBS culture 1
Laboratories should use techniques that maximize GBS recovery, including 1-4 hour incubation in appropriate enrichment broth medium 4

For women without penicillin allergy: Penicillin G, 5 million units IV initial dose, then 2.5 million units IV every 4 hours until delivery 5
Alternative for non-allergic women: Ampicillin, 2g IV initial dose, then 1g IV every 4 hours until delivery 5
Antimicrobial agents should not be used before the intrapartum period to eradicate GBS colonization, as this is ineffective and may cause adverse consequences 5, 6

For women with threatened preterm labor: obtain vaginal-rectal swab for GBS culture and start GBS prophylaxis 7
If determined not to be in true labor, discontinue GBS prophylaxis 4
For women with preterm premature rupture of membranes (pPROM): obtain GBS culture and start antibiotics 8
Antibiotics given for latency in pPROM that include ampicillin 2g IV once, followed by 1g IV every 6 hours for at least 48 hours are adequate for GBS prophylaxis 8

All GBS isolates from urine should be treated regardless of colony count, as GBS bacteriuria is a marker for heavy genital tract colonization 6
Women with symptomatic or asymptomatic GBS UTI during pregnancy should receive treatment according to standard UTI protocols 6
These women must also receive intrapartum antibiotic prophylaxis during labor and do not need additional GBS screening at 35-37 weeks 6

Attempting to eradicate GBS colonization before labor with antibiotics is ineffective and may cause adverse consequences 6
Withholding intrapartum prophylaxis for women with history of GBS bacteriuria in the current pregnancy, even if subsequent cultures are negative, is not recommended 6
GBS colonization during a previous pregnancy is not an indication for prophylaxis in subsequent deliveries without current positive screening 1