Treatment of Group B Streptococcus in Urine
Critical Context: Pregnancy Status Determines Everything
The treatment of GBS bacteriuria depends entirely on whether the patient is pregnant—if pregnant, any concentration of GBS in urine requires immediate treatment of symptomatic UTI plus mandatory intrapartum antibiotic prophylaxis during labor; if not pregnant, treatment is only indicated for symptomatic infection. 1, 2
For Pregnant Women
Immediate Management of GBS Bacteriuria
Any concentration of GBS in urine during pregnancy (including counts as low as 10,000 CFU/mL) requires treatment because GBS bacteriuria is a marker for heavy genital tract colonization and significantly increases the risk of early-onset neonatal disease. 3, 1
If the patient has symptomatic UTI, treat the acute infection immediately according to standard pregnancy UTI protocols using pregnancy-safe antibiotics. 3, 2
Critical pitfall to avoid: Treating the UTI during pregnancy does NOT eliminate GBS colonization from the genitourinary tract—recolonization after oral antibiotics is typical, which is why intrapartum IV prophylaxis remains mandatory even if bacteriuria was treated earlier in pregnancy. 3, 1, 4
Intrapartum Antibiotic Prophylaxis (Mandatory During Labor)
All pregnant women with GBS bacteriuria at any point during the current pregnancy must receive intrapartum antibiotic prophylaxis during labor, regardless of when or if the UTI was treated. 3, 2, 4
First-Line Regimens (No Penicillin Allergy):
- Penicillin G: 5 million units IV initially, then 2.5-3 million units IV every 4 hours until delivery 2, 5
- Ampicillin: 2 g IV initially, then 1 g IV every 4 hours until delivery 3, 2, 6
Alternative Regimens (Penicillin Allergy):
For patients NOT at high risk for anaphylaxis: Cefazolin 2 g IV initially, then 1 g IV every 8 hours until delivery 2
For patients at HIGH risk for anaphylaxis (history of anaphylaxis, angioedema, respiratory distress, or urticaria following penicillin/cephalosporin):
Key Clinical Points for Pregnancy
Intrapartum prophylaxis administered ≥4 hours before delivery is 78% effective in preventing early-onset neonatal GBS disease. 3
Women with GBS bacteriuria during pregnancy do NOT need additional GBS screening at 35-37 weeks' gestation—the bacteriuria itself is sufficient indication for intrapartum prophylaxis. 3, 4
Exception: Intrapartum prophylaxis is NOT routinely recommended for planned cesarean deliveries performed before onset of labor with intact amniotic membranes, as the risk of transmission is extremely low in this specific circumstance. 3
For Non-Pregnant Patients
Treatment Approach
Non-pregnant patients with GBS bacteriuria at concentrations of 10,000-49,000 CFU/mL should NOT be treated unless they are symptomatic or have underlying urinary tract abnormalities. 2
The Infectious Diseases Society of America provides strong evidence against screening for or treating asymptomatic bacteriuria in non-pregnant populations, as treatment leads to unnecessary antibiotic exposure, resistance development, and potential adverse effects without clinical benefit. 2
If symptomatic UTI is present in non-pregnant adults, treat according to standard UTI protocols with appropriate antibiotics based on susceptibility testing. 8
Clinical Context for Non-Pregnant Adults
GBS accounts for approximately 2% of positive urine cultures in non-pregnant adults, with 85% occurring in women and 95% having at least one underlying condition (urinary tract abnormalities in 60%, chronic renal failure in 27%). 8
GBS presence in non-pregnant adults signals a need for screening for urinary tract abnormalities. 8
Antibiotic Susceptibility Considerations
All GBS isolates worldwide remain universally susceptible to penicillin—no penicillin-resistant GBS has ever been documented. 1
Resistance to erythromycin and clindamycin is increasingly common (23-31% for erythromycin, 10-19% for clindamycin in some studies), making susceptibility testing essential for penicillin-allergic patients at high risk for anaphylaxis. 9, 10
Testing for inducible clindamycin resistance should be performed on GBS isolates that are susceptible to clindamycin but resistant to erythromycin in penicillin-allergic patients at high risk for anaphylaxis. 3
Critical Pitfalls to Avoid
Never assume that treating GBS bacteriuria with oral antibiotics during pregnancy eliminates the need for intrapartum IV prophylaxis—only IV antibiotics given ≥4 hours before delivery are effective in preventing neonatal disease. 3, 1
Never treat asymptomatic GBS bacteriuria in non-pregnant patients—this represents colonization, not infection, and treatment provides no benefit while promoting resistance. 2
Never confuse pregnancy and non-pregnancy management guidelines—the CDC guidelines mandating treatment of any GBS bacteriuria apply specifically to pregnant women to prevent neonatal disease. 1
Ensure laboratories are informed when urine specimens are from pregnant women so they report GBS at concentrations ≥10,000 CFU/mL (≥10^4 CFU/mL). 3