What is the management for a pregnant woman near term with 1,000-9,000 Colony-Forming Units per Milliliter (CFU/ML) of Group B Streptococcus (GBS) colonization?

Management of 1,000-9,000 CFU/mL GBS in Pregnant Women Near Term

Any concentration of GBS in urine during pregnancy—including 1,000-9,000 CFU/mL—requires immediate treatment of the urinary tract infection followed by mandatory intrapartum IV antibiotic prophylaxis during labor, regardless of whether the UTI is treated today. 1

Why This Colony Count Matters

• GBS bacteriuria at any concentration during pregnancy is a marker for heavy genital tract colonization and significantly increases the risk of early-onset neonatal GBS disease. 1
• The CDC guidelines specify that laboratories should report GBS present at ≥10,000 CFU/mL (≥10⁴ CFU/mL) as the threshold for clinical significance in pregnancy, but even lower concentrations (1,000-9,000 CFU/mL) have been associated with elevated risk for early-onset GBS disease in infants. 1
• Women with GBS bacteriuria are heavily colonized and at increased risk of delivering an infant with early-onset GBS disease. 1

Immediate Treatment of the UTI

Treat the acute UTI now according to standard pregnancy UTI protocols:

• Penicillin G (5 million units IV initially, then 2.5 million units IV every 4 hours) is the preferred agent for inpatient treatment due to its narrow spectrum of activity and high efficacy against GBS. 1
• Ampicillin (2 g IV initial dose, then 1 g IV every 4 hours) is an acceptable alternative for inpatient treatment. 1
• Complete the full prescribed course of antibiotics to ensure eradication and prevent recurrence. 1

Critical Pitfall: Treatment Does NOT Eliminate Colonization

Treating the UTI during pregnancy does NOT eliminate GBS colonization from the genitourinary tract—recolonization after oral antibiotics is typical. 1 This is why intrapartum IV prophylaxis remains mandatory even if bacteriuria was treated earlier in pregnancy. 1

Mandatory Intrapartum Prophylaxis 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. 1

First-Line Intrapartum Regimen (No Penicillin Allergy):

• Penicillin G: 5 million units IV initially, then 2.5-3.0 million units IV every 4 hours until delivery. 1
• Alternative: Ampicillin 2 g IV initially, then 1 g IV every 4 hours until delivery. 1

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

For patients at HIGH risk for anaphylaxis (history of immediate hypersensitivity reactions, angioedema, urticaria, or asthma):

• Clindamycin: 900 mg IV every 8 hours until delivery (if isolate is confirmed susceptible). 1
• Vancomycin: 1 g IV every 12 hours until delivery (if susceptibility is unknown or isolate is resistant to clindamycin). 1

Timing is Critical

• Intrapartum prophylaxis must be administered ≥4 hours before delivery for maximum effectiveness. 1
• When given ≥4 hours before delivery, prophylaxis is 78% effective in preventing early-onset neonatal GBS disease. 1, 2

No Need for Repeat Screening

Women with documented GBS bacteriuria at any point in pregnancy should NOT be re-screened with vaginal-rectal cultures at 35-37 weeks. 1 They are presumed to be GBS colonized and automatically qualify for intrapartum prophylaxis. 1

Documentation and Communication

• Ensure that laboratory reports of GBS bacteriuria are communicated to both the anticipated site of delivery and the ordering provider. 1
• Document clearly in the prenatal record that this patient requires intrapartum prophylaxis due to GBS bacteriuria. 1

Common Clinical Errors to Avoid

• Do NOT assume that treating the UTI eliminates the need for intrapartum prophylaxis—this is a common and dangerous error. 1
• Do NOT use oral or IV antibiotics before labor to eliminate GBS colonization—such treatment is completely ineffective at eliminating GBS colonization and should never be used for asymptomatic vaginal colonization. 1
• Do NOT underdose or prematurely discontinue therapy—this may lead to treatment failure or recurrence. 1