Does Group B strep (Streptococcus agalactiae) in urine require treatment?

Treatment of Group B Streptococcus in Urine

Group B Streptococcus (GBS) detected in urine during pregnancy should be treated with antibiotics regardless of colony count, as it represents heavy genital tract colonization and increases risk for maternal and neonatal complications. 1

Rationale for Treatment

GBS bacteriuria is a significant marker for heavy genital tract colonization and requires treatment for several important reasons:

• It indicates increased risk for early-onset neonatal GBS disease 2, 1
• It can lead to maternal complications including pyelonephritis and chorioamnionitis 1
• Treatment may reduce rates of preterm labor 3
• The CDC guidelines specifically recommend treatment of GBS bacteriuria during pregnancy regardless of colony count 2, 1

Treatment Recommendations

For Pregnant Women:

• First-line treatment: Penicillin G or ampicillin 1
• For penicillin-allergic patients:
  • Minor allergy: Cefazolin 4
  • Serious allergy risk: Clindamycin (if organism is susceptible) or vancomycin (if resistance or unknown susceptibility) 4
• For uncomplicated lower UTIs: Nitrofurantoin may be considered 1
• For complicated UTIs/pyelonephritis: Beta-lactams for 10-14 days 1

Additional Management for Pregnant Women:

• Intrapartum antibiotic prophylaxis is required during labor regardless of whether treatment was provided earlier in pregnancy 2, 1
• No need for vaginal and rectal screening at 35-37 weeks if GBS bacteriuria was detected earlier in pregnancy 2, 1
• Follow-up urine culture after treatment completion is recommended 1

For Non-Pregnant Adults:

• Treatment follows standard UTI protocols based on symptoms and colony count
• Significant bacteriuria (≥100,000 CFU/mL) should be treated 5

Laboratory Considerations

• Laboratories should report GBS in urine specimens when present at concentrations of ≥10^4 colony-forming units/ml in pure culture or mixed with a second microorganism 2, 1
• Proper labeling of urine specimens from pregnant women is crucial for appropriate laboratory processing 2

Common Pitfalls to Avoid

1. Failure to treat low colony counts in pregnancy: Even low concentrations of GBS in urine can indicate heavy genital tract colonization 2, 1

2. Assuming treatment during pregnancy eliminates the need for intrapartum prophylaxis: Antibiotics during pregnancy do not eliminate GBS from genitourinary and gastrointestinal tracts, and recolonization after treatment is common 2

3. Unnecessary repeat screening: Women with documented GBS bacteriuria should not be re-screened by genital tract culture or urinary culture in the third trimester, as they are presumed to be GBS colonized 5

4. Overlooking proper specimen labeling: Urine specimens from pregnant women should be clearly labeled to ensure appropriate laboratory processing and reporting 2

By following these evidence-based recommendations, clinicians can effectively manage GBS bacteriuria and reduce the risk of associated maternal and neonatal complications.