What is the recommended treatment for a Group B strep (Streptococcus agalactiae) urinary tract infection (UTI)?

Treatment of Group B Streptococcus Urinary Tract Infection

Penicillin G or ampicillin is the first-line treatment for Group B Streptococcus (GBS) urinary tract infections, with a standard duration of 7-14 days. 1

First-Line Treatment Options

For Non-Pregnant Adults:

• First choice: Penicillin G (intravenous) or Ampicillin

  • Penicillin G: 2-3 million units IV every 4-6 hours 2
  • Ampicillin: 500 mg every 6 hours 3

• For penicillin-allergic patients (low risk of anaphylaxis):

  • Cefazolin: 1-2 g IV every 8 hours 1

• For penicillin-allergic patients (high risk of anaphylaxis):

  • Clindamycin (if susceptible): 600 mg IV every 8 hours 1
  • Vancomycin (if clindamycin-resistant): 15-20 mg/kg IV every 8-12 hours 1

Special Considerations for Pregnant Women

GBS bacteriuria during pregnancy requires special attention as it indicates heavy colonization and is a risk factor for early-onset GBS disease in newborns:

• Treat symptomatic UTI with appropriate antibiotics
• All pregnant women with GBS bacteriuria at any colony count during pregnancy require intrapartum antibiotic prophylaxis (IAP) during labor regardless of whether they received treatment earlier in pregnancy 1
• No need to re-screen pregnant women with documented GBS bacteriuria by genital tract culture or urinary culture in the third trimester 4

Antimicrobial Susceptibility

GBS generally shows high susceptibility to:

• Beta-lactam antibiotics (penicillins, cephalosporins)
• Vancomycin
• Norfloxacin (96.9%)
• Nitrofurantoin (95.5%) 5

GBS commonly shows resistance to:

• Tetracyclines (up to 81.6%)
• Co-trimoxazole (up to 68.9%) 5
• Erythromycin resistance is increasing 1

Treatment Duration

• Standard duration for uncomplicated GBS UTI: 7-14 days 1
• For complicated infections or bacteremia: Consider longer treatment course and further evaluation

Management Algorithm

1. Confirm diagnosis:

   • Urine culture with colony count
   • Assess for symptoms (dysuria, frequency, urgency, suprapubic pain)

2. Initial treatment:

   • Start empiric therapy with penicillin G or ampicillin
   • Adjust based on susceptibility testing when available

3. For pregnant patients:

   • Document GBS bacteriuria in medical record
   • Flag for intrapartum antibiotic prophylaxis during labor
   • Communicate GBS status to all providers involved in care 1

4. For patients with bacteremia:

   • Evaluate for potential sources of infection (skin/soft tissue, pneumonia)
   • Consider echocardiography to rule out endocarditis
   • Obtain follow-up blood cultures to document clearance 1

Clinical Pearls and Pitfalls

• GBS bacteriuria in pregnancy is significant at any colony count, not just ≥100,000 CFU/mL 1, 4
• Erythromycin is no longer recommended for GBS due to increasing resistance 1
• In non-pregnant patients with uncomplicated cystitis, oral therapy is typically sufficient after initial IV therapy
• Seasonal variations have been observed with higher rates of GBS UTI in winter months (December/January) 5

Remember that appropriate treatment of GBS UTI is essential not only to resolve the current infection but also to prevent complications, especially in pregnant women where it can affect both maternal and neonatal outcomes.