What is the recommended treatment for a group B streptococcus (GBS) urine culture?

Treatment for Group B Streptococcus Urinary Tract Infection

Penicillin G or ampicillin are the first-line treatments for Group B Streptococcus (GBS) urinary tract infections due to their narrow spectrum of activity and proven effectiveness against GBS. 1

Treatment Recommendations for Non-Pregnant Adults

First-Line Treatment Options:

• Penicillin G: 5 million units IV initial dose, then 2.5-3.0 million units IV every 4 hours until clinical improvement 1
• Ampicillin: 2 g IV initial dose, then 1 g IV every 4 hours until clinical improvement 1

Alternative Options (for penicillin-allergic patients):

• Cefazolin: 2 g IV initial dose, then 1 g IV every 8 hours 1
• Clindamycin: 900 mg IV every 8 hours (only if susceptibility testing confirms sensitivity) 1
• Vancomycin: 1 g IV every 12 hours (for clindamycin-resistant strains) 1
• Nitrofurantoin: For uncomplicated lower UTIs caused by GBS 2

Important Considerations

Susceptibility Testing

• Susceptibility testing is essential for penicillin-allergic patients due to increasing resistance to alternative antibiotics 1
• Recent studies have shown concerning resistance patterns:
  • 18.3% resistance to penicillin and 81.6% to ampicillin in some regions 3
  • 23.3% resistance to clindamycin and 30% to vancomycin 3
  • 31% resistance to azithromycin and ceftriaxone 2

Treatment Duration

• Uncomplicated UTIs: 7-10 days
• Complicated UTIs or pyelonephritis: 10-14 days
• Continue treatment for at least 48-72 hours after the patient becomes asymptomatic 1

Special Considerations for Pregnant Women

Pregnant women with GBS bacteriuria require special management:

1. Treatment of Current Infection:

   • Treat any GBS bacteriuria during pregnancy regardless of colony count 4, 5
   • GBS in urine at any concentration (even <100,000 CFU/mL) indicates heavy colonization 4

2. Intrapartum Prophylaxis:

   • Women with GBS bacteriuria during pregnancy should receive intrapartum antibiotic prophylaxis during labor to prevent early-onset neonatal GBS disease 4, 5
   • No need for repeat GBS screening at 35-37 weeks if GBS bacteriuria was documented during the current pregnancy 5

3. Prophylaxis Regimen During Labor:

   • Penicillin G: 5 million units IV initially, then 2.5 million units IV every 4 hours until delivery 4
   • Ampicillin: 2 g IV initially, then 1 g IV every 4 hours until delivery (acceptable alternative) 4
   • For penicillin-allergic women: clindamycin or erythromycin (if susceptible) 4

Clinical Pitfalls to Avoid

1. Failing to distinguish between treatment and prophylaxis: Treatment of GBS UTI during pregnancy is separate from intrapartum prophylaxis to prevent neonatal GBS disease 1

2. Not performing susceptibility testing in penicillin-allergic patients: With increasing resistance to alternative antibiotics, susceptibility testing is crucial 1, 3

3. Overlooking GBS bacteriuria at any colony count during pregnancy: Any level of GBS in urine during pregnancy indicates heavy colonization and requires both treatment and intrapartum prophylaxis 4, 5

4. Re-screening pregnant women with documented GBS bacteriuria: Women with GBS bacteriuria during pregnancy should not be re-screened at 35-37 weeks as they are presumed to be GBS colonized 5

5. Using inappropriate antibiotics: Avoid erythromycin due to increasing resistance, and fluoroquinolones when alternatives exist 1