What is the recommended oral medication for a urinary tract infection (UTI) caused by Group B streptococcus (GBS)?

Treatment of UTI Caused by Group B Streptococcus (GBS)

For urinary tract infections caused by Group B streptococcus, penicillin remains the first-line oral treatment option, with amoxicillin as an acceptable alternative. 1

First-line Treatment Options

Penicillin-based options:

• Penicillin G: First-line agent for GBS infections 1
• Amoxicillin: 500 mg orally every 8 hours 1
  • Preferred oral option due to good GI absorption and sustained serum concentrations 1

Alternative Treatment Options for Penicillin-Allergic Patients

For patients with penicillin allergy, consider:

• Nitrofurantoin: 100 mg orally every 6 hours 1, 2

  • Particularly recommended for GBS bacteriuria 2
  • Shows excellent sensitivity against GBS isolates 2

• Fosfomycin: 3 g single oral dose 1, 3

  • Effective for uncomplicated UTIs
  • Minimal impact on normal vaginal flora

• Clindamycin: 600 mg orally 1

  • Only if the GBS isolate is confirmed susceptible
  • Resistance rates of 19-23% have been reported 2, 4

Important Considerations

Antimicrobial Resistance

• Recent studies show increasing resistance patterns in GBS:
  • Up to 18.3% resistance to penicillin 4
  • 81.6% resistance to ampicillin in some regions 4
  • 23.3% resistance to clindamycin 4

Treatment Duration

• Uncomplicated lower UTI: 5-7 days
• Complicated or upper UTI: 10-14 days

Special Populations

Pregnant Women

• GBS in urine during pregnancy (any concentration) requires treatment to prevent perinatal GBS disease 1
• Intrapartum prophylaxis is recommended for women with GBS bacteriuria during current pregnancy 1

Clinical Pearls and Pitfalls

1. Always check susceptibility: Due to increasing resistance patterns, antibiotic susceptibility testing should be performed on all GBS isolates 4, 2

2. Consider underlying conditions: GBS UTIs in non-pregnant adults often signal urinary tract abnormalities (60% of cases) or chronic renal failure (27%) 5

3. Avoid empiric use of trimethoprim-sulfamethoxazole and fluoroquinolones: High resistance rates in many communities make these suboptimal choices 3

4. Monitor for treatment failure: Poor clinical outcomes have been reported in 18% of GBS UTI episodes despite treatment 5

5. Follow-up urine culture: Consider obtaining a test of cure, especially in pregnant women or patients with complicated infections

By following these treatment recommendations and considering the patient's allergy status and local resistance patterns, GBS urinary tract infections can be effectively managed to reduce morbidity and prevent complications.