What is the recommended treatment for Streptococcus (Group B Streptococcus, GBS) agalactiae in urine?

Treatment of Streptococcus agalactiae (Group B Streptococcus) in Urine

For Group B Streptococcus (GBS) urinary tract infections, amoxicillin-clavulanic acid, nitrofurantoin, or sulfamethoxazole-trimethoprim are the first-line treatment options, with treatment duration of 5-7 days for uncomplicated UTIs and 10-14 days for complicated UTIs. 1

First-Line Treatment Options

Non-pregnant Adults

• First-line options:
  • Amoxicillin-clavulanic acid
  • Nitrofurantoin
  • Sulfamethoxazole-trimethoprim
• Treatment duration:
  • Uncomplicated UTIs: 5-7 days
  • Complicated UTIs: 10-14 days

Amoxicillin-clavulanic acid is preferred over amoxicillin alone due to better activity against urinary pathogens 1. While GBS is generally susceptible to penicillins, the addition of clavulanic acid helps overcome potential resistance mechanisms.

Antibiotic Susceptibility Considerations

• GBS isolates typically show high sensitivity (>95%) to:

  • Ampicillin
  • Amoxicillin-clavulanic acid (Augmentin)
  • Cephalosporins (e.g., cephalothin)
  • Penicillin 2

• Resistance concerns:

  • High resistance rates to tetracycline (96%)
  • Moderate resistance to erythromycin (35%) and clindamycin (35%)
  • Chloramphenicol resistance (45%) 3

Special Population: Pregnant Women

For pregnant women with GBS bacteriuria:

1. Treat the acute UTI with appropriate antibiotics for 5-7 days
2. Additionally require intrapartum antibiotic prophylaxis during labor regardless of treatment completion 1

Recommended intrapartum regimen (no penicillin allergy):

• Penicillin G: 5 million units IV initial dose, then 2.5 million units IV every 4 hours until delivery
• Alternative: Ampicillin 2 g IV initial dose, then 1 g IV every 4 hours until delivery 4, 1

For penicillin-allergic pregnant women:

• Non-anaphylactic allergy: Cefazolin 2 g IV initial dose, then 1 g IV every 8 hours until delivery
• High risk for anaphylaxis: Susceptibility testing for clindamycin and erythromycin is essential 4, 1

Important Clinical Considerations

1. Identification of infection reservoirs:

   • Check for concurrent colonization in vagina, urethra, or gastrointestinal tract in women
   • These reservoirs may require additional treatment to prevent recurrence 2

2. Laboratory reporting:

   • GBS in urine should be reported when present at concentrations of ≥10⁴ colony-forming units/ml in pure culture or mixed with a second microorganism 4
   • Any colony count of GBS in pregnant women indicates heavy genital tract colonization 1

3. Treatment pitfalls to avoid:

   • Do not use amoxicillin without susceptibility testing due to potential resistance
   • Avoid erythromycin due to increasing resistance rates
   • Do not attempt to treat GBS colonization with oral antibiotics in pregnant women during the third trimester (ineffective in eliminating carriage) 1
   • Fluoroquinolones should be reserved for pyelonephritis or severe cases 1

4. Clinical presentation:

   • In non-pregnant adults, GBS UTIs most commonly present as uncomplicated cystitis (66.1%)
   • More common in women over 40 years old 5
   • Pyuria is present in approximately 73% of cases 5

By following these evidence-based recommendations, clinicians can effectively treat GBS urinary tract infections while minimizing the risk of treatment failure and antimicrobial resistance.