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

Treatment of Streptococcus agalactiae (Group B Strep) in Urine

Women with GBS isolated from the urine in any concentration during pregnancy should receive intrapartum antibiotic prophylaxis, and those with symptomatic or asymptomatic GBS urinary tract infection should be treated according to current standards of care for urinary tract infection during pregnancy. 1

Diagnosis and Reporting

• Laboratories should report GBS in urine culture specimens when present at concentrations of ≥10^4 colony-forming units/ml in pure culture or mixed with a second microorganism 1
• For pregnant women, urine specimen labels should clearly state pregnancy status to assist laboratory processing and reporting of results 1

Treatment Recommendations

For Pregnant Women:

1. Symptomatic or Asymptomatic UTI during pregnancy:

   • Treat according to standard UTI protocols
   • Additionally, these women require intrapartum antibiotic prophylaxis during delivery regardless of subsequent negative screening results 1

2. Intrapartum Prophylaxis Regimen:

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

3. For Penicillin-Allergic Patients:

   • Without history of anaphylaxis: Cefazolin (2 g IV initial dose, then 1 g IV every 8 hours until delivery) 1
   • With history of anaphylaxis and susceptible GBS: Clindamycin (900 mg IV every 8 hours until delivery) OR erythromycin (500 mg IV every 6 hours until delivery) 1
   • With history of anaphylaxis and resistant or unknown susceptibility: Vancomycin (1 g IV every 12 hours until delivery) 1

For Non-Pregnant Adults:

• First-line: Penicillin or ampicillin 2

  • All GBS strains remain fully sensitive to penicillin and ampicillin based on recent studies 2

• Alternative options for penicillin-allergic patients:

  • Vancomycin (for serious infections) 2
  • For uncomplicated UTIs:
    • Fosfomycin 3 g PO single dose 1
    • Nitrofurantoin 100 mg PO every 6 hours 1

Important Clinical Considerations

• Antibiotic resistance patterns: Recent studies show high resistance rates to clindamycin (77.34%) and erythromycin (up to 46%) among GBS isolates, making these suboptimal empiric choices for penicillin-allergic patients 2, 3

• Treatment duration:

  • For uncomplicated UTIs: Standard UTI treatment duration (typically 3-7 days)
  • For complicated infections: Extended therapy based on clinical response

• Special populations:

  • For pregnant women: Always report GBS bacteriuria to obstetric providers as this indicates heavy colonization and increased risk for early-onset neonatal GBS disease 1
  • Women aged 25-34 years may have higher risk of GBS UTIs 2

Pitfalls to Avoid

1. Failing to recognize the significance of GBS in pregnant women's urine: Any concentration of GBS in urine during pregnancy indicates heavy colonization and requires intrapartum prophylaxis 1

2. Using erythromycin or clindamycin empirically: Due to increasing resistance rates, susceptibility testing should be performed before using these antibiotics in penicillin-allergic patients 3

3. Not identifying infection reservoirs: Successful treatment requires identification of all potential reservoirs (vagina, urethra, gastrointestinal tract) that may lead to recurrence 4

4. Overlooking the need for follow-up cultures: Consider post-treatment cultures in cases of recurrent infections or persistent symptoms

By following these evidence-based recommendations, clinicians can effectively manage GBS urinary tract infections while reducing the risk of complications, especially in pregnant patients where prevention of neonatal GBS disease is a critical concern.