Treatment of Group B Streptococcal Urinary Tract Infection
For non-pregnant patients with Group B Streptococcal (GBS) urinary tract infection, penicillin G is the preferred first-line treatment due to its narrow spectrum of activity and high efficacy. 1
First-Line Treatment Options
- Penicillin G is the treatment of choice for GBS infections because of its proven efficacy, safety, narrow spectrum, and low cost 2
- Alternative first-line option is ampicillin, though penicillin G is preferred due to its narrower spectrum and reduced likelihood of selecting for resistant organisms 2
- For the urinary tract infection identified in this case (10,000-49,000 CFU/mL of Group B Streptococcus), treatment is necessary as GBS at concentrations ≥10^4 CFU/ml represents a clinically significant finding 3
Treatment for Penicillin-Allergic Patients
- For patients with penicillin allergy who are not at high risk for anaphylaxis (no history of immediate hypersensitivity reactions), cefazolin is the preferred alternative 2
- For patients at high risk for anaphylaxis (history of anaphylaxis, angioedema, or urticaria with penicillin), options include: 2
- Clindamycin (if the isolate is confirmed susceptible)
- Vancomycin (if susceptibility testing is not available or isolate is resistant to clindamycin)
Importance of Susceptibility Testing
- Susceptibility testing should be performed on GBS isolates from penicillin-allergic patients at high risk for anaphylaxis 1
- Approximately 20% of GBS isolates are resistant to clindamycin, highlighting the importance of susceptibility testing 1
- In this case, the laboratory report notes that "Beta-hemolytic streptococci are predictably susceptible to Penicillin and other beta-lactams" but susceptibility testing for other antibiotics was not performed 3
Dosing Recommendations
For non-pregnant patients with GBS UTI: 1
- Penicillin G: 5 million units IV initial dose, then 2.5 million units IV every 4 hours
- Ampicillin: 2 g IV initial dose, then 1 g IV every 4 hours
- For oral therapy after initial IV treatment: Amoxicillin 500 mg three times daily
For penicillin-allergic patients: 2
- Cefazolin: 2 g IV initial dose, then 1 g IV every 8 hours
- Clindamycin: 900 mg IV every 8 hours (if susceptible)
- Vancomycin: 1 g IV every 12 hours (for severe infections or when susceptibility results are unavailable)
Special Considerations for Pregnant Patients
- The laboratory report specifically mentions: "If this patient is pregnant, please refer to ACOG guidelines for appropriate screening and management of pregnant women" 2
- Pregnant women with GBS bacteriuria in any concentration should receive intrapartum antimicrobial prophylaxis during labor to prevent early-onset neonatal GBS disease 4
- For pregnant women, GBS in urine is a marker for heavy genital tract colonization and increases the risk for early-onset neonatal GBS disease 4
Clinical Pitfalls and Caveats
- Erythromycin and clindamycin are not recommended for treatment of urinary tract infections, as noted in the laboratory report 1
- Resistance rates to clindamycin (28%) and erythromycin (30%) are increasing, so these antibiotics should not be used without susceptibility testing 5
- Complete the full prescribed course of antibiotics to ensure complete eradication and prevent recurrence 1
- Underdosing or premature discontinuation of therapy may lead to treatment failure or recurrence 1
Duration of Treatment
- Standard duration for uncomplicated UTI is 7-10 days 1
- Extended therapy may be considered if symptoms are severe or if there are complicating factors such as urinary tract abnormalities 3
- Urinary tract abnormalities are common (60%) among non-pregnant adults with GBS UTI, suggesting the need for further evaluation of the urinary tract after treatment 6