What is the recommended antibiotic treatment for beta-hemolytic Streptococcus (Group B Streptococcus) urinary tract infection?

Treatment of Beta-hemolytic Streptococcus Group B Urinary Tract Infection

Penicillin G or ampicillin should be used as first-line therapy for Group B Streptococcal (GBS) urinary tract infections due to their narrower spectrum of activity and lower likelihood of selecting for resistant organisms. 1

First-Line Treatment Options

For Outpatient Management:

• Ampicillin: 500 mg orally four times daily for 7-10 days 2
• Penicillin V: 500 mg orally four times daily for 7-10 days 1
• Cephalexin: 500 mg orally four times daily for 7-10 days 1

For Inpatient Management (Severe Infection):

• Penicillin G: 5 million units IV initially, then 2.5-3.0 million units IV every 4 hours 1
• Ampicillin: 2 g IV initially, then 1 g IV every 4 hours 1

Alternative Options for Penicillin-Allergic Patients

For Non-Anaphylactic Penicillin Allergy:

• Cefazolin: 2 g IV initial dose, then 1 g IV every 8 hours 3, 1

For Anaphylactic Penicillin Allergy (only if susceptibility confirmed):

• Clindamycin: 300-450 mg orally three times daily or 900 mg IV every 8 hours 3, 1
• Vancomycin: 1 g IV every 12 hours (for clindamycin-resistant strains) 1

Treatment Duration

• Uncomplicated UTIs: 7-10 days 1
• Complicated UTIs or pyelonephritis: 10-14 days 1
• Continue treatment for at least 48-72 hours after the patient becomes asymptomatic 2

Important Considerations

Antimicrobial Susceptibility

• All GBS isolates generally remain susceptible to penicillin, ampicillin, cefazolin, and vancomycin 1
• However, resistance to alternative agents is increasing, with recent studies showing concerning levels of resistance to penicillin (18.3%), ampicillin (81.6%), clindamycin (23.3%), and vancomycin (30%) in some regions 4
• Susceptibility testing is essential for penicillin-allergic patients due to increasing resistance to alternative antibiotics 1

Special Considerations in Pregnancy

• Any amount of GBS in urine during pregnancy indicates heavy colonization, requiring both immediate treatment of the current infection and intrapartum prophylaxis during labor 1
• Follow-up urine culture after completion of treatment is recommended to confirm eradication 1
• Intrapartum prophylaxis is required regardless of whether the patient received treatment earlier in pregnancy 1

Antibiotic Selection Pitfalls

1. Avoid fluoroquinolones for uncomplicated UTIs when alternatives exist, due to FDA warnings about serious side effects 1
2. Avoid erythromycin for GBS infections due to increasing resistance 1
3. Avoid tetracyclines in pregnancy and in children <8 years of age due to potential harmful effects 1
4. Don't use trimethoprim-sulfamethoxazole (TMP-SMX) as empiric therapy for GBS UTIs, as Group B streptococci are frequently resistant 3

Follow-up Recommendations

• Obtain a urine culture after completion of treatment to confirm eradication of the infection 1
• For pregnant women, screening for GBS at 35-37 weeks gestation is still recommended, regardless of previous GBS UTI treatment 3, 1

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