What is the best treatment for Group B streptococcal (GBS) urinary tract infection (UTI)?

Treatment of Group B Streptococcal (GBS) Urinary Tract Infection

Penicillin G is the first-line treatment for Group B streptococcal (GBS) urinary tract infection, with ampicillin as an acceptable alternative due to their narrow spectrum of activity and proven effectiveness against GBS. 1

First-Line Treatment Options

For Non-Penicillin Allergic Patients:

• Penicillin G: 5 million units IV initial dose, then 2.5-3.0 million units IV every 4 hours until infection resolves 1
  • Preferred due to its narrow spectrum of activity
• Ampicillin: 2 g IV initial dose, then 1 g IV every 4 hours 1
  • For outpatient treatment: 500 mg orally four times daily for uncomplicated GBS UTI 2

Treatment for Penicillin-Allergic Patients

For Patients Without History of Anaphylaxis:

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

For Patients With History of Anaphylaxis:

1. If susceptibility testing is available and isolate is susceptible:

   • Clindamycin: 900 mg IV every 8 hours 1
   • Erythromycin: 500 mg IV every 6 hours 1

2. If susceptibility testing is unavailable or isolate is resistant to clindamycin/erythromycin:

   • Vancomycin: 1 g IV every 12 hours 1

Treatment Duration

• Uncomplicated UTI: 7-10 days of therapy
• Complicated UTI: 14 days of therapy
• Treatment should continue for at least 48-72 hours after the patient becomes asymptomatic 2

Special Considerations

Pregnant Women

• GBS bacteriuria during pregnancy (in any concentration) requires treatment as it:
  • Indicates heavy colonization
  • Increases risk of preterm delivery
  • Necessitates intrapartum antibiotic prophylaxis during delivery 1

Antimicrobial Resistance Patterns

• Recent studies have shown concerning resistance patterns in some regions:
  • One study reported 18.3% resistance to penicillin and 81.6% to ampicillin among GBS urinary isolates 3
  • Another study found GBS most sensitive to cephalothin (100%), norfloxacin (96.9%), ampicillin (96%), and nitrofurantoin (95.5%) 4
  • Highest resistance was observed against tetracycline (81.6%) and co-trimoxazole (68.9%) 4

Follow-Up

• Obtain urine culture after completion of treatment to confirm eradication
• For pregnant women, follow GBS screening protocols at 35-37 weeks gestation regardless of previous GBS UTI treatment 1

Pitfalls to Avoid

1. Do not treat asymptomatic GBS colonization outside of pregnancy (except for UTI)
2. Do not use oral antibiotics for severe infections or in patients with nausea, vomiting, or gastrointestinal motility disorders 5
3. Do not forget susceptibility testing for penicillin-allergic patients, as resistance to alternative antibiotics is increasing 1, 3
4. Do not discontinue therapy prematurely before complete resolution, as this may lead to recurrence or complications 2

By following these evidence-based treatment guidelines, clinicians can effectively manage GBS UTIs while minimizing complications and reducing the risk of antimicrobial resistance.