What is the treatment for recurrent Group B strep (Streptococcus agalactiae) on urinalysis?

Treatment for Recurrent Group B Streptococcus (GBS) on Urinalysis

For recurrent Group B streptococcus (Streptococcus agalactiae) on urinalysis, continuous or postcoital antimicrobial prophylaxis should be used when non-antimicrobial interventions have failed, with penicillin or ampicillin as the preferred agents due to their proven efficacy against GBS. 1

Diagnostic Approach

1. Confirm diagnosis with urine culture

   • A positive urinalysis showing GBS should be confirmed with a urine culture 1
   • 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 2

2. Rule out complicating factors

   • Assess for structural abnormalities of the urinary tract
   • Evaluate for risk factors such as diabetes mellitus, which increases risk for invasive GBS infections 3
   • Consider pregnancy status, as management differs in pregnant women 1, 4

Treatment Algorithm

Initial Treatment for Symptomatic UTI

For acute symptomatic UTI with GBS, use one of the following:

• First-line options:

  • Penicillin (preferred for GBS) - oral dosing for genitourinary infections 5
  • Ampicillin 500 mg four times daily for 7-10 days 6
  • Nitrofurantoin 100 mg twice daily for 5 days 1, 2
  • Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days (if susceptible) 1, 2

• For penicillin-allergic patients:

  • First-generation cephalosporins (if no immediate-type hypersensitivity to β-lactams) 1
  • Clindamycin (if susceptibility confirmed) 1

Management of Recurrent GBS UTIs

After treating the acute infection, implement a stepwise approach for prevention:

1. Non-antimicrobial interventions (try first):

   • Increase fluid intake (especially in premenopausal women) 1
   • Vaginal estrogen replacement for postmenopausal women 1, 2
   • Immunoactive prophylaxis 1
   • Consider probiotics, cranberry products, or D-mannose (weak evidence) 1, 2
   • Methenamine hippurate (strong recommendation for women without urinary tract abnormalities) 1, 2

2. If non-antimicrobial interventions fail:

   • Continuous or postcoital antimicrobial prophylaxis 1, 2
     • Penicillin (preferred for GBS)
     • Trimethoprim-sulfamethoxazole 40mg/200mg once daily or three times weekly 2
     • Nitrofurantoin 50-100mg daily 2
     • Cephalexin 125-250mg daily 2
     • Fosfomycin 3g every 10 days 2

3. For patients with good compliance:

   • Self-administered short-term antimicrobial therapy at symptom onset 1

Special Considerations

Pregnant Women

• GBS bacteriuria during pregnancy (regardless of colony count) requires intrapartum antibiotic prophylaxis during labor to prevent neonatal GBS disease 1, 4
• No need to re-screen women with documented GBS bacteriuria by genital tract culture or urinary culture in the third trimester 4

Patients with Renal Impairment

• Avoid nitrofurantoin if creatinine clearance <30 mL/min 2
• Fosfomycin 3g single dose is preferred for patients with renal impairment 2

Elderly Patients

• Adjust antibiotic choice based on renal function 2
• Consider comorbidities that may increase risk of GBS infections 7

Monitoring and Follow-up

• Assess clinical response within 48-72 hours of starting treatment 2
• If symptoms persist beyond 72 hours:
  • Obtain urine culture
  • Change antibiotic based on culture results
  • Evaluate for complications or anatomical abnormalities 2

Common Pitfalls to Avoid

1. Treating asymptomatic bacteriuria (except in pregnancy) is not recommended 2
2. Inadequate treatment duration - ensure full course of antibiotics for acute infection
3. Failure to distinguish between colonization and infection - GBS carriers without symptoms or immune response may not require treatment 1
4. Overlooking underlying conditions - diabetes mellitus significantly increases risk for GBS infections 3
5. Not considering antibiotic resistance - test for susceptibility in penicillin-allergic patients 1

Remember that recurrent UTIs significantly impact quality of life, with reductions in social and sexual relationships, self-esteem, and work capacity 1. Proper management is essential to improve patient outcomes and quality of life.