What are the treatment guidelines for fungal urinary tract infections (UTIs)?

Treatment Guidelines for Fungal Urinary Tract Infections

For symptomatic fungal UTIs, fluconazole 200 mg orally daily for 14 days is the first-line treatment due to its excellent urinary concentrations and effectiveness against most Candida species. 1

Diagnosis and Assessment

• Diagnosis of fungal UTI is based on:

  • Fungal concentration >10³/mm³ in urine 2
  • Presence of symptoms (dysuria, frequency, urgency, suprapubic pain)
  • Leukocyturia (although no specific cutoff has been established) 2

• Before initiating treatment:

  • Obtain urine culture to identify causative organism and susceptibility 3
  • Consider blood cultures to rule out fungemia, especially in febrile patients 1
  • Assess for and remove any urinary catheters if present (catheter removal alone resolves ~50% of fungal UTIs) 1

Treatment Algorithm Based on Clinical Presentation

1. Asymptomatic Funguria

• Generally no treatment required 3, 1
• Exceptions (treat even if asymptomatic):
  • Neutropenic patients
  • Patients undergoing urologic procedures
  • Neonates and high-risk surgical patients
  • Patients with suspected disseminated fungal infection 1, 4

2. Symptomatic Fungal Cystitis

• First-line: Fluconazole 200 mg orally daily for 14 days 3, 1
• For fluconazole-resistant species:
  • Amphotericin B deoxycholate 0.3-0.6 mg/kg/day for 1-7 days 3, 1
  • Flucytosine 25 mg/kg four times daily for 7-10 days (not as monotherapy) 1

3. Fungal Pyelonephritis

• First-line: Fluconazole 200-400 mg daily for 14 days 3, 1
• For severe infection or fluconazole-resistant species:
  • Amphotericin B deoxycholate with or without flucytosine for 7-14 days 3
  • Treat as candidemia for patients with pyelonephritis and suspected disseminated candidiasis 3

Species-Specific Considerations

Candida albicans

• Most common species (60-70% of cases) 2, 5
• Generally susceptible to fluconazole 4

Non-albicans Candida species

• C. glabrata: Often fluconazole-resistant (MIC90 of 64 μg/ml) 6
  • Consider amphotericin B deoxycholate or flucytosine 1
• C. krusei: Intrinsically fluconazole-resistant
  • Options include echinocandin, liposomal amphotericin B, or voriconazole 3
• C. tropicalis: Variable susceptibility (MIC90 of 16 μg/ml) 6
  • Higher dose fluconazole or alternative agents based on susceptibility

Special Considerations

Catheter-Associated Fungal UTIs

• Remove or replace urinary catheter when possible 1
• Catheter replacement alone results in 87-93% clearance of funguria at 8 weeks 6
• Adding fluconazole provides more rapid clearance of funguria and urinary WBCs 6

Fungal Balls or Abscesses

• Require aggressive surgical debridement in addition to antifungal therapy 1
• Consider local irrigation with amphotericin B (50 mg/L of sterile water) as an adjunct to systemic therapy 1

Renal Impairment

• Fluconazole: Dose adjustment required based on creatinine clearance
• Flucytosine: Significant dose adjustment needed; drug level monitoring recommended 1
• Amphotericin B: Monitor for nephrotoxicity 1

Important Caveats and Pitfalls

1. Do not use echinocandins or newer azoles for uncomplicated fungal UTIs due to poor urinary concentrations 1

2. Do not use lipid formulations of amphotericin B for lower UTIs due to inadequate urine concentrations 1

3. Do not use flucytosine as monotherapy due to risk of resistance development 1

4. Avoid unnecessary treatment of asymptomatic funguria in non-high-risk patients 1

5. Address underlying risk factors to prevent recurrence:

   • Control diabetes mellitus
   • Limit broad-spectrum antibiotics
   • Remove urinary catheters
   • Correct urinary tract abnormalities 2

Follow-up urine cultures should be obtained to confirm eradication, with treatment continuing until symptoms resolve and cultures become negative 1.