What is the treatment for a urinary tract infection (UTI) with greater than 100,000 colony-forming units (CFU) of yeast per milliliter (mL) of urine?

Management of Urinary Tract Infection with >100,000 CFU/mL of Yeast

Initial Clinical Decision: Treat or Observe?

Most patients with candiduria >100,000 CFU/mL do NOT require antifungal treatment unless they are symptomatic, neutropenic, very low-birth-weight infants (<1500g), or undergoing urologic procedures. 1, 2

High-Risk Patients Requiring Treatment (Even if Asymptomatic)

• Neutropenic patients 1
• Very low-birth-weight infants (<1500g) 1
• Patients scheduled for urologic procedures within several days 1
• Patients with fever and candiduria who are severely immunocompromised (concern for disseminated candidiasis) 1

First-Line Management Before Antifungals

Remove or replace indwelling urinary catheters if present—this alone resolves candiduria in approximately 50% of cases. 3, 4, 5 This is the critical first step and may eliminate the need for antifungal therapy entirely. 1

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Treatment Algorithm for Symptomatic Candiduria

For Symptomatic Cystitis (Lower UTI)

Oral fluconazole 200 mg (3 mg/kg) daily for 14 days is the first-line treatment for fluconazole-susceptible Candida species. 1, 3, 2

• Fluconazole achieves high urinary concentrations and has demonstrated 82% efficacy in clinical trials 3, 4
• A loading dose of 400 mg on day 1 followed by 200 mg daily is an acceptable alternative 6
• Treatment duration should be at least 2 weeks to decrease likelihood of relapse 1, 3

Alternative Regimens for Fluconazole-Resistant Organisms (especially C. glabrata)

• Amphotericin B deoxycholate 0.3-0.6 mg/kg IV daily for 1-7 days 1, 2
• Oral flucytosine 25 mg/kg four times daily for 7-10 days 1, 2
• Amphotericin B bladder irrigation (50 mg/L sterile water) may be considered for refractory C. glabrata or C. krusei cystitis, though relapse rates are high (>80-90%) 1, 2

Critical Pitfall: Other azoles (voriconazole, posaconazole, itraconazole) and all echinocandins achieve inadequate urine concentrations and should NOT be used for Candida UTI. 1, 4, 5 Lipid formulations of amphotericin B also fail to achieve adequate urinary levels. 1

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For Pyelonephritis (Upper UTI)

Oral fluconazole 200-400 mg (3-6 mg/kg) daily for 14 days is first-line for fluconazole-susceptible organisms. 1, 3, 6

• Use the higher dose range (400 mg daily) for more severe upper tract infections 3
• For fluconazole-resistant strains (especially C. glabrata):
  • Amphotericin B deoxycholate 0.5-0.7 mg/kg IV daily with or without flucytosine 25 mg/kg four times daily for 14 days 1, 6
  • Flucytosine alone at 25 mg/kg four times daily for 14 days is an alternative 1

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For Patients Undergoing Urologic Procedures

Prophylactic treatment is required even if asymptomatic: 1, 2

• Oral fluconazole 400 mg (6 mg/kg) daily OR
• Amphotericin B deoxycholate 0.3-0.6 mg/kg IV daily
• Administer for several days before AND after the procedure 1, 2

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Special Clinical Scenarios

Fungus Balls (Bezoars)

Surgical or endoscopic removal is mandatory in adults, combined with antifungal therapy. 1

• Antifungal regimen: Same as for cystitis or pyelonephritis (fluconazole 200-400 mg daily) 1
• If nephrostomy tubes are present, irrigation with amphotericin B deoxycholate 25-50 mg in 200-500 mL sterile water through the tube 1
• Continue treatment until symptoms resolve AND urine cultures are negative for Candida 1

Suspected Disseminated Candidiasis

If candiduria occurs with fever in a severely immunocompromised patient, treat as candidemia with echinocandin therapy (not fluconazole). 1 This represents hematogenous seeding of the kidneys, not ascending UTI.

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Critical Monitoring and Follow-Up

• Obtain follow-up urine cultures to document clearance after completing therapy 7
• If treatment fails despite appropriate therapy, obtain imaging (ultrasound or CT) to identify:
  • Fungus balls 3
  • Hydronephrosis 3
  • Abscesses 3
  • Structural abnormalities 3
• Consider removing or replacing nephrostomy tubes or ureteral stents if present 2

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Common Pitfalls to Avoid

1. Do not treat asymptomatic candiduria in non-high-risk patients—this leads to unnecessary antifungal exposure and potential resistance. 1, 2

2. Colony count cannot reliably differentiate colonization from infection, especially with indwelling catheters—clinical symptoms and risk factors must guide treatment decisions. 2

3. Never use echinocandins or non-fluconazole azoles for Candida UTI—they do not achieve therapeutic urinary concentrations. 1, 4, 5

4. Always remove catheters before or during treatment—failure to address this predisposing factor leads to treatment failure and relapse. 1, 3, 4

5. Bladder irrigation with amphotericin B has >80% relapse rates—reserve this only for refractory fluconazole-resistant cystitis when systemic therapy has failed. 1, 2