How should a candidal urinary tract infection be treated in an adult, particularly if the patient has a urinary catheter, diabetes, or is immunocompromised?

Treatment of Candidal Urinary Tract Infection

For symptomatic candidal UTI with fluconazole-susceptible organisms, treat with oral fluconazole 200 mg daily for 2 weeks for cystitis or 200-400 mg daily for 2 weeks for pyelonephritis, and remove the urinary catheter if present. 1

Critical First Steps

Catheter Management

• Remove indwelling bladder catheters immediately if feasible - this is the single most important intervention and resolves candiduria in approximately 50% of asymptomatic patients 1
• Catheter removal is a strong recommendation even before initiating antifungal therapy 1
• For patients with nephrostomy tubes or stents, consider removal or replacement if possible 1

Determine If Treatment Is Actually Needed

Most candiduria represents colonization, not infection. Do NOT treat asymptomatic candiduria except in three specific situations 1:

• Very low-birth-weight neonates
• Neutropenic patients
• Patients undergoing urologic procedures (treat prophylactically with fluconazole 400 mg daily or amphotericin B deoxycholate 0.3-0.6 mg/kg daily for several days before and after the procedure) 1

Treatment Algorithm for Symptomatic Infection

For Cystitis (Lower UTI)

Fluconazole-susceptible species (most C. albicans):

• Oral fluconazole 200 mg (3 mg/kg) daily for 2 weeks 1
• This is a strong recommendation with moderate-quality evidence 1

Fluconazole-resistant C. glabrata:

• Amphotericin B deoxycholate 0.3-0.6 mg/kg IV daily for 1-7 days, OR
• Oral flucytosine 25 mg/kg four times daily for 7-10 days 1
• Alternative: Amphotericin B bladder irrigation (50 mg/L sterile water daily for 5 days) - though this is a weak recommendation and recurrence is common 1

C. krusei:

• Amphotericin B deoxycholate 0.3-0.6 mg/kg IV daily for 1-7 days 1

For Pyelonephritis (Upper UTI)

Fluconazole-susceptible species:

• Oral fluconazole 200-400 mg (3-6 mg/kg) daily for 2 weeks 1
• Higher dose (400 mg) recommended for more severe disease

Fluconazole-resistant C. glabrata:

• Amphotericin B deoxycholate 0.3-0.6 mg/kg IV daily for 1-7 days with or without oral flucytosine 25 mg/kg four times daily 1
• Alternative monotherapy: Oral flucytosine 25 mg/kg four times daily for 2 weeks (weak recommendation) 1

C. krusei:

• Amphotericin B deoxycholate 0.3-0.6 mg/kg IV daily for 1-7 days 1

Critical: Eliminate any urinary tract obstruction - this is a strong recommendation 1

Special Considerations for High-Risk Populations

Patients with Diabetes

• Diabetes is a major risk factor for candidal UTI 2, 3
• Follow the same treatment algorithm as above
• Optimize glycemic control to reduce recurrence risk
• Be particularly vigilant about catheter removal

Immunocompromised Patients

• Neutropenic patients require treatment even if asymptomatic 1
• Consider that candiduria may indicate disseminated candidiasis, especially in neutropenic patients 1
• Follow candidemia treatment protocols if disseminated disease is suspected 1
• Duration: minimum 2 weeks after documented clearance and resolution of neutropenia 1

Catheterized Patients

• Catheter removal is mandatory for cure - candiduria persists in most patients with retained catheters 1
• If catheter cannot be removed, treatment will likely fail or recur
• Replace catheter if removal is not feasible 1

Critical Pitfalls to Avoid

Drug Selection Errors

• Do NOT use lipid formulations of amphotericin B for UTI - they do not achieve adequate urine concentrations 1
• Do NOT use echinocandins (caspofungin, micafungin, anidulafungin) for UTI - minimal urinary excretion makes them ineffective 1, 4
• Do NOT use other azoles (voriconazole, posaconazole, itraconazole) for UTI - poor urinary excretion 1, 4
• Exception: Echinocandins may work for hematogenous renal infection (not ascending UTI) because tissue concentrations are adequate 1

Why Fluconazole Is Preferred

Fluconazole is the drug of choice because 1:

• Oral formulation available
• Excreted in active form in urine
• Achieves urine levels far exceeding MIC for most Candida species
• Proven efficacy in the only randomized controlled trial of candiduria treatment

Diagnostic Confusion

• Pyuria cannot differentiate infection from colonization in catheterized patients 1
• Colony counts are unreliable, especially with catheters 1
• Obtain imaging (ultrasound or CT) if concerned about complications: hydronephrosis, abscess, emphysematous pyelonephritis, or fungus balls 1

Fungus Balls and Complicated Infections

If fungus balls are present (aggregations of mycelia and yeasts causing obstruction):

• Surgical or endoscopic removal is mandatory - antifungals alone will fail 1
• Add antifungal therapy as outlined above for cystitis or pyelonephritis 1
• For nephrostomy tubes: irrigate with amphotericin B deoxycholate 25-50 mg in 200-500 mL sterile water 1

Monitoring and Follow-up

• Repeat urine cultures are not routinely needed for asymptomatic patients after catheter removal
• For treated symptomatic infections, confirm clearance if symptoms persist
• Chronic suppressive therapy is usually unnecessary 1