How do you treat Candida krusei in a urinary tract infection (UTI)?

Treatment of Candida krusei in Urinary Tract Infections

For Candida krusei urinary tract infections, amphotericin B deoxycholate at a dose of 0.3-0.6 mg/kg daily for 1-7 days is the recommended first-line treatment. 1

Primary Treatment Approach

1. Amphotericin B deoxycholate therapy:

   • Dosage: 0.3-0.6 mg/kg daily
   • Duration: 1-7 days
   • Strong recommendation with low-quality evidence 1

2. Adjunctive measures:

   • Remove indwelling bladder catheter if present (strong recommendation) 1, 2
   • Eliminate urinary tract obstruction if present (strong recommendation) 1
   • Consider removal or replacement of nephrostomy tubes or stents if feasible 1

3. Alternative local therapy option:

   • Amphotericin B deoxycholate bladder irrigation (50 mg/L sterile water daily for 5 days) may be useful for refractory cystitis 1, 2
   • If nephrostomy tubes are present, irrigation with amphotericin B (25-50 mg in 200-500 mL sterile water) is recommended 1

Special Considerations

Why fluconazole is not an option:

C. krusei exhibits intrinsic resistance to fluconazole, making this common antifungal ineffective 3, 4.

Limitations of other antifungals:

• Echinocandins (e.g., caspofungin, micafungin) and newer azoles (voriconazole, posaconazole) generally achieve poor urinary concentrations and are not recommended for uncomplicated fungal UTIs 2, 4
• However, in complex cases with tissue invasion or in transplant recipients where amphotericin B is contraindicated due to toxicity concerns, higher-dose echinocandins may be considered as demonstrated in case reports 3

Treatment approach based on infection severity:

1. For asymptomatic candiduria:

   • Treatment is NOT recommended unless the patient belongs to a high-risk group 1, 2
   • High-risk groups requiring treatment include:
     • Neutropenic patients
     • Very low-birth-weight infants (<1500g)
     • Patients undergoing urologic manipulation

2. For symptomatic cystitis:

   • Amphotericin B deoxycholate as outlined above 1

3. For pyelonephritis:

   • Same treatment as cystitis with focus on eliminating obstruction 1

4. For fungal balls or abscesses:

   • Surgical intervention is strongly recommended in addition to antifungal therapy 1, 2

Common Pitfalls to Avoid

1. Using fluconazole for C. krusei infections (intrinsic resistance)
2. Failing to remove indwelling catheters when feasible
3. Not addressing underlying urinary tract obstruction
4. Using antifungals with poor urinary concentrations (echinocandins, newer azoles) as primary therapy
5. Treating asymptomatic candiduria in low-risk patients
6. Not distinguishing between colonization and true infection

Monitoring and Follow-up

• Assess clinical improvement of symptoms
• Obtain follow-up urine cultures to confirm eradication
• Continue treatment until symptoms resolve and cultures become negative
• Consider surgical intervention for persistent infections or fungal balls

In refractory cases or patients with contraindications to amphotericin B, consultation with infectious disease specialists is warranted to consider alternative approaches such as higher-dose echinocandins in special circumstances 3.