What is the correlation and treatment for Candida krusei (Pichia kudriavzevii) detected in urine with cycling fevers in a pediatric patient?

Candida krusei Urinary Tract Infection in a 9-Year-Old with Fever

Clinical Correlation and Significance

The presence of C. krusei in urine with cycling fevers in this 9-year-old requires urgent evaluation to distinguish between asymptomatic candiduria, symptomatic urinary tract infection, or disseminated candidiasis with urinary involvement. 1

The correlation between candiduria and fever depends critically on:

• Presence of urinary symptoms (dysuria, frequency, urgency, flank pain) suggests true UTI rather than colonization 1
• Neutropenia status - if neutropenic, candiduria may represent disseminated candidiasis even without urinary symptoms 1
• Presence of indwelling urinary catheter - makes colonization more likely than infection 1
• Blood culture results - essential to rule out candidemia, as fever may indicate hematogenous spread to kidneys rather than ascending UTI 2

In pediatric patients, candiduria without a urinary catheter may indicate disseminated candidiasis, particularly if fever persists without explanation. 1

Immediate Diagnostic Steps

Before initiating treatment, obtain:

• Blood cultures to exclude candidemia (fever suggests possible disseminated disease) 1
• Repeat urine culture to confirm persistent candiduria and quantify colony counts 1
• Renal imaging (ultrasound or CT) if pyelonephritis or fungus balls are suspected 1
• Assessment for neutropenia and other immunocompromising conditions 1

Treatment Algorithm

If Asymptomatic Candiduria (No Fever, No Urinary Symptoms)

Treatment is NOT indicated unless the patient is neutropenic, undergoing urologic procedures, or is a very low-birth-weight infant. 1

• Remove any indwelling urinary catheter if present 1
• Monitor clinically without antifungal therapy 1

If Symptomatic UTI (Fever + Urinary Symptoms, Blood Cultures Negative)

For C. krusei cystitis or pyelonephritis, amphotericin B deoxycholate 0.3-0.6 mg/kg IV daily for 1-7 days is the preferred treatment due to C. krusei's intrinsic fluconazole resistance. 1

Alternative options include:

• Voriconazole (licensed in Europe for fluconazole-resistant Candida including C. krusei) at 6 mg/kg IV twice daily for 2 doses, then 3 mg/kg twice daily 1, 3
• Echinocandins (caspofungin, micafungin, anidulafungin) are active against C. krusei but achieve minimal urinary concentrations and should be reserved for cases where amphotericin B cannot be used 1, 4

Treatment duration: Continue for 2 weeks after symptom resolution and negative urine cultures. 1

If Candidemia or Disseminated Candidiasis (Positive Blood Cultures or High Clinical Suspicion)

An echinocandin is preferred for invasive C. krusei infection: 1

• Caspofungin: 70 mg loading dose, then 50 mg daily (pediatric dosing: 70 mg/m² loading dose, then 50 mg/m² daily, maximum 70 mg) 1
• Micafungin: 100 mg daily 1
• Anidulafungin: 200 mg loading dose, then 100 mg daily 1

Alternative: Amphotericin B deoxycholate 1.0 mg/kg IV daily 1

Continue treatment for at least 2 weeks after documented clearance from bloodstream and resolution of symptoms. 1

Critical Management Considerations

Catheter Management

• Remove indwelling urinary catheter immediately if present - this alone resolves candiduria in approximately 50% of cases 1, 2
• Eliminate any urinary tract obstruction (nephrostomy tubes, stents, anatomical abnormalities) 1

Common Pitfalls to Avoid

• Do NOT use fluconazole - C. krusei is intrinsically resistant to fluconazole 1
• Do NOT use lipid formulations of amphotericin B for isolated UTI - they do not achieve adequate urinary concentrations 1
• Do NOT rely on echinocandins for lower UTI - despite excellent activity against C. krusei systemically, they achieve minimal urinary drug levels and are ineffective for isolated cystitis 1, 2, 4
• Do NOT treat asymptomatic candiduria unless the patient is neutropenic or undergoing urologic procedures 1

Special Pediatric Considerations

For neonates with disseminated candidiasis, amphotericin B deoxycholate 1 mg/kg daily is recommended. 1

For older children (like this 9-year-old), adult dosing guidelines apply with weight-based adjustments 1

Monitoring and Follow-Up

• Obtain follow-up urine cultures to document clearance of infection 1
• Monitor for clinical improvement within 48-72 hours of initiating therapy 1
• If fever persists despite appropriate therapy, obtain imaging to identify fungus balls, abscesses, or anatomical abnormalities 1
• If fungus balls are identified, surgical intervention is required in addition to antifungal therapy 1

Risk Factors to Address

Identify and eliminate predisposing factors: 1

• Prolonged broad-spectrum antibiotic use
• Indwelling urinary catheter
• Diabetes mellitus
• Immunosuppressive medications
• Urinary tract obstruction
• Recent urologic procedures