What is the treatment for a patient with budding yeast in their urine, specifically a fungal urinary tract infection (UTI) likely caused by Candida species?

Treatment of Fungal Urinary Tract Infections with Budding Yeast

For symptomatic Candida urinary tract infections, oral fluconazole at a dosage of 200 mg (3 mg/kg) daily for 2 weeks is the treatment of choice for fluconazole-susceptible Candida species. 1

Diagnostic Considerations

Before initiating treatment, it's important to distinguish between colonization and true infection:

• Asymptomatic candiduria in patients without risk factors generally requires no treatment
• Presence of symptoms (dysuria, frequency, urgency, suprapubic pain) suggests true infection
• Pyuria alone cannot differentiate colonization from infection, especially in catheterized patients
• Imaging (ultrasound or CT) may be helpful to identify structural abnormalities, hydronephrosis, or fungus balls

Treatment Algorithm Based on Clinical Presentation

1. Asymptomatic Candiduria

• No treatment recommended unless patient belongs to high-risk group 1
• High-risk groups requiring treatment despite lack of symptoms:
  • Neutropenic patients
  • Low birth weight infants
  • Patients undergoing urologic procedures
• Removal of predisposing factors (catheters, antibiotics) often resolves candiduria in ~50% of cases 2

2. Symptomatic Candida Cystitis

• First-line: Fluconazole 200 mg (3 mg/kg) daily for 2 weeks 1
• For fluconazole-resistant species (C. glabrata, C. krusei):
  • Amphotericin B deoxycholate 0.3-0.6 mg/kg daily for 1-7 days OR
  • Flucytosine 25 mg/kg 4 times daily for 7-10 days 1
• Strongly recommended: Remove indwelling bladder catheter if present 1

3. Candida Pyelonephritis

• First-line: Fluconazole 200-400 mg (3-6 mg/kg) daily for 2 weeks 1
• For fluconazole-resistant species:
  • Amphotericin B deoxycholate 0.5-0.7 mg/kg daily with or without flucytosine 25 mg/kg 4 times daily OR
  • Flucytosine alone 25 mg/kg 4 times daily for 2 weeks 1
• Critical intervention: Eliminate urinary tract obstruction if present 1
• Consider removal/replacement of nephrostomy tubes or stents if present 1

4. Fungus Balls

• Mandatory: Surgical intervention in adults 1
• Systemic antifungal therapy as described above
• If access to renal collecting system is available, irrigation with Amphotericin B deoxycholate (25-50 mg in 200-500 mL sterile water) 1
• Continue treatment until symptoms resolve and urine cultures are negative for Candida 1

Important Clinical Considerations

1. Pharmacokinetic considerations: Fluconazole is highly water-soluble, primarily excreted in urine in active form, and achieves high urine concentrations exceeding MICs for most Candida strains 1, 3

2. Limitations of other antifungals:

   • Other azoles and echinocandins have minimal excretion into urine and are generally ineffective for UTIs 1, 2
   • Lipid formulations of Amphotericin B do not achieve adequate urine concentrations 1

3. Species-specific considerations:

   • C. glabrata accounts for ~20% of urine isolates in adults and often requires alternative therapy 1
   • C. krusei is intrinsically resistant to fluconazole and requires Amphotericin B treatment 1

4. Bladder irrigation:

   • Generally not recommended except for refractory cases with fluconazole-resistant organisms 1
   • When used, Amphotericin B deoxycholate at 50 mg/L of sterile water is recommended 1
   • High relapse rate despite initial 80-90% resolution of candiduria 1

Treatment Duration

• For cystitis: 2 weeks of therapy 1
• For pyelonephritis: 2 weeks of therapy 1
• For fungus balls: Continue until symptoms resolve and urine cultures no longer yield Candida species 1

The 2016 IDSA guidelines provide the most current and authoritative recommendations for treating fungal UTIs, emphasizing the importance of species identification, susceptibility patterns, and anatomical location of infection in guiding therapy selection.