Fluconazole Dosing for Fungal UTI
For symptomatic candidal urinary tract infections with fluconazole-susceptible organisms, use oral fluconazole 200 mg daily for 2 weeks, which is the evidence-based standard recommended by the Infectious Diseases Society of America. 1
Treatment Algorithm by Clinical Scenario
Candidal Cystitis (Lower UTI)
- Fluconazole 200 mg (3 mg/kg) orally once daily for 14 days is the first-line treatment for fluconazole-susceptible Candida species 1
- Remove indwelling bladder catheters whenever feasible, as this is critical for treatment success 1
- A loading dose of 200 mg followed by 100 mg daily for at least 4 days may be considered as an alternative regimen 2
Candidal Pyelonephritis (Upper UTI)
- Fluconazole 200-400 mg (3-6 mg/kg) orally once daily for 14 days for fluconazole-susceptible organisms 1
- The higher dose (400 mg) should be used when upper tract involvement is confirmed or suspected 1
- Eliminate any urinary tract obstruction and consider removing/replacing nephrostomy tubes or stents if present 1
Species-Specific Considerations
Fluconazole-Resistant C. glabrata
- Use amphotericin B deoxycholate 0.3-0.6 mg/kg daily for 1-7 days, OR oral flucytosine 25 mg/kg four times daily for 7-10 days 1
- Amphotericin B bladder irrigation (50 mg/L sterile water daily for 5 days) may be useful for resistant cystitis 1
C. krusei
- Use amphotericin B deoxycholate 0.3-0.6 mg/kg daily for 1-7 days 1
Critical Pitfalls to Avoid
Do NOT treat asymptomatic candiduria unless the patient falls into high-risk categories: neutropenic patients, very low-birth-weight infants (<1500 g), or patients undergoing urologic procedures 1
For patients undergoing urologic manipulation with candiduria, use fluconazole 400 mg (6 mg/kg) daily OR amphotericin B deoxycholate 0.3-0.6 mg/kg daily for several days before and after the procedure 1
Duration and Monitoring
- The standard 14-day duration is essential to prevent relapse, particularly in patients with diabetes or other immunocompromising conditions 3
- Urine colony counts cannot reliably differentiate infection from colonization, especially with indwelling catheters 1
- If symptoms do not resolve by end of treatment, obtain urine culture with susceptibility testing and assume the organism is not susceptible to the original agent 1
Pharmacokinetic Rationale
Fluconazole achieves excellent urinary concentrations with approximately 60% of the dose recovered unchanged in urine within 48 hours, supporting its efficacy in UTI treatment 4. The long half-life (31-37 hours) allows once-daily dosing 4, 5.