What antifungal agent is used to treat a urine culture that grows Candida buds?

Treatment of Candida in Urine Culture

Fluconazole 200 mg (3 mg/kg) orally daily for 2 weeks is the first-line antifungal agent for symptomatic Candida urinary tract infections caused by fluconazole-susceptible species. 1, 2

Initial Assessment and Context

Before initiating antifungal therapy, you must determine whether the candiduria represents true infection versus colonization or contamination:

• Asymptomatic candiduria without predisposing conditions requires only observation—no antifungal treatment is needed. 1
• Remove or replace indwelling urinary catheters when feasible, as this alone eliminates candiduria in approximately 50% of cases without requiring antifungal therapy. 2, 3
• Treat aggressively if the patient has fever with severe immunosuppression, is a low-birth-weight neonate, or is undergoing urologic procedures, as disseminated candidiasis must be considered. 1, 2

Treatment Algorithm Based on Clinical Presentation

For Symptomatic Cystitis (Lower UTI)

• Fluconazole 200 mg (3 mg/kg) orally daily for 2 weeks is recommended for fluconazole-susceptible Candida species. 1, 2
• Fluconazole is preferred because it achieves high urinary concentrations in its active form, is available orally, and is highly water-soluble. 1, 4

For Fluconazole-Resistant Organisms (C. glabrata, C. krusei)

• Amphotericin B deoxycholate 0.3–0.6 mg/kg IV daily for 1–7 days is the alternative for cystitis caused by fluconazole-resistant species. 1, 2
• Oral flucytosine 25 mg/kg four times daily for 7–10 days is another alternative, though it should not be used as monotherapy due to toxicity and rapid resistance development. 1, 2
• C. krusei should be considered intrinsically resistant to fluconazole and requires amphotericin B. 5, 6

For Pyelonephritis (Upper UTI)

• Fluconazole 200–400 mg (3–6 mg/kg) orally daily for 2 weeks is recommended for fluconazole-susceptible organisms. 1
• For fluconazole-resistant C. glabrata causing pyelonephritis, use amphotericin B deoxycholate 0.5–0.7 mg/kg daily with or without flucytosine 25 mg/kg four times daily for 2 weeks. 1

For Fungus Balls

• Surgical intervention is strongly recommended in non-neonates, combined with fluconazole 200–400 mg (3–6 mg/kg) daily. 1
• If access to the renal collecting system is available, adjunctive irrigation with amphotericin B at 50 mg/L of sterile water can be used alongside systemic therapy. 1
• Continue treatment until symptoms resolve and urine cultures no longer yield Candida species. 1

Critical Pharmacological Considerations

• No other azole antifungals besides fluconazole are useful for urinary tract infections because they achieve minimal urinary excretion of active drug. 1
• Echinocandins are not recommended for Candida UTIs due to poor urinary concentrations, despite limited reports of success in renal parenchymal infections. 1, 2
• Lipid formulations of amphotericin B should not be used as they do not achieve adequate urine or renal tissue concentrations, with documented treatment failures. 1, 7

Common Pitfalls to Avoid

• Do not treat asymptomatic candiduria in most patients—colony counts cannot reliably differentiate colonization from infection, especially with catheters present. 2, 4
• Bladder irrigation with amphotericin B resolves candiduria in >90% of patients but has high relapse rates and is generally discouraged except for refractory azole-resistant cystitis. 1
• Address urinary tract obstruction, nephrostomy tubes, or stents—elimination of obstruction or device removal/replacement is critical for treatment success. 7, 2
• C. glabrata accounts for approximately 20% of adult urine isolates and frequently requires amphotericin B due to reduced fluconazole susceptibility. 1

Monitoring and Duration

• Continue treatment until symptoms resolve and follow-up urine cultures confirm clearance of Candida species. 1
• For persistent infection despite appropriate therapy, obtain imaging to rule out anatomical abnormalities or fungus balls. 7