What is the recommended treatment for a female patient with a suspected yeast infection of the urinary tract, assuming no significant underlying medical conditions or severe immunocompromise?

Treatment of Yeast Infection in the Urinary Tract

For symptomatic Candida urinary tract infections (UTIs), fluconazole is the treatment of choice, while asymptomatic candiduria in otherwise healthy patients requires no treatment at all. 1

Asymptomatic Candiduria (No Treatment Needed)

• Most patients with candiduria are colonized and do not require antifungal therapy. 1, 2, 3
• Treatment is not recommended unless the patient belongs to a high-risk group at risk of dissemination. 1
• Simply removing predisposing factors (such as indwelling catheters or stopping broad-spectrum antibiotics) resolves candiduria in approximately 50% of asymptomatic patients without any antifungal therapy. 1, 3
• Identifying Candida in urine without symptoms should not lead to treatment, as approximately 10-20% of women normally harbor Candida species. 1

High-Risk Exceptions Requiring Treatment

• Neutropenic patients, very low-birth-weight infants, and patients undergoing urologic procedures require treatment even when asymptomatic. 1, 2
• For patients undergoing urologic procedures, fluconazole 200-400 mg (3-6 mg/kg) daily or amphotericin B deoxycholate 0.3-0.6 mg/kg daily for several days before and after the procedure is recommended. 1

Symptomatic Candida Cystitis (Bladder Infection)

• For cystitis due to fluconazole-susceptible Candida species, oral fluconazole 200 mg (3 mg/kg) daily for 2 weeks is the first-line treatment. 1
• Fluconazole is preferred because it is highly water-soluble, primarily excreted in active form in urine, and easily achieves urine concentrations exceeding the minimum inhibitory concentration (MIC) for most Candida strains. 1, 2
• No other currently available azole (including voriconazole, itraconazole, or posaconazole) is useful for urinary tract infections because of minimal excretion of active drug into urine. 1, 3

Alternative Treatments for Fluconazole-Resistant Organisms

• For fluconazole-resistant organisms (especially Candida glabrata), alternatives include 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 is generally not recommended but may be useful for patients with fluconazole-resistant species, particularly C. glabrata. 1
• Flucytosine is concentrated in urine and demonstrates good activity against most Candida isolates, but its use is limited by toxicity and development of resistance when used alone. 1, 4

Candida Pyelonephritis (Kidney Infection)

• For pyelonephritis due to fluconazole-susceptible organisms, oral fluconazole 200-400 mg (3-6 mg/kg) daily for 2 weeks is recommended. 1
• For fluconazole-resistant strains (especially C. glabrata, which accounts for approximately 20% of urine isolates in adults), alternatives include amphotericin B deoxycholate 0.5-0.7 mg/kg daily with or without flucytosine 25 mg/kg four times daily, or flucytosine alone at the same dose for 2 weeks. 1
• Liposomal amphotericin B should not be considered first choice because of presumed low concentrations in renal tissue, with documented treatment failures. 1

Fungus Balls (Mycetoma)

• Surgical intervention is strongly recommended for fungus balls in non-neonates. 1
• Fluconazole 200-400 mg (3-6 mg/kg) daily is recommended as medical therapy. 1
• If access to the renal collecting system is available through a nephrostomy tube, irrigation with amphotericin B at a concentration of 50 mg/L of sterile water can be used as an adjunct to systemic therapy. 1
• Treatment should continue until symptoms resolve and urine cultures no longer yield Candida species. 1

Critical Pitfalls to Avoid

• Do not treat asymptomatic candiduria in otherwise healthy patients—this only promotes resistance and does not improve outcomes. 1, 2, 3
• Echinocandins (caspofungin, micafungin, anidulafungin) are not recommended for urinary tract infections because they do not achieve adequate urine concentrations, despite some limited case reports of success. 1, 5, 3
• Newer azole agents like voriconazole and posaconazole should not be used for urinary tract infections due to poor urinary excretion. 1, 3
• Be aware that C. glabrata accounts for 10-20% of patients with recurrent vulvovaginal candidiasis and 20% of urine isolates, and conventional antimycotic therapies are less effective against this species compared to C. albicans. 1
• Bladder irrigation with amphotericin B resolves candiduria in over 90% of patients but has a high relapse rate and is generally discouraged except for refractory cystitis due to azole-resistant organisms. 1, 4