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Fungal Urinary Tract Infections


Talha H. Imam

, MD, University of Riverside School of Medicine

Reviewed/Revised Nov 2022 | Modified Jun 2023

Fungal infections of the urinary tract primarily affect the bladder and kidneys.

Species of Candida, the most common cause, are normal commensals in humans. Candida colonization differs from infection in that infection produces tissue reaction. All invasive fungi Overview of Fungal Infections Fungi are eukaryotic organisms that exist as yeast, molds, or both forms. Yeasts consist of solitary cells that reproduce by budding. Molds occur in filaments, also known as hyphae, which extend... read more (eg, Cryptococcus neoformans, Aspergillus species, Mucoraceae species, Histoplasma capsulatum, Blastomyces species, Coccidioides immitis) may infect the kidneys as part of systemic or disseminated mycotic infection. Their presence alone indicates infection.

Lower urinary tract infection (UTI) with Candida usually occurs in patients with urinary catheters, typically after antibiotic therapy, although candidal and bacterial infections frequently occur simultaneously. C. albicans prostatitis Prostatitis Prostatitis refers to a disparate group of prostate disorders that manifests with a combination of predominantly irritative or obstructive urinary symptoms and perineal pain. Some cases result... read more occurs infrequently in patients with diabetes, usually after instrumentation.

Renal candidiasis is usually spread hematogenously and commonly originates from the gastrointestinal tract. Ascending infection is possible and occurs mainly in patients with nephrostomy tubes, other permanent indwelling devices, and stents. At high risk are patients with diabetes and those who are immunocompromised because of tumor, AIDS, chemotherapy, or immunosuppressants. A major source of candidemia in such high-risk hospitalized patients is an indwelling intravascular catheter. Renal transplantation Kidney Transplantation Kidney transplantation is the most common type of solid organ transplantation. (See also Overview of Transplantation.) The primary indication for kidney transplantation is End-stage renal failure... read more increases the risk because of the combination of indwelling catheters, stents, antibiotics, anastomotic leaks, obstruction, and immunosuppressive therapy.

Symptoms and Signs of Fungal UTIs

Most patients with candiduria are asymptomatic. Whether Candida can cause urethral symptoms (mild urethral itching, dysuria, watery discharge) in men is uncertain. Rarely, dysuria in women is caused by candidal urethritis, but it may result from the urine coming into contact with periurethral tissue that is inflamed due to candidal vaginitis.

Most patients with renal candidiasis that is hematogenously spread lack symptoms referable to the kidneys but may have antibiotic-resistant fever, candiduria, and unexplained deteriorating renal function. Fungus ball elements in the ureter and renal pelvis frequently cause hematuria and urinary obstruction. Occasionally, papillary necrosis or intrarenal or perinephric abscesses cause pain, fever, hypertension, and hematuria. Patients may have manifestations of candidiasis in other sites (eg, central nervous system, skin, eyes, liver, spleen).

Diagnosis of Fungal UTIs

  • Urine culture

  • Evidence of tissue reaction (in cystitis) or pyelonephritis

Candida urinary tract infection (UTI) is considered in patients with predisposing factors and symptoms suggesting UTI and in all patients with candidemia. Candida should be suspected in men with symptoms of urethritis Urethritis Bacterial urinary tract infections (UTIs) can involve the urethra, prostate, bladder, or kidneys. Symptoms may be absent or include urinary frequency, urgency, dysuria, lower abdominal pain... read more only when all other causes of urethritis have been excluded.

Diagnosis of Candida UTI is by culture, usually from urine. The level at which candiduria reflects true Candida UTI and not merely colonization or contamination is unknown. Differentiating Candida colonization from infection requires evidence of tissue reaction.

Renal candidiasis is considered in patients with candiduria, passage of fungus balls, or risk factors, particularly with fever. Severe renal failure suggests postrenal obstruction. Imaging of the urinary tract may help reveal the degree of involvement. Blood cultures for Candida are often negative.

Unexplained candiduria should prompt evaluation of the urinary tract for structural abnormalities.

Treatment of Fungal UTIs

  • Only for symptomatic or high-risk patients

  • Fluconazole or, for resistant organisms, amphotericin B; sometimes flucytosine is added

Fungal colonization of catheters does not require treatment. Asymptomatic candiduria rarely requires therapy. Candiduria should be treated in the following:

  • Symptomatic patients

  • Neutropenic patients

  • Patients with renal allografts

  • Patients who are undergoing urologic manipulation

Urinary stents and Foley catheters should be removed (if possible). For symptomatic cystitis Cystitis Bacterial urinary tract infections (UTIs) can involve the urethra, prostate, bladder, or kidneys. Symptoms may be absent or include urinary frequency, urgency, dysuria, lower abdominal pain... read more , treatment is with fluconazole 200 mg orally once a day. For pyelonephritis, fluconazole 200 to 400 mg orally once a day is preferred. Therapy in both cases should be for 2 weeks. For fungi resistant to fluconazole, amphotericin B is recommended at a dose of 0.3 to 0.6 mg/kg IV once a day for 2 weeks for cystitis and 0.5 to 0.7 mg/kg IV once a day for 2 weeks for pyelonephritis Acute pyelonephritis Bacterial urinary tract infections (UTIs) can involve the urethra, prostate, bladder, or kidneys. Symptoms may be absent or include urinary frequency, urgency, dysuria, lower abdominal pain... read more .

For resistant pyelonephritis, flucytosine 25 mg/kg orally 4 times a day is added to the regimen if patients have adequate renal function; if not, the dose should be modified based on creatinine clearance (see Antifungal Drugs Antifungal Medications Medications for systemic antifungal treatment include the following (see also table ): Amphotericin B (and its lipid formulations) Various azole derivatives (fluconazole, isavuconazonium [also... read more ).

Flucytosine may help eradicate candiduria due to non-albicans species of Candida; however, resistance may emerge rapidly when this compound is used alone. Bladder irrigation with amphotericin B may transiently clear candiduria but is no longer indicated for cystitis or pyelonephritis. Even with apparently successful local or systemic antifungal therapy for candiduria, relapse is frequent, and this likelihood is increased by continued use of a urinary catheter. Clinical experience with using voriconazole to treat urinary tract infections (UTIs) is scant.

Key Points

  • Fungal UTI affects mainly patients who have urinary tract obstruction or instrumentation, immunocompromise (including diabetes), or both.

  • Suspect fungal UTI in patients at risk or with candidemia who have clinical or laboratory findings consistent with UTI.

  • Use antifungal drug therapy only if patients will undergo urologic manipulation or have symptoms, neutropenia, or renal allografts.

Drugs Mentioned In This Article

Drug Name Select Trade
Amphocin, Fungizone
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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