Candiduria
Also known as: Candida Urinary Tract Infection, Funguria, Candida in Urine
Candiduria is the presence of Candida in the urine. It is very common in hospitalised patients with indwelling urinary catheters and is, in most cases, colonisation or a marker of mucosal and catheter colonisation, and it needs no antifungal therapy. The clinical problem is to separate the patient who needs treatment (symptomatic urinary infection, a neutropenic or very low birth weight patient, or a patient who is about to undergo a urological procedure) from the large majority who need only catheter removal and correction of risk factors.
Candida species account for about 10 to 15 percent of healthcare associated urinary tract infections, and Candida ranks among the top organisms in catheter associated urinary tract infection in intensive care units. Candidaemia from a urinary source is uncommon, and urine is rarely the origin of candidaemia unless there is obstruction or instrumentation.
| Term | Definition |
|---|---|
| Candiduria | Yeast in urine at or above 10 to the power of 3 colony forming units per mL in a catheter specimen, or at or above 10 to the power of 5 per mL in a clean catch specimen |
| Colonisation | Yeast in urine without symptoms, or tissue invasion |
| Candida cystitis | Dysuria, frequency, suprapubic pain, and candiduria, in a patient with no other cause |
| Candida pyelonephritis | Fever, flank pain, and renal tenderness, with candiduria or candidaemia and imaging changes |
| Fungus ball | Mass of hyphae and debris in the renal pelvis, ureter, or bladder, causing obstruction |
Colony count and pyuria do not reliably separate colonisation from infection, and quantitative thresholds are unhelpful in catheterised patients.
Candida albicans causes about half of cases. Candida glabrata (15 to 25 percent) predominates in older diabetic patients and after fluconazole exposure, Candida tropicalis causes 10 to 15 percent, and Candida parapsilosis, Candida krusei, and Candida auris are less common. A non albicans isolate is more likely to be fluconazole resistant, so species identification matters before treatment.
Infection is mainly ascending, from the perineal and urethral flora, along or inside the catheter and with biofilm formation on the catheter surface. Haematogenous seeding of the kidney (cortical microabscesses) happens in candidaemia, and candiduria in that setting is a marker of disseminated disease rather than its cause.
Risk factors are:
- Indwelling urinary catheter (the strongest factor) and its duration.
- Diabetes mellitus and glycosuria (including with sodium glucose cotransporter 2 inhibitors).
- Broad spectrum antibacterials and prolonged hospitalisation, especially intensive care.
- Older age and female sex.
- Urinary tract abnormality, obstruction, vesicoureteric reflux, neurogenic bladder, and stents.
- Immunosuppression, corticosteroids, renal transplantation, and neutropenia.
- Prematurity and very low birth weight in neonates.
- Recent urological surgery or instrumentation.
Most patients have no symptoms. Symptomatic cystitis causes dysuria, frequency, urgency, and suprapubic discomfort. Pyelonephritis causes fever, loin pain, and tenderness, and pyuria with a rising creatinine in obstruction. Candidaemia with candiduria presents with sepsis and, often, deep tissue disease. Urinary fungus balls cause obstruction with anuria in neonates, passage of material in urine, and hydronephrosis. Emphysematous cystitis and pyelitis occur in diabetic patients.
| Condition | Points that separate it |
|---|---|
| Bacterial catheter associated urinary tract infection | Bacterial growth and response to antibacterials; yeast absent |
| Contamination from vulvovaginal candidiasis | Clean catch specimen contaminated by genital flora; repeat catheter specimen is negative |
| Colonisation of the catheter or drainage bag | Asymptomatic, with no pyuria beyond baseline |
| Renal tuberculosis | Sterile pyuria and acid fast bacilli |
| Urolithiasis and obstruction | Imaging and clinical course |
| Genitourinary malignancy | Haematuria and imaging; cystoscopy |
| Disseminated candidiasis | Positive blood cultures, beta D glucan, and other organ involvement |
- Confirm and repeat: a repeat urine sample from a fresh, newly placed catheter (not the old catheter or the drainage bag) separates colonisation from true infection. Candiduria that clears after catheter change was colonisation.
- Examine for symptoms and risk. Identify neutropenia, planned urological procedure, renal transplant, and very low birth weight.
- Imaging: renal and bladder ultrasonography, or computed tomography, in patients with persistent candiduria after catheter change, high risk patients, those with symptoms, or diabetes, to look for obstruction, abscess, or fungus ball.
- Blood cultures and beta D glucan when systemic signs, neutropenia, or candiduria with sepsis occur, because candidaemia can accompany candiduria in that setting.
- Species identification and susceptibility before therapy.
- Urinalysis (pyuria), colony count, and screening of asymptomatic patients with a urine culture are not recommended as a basis for treatment.
Asymptomatic candiduria
Treatment is not needed in most patients. The steps are removal or replacement of the urinary catheter, discontinuation of unnecessary antibacterials, and correction of glycaemic control and of obstruction. Treating asymptomatic candiduria with antifungal agents clears the yeast transiently but does not change outcome, and recurrence after stopping therapy is common.
Treatment is indicated in the following asymptomatic patients, because of the risk of dissemination:
- Neutropenic patients.
- Very low birth weight infants (below 1500 g).
- Patients about to undergo urological manipulation (fluconazole 400 mg or 6 mg per kg daily, or amphotericin B deoxycholate 0.3 to 0.6 mg per kg daily, for several days before and after the procedure).
- Renal transplant recipients in the early post transplant period (clinical judgement).
Symptomatic cystitis
| Agent | Dose | Duration | Notes |
|---|---|---|---|
| Fluconazole | 200 mg (3 mg per kg) orally once daily | 2 weeks | First line for susceptible isolates; urinary excretion of active drug is high (about 80 percent unchanged); halve the dose when creatinine clearance is below 50 mL per minute |
| Amphotericin B deoxycholate | 0.3 to 0.6 mg per kg intravenously once daily | 1 to 7 days | For fluconazole resistant Candida glabrata and Candida krusei; nephrotoxic |
| Flucytosine | 25 mg per kg orally every 6 hours | 7 to 10 days | For fluconazole resistant Candida glabrata and Candida krusei; excreted unchanged in urine, with resistance developing on monotherapy; adjust to renal function and monitor levels |
| Flucytosine with amphotericin B deoxycholate | Flucytosine 25 mg per kg every 6 hours with amphotericin B deoxycholate 0.3 to 0.6 mg per kg once daily | 1 to 7 days | Alternative where monotherapy is not suitable |
| Bladder irrigation with amphotericin B | 50 mg per litre of sterile water daily by continuous irrigation, for 5 days | 5 days | Not routinely recommended; benefit lasts only during irrigation and relapse is common; limited evidence |
Echinocandins reach very low urinary concentrations (under 1 percent excreted as active drug), and case reports of success in cystitis and pyelonephritis do not support routine use. Voriconazole, posaconazole, and isavuconazole also have very low urinary excretion of active drug and are not used for urinary disease. Lipid formulations of amphotericin B achieve low urinary levels, with case reports of use.
Pyelonephritis and renal candidiasis
Fluconazole 200 to 400 mg (3 to 6 mg per kg) daily for 2 weeks in susceptible disease. For fluconazole resistant Candida glabrata, amphotericin B deoxycholate 0.3 to 0.6 mg per kg daily with or without oral flucytosine 25 mg per kg every 6 hours for 1 to 7 days is used.
Obstruction is relieved by nephrostomy or stent removal. Fungus balls need surgical removal and, where obstruction is present, instillation of amphotericin B through a nephrostomy tube.
Irrigation of the renal pelvis with amphotericin B deoxycholate 25 to 50 mg per litre of sterile water has been described.
Candiduria with candidaemia
Candiduria in a patient with systemic signs or neutropenia needs blood cultures and an echinocandin 70 mg then 50 mg daily (caspofungin), or fluconazole 800 mg then 400 mg daily for susceptible isolates, because the kidney is a site of disseminated disease.
Neonates
Candiduria in neonates, especially premature infants below 1500 g, needs the regimens used for neonatal invasive candidiasis, because it is often the result of disseminated disease. Fluconazole 12 mg per kg daily or amphotericin B deoxycholate 1 mg per kg daily is used, with renal ultrasonography, lumbar puncture, retinal examination, and echocardiography.
Follow up urine culture after treatment confirms clearance in high risk or symptomatic patients, with renal imaging repeated when obstruction was present. Prevention is by avoiding unnecessary catheterisation, early catheter removal, closed drainage, avoidance of unneeded antibacterials, glycaemic control, and catheter care bundles. Routine screening for candiduria in asymptomatic patients and treatment of positive screens does not improve outcome and drives resistance.
