Emery Haley, PhD, Scientific Writing Specialist
Candida albicans
Clinical Summary
- C. albicans is recognized as a classical, biofilm-forming, yeast uropathogen.
- C. albicans is associated with complicated, persistent, and recurrent UTI.
- In symptomatic UTI patients, C. albicans:
- Is not a contaminant (is found in catheter-collected urine specimens).
- Is viable (can grow out on culture).
- Is pathogenic (associated with elevated urine biomarkers of infection).
- Reported severe complications of C. albicans UTI include candidemia and urosepsis.
Yeast Characteristics
Growth Requirements
A Yeast (slow growth, prefers yeast extract peptone dextrose medium and acidic pH)
Biofilm Formation
Yes
Nitrate Reduction
No
Pathogenicity
Colonizer or Pathobiont
Clinical Relevance in UTI
UTIs can be caused by yeasts and Candida yeast species are classically recognized as uropathogens.[1–4]
Unlike common bacterial uropathogens, viruses do not display nitrate reductase activity, so screening strategies involving urinalysis for nitrite positivity will be false-negative.[5,6]
C. albicans is primarily seen in complicated, recurrent, and persistent UTIs among high-risk patient populations such as young children, individuals with abnormalities of the urinary tract and/or indwelling catheters, adults with immunocompromising comorbidities including diabetes mellitus, and hospitalized patients admitted to intensive care units.[7–11] C. albicans also exhibits synergy with classical bacterial uropathogens including S. aureus and S. agalactiae.[12]
In a study of older adult males and females with clinically suspected complicated UTI, C. albicans was detected in both midstream voided and in-and-out-catheter collected specimens indicating that it was truly present in the bladder, not simply a contaminant picked up during voiding.[13] Furthermore, elevated markers of immune system activation in the urinary tract have been measured from the same clinical urine specimens in which C. albicans was detected, indicating that the presence of C. albicans was associated with an immune response to urinary tract infection.[14–16]
Severe complications of C. albicans UTI, including candidemia and urosepsis, have been reported.[17,18]
Together, these findings indicate that C. albicans should be seriously considered as a uropathogen and demonstrate the value of detecting this organism, particularly in individuals with immune compromise, urinary tract abnormalities, or other risk factors for complicated UTI.
Treatment
Clinically recommended antifungal agents for the treatment of C. albicans UTIs are Fluconazole (PO/IV) or Flucytosine (PO).[19] Note that other antifungal agents do not reach therapeutic concentrations in the urine.