A previously healthy 74-year-old female was admitted to the ICU nine days ago for treatment of severe streptococcal pneumonia. Her initial urine culture, which was collected on hospital day one, showed no growth; however, Candida albicans was isolated from a urine culture collected seven days later. Her second urinalysis revealed mild pyuria. What is the appropriate evaluation and treatment of funguria?
Funguria is a relatively common clinical finding, and it is considerably more prevalent in patients with severe illnesses compared with healthy individuals. One study found that 2.2% of healthy, community-dwelling patients have Candida species (spp) in their urine.1 Candida spp are opportunistic organisms, which is implied by the fact that they can be isolated from 22% of patients admitted to an ICU.2
Despite the frequent isolation of Candida spp from urine cultures, the clinical significance is often unclear. It is difficult to determine if the funguria is caused by contamination, colonization, or a true urinary tract infection (UTI)—there is no test to reliably differentiate between these three possibilities. This is in contrast to bacterial UTIs, in which the findings of pyuria, bacteriuria, and a defined number of colony-forming units strongly support this diagnosis.3
Since it often is difficult to determine the true importance of funguria, its treatment has been controversial.3 The presence of a chronically indwelling urinary catheter often results in the funguria development, and, in many instances, simply removing the catheter will lead to its resolution.4 Furthermore, it has been demonstrated that for most patients with asymptomatic funguria, treatment with antifungal therapy has no effect on morbidity or mortality.5,6 Also, the propensity for funguria recurrence after completion of a course of antifungal therapy often discourages clinicians from ordering pharmacologic therapy.7,8
Review of the Data
The prevalence of funguria is increasing worldwide, primarily due to the increased use of antibiotics and immunosuppressive therapy, as well as the more frequent utilization of invasive procedures.1,7 Candida spp cause as many as 30% of all nosocomial UTIs, and they are most commonly isolated from patients who require ICU treatment.9 In fact, in one large study, only 10.9% of 861 patients with funguria had no underlying illnesses.10
Common risk factors for funguria development include the use of urinary tract drainage devices, hyperalimentation, steroids, recent antibiotic therapy, diabetes mellitus, increased age, urinary tract abnormalities, female sex, malignancy, and a previous surgical procedure.1,2,3,7,10,11,12,13,14
By far, the most common cause of funguria is Candida spp. C. albicans is responsible for at least 50% of all cases of funguria.1,10 Other yeasts that cause funguria include C. glabrata (15.6%), C. tropicalis (7.9%), C. parapsilosis (4.1%), and C. krusei (1%).10
C. glabrata most often is isolated from individuals who have been treated with fluconazole, while C. parapsilos is seen most frequently in neonates. It is noteworthy that for approximately 10% of patients with candiduria, at least two types of Candida spp are isolated from the same urine culture.6,7,14 Other types of fungi that are infrequently isolated from the urine include Aspergillus, Cryptococcus, Fusarium, Trichosporon, and such dimorphic fungi as Histoplasma capsulatum and Coccidioides immitis.6 The latter organisms tend to cause funguria in individuals who have a disseminated fungal infection.