Detection of Candida casts in experimental renal candidiasis: implications for the diagnosis and pathogenesis of upper urinary tract infection
ABSTRACT The distinction between upper versus lower urinary tract infection in patients with candiduria is a commonly encountered and therapeutically important diagnostic dilemma. Candida casts have been reported in the urine of several individual case reports of human renal candidiasis. The specificity of Candida casts would identify unequivocally a patient with upper urinary tract disease. Little is known, however, about the sensitivity and the formation of Candida casts. We therefore studied the diagnostic yield, methods for detection and pathogenesis of Candida cast formation in serially collected urine specimens from immunologically intact and granulocytopenic rabbit models of haematogenous disseminated candidiasis. Refractile blastoconidia and pseudohyphae of Candida encased in the granular matrix were seen on wet mounts while Candida stained a brilliant red in the fuschia pink tubular matrix on periodic acid Schiff (PAS) stained cytopathology filters. Among 24 rabbits with disseminated candidiasis, 11 (46%) had Candida casts detectable by wet mount and PAS-stained urine filters in comparison to none of 10 non-infected immunologically normal controls (P = 0.014). Fifteen (70%) of 21 episodes of Candida casts were detected within the first 3 days of infection, indicating possible utility in the early diagnosis of renal candidiasis. No Candida casts were detected in the urine of granulocytopenic rabbits, possibly due to the rapid destruction of tubules and abrogation of cast formation. This absence of detectable Candida in eight infected granulocytopenic rabbits differed significantly from that of 24 non-granulocytopenic infected rabbits, in which Candida casts were detected in 11 (46%) (P = 0.029). Candida cast formation occurred predominantly in the cortex. Histopathological examination demonstrated invasion of Candida into the glomerular tufts and peritubular capillaries, followed by development of Candida casts in the proximal and distal tubules, respectively. Detection of renal Candida casts may be a useful diagnostic marker in distinguishing upper versus lower urinary tract candidiasis.
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- "So far, candiduria has been investigated predominantly in mice, rats and rabbits (Chen et al., 2006; Hurley & Winner, 1963; Khan & Owais, 2006; Navarro et al., 1994; Nishiksawa et al., 1997; Silva et al., 2007; Tarry et al., 1989; Toth & Hughes, 2006). Experiments in larger animals are more costly, cannot be done with large numbers and genetic-knockout strains are limited or do not exist. "
ABSTRACT: Candiduria is a common finding in hospitalized patients with indwelling urine-draining devices. Animal models for candiduria are not well-developed and, despite its prevalence and associated mortality, candiduria is understudied. The presence of Candida in urine does not imply disease because it is also a commensal. Biofilm formation on catheters and the host-pathogen interaction are likely to be important factors that contribute to the pathogenesis. The objective of this study was to establish a candiduria model in mice with indwelling catheters. Our data demonstrate that biofilm formation on indwelling catheters and persistent candiduria can be established in mice. The study supports the concept that biofilm formation contributes to persistence. It also outlines differences between catheter-related candiduria in mice and humans. Specifically, mice exhibit higher levels of leukocyturia. In addition, mean daily fungal burden in urine in the murine model is 10- to 100-fold lower than that in humans. These important findings must be taken into consideration when using this model to study host-pathogen interaction in the setting of candiduria.Journal of Medical Microbiology 05/2011; 60(Pt 10):1523-9. DOI:10.1099/jmm.0.026294-0 · 2.27 Impact Factor
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ABSTRACT: Yeast infections of the lower urinary tract are common, with the vast majority due to Candida species. Though not life-threatening, candiduria may be a marker for overall severity of illness in hospitalized patients, as it appears to predict increased mortality, particularly in critically ill patients. Diagnosis is relatively simple through culture, but exact definitions of clinical disease are elusive. Management of asymptomatic patients is generally observation with reduction of predisposing factors, whereas symptomatic patients should be treated. Therapeutic options for these infections are limited and not well studied compared with therapies for systemic candidiasis. Further studies are needed to optimize management of these patients. KeywordsCandida-Candidiasis-Fluconazole-Urinary tract infectionCurrent Fungal Infection Reports 09/2010; 4(3):175-178. DOI:10.1007/s12281-010-0024-8
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ABSTRACT: Fungal infections of the urinary tract are increasing in incidence, mostly because of the increasing use of antibacterial agents and indwelling urinary catheters. This review will focus mainly on the spectrum of genitourinary infections caused by Candida spp., including asymptomatic candiduria, cystitis, pyelonephritis, and renal candidiasis. Special emphasis will be placed on the therapeutic approach to the various clinical entities. Other fungal infections, such as urinary aspergillosis and cryptococcosis will be discussed briefly.Le Journal médical libanais. The Lebanese medical journal 01/2004; 52(4):202-9.