Mitsuhiro Takashima

Clinical Significance of Measurement of Serum D-Arabinitol Levels in Candiduria Patients

D-Arabinitol, a major candidal metabolite, is reported to be a useful parameter to diagnose disseminated candidiasis. Conventional determination of serum D-arabinitol levels using gas-liquid chromatography is complicated and time-consuming compared with the enzymatic fluorometric assay, newly available in kits. D-Arabinitol concentrations were determined by both enzymatic fluorometric assay kits and gas-liquid chromatography, and a significant correlation (r = 0.943, p less than 0.01) was found between the two methods in 25 sera from 15 patients with candiduria. D-Arabinitol/creatinine ratios were determined using the enzymatic fluorometric assay in 39 candiduria patients (21 febrile and 18 afebrile) and 22 patients without candiduria as the control. The ratios in the febrile patients were significantly greater than those in the afebrile and the nondocumented candidiasis groups. These results suggest that knowledge of the serum D-arabinitol concentration may help to promptly diagnose invasive candidiasis, particularly Candida pyelonephritis. In addition, enzymatic fluorometric assay kits are considered to be advantageous in that they require little time and are simple to use, as compared with gas-liquid chromatography.

D-arabinitol versus mannan antigen and candidal protein antigen as a serum marker for Candida pyelonephritis.

To evaluate serum markers for the diagnosis ofCandida pyelonephritis, levels of D-arabinitol, candidal mannan antigen and candidal protein antigen were measured using an enzymatic fluorometric assay, an enzyme immunoassay and a latex agglutination assay, respectively. The study group comprised 36 patients with candiduria (11 disseminated candidiasis, 9Candida pyelonephritis and 16 colonization) and 27 without candiduria. The D-arabinitol/creatinine ratio was the only marker that differentiated betweenCandida pyelonephritis and colonization (p<0.01). Using the cut-off values (1.4 µmol/mg of D-arabinitol/creatinine ratio, 0.28 of mannan/creatinine ratio (×104) and 1:4 of protein antigen titer) D-arabinitol/creatinine ratio showed the highest sensitivity inCandida pyelonephritis (77.8 %) as compared to mannan/creatinine ratio (55.6 %) and protein antigen titer (11.1 %) although there were no differences in specificity, positive predictive value or negative predictive value. These results suggest that D-arabinitol/creatinine ratio is the most useful marker ofCandida pyelonephritis.

In vitro susceptibility testing of Candida isolates from clinical specimens to four antifungal agents.

A total of 231 isolates of Candida species including 163 of Candida albicans (132 of serotype A and 31 of serotype B), 42 of Candida tropicalis, 17 of Candida glabrata, 7 of Candida parapsilosis and 2 of Candida krusei were collected from clinical specimens in two medical centers, one in Japan and the other in the United States. The in vitro antifungal activities of amphotericin B, 5-fluorocytosine, miconazole and fluconazole were evaluated for the above isolates by means of a photo-read broth microdilution method for determination of the 30% inhibitory concentration (IC30). The results showed that IC30 values of fluconazole were generally great compared with those of the other drugs, regardless of Candida species. The isolates of C. albicans serotype B showed a significantly lessened susceptibility to 5-fluorocytosine compared with those of serotype A (p less than 0.01). This method has the advantage of objective measurement, thus minimizing observer variability as compared with the agar dilution test.

Diagnostic value of determination of serum mannan concentrations in patients with candiduria

The diagnostic value of determination of serum mannan levels was studied in 41 patients with candiduria and 20 control patients without candiduria. The patients with candiduria comprised 18 asymptomatic afebrile patients (group 1) and 23 febrile patients with suspectedCandida pyelonephritis (group 2). Mannan antigenemia (≥0.5 ng/ml) was detected in 14 patients in group 2, this rate being significantly higher than the rate of four patients in group 1 (p<0.05) and none in the control group (p<0.01). Serum mannan levels decreased gradually and became undetectable in six patients in whom therapy with an anticandidal agent was effective. Determination of serum mannan levels may be a useful parameter in diagnosingCandida pyelonephritis and deciding on effective treatment.

Experimental study of ascending Candida albicans pyelonephritis focusing on the hyphal form and oxidant injury.

To investigate the pathogenicity of the hyphal form of Candida in pyelonephritis a Candida albicans strain, assuming only the yeast form but not the hyphal form when induced by ultraviolet mutagenesis, and a revertant strain from this mutant strain showing bimorphism were compared in a rat experimental model with regard to the incidence of ascending Candida pyelonephritis and the grade of inflammation. To increase the frequency of pyelonephritis unilateral incomplete ureteral stenosis was created. The revertant strain assuming the hyphal form showed a significantly (p < 0.01) higher frequency of pyelonephritis as compared with the mutant strain not assuming this form, and the grade of inflammation was also higher in the revertant strain group. Also, higher renal tissue and serum levels of both lipid peroxide and superoxide dismutase, which are related to marked renal oxidant injury, tended to be correlated with the degree of neutrophil infiltration in the acute phase. These findings suggest that the hyphal form plays an important role in the development of C. albicans pyelonephritis and also that the oxygen radicals from neutrophils appearing at the sites of inflammation play a major part in the further extension of inflammatory lesions.

Rat Models of Ascending Pyelonephritis due to Candida albicans

Publisher Summary This chapter presents two experimental rat models of ascending Candida pyelonephritis with combination pretreatments of leukopenia and vesicourethral reflux, and of unilaterally incomplete ureteral obstruction and VUR. Female Wistar rats weighing 200–250 g each are used in these models. The animals are allowed free access to standard laboratory chow and tap water. Candida albicans ATCC 10259 strain (serotype A) is used in this model. Candida cells grown for 48 hours at 37° C in Sabourauds broth are harvested by centrifugation at 4° C for 10 minutes, washed twice with distilled water, and resuspended in sterile physiological saline. In the first model, the rats are rendered leukopenic by a single transperitoneal injection of 200 mg/kg body weight of cyclophosphamide, three days before inoculation of the Candida cells. Gentamicin (8 mg/kg) is administered once a day for one week following the administration of cyclophosphamide to prevent contaminating bacterial infections. Kidney histology is normally used to monitor the progress of infection. Within three days of inoculation, microcopy reveals acute pyelonephritis showing polymorphonuclear leukocyte infiltration, mucosal edema, and bleeding, together with Candida cells invading from the renal fornix in about half of the infected kidneys. In the second model, a midline incision is made at the lower abdomen after the skin is shaved with an electric clipper and then disinfected with an iodine-based solution. To produce open hydronephrosis, incomplete occlusion of the left ureter is induced by exposing and detaching the left ureter and applying a drop of an instant adhesive to the inferior end of the ureter.