β-D-Glucan Assay in Diagnosis and Monitoring the Systemic Candidiasis in a Rat Model

BACKGROUND: Determination of β-D-Glucan (BDG) in the serum aids to diagnose the invasive fungal infections. The current study evaluated the diagnostic potential value of BDG assay in monitoring the disease in experimental systemic candidiasis in a rat model. The results can provide a useful preliminary data to improve this approach in developing countries. OBJECTIVES: The present study aimed to evaluate β-D-Glucan assay in diagnosis and monitoring the systemic candidiasis in a rat model. MATERIALS AND METHODS: Twenty one rats were infected with 10(6) Candida albicans blastospore per rat. Twelve rats were considered as the negative controls (six immunocompromised rats without infection and six intact rats). During a week, every 24 hours the BDG sera level was determined by both Fungitell and Wako kits. To confirm the systemic infection in each rat, the suspensions of their internal organs were cultivated on agar plates and the number of colony forming units (CFU) of C. albicans was counted. RESULTS: All the infected rats were positive with BDG tests. An increasing level of BDG was observed during early days after injection. The cutoff value for discrimination of BDG positive sera was obtained from the negative sera by the Fungitell kit. The sensitivity, specificity, positive and negative predictive values assessed for the Fungitell kit were 95%, 66.6%, 90.47% and 80%, respectively. These criteria for those of Wako were 90%, 83.3%, 94.7% and 71.4%, respectively. CONCLUSIONS: While BDG assay seems to be a sensitive and specific adjunctive tool to diagnose and monitor the experimental systemic candidiasis, it seems that measuring the positive cutoff value in different laboratory conditions is necessary for favorable establishment of these tests.