[Evaluation of a rapid trehalase test for the identification of Candida glabrata]

Candida species which cause local infections, may also lead to fatal systemic infections. The increasing incidence of non-albicans Candida, especially fluconazole susceptible or resistant dose-dependent C. glabrata, increased the importance of rapid and accurate species level identification for Candida. Rapid and correct identification of C. glabrata is essential for the initiation of the appropriate antifungal therapy. This study was conducted to evaluate the performance of the rapid trehalase test in the diagnosis of C. glabrata isolates. A total of 173 Candida strains isolated from various clinical specimens and identified according to germ tube test, growth on cornmeal Tween 80 agar and the colony morphologies on Mast-CHROMagar Candida medium (Mast Diagnostics, UK), were included to the study. The identification of non-albicans Candida species were also confirmed by API 20CAUX (BioMerieux, France) system. Accordingly 86 (50%) of the isolates were identified as C. glabrata, 48 (28%) C. albicans, 17 (10%) C. krusei, 13 (8%) C. tropicalis, 5 (3%) C. parapsilosis, 3 (2%) C. kefyr and 1 (1%) Cutilis. In order to detect the presence of trehalase enzyme in Condida strains, all isolates were grown on Sabouraud dextrose agar containing 4% glucose and then one yeast colony was emulsified in 50 microl of citrate buffer containing 4% (wt/vol) trehalose for 3 h at 37 degrees C. Presence of glucose which emerged after the action of trehalase on trehalose, was detected by a commercial "urinary glucose detection dipstick" (Spinreacta, Spain). All C. glabrata strains yielded positive result by trehalase test. None C. glabrata isolates were found negative by trehalase test except for one strain of C. tropicalis. In this study, the trehalase test allowed identification of C. globrata with 100% sensitivity and 98.9% specificity. It was concluded that trehalase test is a rapid, cost-effective and simple test that can be used for the accurate identification of C. glabrata.