Evaluation of a rapid colorimetric test based on trehalose use for identification of Candida glabrata

S. Kirdar, B. Gultekin, G. Evcil, A. Ozkutuk, G. Sener, N. Aydin

Author address: 

S. Kirdar, B. Gultekin, G. Evcil, A. Ozkutuk, G. Sener, N. Aydin

Abstract: 

Objective: Non-Candida albicans Candida species have increasingly become important cause of morbidity and mortality in immunocompromised patients. Candida albicans remains the most frequent cause of candidiasis, and Candida glabrata is the second most frequent agent isolated from clinical infections. Due to developing resistance to many azole antifungal agents, including fluconazole, the rapid identification of C. glabrata is essential for appropriate antifungal therapy. Many tests have been developed for identification of C. glabrata based on their trehalose use, which is characteristic property of this species. The aim of this study was to determine the ability of a rapid trehalase test to identify C. glabrata isolates. Methods: One hundred and fifty-four isolates from several clinical specimens were tested by a method developed by Peltroche-Llacsahuanga et al. to evaluate its ability to discriminate C. glabrata strains. Candida strains were identified by germ tube test, their growth on corn meal Tween 80 agar, colonies appeared on Mast ID-CHROMagar Candida medium (Mast Diagnostics, Merseyside, UK), and if required by API 20C AUX (bioMí©rieux, France) commercial kit. All isolates were taken from Sabouraud dextrose agar containing 4% glucose incubated at 37 °C for 24 hours. The reference strains (C. glabrata standard laboratory strain, C. albicans ATCC 90028, C. tropicalis ATCC 750, C. krusei ATCC 6258) were used as control. One yeast colony emulsified in 50 μl of citrate buffer (0.1 M, pH: 5.0) containing 4% (wt/vol) trehalose for 3 hours at 37 °C. Presence of glucose was detected by spotting 10 μl of this suspension onto a dipstick. Glucose, generated by cleavage due to cell-bound trehalase enzyme, was detected a commercial dipstick. Results: Among 151 strains tested, 76 were C. glabrata, 47 were C. albicans, 17 were C. krusei, five were C. parapsilosis, four were C. tropicalis, three were C. keyfr, and one was C. utilis. Among 76 C. glabrata strains tested all were found positive by trehalase test. Non-C. glabrata isolates were found negative by rapid trehalase test. The trehalase tests allowed identification of C. glabrata in 3 hours with 100% sensitivity and 100% specificity. Conclusion: Our study showed that the trehalose assimilation test is rapid, cost-effective, and simple to use. This test may be helpful as a rapid identification method of C. glabrata in routine medical mycology laboratory.
2006

abstract No: 

P860

Full conference title: 

16th European Congress of Clinical Microbiology and Infectious Diseases
    • ECCMID 16th (2006)