Rapid Identification of Candida glabrata by Using a Dipstick To Detect Trehalase-Generated Glucose

Abstract

ABSTRACT Candida glabrata is a yeast frequently isolated from human specimens. Based upon its well-known ability to rapidly hydrolyze trehalose, we have developed a novel and cost-effective test incubating one yeast colony emulsified in 50 μl of citrate buffer (0.1 M [pH 5.0]) containing 4% (wt/vol) trehalose for 3 h at 37°C. Trehalase-generated glucose is detected with a commercially available dipstick (range, 1.0 to 50 g/liter). For evaluation, consecutive clinical isolates and several reference strains of C. glabrata ( n = 160), C. albicans ( n = 120), and other yeast species with potential ability for utilization of trehalose ( C. dubliniensis , n = 11; C. famata , n = 15; C. guilliermondii , n = 5; C. lusitaniae , n = 16; C. parapsilosis , n = 20; C. tropicalis , n = 34; C. viswanathii , n = 5; Pichia angusta , n = 2; C. zeylanoides , n = 2; Saccharomyces cerevisiae , n = 16; C. neoformans , n = 7) were tested. Identification of C. glabrata is achieved within 3 h, with a specificity of 99.1% and a sensitivity of 98.8% when grown on Sabouraud dextrose agar supplemented with 4% glucose.