A 'one minute' trehalase detection test for the identification of Candida glabrata

Introduction. Candida glabrata, one of the most common pathogenic Candida s pecies, is frequently resistant to fluconazole. Its rapid identification is therefore imperative for prompt institution of appropriate antifungal ther apy. We have developed a 'one minute' strip test for C. glabrata, based on a commercially available glucose oxidase rest and which involves no incubat ion period. This test is based on the ability of C. glabrata to hydrolyze t rehalose rapidly. Materials and Methods. To assess the performance of this test, 109 stock is olates and 5 reference strains representing a total of 15 different yeast s pecies were grown on three formulations of Sabouraud agar and four chromoge nic agar media. The colonies were tested for trehalase activity after 24 an d 48 h of growth at 30 degreesC. Results. On Albicans ID2, Candida ID and CandiSelect agars, 100% of 58 C. g labrata isolates were identified in 30 seconds after incubation for 24 h an d 48 h. Depending on the medium, 1 to 2 of 18 C. tropicalis isolates tested yielded a false-positive result. The test could not be performed on coloni es grown on CHROMagar Candida. For isolates grown on Sabouraud agar, depend ing on the formulation, the test sensitivities varied from 55% to 100% and 74% to 100% after incubation for 24 h and 48 h respectively The specificity was 100% on all three formulations. For yeasts isolated on chromogenic med ia, because some Candida species can be recognized directly, only the non-i dentifiable colonies need to be tested, reducing handling, reagent consumpt ion, time and cost. A simultaneous test for maltose breakdown, using the sa me principle as the trehalose test, allowed a clear discrimination between 15 isolates of C. glabrata and 6 isolates of C, tropicalis, including the t wo that gave false-positive trehalase results. Conclusion. This rapid trehalase detection test offers a particularly simpl e, rapid and economic method for C, glabrata identification.