Routine use of a one minute trehalase and maltase test for the identification of Candida glabrata in four laboratories

Abstract

Aims: To evaluate the rapid identification of Candida glabrata using a one minute trehalase and maltase test in four clinical laboratories. Method: The test was evaluated with 944 freshly isolated yeasts comprising 572 C glabrata and 372 non-C glabrata strains. These strains were isolated on one of three differential media—Candida ID, CHROMagar Candida, or Albicans ID2 medium—and all strains were fully identified using standard methods. Results: The trehalase and maltase test allowed the overall identification of 550 of 572 C glabrata strains (sensitivity, 96.2%) and only 11 of 372 isolates of other yeast species yielded a false positive result (specificity, 96.8 %). Sensitivity and specificity were consistent from one laboratory to another. Using Candida ID medium, the rapid trehalase and maltase test showed a sensitivity of 95% and specificity of 96.2%. Using CHROMagar Candida, sensitivity and specificity were 95.6% and 98.1%, respectively. Using Albicans ID2 medium (tested by two laboratories), the sensitivity was 100% and 98.5% and specificity was 98.1% and 98.2%. In 60% of cases, the test could be performed directly from the primary isolation medium, thus reducing the time for identification. Conclusion: The rapid trehalase and maltase test was highly reliable for the presumptive identification of C glabrata on primary isolation using three different chromogenic media. Direct recognition of C albicans by means of their characteristic colour on chromogenic media coupled with one minute trehalase maltase testing performed only on suspect colonies of C glabrata allowed for rapid presumptive identification of the two yeast species most commonly encountered in clinical samples.