Identification of Candida glabrata and other common Candida species using chromogenic agar and germ tube test

Abstract

Introduction: Chromogenic agar and germ tube test have been used for decades to identify C. albicans. However, neither of these tests separately allows identification of C. glabrata. Objective: To test the efficacy of chromogenic agar and germ tube test used serially to identify the most common Candida species found in clinical practice, with emphasis on C. glabrata. Methods: 436 isolates were identified using the chromogenic medium followed by the germ tube test. Biochemical tests were used as gold standard. Sensitivity, specificity and confidence intervals (95 %) of the serial identification system were determined. Results: Sensitivity was 97.9 % (IC95 %: 96.0-99.9) to identify C. albicans/dubliniensis, and 90.9 % (IC95 %: 84.0-97.8) for C. tropicalis; specificity was 100 % for both species. Sensitivity was 92.5 % (IC95 %: 86.2-98.8) for identification of C. glabrata with 96.6 % (IC95 %: 95.0- 98.6) specificity. Concerning identification of the C. parapsilosis complex, specificity was 96.3 % (IC95 %: 94.5-98.1). Conclusion: The proposed serial scheme has adequate sensitivity and specificity for identification of C. albicans/dubliniensis, C. tropicalis and C. glabrata. It could be useful in low-resources clinical settings.

Keywords

• Candida glabrata
• Candida albicans
• Candida tropicalis
• Species identification