21st European Congress of Clinical Microbiology and Infectious Diseases

Evaluation of the Neo-Sensitabs diffusion method for determining the antifungal susceptibilities of Candida species

Abstract number: R2612

Satana D., Erkose Genc G., Sariguzel N., Akyar I., Uzun M., Erturan Z.

Objectives: The purpose of this study was to compare the Neo-Sensitabs method with the CLSI reference broth microdilution (document M27-A3, S3) method for testing the susceptibility of 98 Candida spp. isolates to five antifungal agents (amphotericin B, fluconazole, itraconazole, ketoconazole, and voriconazole).

Methods: In this study, the broth microdilution method was performed according to the CLSI recommendations. The Neo-Sensitabs method was performed according to the manufacturer's instructions (Neo-Sensitabs; A/S Rosco Diagnostica, Taastrup, Denmark). C. parapsilosis ATCC 22019 was used as quality control strain.

Results: A total of 98 isolates of Candida spp.[C. albicans (n = 56), C. tropicalis (n = 22), C. parapsilosis (n = 6), C. glabrata (n = 4), C. dubliniensis (n = 3), C. krusei (n = 3), C. famata (n = 2), C. lusitaniae (n = 1), C. pelliculosa (n = 1)] were evaluated by both of the methods. MIC ranges were found as 0.03–8.0 mg/ml, 0.05–64 mg/ml, 0.03–0.5 mg/ml, 0.03–1.0 mg/ml, and 0.03–0.12 mg/ml for amphotericin B, fluconazole, itraconazole, ketoconazole, and voriconazole for the microdilution method respectively. All isolates were susceptible to voriconazole by both of the methods. Ninety one (93%) of all isolates were determined as susceptible, two (2%) (C. albicans) were found susceptible dose dependent (SDD), and five (5%) [C. krusei (n = 3), C. glabrata (n = 1), C. albicans (n = 1)] were found resistant to fluconazole by both of the methods. Ninety two (94%) of all isolates were determined as susceptible, six (6%) [C. krusei (n = 3), C. albicans (n = 3)] were found SDD to itraconazole by both of the methods. There was 100% agreement between two of the methods for these three antifungal agents in this study. Two (2%; C. albicans, C. glabrata) and eight [8%; C. albicans(n = 3), C. krusei(n = 3), C. glabrata, C. tropicalis] isolates were determined as resistant to amphotericin B and ketoconazole by both of the methods respectively. One (C. albicans) and three [C. albicans (n = 2), C. glabrata] isolates were intermediate to amphotericin B and ketoconazole by Neo-Sensitabs method, but the same strains were susceptible to these antifungals by standard method. In this situation minor errors were calculated 0.01% for amphotericin B, and 0.03% for ketoconazole by Neo-Sensitabs method.

Conclusion: The Neo-Sensitabs method may be an alternative and easy method for the clinical laboratories to determine the susceptibility of yeast isolates.