Comparative Evaluation of a New Commercial Colorimetric Microdilution Assay (SensiQuattro Candida EU) with MIC Test Strip and EUCAST Broth Microdilution Methods for Susceptibility Testing

Candidemia is an important cause of morbidity andmortality in immunosuppressed patients. Candida isolates must be culti-vated, identified, and tested for susceptibility. We compared the performance of a new colorimetric broth microdilution panel (SensiQuattro Candida EU) for antifungal susceptibility testing to that of Liofilchem’s MIC test strip and the EUCAST reference broth microdilution protocol. We tested 187 blood culture isolates of 5 Candida spp. (120 C. albicans, 38 C. glabrata, 10 C. parapsilosis, 12 C. tropicalis, and 7 C. krusei) against seven antifungal agents (amphotericin B, fluconazole, voriconazole, po-saconazole, caspofungin, anidulafungin, andmicafungin) and interpreted theMICs according to the EUCAST recommenda-tions. If applicable, the overall essential agreement (EA) of the SensiQuattro panel with the reference broth microdilution was slightly higher for C. albicans (87%) than for other species (85.8%). We found that SensiQuattro performed best in testing amphotericin B (EA, 100%), voriconazole (EA, 93.7%), and posaconazole (EA, 94.8%) against C. albicans, but its error rate for this species was high (29.6%) because of mainly major errors (26.7%) in testing anidulafungin andmicafungin. Compared to the SensiQuattro panel, the MIC test strip exhibited a higher level of agreement for most isolates. SensiQuattro assays are easy to perform, but they are currently not suitable for testing echinocandins against Candida spp. Bloodstream infections caused by Candida spp. are the mostcommon invasive fungal infections (1, 2). Patients at risk of candidemia are those who are immunocompromised, e.g., those with hematologic and solid-organ malignancies, those receivin