Hot Topics in Antifungal Susceptibility Testing: a New Drug, a Bad Bug, Sweeping Caspofungin Testing under the Rug, and Solving the Epidemiological Cutoff Value Shrug

There are several new hot topics in antifungals and antifungal susceptibility testing. In this review, four topics of general interest to the clinical microbiology community are discussed. The first topic is the introduction of isavuconazole, a new triazole approved for clinical use in the United States. The second is triazole resistance in Aspergillus fumigatus isolates. A specific set of mutations are being found with greater frequency in isolates globally, including the U.S. The third topic of interest is a word of caution about antifungal susceptibility testing for caspofungin in Candida isolates; some laboratories have reported susceptible isolates with high MIC values that would be interpreted as resistant. The final topic is an introduction to epidemiological cutoff values and their use in the clinical mycology laboratory.