We compared the antifungal susceptibility of 92 Mucorales isolates obtained by visual inspection and spectrophotometric readings following EUCAST (European Committee on Antimicrobial Susceptibility Testing) testing. Amphotericin B minimum inhibitory concentrations (MICs) were up to 1 mg/l against most isolates and variable among species, except for Cunninghamella bertholletiae. Posaconazole MICs against most isolates were up to 1 mg/l and high against Mucor circinelloides, some Rhizopus arrhizus, and Rhizopus microsporus. Isavuconazole MICs ranged between 1 and 8 mg/l but were invariably >8 mg/l against M. circinelloides and C. bertholletiae. The agreement between MICs obtained by visual endpoint or spectrophotometric readings was moderate and higher when using the ≥90% fungal growth inhibition endpoint.
Keywords: EUCAST; MIC; Mucorales; isavuconazole; spectrophotometric readings.
The agreement between minimum inhibitory concentration (MIC) values obtained by visual inspection or spectrophotometric readings was moderate and higher when the ≥90% fungal growth inhibition endpoint was chosen. Isavuconazole presented higher MICs than posaconazole, regardless of the inhibition endpoint used.
© The Author(s) 2023. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology.