Presence of L701 M mutation in the FKS1 gene of echinocandin-susceptible Candida krusei isolates

Resistance of Candida krusei isolates to echinocandins, the recommended drugs to treat candidemia, has been associated with mutations in hot spot (HS) regions of the FKS1 gene or L701 M mutation in a region between HS1 and HS3 of FKS1. However, the role of L701 M mutation alone in causing reduced echinocandins susceptibility is still unclear. We analyzed a region between HS1 and HS3 of FKS1 of 25 C. krusei isolates from clinical samples. Susceptibility to echinocandins was determined by a commercial broth microdilution assay and by the microdilution method according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST). The L701 M mutation was detected in 22/25 (88%) C. krusei isolates with low MIC values in the absence of other HS mutations. The presence of isolated L701 M mutation in C. krusei clinical isolates susceptible to echinocandins suggests that this mutation may be just associated to polymorphism in the C. krusei population.