The interaction of the tested compounds with FLC against Candida species. To assess the
nature of the in vitro interactions between the tested agents and FLC against C. albicans and C. tropicalis
strains, an FICI model was used to characterize the interactions between the tested agents and FLC through
analysis of the data obtained from broth microdilution checkerboard assays. The FICI model is described as Σ
FIC = FICA + FICB = MICAB/MICA + MICBA/MICB, where MICA and MICB are the MICs of drugs A and B when
used alone, and MICAB and MICBA are the concentrations of drugs A and B in the iso-effective combinations,
respectively. According to the results calculated from each dataset, synergy corresponds to a FICI value of ≤ 0.5,
while antagonism reflects a FICI value of > 4; otherwise, indifference is concluded54.