Table 2.

Fluconazole susceptibility of S. cerevisiaestrains expressing C. albicans CYP51A1 genes as determined by disk diffusion tests

Patient no.C. albicansisolateExpressed CYP51A1geneaMean (± SD) zone of inhibition (mm)bRelative increase in MIC of the following azole for S. cerevisiae Leu+transformantscAmino acid mutation(s)
IC23 -C23-1 50 ± 2111
C23 -C23-2 38 ± 2442S405F
C39 -C39 33 ± 3442S405F
IIIC33 -C33 47 ± 3111
C34 -C34 32 ± 2442S405F
C82 -C82 31 ± 2442S405F
C26 -C26  0>64328S405F, Y132H
IVC27 -C27 42 ± 3111
C37 -C37 21 ± 2882G464S, R467K
C40 -C40-1 23 ± 1882G464S, R467K
C40 -C40-2  0>64>328G464S, R467K, Y132H
VC43 -C43 43 ± 3111
C56 -C56 21 ± 23241G129A, G464S
  • a The nomenclature indicates the isolate and, for multiple-protein-encoding genes, the protein; e.g., -C23-1 is an abbreviation for CYP51A1-C23-1, which is a gene encoding one of the two CYP51A1 proteins of isolate C23.

  • b Mean diameters were obtained by measuring the zones of inhibition produced by at least six independent S. cerevisiae Leu+ transformants. The mean diameter (± SD) for YKKB-13 transformed with YEp51 alone was 62 ± 2 mm.

  • c The numbers given are fold increases in MICs of azole derivatives relative to the MICs of the S. cerevisiae strains expressing a C. albicans CYP51A1gene from the most susceptible isolate of a given patient. Assays of MICs of azole antifungal agents for S. cerevisiae strains expressing the different CYP51A1 genes were repeated three times without changes in obtained values.