Article Figures & Data
Figures
- Fig. 1.
Effect of medium on trailing. The susceptibility of isolate 707-15 to fluconazole was tested in RPMI 1640 (solid symbols) and YAD (open symbols), using the microtiter version of the M27-A method, as described in the text. Relative growth ( y axis) is calculated as the percentage of growth (optical density at 530 nm) relative to growth in a drug-free well (Growth Control) for serial dilutions of fluconazole ( x axis). The squares represent 48-h readings, and the circles represent 24-h readings of the same plate. The results represent the means from experiments performed in triplicate.
- Fig. 2.
Effect of medium pH on trailing. C. albicansisolate 707-15 was grown for 48 h in MOPS-buffered RPMI 1640 (solid symbols) and unbuffered YAD (open symbols), as described in the text. Relative growth ( y axis) is calculated as the percentage of growth (optical density at 530 nm) relative to growth in a drug-free well (Growth Control) for serial dilutions of fluconazole ( x axis). Significant trailing was seen with both media adjusted to a pH of 7.0 (squares) but not in media adjusted to a pH of 4.0 (circles).
- Fig. 3.
pH arrays in RPMI 1640 and YAD. C. albicanstrailing isolate 707-15 was used to assess trailing in RPMI 1640 (A) and YAD (B) adjusted to pHs 7 (solid squares), 6.5 (solid diamonds), 6.0 (solid triangles), 5.5 (solid circles), 5.0 (open triangles), 4.5 (open squares), and 4.0 (open diamonds). All media were buffered in MOPS (0.165 M) and incubated with shaking at 33°C. Relative growth ( y axis) is calculated as the percentage of growth (optical density at 530 nm) relative to growth in a drug-free well (Growth Control), for serial dilutions of fluconazole ( x axis). Shown are the results of growth after 48 h.
Tables
- Table 1.
Results of MIC testing of multipleCandida speciesa
Isolate Species 24-/48-h MIC MIC phenotype YAD RPMI YAD RPMI 707-15 C. albicans 0.5/4 0.5/>64 L/L L/H 630-11 C. albicans 2/4 2/>64 L/L L/H 623-11 C. albicans 2/2 2/>64 L/L L/H 578-8 C. albicans 2/2 2/>64 L/L L/H 572-10 C. albicans 4/8 2/>64 L/L L/H 34-504-040 C. albicans 2/2 2/64 L/L L/H 34-028-117 C. albicans 2/2 1/>64 L/L L/H 630-20 C. albicans 2/4 2/>64 L/L L/H 34-023-096 C. albicans 2/2 1/>64 L/L L/H 34-013-027 Candida parapsilosis 8/16 2/8 L/L L/L 572-9 C. parapsilosis 16/8 64/>64 L/L H/H 34-013-0129 C. parapsilosis 1/4 64/>64 L/L H/H 572-36 C. tropicalis 0.5/8 0.25/64 L/L L/H 572-35.1 C. tropicalis 2/2 4/>64 L/L L/H A9763 Saccharomyces cerevisiae 16/16 8/16 L/L L/L 707-9 Candida lipolytica 64/>64 64/>64 H/H H/H Y533 C. lusitaniae 4/4 1/>64 L/L L/H 34-013-028 C. lusitaniae 0.25/4 64/>64 L/L H/H 559-7.1 C. lusitaniae 8/16 4/8 L/L L/L 625-4 Candida glabrata 3/8 64/>64 L/L H/H 625-4 C. glabrata 64/>64 16/64 H/H H/H 572-32 C. glabrata 64/>64 16/64 H/H H/H 630-10 Candida krusei 64/>64 64/64 H/H H/H A6258 C. krusei 64/>64 64/>64 H/H H/H 9013-8 C. krusei 64/64 64/>64 H/H H/H ↵a Shown are 24- and 48-h MICs and the MIC phenotype (as defined in Materials and Methods) in unbuffered YAD (pH 4.5) and MOPS-buffered RPMI 1640 (pH 7.0). Note that all isolates having a low-high (L/H) phenotype in RPMI 1640 had a low-low (L/L) phenotype in YAD. Isolate 707-15, used in many of the experiments in this study, was tested in an animal model and was found to respond as a fluconazole-susceptible isolate (10). Isolates having MICs that resulted in discrepant susceptibility interpretations (L/L versus high-high [H/H] phenotypes) are highlighted in boldface.
