Fig 2.

Doxycycline eliminates fluconazole tolerance. (A) A 5-μl concentration of each well from one of the checkerboard assays was spotted onto a YPD plate after 48 h of incubation, to monitor the viability of drug-treated cells. The recovery plate was incubated for 2 days before being scanned. (B) Viable cell counts after 48 h of incubation in the presence of fluconazole alone or with 25, 50, or 100 μg/ml doxycycline added (corresponding to rows 7, 4, 3, and 2 in panel A, respectively). Circles, fluconazole alone; diamonds, fluconazole plus 25 μg/ml doxycycline; squares, fluconazole plus 50 μg/ml doxycycline; triangles, fluconazole plus 100 μg/ml doxycycline. Values falling below the detection limit of 10¹ CFU/ml were approximated to 0.5 × 10¹ CFU/ml. Mean values from three independent experiments are shown. (C) Etest measurement of the fluconazole MIC of strain SC5314 on RPMI-glucose plates. The left panel shows medium without doxycycline, and the right panel shows medium with 50 μg/ml doxycycline.