The combination of FLC + RC21v3 was, however, more effective than FLC alone. These results confirmed that FLC was effective against oral candidiasis caused by FLC-susceptible MML610
without co-treatment with RC21v3 and check details also suggested that RC21v3 improved treatment by inhibiting the low levels of Cdr1p expressed by this strain. In a similar set of experiments, mice were inoculated with FLC-resistant C. albicans strain MML611 to induce oral candidiasis. The therapeutic effects of FLC alone on the oral candidiasis were very limited, as expected (Fig. 2a and b). FLC treatment of 0.3 mg kg−1 of body weight per dose only partially reduced the lesion score of tongue lesions (Fig. 2a) and gave no significant reduction in the number of viable C. albicans cells in the oral cavity (Fig. 2b). It was noted that for the control mice without FLC treatment, the
number of viable MML611 cells recovered (~ 105.2 ± 0.4 CFU) was less than the number of MML610 cells recovered (Fig. 1b; ~ 105.9 ± 0.1 CFU). A similar reduced recovery buy GSI-IX of strain MML611 from untreated mice was observed in subsequent experiments (Figs 3b and 6b; ~ 105.4 ± 0.1 and 105.5 ± 0.3, respectively). This may reflect a reduced fitness of strain MML611 relative to the parental strain because of the overexpression of resistance genes, although growth of the two strains in vitro was not affected. The combination of RC21v3 and FLC reduced the lesion score and the viable cell number in a dose-dependent
fashion with a statistically significant drop in both parameters at 0.02 μmol per dose of RC21v3 (Fig. 2a and b). The synergistic effect of RC21v3 was even greater when the FLC dose was 0.5 mg kg−1 of body weight per dose (Fig. 3). Again the therapeutic effects of RC21v3 were synergistic with FLC as it had no effect on its own. Visual inspection most revealed that the tongues of the mice treated with both FLC and RC21v3 appeared normal, whereas multiple lesions were present on the tongues of mice treated with saline or with either agent on their own (Fig. 4). Histopathological examination showed that FLC treatment alone decreased the number of hyphae on the surface of tongues compared to the saline control (Fig. 5a and c), but much greater fungal clearance was evident in mice treated with RC21v3 and FLC (Fig. 5c and d). In these mice, the lingual papillae that are obscured in oral candidiasis were evident (Fig. 5d arrows). Candida albicans MML611 is cross-resistant to other azoles including ITC, which is also used to treat oral candidiasis (Blatchford, 1990; de Repentigny & Ratelle, 1996). We determined whether RC21v3 acted synergistically with ITC to combat ITC-resistant oral candidiasis. Because ITC has limited solubility in water, it was applied topically on the tongue surface using a round-end needle and not via drinking water. As with FLC, ITC alone (0.