Mouse model of oropharyngeal candidiasis.

The mating capacity and pathogenicity of the C. albicans strains were tested in the immunosuppressed mouse model of OPC as previously described (37). Male BALB/c mice were injected subcutaneously with cortisone acetate (225 mg/kg of body weight) on days −1, 1, and 3 relative to infection. For inoculation, C. albicans cells were grown overnight in sLee's medium at 25°C and then diluted and preincubated in fresh sLee's medium at 30°C for 30 min. The animals next were sedated with ketamine and xylazine, and a swab saturated with 10⁶ C. albicans cells per ml was placed sublingually for 75 min. After 2 and 5 days of infection, the mice were sacrificed and the tongues were harvested. One-half was weighed, homogenized, and quantitatively cultured. The other one-half was fixed in zinc-buffered formalin, embedded in paraffin, sectioned, and stained with periodic acid-Schiff (PAS). To quantify the depth of fungal invasion into the tongue, images of the sections were obtained by light microscopy, after which the depth of fungal invasion relative to the surface of the adjacent, uninfected mucosa was quantified using Infinity Analysis software (Lumenera).