A New Model of Vaginal Infection by Candida albicans in Rats

Vulvovaginal candidiasis (VVC) is regarded as an important public health issue, and several aspects of its pathogenesis are not yet sufficiently clear. Experimental in vivo models of vaginal infection with Candida albicans have been extremely useful in the identification of factors concerning hormonal influences on the infection, the virulence of the yeasts, the susceptibility, and the treatment of the infection. The development of easily manageable, reproducible, and economically viable animal models of VVC is highly important. We describe a simple experimental model of VVC in rats, using a pharmaceutical brand of estradiol hexa-hydrobenzoate for human treatment. All the steps of this model were standardized; and after the experiments, the rats were euthanized for further examination of their tissues by scanning and transmission electron microscopy. Standardized features included the use of non-ovariectomized rats, sterile distilled water as the hormone vehicle, estradiol hexa-hydrobenzoate administered at 0.20 mg/week/rat fractionated three times/week, and a yeast suspension of 5 x 10(8) yeasts/ml in a single vaginal administration 1 week after hormone induction. In this way, 100% of the rats were in pseudo-estrus and developed and maintained the infection until the third week of the experiment. Electron microscopy observation of the vagina of the rats confirmed the presence of both pseudo-estrus and vaginal infection. The standardized experimental model proved inexpensive, reproducible, and easily feasible for the induction of vaginal infection with C. albicans and may help to clarify important aspects of the pathogenesis and treatment of VVC.