Hormonal factors in vaginal candidiasis in rats

Abstract

The hormonal status of rats affected vaginal infection with Candida albicans. Four hours after infection viable counts were higher and germ tubes were longer in those animals in estrous than in other animals. However, the infection was not maintained with the change in epithelial cell type which occurred as part of the estrous cycle. Estrogen dosing following ovariectomy predisposed toward infection, while progesterone dosing did not. In rats injected with progesterone, germ tube clumping was seen, leukocytes were present, and elimination occurred before hyphal growth was evident. In rats injected with estrogen, however, infection was maintained, with hyphal growth extending throughout the cornified epithelial layer. Vaginal washings from rats dosed with estrogen promoted elongation of germ tubes in vitro to a greater extent than washings from other rats. Preincubation of blastospores in progesterone and subsequent infection of rats in pseudoestrous promoted clumping of germ tubes in the vagina. Strains of C. albicans varied in their virulence, which correlated with their ability to produce germ tubes in vitro. Loss of virulence occurred on subculture of a clinical isolate.

Estrogen‐dependent induction of persistent vaginal candidosis in naïve mice

“…6 Estrogen has been shown to promote C. albicans adhesion by inducing hyphal growth. 7,8 Additionally, estriols, pregnanediols, pregnanetrials and estradiols have been shown to increase germination of C. albicans. 9,10 The pleotropic effects of estrogen on the epithelium of the reproductive tract are thought to facilitate and enhance C. albicans adhesion, growth and colonization.…”

“…9,10 The pleotropic effects of estrogen on the epithelium of the reproductive tract are thought to facilitate and enhance C. albicans adhesion, growth and colonization. 8,11,12 Several investigators have used estrogen in conjunction with C. albicans vaginal inoculation to construct animal models of persistent VC; among these models is the estrogen-dependent VC (EDVC) murine model. [13][14][15] This model has proved to be useful in evaluating the various aspects of pathogenesis of VC as VC in the absence of estrogen treatment in the murine system is transient and only lasts for few days.…”

Experimental rat vaginal infection with Candida parapsilosis

“…Despite these limitations the data reported here are, to our knowledge, the first description of a successful rat experimental vaginal infection with the yeast Candida parapsilosis. This infection was seen not to differ in number of vaginal CFU from that caused by a vaginitis isolate of C. albicans, and estrogen administration was, as for C. albicans-rat vaginitis [11], essential for the maintenance of infection. Yeast viable counts in the vaginal fluid of our C. albicans-positive control experiments were comparable to those measured by others in a similar model of experimental rat vaginitis given by a fresh vaginal isolate of C. albicans [11].…”

“…This infection was seen not to differ in number of vaginal CFU from that caused by a vaginitis isolate of C. albicans, and estrogen administration was, as for C. albicans-rat vaginitis [11], essential for the maintenance of infection. Yeast viable counts in the vaginal fluid of our C. albicans-positive control experiments were comparable to those measured by others in a similar model of experimental rat vaginitis given by a fresh vaginal isolate of C. albicans [11]. Two other isolates of C. parapsilosis were unable to cause a prolonged infection, and it is of interest that one of them was isolated from the vagina of an asymptomatic subject.…”

“…The limitations of present models of experimental rat vaginitis, including the quantitative assessment of viable yeast counts in the vagina are well known and have been discussed by others [9][10][11]. Nonetheless, this model has found wide applications for chemotherapeutic purposes, with success in monitoring the differential ability of yeast species and strains to colonize and/or persist in the vaginal environment [10,11]. In the present study, straightforward comparisons in the quantitation of yeasts in the vagina must also take account of the different forms of growth of C. albicans and C. parapsilosis in the vaginal environment.…”