Experimental Administration of Estradiol on the Colonization of Lactobacillus fermentum and Escherichia coli in the Urogenital Tract of Mice.

Abstract

The physiological condition of the urogenital tract changes during the life of different animals or humans, altering the normal microbial flora.1) The number and species of bacterial populations depends on the stage of human life: premenarche, menarche, menstrual cycle, active reproductive cycle, or menopause. There is not much knowledge about the microbiological implications of the steroid-hormonal effect on the urogenital tract. Different characteristics can be influenced by hormones involved in the maintenance of the micro ecosystem.2) The first is the vaginal epithelium that represents a system with constant cellular renovation. Cellular maturation, width of surface layer, and cell desquamation depend on the estrogenic stimulation period 1) in which the cells are divided. The second one is the microbial flora itself. The concept that the urogenital tract is colonized only by lactobacilli has been modified, particularly by those researchers who isolated anaerobic microorganisms, describing a diversity of microbial species.3,4) The third aspect to be considered is the complexity of interactions between host-microorganisms and endogenous and exogenous species which can be, in turn, antagonistic or synergistic. 1)In a previous paper, an experimental model to study the protective and preventive effect of lactobacilli in the urogenital tract of mice was set up, 5) and the antibiotic effect on the colonization kinetics of both L. fementum and uropathogenic E. coli was studied. 6) L. fermentum was intraurethrally inoculated as agarose beads, and E. coli as a suspension. The aim of the present work was to study the effect of estradiol on the kinetics of colonization of both groups of microorganisms, and the histological modifications produced by them. MATERIALS AND METHODSMicroorganisms L. fermentum CRL 1058 was isolated from the vagina of BALB/c mice, as described before.7) E. coli was isolated from the infected urinary tract of adult women and identified by biochemical tests according to Orskov.8) The latter strain was uropathogenic, because it possessed type P fimbriae and produced hemolysins, and also showed pyelonephritogenic effects when subjected to a hemagglutination test, as tested in mice. 9)Culture Media and Growth Conditions Media, lactobacilli culture conditions, and the preparation of microscopic agarose beads for intra-urethral administration were described previously.10) Uropathogenic strains were grown in either Brain Heart Infusion (BHI) supplemented with 0.5% yeast extract, or LAPTg broth.11) Not more than three-fold subcultures were performed in order to avoid changes in adhesion properties. Microorganisms were harvested by centrifugation, washed twice with phosphate buffer saline (PBS) pH 7.0 and suspended in 0.5% peptone-water. For intra-urethral inoculation of pathogens, suspensions of microorganisms were prepared in 0.5% peptone-water. Microorganism concentrations used are indicated in each experiment.Animals Two-month-old female BALB/c mice from the inbreed colony of the Instituto de Microbio...

Estrogen Supports Urothelial Defense Mechanisms

“…It has also been argued that rising vaginal pH and changes in vaginal microflora enhance susceptibility toward UTI after menopause (34). For example, in fertile female mice, estrogen supplementation modulated E. coli colonization of the bladder, not only directly but also indirectly by affecting the commensal flora of the vaginal epithelium (32). By instillation of bacteria directly into the bladder, we bypassed this complex interaction and were able to focus our investigation on urothelial factors and estradiol alone.…”

Lactic Acid Bacteria in the Prevention of Urogenital and Respiratory Infections

“…fermentum colonization. No histological modifi cations were observed in these probiotic treatments (Silva de Ruiz et al 2001, 2003 and both viable and nonviable Lact. fermentum cells can be used efficiently as probiotics in E. coli infections (Silva de Ruiz and Nader -Mac í as 2007 ).…”

Probiotics in the Prevention of Urogenital Tract Infections. Mechanisms Involved

“…The protective effect against uropathogenic E. coli, and Klebsiella pneumoniae when lactobacilli were intraurethrally inoculated was also demonstrated [186]. The effect of estrogens and antibiotics was more effective in the protection against the pathogen [187,188] when mice were previously inoculated with lactobacilli. The administration of lactobacilli either in the urinary or vaginal tract does not produce any adverse effect on the mice, nor structural or ultrastructural modifications [189].…”