Urogenital infections of bacterial origin have a high incidence
among the world female population at reproductive age.
Lactobacilli, the predominant microorganisms of the healthy
vaginal microbiota, have shown a protective effect against the
colonization and overgrowth of urogenital pathogens that increased
the interest for including them into probiotics products assigned
to restore the urogenital balance. In the present work, we
determined in a mouse animal model the capability of Lactobacillus paracasei CRL 1289, a human vaginal strain
with probiotic properties, to prevent the vaginal colonization of
a uropathogenic strain of Staphylococcus aureus.
Six-week-old female BALB/c mice, synchronized in their estral
cycle, were intravaginally inoculated with two doses of 109 lactobacilli before challenging them with a single dose of 105 or 107 CFU of S. aureus. The vaginal
colonization of both microorganisms and the effect on the vaginal
structure were determined at 2, 5, and 7 days after pathogen
inoculation. Control mice and those challenged only with the
pathogen showed an insignificant lactobacilli population, whereas 105 lactobacilli/mL of vaginal homogenate were recovered at 2
days after challenge from the L. paracasei CRL 1289 and
the probiotic + pathogen groups, decreasing this number on the
following days. The treatment with L. paracasei CRL 1289
decreased significantly the number of staphylococci recovered at 2
and 5 days when mice were challenged only with 105 CFU of
pathogen. The inoculation of S. aureus produced a
remarkable inflammatory response and structural alterations in the
vaginal mucosa that decreases in a significant manner when the
mice were protected with L. paracasei CRL 1289. The
results obtained suggest that this particular
Lactobacillus strain could prevent the onset of
urogenital infections by interfering with the epithelial
colonization by uropathogenic S. aureus.