Lactobacilli in the Vagina Utilize an Arsenal of Defensive Tactics

  Some release powerful chemicals that stunt the growth of potential pathogens. Others stubbornly cling to strategic positions in the inner lining of an organ, preventing harmful microorganisms from gaining a foothold. Still others knock loose "bad" bacteria already fastened to cell receptors. These are just some of the tricky defense strategies used by "good" Lactobacillus bacteria to ward off potential pathogens and keep them from overpopulating - in the gastrointestinal tract as well as in the vagina. Mounting evidence indicates that the outcome of this bacterial "push and shove" plays an important role in the sexual and reproductive health of women.

Interestingly, the defense strategy of lactobacilli seems to adapt to the body's immediate needs. When the vagina is healthy, lactobacilli chiefly use adhesion to block uropathogens from gaining access to the epithelium. When microbial imbalances create a high risk of urinary tract infection, however, lactobacilli may employ another tactic - "bumping off" infectious microrganisms that are already occupying positions within the vaginal lining.  " Lactobacillus strains are able to block the attachment of uropathogens to vaginal epithelium and, moreover, are able to excrete substances that inhibit their multiplication, which are 2 important steps in the pathogenesis of urinary infection," investigators concluded ( mechanisms observed in other friendly bacteria are -- adhesion to epithelial cells, inhibition of pathogen growth, and production of a biosurfactant protein to resist pathogen adhesion.)

Characterisation and selection of a Lactobacillus species to re-colonise the vagina of women with recurrent bacterial vaginosis.   

This paper reports the results of characterising and selecting a strain of Lactobacillus for potential use as a probiotic in regenerating the vaginal flora of women with recurrent episodes of bacterial vaginosis (BV).


Other studies:

L. reuteri has also been identified in the vagina. In the most recent issue of Journal of Infectious Diseases, it is one of seven strains described as having "sufficiently substantial data published on their properties that are required of an antipathogen probiotic." The others are L. rhamnosus GG, L. acidophilus NCFM, L. casei Shirota, L. casei CRL-431, L. rhamnosus GR-1, and L. fermentum RC-14.
Sources: Casas IA, Edens FW, Dobrogosz WJ. Lactobacillus reuteri: An effective probiotic for poultry and other animals. In Salminen S, von Wright A, editors. Lactic Acid Bacteria: Microbiology and Functional
Aspects. 2nd ed. New York: Marcel Dekker, Inc., 1998.

Reid G. Probiotic agents to protect the urogenital tract against infection. Am J Clin Nutr 2001;73(Suppl):437S-43S.

Reid G, Bruce AW. Selection of Lactobacillus strains for urogenital probiotic applications. J Infect Dis 2001;183(Suppl 1): S77-80.
NOTE: The Vaginosis Profile features a microscopic examination for bacteria such as beneficial Lactobacillus, which may play an important role in influencing mechanisms of vaginal infection and disease. Based on levels of bacteria, including Gardnerella, Mobiluncus (curved gram negative rods), and Lactobacillus, a Bacterial Vaginosis Index is computed to indicate the balance of microbial flora in the vagina.

Source: Osset J, Bartolome RM, Garcia E. Assessment of the capacity of Lactobacillus to inhibit the growth of uropathogens and block their adhesion to vaginal epithelial cells. J Infect Dis 2001;183:485-91.