Adherence of human vaginal lactobacilli to vaginal epithelial cells and interaction with uropathogens

Abstract

Three strains of Lactobacillus, identified as Lactobacillus acidophilus, Lactobacillus gasseri, and Lactobacillus jensenii, were selected from among 70 isolates from the vaginas of healthy premenopausal women for properties relevant to mucosal colonization or antagonism. All three self-aggregated and adhered to epithelial vaginal cells, displacing well-known vaginal pathogens, such as G. vaginalis, and inhibiting the growth in vitro of Escherichia coli and Streptococcus agalactiae. The surface components involved in self-aggregation appeared to be proteins for L. gasseri and lipoproteins for L. acidophilus and L. jensenii, as judged by susceptibility to treatment with appropriate degrading enzymes. The factors responsible for adherence to epithelial vaginal cells seemed to be glycoproteins (L. acidophilus and L. gasseri) and carbohydrate (L. jensenii). The receptors of the vaginal cells were glycolipids, which presumably were the targets of the competition observed between the lactobacilli and the pathogenic microbes.

FIG. 1

Microscopic observations of autoaggregating L. acidophilus. (A) Control. (B) Cells treated with proteinase K or lipase.

FIG. 2

Electron micrographs of negatively stained L. acidophilus. (A) Control. (B) Cells treated with proteinase K or lipase.

FIG. 3

Adherence of lactobacilli to vaginal epithelial cells. (A) Gram-stained preparation of adherent L. acidophilus isolated from human vaginal cells. (B) As a negative control, L. plantarum LL 441, isolated from dairy products, is shown.

FIG. 4

Microscopic observations of coaggregation between L. acidophilus and C. albicans (A) and the lack of coaggregation between L. acidophilus and S. agalactiae (B).