Comparative effect of viable, heat- killed or sonicated Lactobacil- lus fermentum CRI 1058 in the protection of uropathogenic E. coli in the urinary tract of a murine experimental model

Lactobacilli play a protective role against pathogens in the urogenital tract by a combination of multiple mechanisms, not fully understood until now. The purpose of the present paper was to study whether live, heat killed or sonnicated cells of Lactobacillus fermentum are able to protect against the challenge of uropathogenic Escherichia coli in the urinary tract of mice as experimental model. Sonicated, heat treated and live cells of L. fermentum CRL 1058 attached to agarose beads were inoculated intra-urethrally to different groups of 2months-old female BALB/c mice in three doses of 10 CFU/dose. Thereafter, these mice were challenged with an uropathogenic strain, Escherichia coli, also inoculated in the urethra of the animals. A reinoculation of Lactobacilli at the same dose was performed on day 6 and after. Treated cells of L. fermentum exert a protective effect against E. coli colonization at different degree, being lower that that produced by viable cells. Our results suggest that L. fermentum can be used as a probiotic in those infections caused by certain pathogens such as E. coli, based in the results obtained in the in vivo experimental model.