Abstract

The prevention of bacterial infections with probiotics is an interesting study field. The objective of this study was to research the preventive effect of Lactobacillus salivarius LPLM-O1, isolated from breast milk, in a murine model of infection with Salmonella typhimurium ATCC 14028. Balb/c mice (n=76), 6 to 8 weeks old, were grouped on: G1 (base diet), G2 (109CFU of LPLM-O1, once daily for 7 d), G3 (108CFU of S. typhimurium), and G4 (daily oral dose of 109CFU of LPLM-O1 for 7 d, and then 108CFU of S. typhimurium). Survival rate, splenic index (SE), specific growth rate (SGR), differential leukocyte count, and bacterial count were quantified. The survival rate in groups G1 and G2 was 100%. In G3 and G4, there was a 40% mortality rate at days 7 and 10, with 100% and 86% rates at day 16, respectively. SGR was for G1=1.6, G2=1.3, G3=0.1, and G4=0.6, with no diarrhea or bleeding. Differential leukocyte count was indicative of acute bacterial infection. The highest Salmonella counts were on infected mice that had not been previously treated with the strain LPLMO1. S. typhimurium count in feces was significantly lower in G4 (105 CFU/g) than in G3 (107 CFU/g) (Pr0.05). Once Salmonella had colonized organs like the liver, spleen, and intestines, LPLMO1 administration did not have an impact on the count. Taking into account the high infection rate, preventive administration of LPLM-O1 slightly raised the SGR and the survival rate, while lowering the pathogenic microbial load in the intestines.