Protective role of lactobacilli in Shigella dysenteriae 1-induced diarrhea in rats

Studies on lactic acid bacteria exemplify their use against various enteropathogens in vitro. Nevertheless, in vivo effects of Lactobacillus during Shigella infection have not been evaluated. The present study evaluated the effect of Lactobacillus rhamnosus and Lactobacillus acidophilus on neutrophil infiltration and lipid peroxidation during Shigella dysenteriae 1-induced diarrhea in rats.

The rats were divided into eight groups (n = 6 in each group). Induced rats received single oral dose of S. dysenteriae (12 x 10(8) colony-forming units [cfu]/mL). Treated rats received L. rhamnosus (1 x 10(7) cfu/mL) or L. acidophilus (1 x 10(7) cfu/mL) orally for 4 d, alone or in combination, followed by Shigella administration. At the end of the experimental period, animals were sacrificed and the assay of the activity of alkaline phosphatase, myeloperoxidase, and antioxidants and the estimation of lipid peroxides were performed. Activity staining of superoxide dismutase and catalase was done in addition to gelatin zymography for matrix metalloproteinase (MMP; MMP-2 and MMP-9) activity. A portion of the intestinal tissue was fixed in 10% formalin for histologic studies.

Administration of S. dysenteriae 1 alone resulted in increased levels of myeloperoxidase, lipid peroxidation, alkaline phosphatase, and the expression of MMP-2 and MMP-9 with concomitant decrease in the antioxidant levels. Pretreatment with the combination of L. rhamnosus (1 x 10(7) cfu/mL) and L. acidophilus (1 x 10(7) cfu/mL) significantly attenuated these changes when compared with the diseased group. Histologic observations were in correlation with biochemical parameters.

Lactobacillus rhamnosus plus L. acidophilus offered better protection when compared with individual treatment with these strains during Shigella infection.