Abstract:
This study aimed to determine the protective effects of Lactobacillus plantarum B7 on Salmonella Typhimurium associated diarrhea in mice. In vitro investigation of antagonistic activity of L. platarum B7 was performed by using agar spot method. In vivo, male mice were randomly divided into 3 groups, all groups were 3 days pre-treated with streptomycin (5 mg/mL). Control group (n = 8) was fed with 1 mL of 0.85% saline, S group (n = 8) was fed with 3x109 CFU/mL of S. Typhimurium and S + LP group (n = 8) was fed with 1x109 CFU/mL of L. plantarum B7and after 2 hours mice were fed 3x109 CFU/mL S. Typhimurium. All groups were treated for 3 days. The body weights of mice were measured and recorded daily. At the end of experiment, fresh feces were collected to determine the number of S. Typhimurium by stool culture with colony counts. Blood samples were collected to determine TNF-α, IL-6 and CXCL1 levels. The feces were tested for the percentage of fecal moisture content (%FMC) and investigated of characteristics. In vitro test showed that L. plantarum B7 produced clear zone of inhibitory activity against S. Typhimurium. In vivo test showed that the number of colony of S. Typhimurium in feces significantly decreased in S + LP group vs S group (7.42 ± 0.05 vs 8.86 ± 0.02 CFU/g, p < 0.05). The level of TNF-α, IL- 6 and CXCL1 was significantly increased in S group vs control group (128.59 ± 12.82 vs 53.49 ± 8.90, 144.44 ± 8.91 vs 66.51 ± 4.04, 96.09 ± 10.81 vs 32.32 ± 4.54 pg/mL, p < 0.05) and significantly decreased in S + LP group vs S group (36.15 ± 9.22 vs 128.59 ± 12.82, 70.36 ± 5.37 vs 144.44 ± 8.91, 35.40 ± 2.77 vs 96.09 ± 10.81 pg/mL, p < 0.05), respectively. The fecal characteristics of S group were soft and loose whereas S + LP group had the rod shape and dark color. The %FMC significantly increased in S group vs control group (43.24 ± 2.05% vs 14.19 ± 1.57%, p < 0.05) and significantly decreased in S + LP group compared with S group (24.65 ± 2.08% vs 43.24 ± 2.05%, p < 0.05). In conclusion, oral administration of L. plantarum B7 can inhibit S. Typhimurium growth, decrease pro-inflammatory cytokine levels, attenuate inflammatory response and improve the moisture content in feces, which can prevent S. Typhimurium associated diarrhea in mice.
