Salmonella-induced changes of the rat intestinal microbiota

The gut microbiome profoundly affects the body functioning: it participates in host protection against pathogenic microorganisms, metabolic events, inhibition of inflammatory responses, formation of innate and adaptive immune response in the intestinal mucosa. One of the causes altering microbiota community is due to antibiotics. Therefore, the processes of antibiotics interaction together with Salmonella enteritidis and Salmonella typhimurium with representatives of normal intestinal microflora are of particular interest. Materials and methods. The quantitative and qualitative analysis of the wall microbiota composition in rats was evaluated by bacteriological method, the statistical data analysis was performed using the software StatSoft Statistica v.12. Results and discussion. Inoculation of vancomycin and S. enteritidis, S. typhimurium in groups II, III, IV resulted in quantitatively decreased E. coli level by 10-, 7- and 110-fold, respectively (p ≤ 0.05). The count of P. aeruginosa decreased markedly only in the group III (p ≤ 0.05). The count of Bacteroides spp. members was profoundly decreased by several thousand times (group II) as well as 70- and 87-fold (groups III and IV), respectively (p ≤ 0.05). The count of E. faecalis and E. faecium decreased by 861-, 6- and several thousand times (groups II, III, IV), respectively (p ≤ 0.05). The count of Proteus spp. markedly decreased in group II by 27-fold and rapidly increased in group IV (p ≤ 0.05). Group III revealed a sharp decline in level of Enterobacter spp. and Klebsiella spp. by 847- and 150-fold, whereas in group II they were increased by 7- and 46-fold, respectively (p ≤ 0.05). The count of Staphylococcus spp. decreased by 10-fold only in group II. The level of Clostridium spp. decreased by several thousand times (group II) and by 5,500 times (group IV) (p ≤ 0.05). The count of Lactobacillus spp. decreased by several thousand times (group II). The count of Bifidobacterium spp. members significantly decreased by 10.9-fold and by several thousand times (groups III, IV). The level of Peptostreptococcus anaerobius profoundly decreased in all three study groups (p ≤ 0.05). The level of Salmonella spp. increased in group II by 49 times, but markedly increased in groups III and IV (p ≤ 0.05). Inoculation of Salmonella after vancomycin pretreatment caused dramatic change in the microbiota composition in groups V and VI, namely: increased count of E. coli by 65- and 105-fold, markedly increased level of P. aeruginosa in group V and VI — by 3-fold. In addition, these groups also showed decreased level of Bacteroides spp. by 9- and 10-fold (p ≤ 0.05). The count of E. faecalis and E. faecium decreased dramatically only in group V (p ≤ 0.05). The count of Proteus spp. decreased by 17 times in group V as well as in group VI (p ≤ 0.05). A sharp increase in level of Enterobacter spp. and Klebsiella spp. members was observed in groups V and VI (p ≤ 0.05). However, representatives of Peptostreptococcus anaerobius in groups V and VI decreased by 20 and 9 times, respectively (p ≤ 0.05). The count of Salmonella spp. decreased only in group V by 7 times (p ≤ 0,05). Inoculating experimental animals with B. fragilis conditioned with S. enteritidis, S. typhimurium and pretreated with vancomycin resulted in markedly decreased level of E. coli in group VII and VIII by 538 times (p ≤ 0.05). The count of P. aeruginosa in groups VII and VIII decreased profoundly, whereas level of Bacteroides spp. members was reciprocally increased (p ≤ 0.05). The level of Lactobacillus spp. decreased by 10.3 times only in group VI. The count of E. faecalis and E. faecium increased by 10 and 19 times in groups VII and VIII, respectively, whereas level of Proteus spp. decreased only in group VII by 322 times (p ≤ 0.05). In addition, a sharp decrease in level of Enterobacter spp. and Klebsiella spp. members (p ≤ 0.05) was found in groups VII and VIII. The count of Peptostreptococcus anaerobius and Lactobacillus spp. members was markedly increased by 7-, 12-, several thousand-fold and 40 times (groups VII and VIII, respectively) (p ≤ 0.05). The count of S. enteritidis and S. typhimurium in groups VII and VIII decreased rapidly (p ≤ 0.05). Conclusion. Inoculation of B. fragilis can be used in treatment of inflammatory bowel diseases or disorders with impaired gut barrier function.