Effect of preventive application of Enterococcus faecium EF55 on intestinal mucosa during salmonellosis in chickens

In the present study the effect of preventive application of Enterococcus faecium EF 55 on the intestinal mucosa was evaluated in experimentally infected chickens with Salmonella enterica subsp. Enteritidis. A total of 120, one-day-old Salmonella-free chickens of Isa Brown hybrid were divided into 4 groups. The chickens in groups E and ES were perorally inoculated with E. faecium EF55 in a dose of 1 × 109 CFU/ml for 7 consecutive days. Placebo was applied to birds in control group C and group S during the first 7 days of life. At the age of 8 days chickens in groups ES and S were perorally infected with S. enterica subsp. Enteritidis phage type 4 in a dose of 1 × 108 CFU/ml. In birds treated with E. faecium EF 55 (group ES) a decreased number of Salmonella spp. positive individuals was recorded from 28.5% 2 days post infection (p.i.) to 10% 14 days p.i. when the difference between group ES and group with the application of Salmonella Enteritidis alone (group S) was significant (P < 0.01). On the contrary, in birds of group S the percentage of Salmonella spp. positive animals showed no constant changes. It increased from 12.5% 2 days p.i. to 37.5% 4 days p.i. The maximum of positive samples 83.3% was found 14 days p.i. The application of E. faecium EF55 reduced colonisation of caeca and minimized translocation of salmonellae into the liver and spleen. Two days p.i. the shortest villi in the jejunum were observed in group S - 1 266.2 µm, when compared to group E with the highest jejunal villi - 1 605 µm (P < 0.05). The growth of the villi was observed 14 days p.i. in all groups except group S. The early exposition of chickens to E. faecium EF55 led to more rapid development of intestinal villi when compared to the untreated control (P < 0.05). Reduced colonisation of the intestinal tract by salmonellae in birds treated with E. faecium EF 55 also preserved the microenvironment of the intestine from harmful effects of the pathogen.