Abstract

The majority of the 11 pathogenic Enterococcus faecalis from lambs developed encephalitis and 45 non-pathogenic E. faecalis from intestinal and respiratory microbiota of healthy lambs were belonged to Streptococcus serotype D. Haemolytic study revealed that 8 of 11 pathogenic stains had stable haemolyticus; 8/30 strains of intestinal normal microbita and 3 of 15 strains from respiratory system showed unstable haemolyticus. Of 11 pathogenics E. faecalis, 8 of 9 virulence factor genes were detected in all the strains; 5 of 11 expressed Esp, CylA, Asa1, Ace, efa, EF0591 and EF3314 simultaneously and 1 of 11 expressed GelE; Two of 11 did not express any of the 9 virulence factor genes. Among 30 strains isolated from the intestinal microbita, only one had 2 (GelE, EF3314) and one had 3 (GelE, EF3314 and Asa1) of the 9 virulence factor genes. The homology of these 3 common virulence gene fragments (GelE, EF3314 and Asa1) was more than 95% between E. faecalis from GenBank and intestinal microbita and 96% when comparing theE. faecalis isolated from intestinal microbita and from those of pathogenic strains. Antibiotic sensitivity study indicated that all of the 11 pathogenic strains were resistance to a variety of antibiotics in various degrees. In comparison, Only 2 strains from normal flora were resistance to individual antibiotics. In vivo challenge study showed that all of the 11 the pathogenic strains could lead to the death of mice, whereas none of the isolates from normal flora could cause the death of the experimental animals.

Key words: Biochemical characteristic, Enterococcus faecalis, lamb, virulence factor gene.