Isolation and identification of Enterococcus faecalis and detection of its virulence factor genes in lambs presenting with encephalitis in Xinjiang province, China

In order to investigate the reasons of lamb death, 11 bacteria were isolated from the brain, liver and other tissues of natural infectious lambs presenting neurological symptoms and septicaemia as the main clinical feature from different farm of two regions in Xinjiang, China in recent years. They were identified as Enterococcus faecalis according to morphological, cultural and biochemical characterization. The infecting strains were identified as belonging to serotype D, G or to an unidentified serotype with Lancefild Group A to G Latex Diagnostic Kit. All 11 E. faecalis pathogens were resistant to norfloxacin, penicillin, tetracycline, streptomycin, gentamicin and erythromycin at varying degrees. PCR screening for nine common virulence factor genes associated with Enterococcus species revealed the presence of eight virulence factor genes (esp, cylA, asa1, ace, efa, gelE, ef0591 and ef3314) in 11 of the isolates, five genes were present in all strains examined and gelE was present in 1 pathogenic strain examined. Nine virulence factor genes were not present in two strains examined. Virulence gene analysis revealed a 96% homology to Enterococcal genes from pathogenic E. faecalis sequences deposited in GenBank. Some genus from Enterococcus can also lead to the infection and death of lambs.