Identification and Virulence Factors of Enterococcus Species Isolated from Raw Milk

Four enterococci isolated from raw milk samples grown on Enterococcus selective medium were identified on genus level by several conventional methods, and species levels using API 20 Strep. The incidence of virulence factors (antibiotics susceptibility, vancomycin resistance, haemolytic activity, production of gelatinase, aggregation substances, hydrophobicity and biofilm formation) were also examined for the isolated Enterococcus species. Results showed that the tested cultures grown on Enterococcus selective medium BEA showed similar behavior that all were able to grow at 10°C and 45°C, pH 9.6, NaCl 6.5%, tolerate  growth in the presence of 40% bile and 0.04% sodium azide. They also survived 60°C/30 min. Four tested Enterococcus spp. Were found  belonging to E. faecium, E. durans and E. faecalis, being one strain, two strains and one strain, respectively.  E.faecium Rm1, E.durans Rm2 and E.durans Rm3 strains were found to be safe as they did not harbored any of tested virulence trait or multi antibiotic resistant. Results also showed that E.faecalis Rm4 was not safe as it harbored some of virulence factors and resisted multi antibiotics. Finally, E.faecium Rm1, E.durans Rm2 and E.durans Rm3 could be considered ideal strains, which could be used as adjunct or starter cultures as they were free from virulence determinants and sensitive to all antibiotic examined.