Antagonistic Activity, Antimicrobial Susceptibility and Potential Virulence Factors of Enterococcus faecalis

Enterococcus faecalis isolates (87) were phenotypically and genotypically identified and subsequently subjected to the antagonism test and antimicrobial susceptibility. The lipolitic, hemolytic and DNAse activities were identified along with the genes gelE, cylL, cylS, ccf, cpd and cob that, encode virulence determinants. Thirty seven percent of isolates inhibited Listeria monocytogenes (CERELA), Listeria innocuous (CERELA), Staphylococcus aureus (ATCC25932), Lactococcus lactis (IL1403), Micrococcus luteus (ATCC10240) and Enterococcus faecalis (ATCC29212). All strains were sensitive to the ampicillin antibiotic, but 47% were resistant to at least one antimicrobial agent and 6% of isolates presented multidrug resistance. Ninety seven percent of isolates contained the gelE gene, but 77% of these isolates showed gelatinase activity. Presence of cylL and cylS genes was observed in 25% of the isolates, but only 5% presented hemolytic activity. None isolates showed lipase and DNAse activities. Eight percent of isolates contained the ccf gene and 2% showed the presence of the cpd and cob genes. The ability to inhibit pathogenic bacteria, low resistance to antibiotics and absence of virulence factors make some of Enterococcus faecalis strains characterized in the present study promising for exploitation in other applications such as probiotics in aquaculture.