Enterococcus faecalis – formerly classified as part of the group D Streptococcus system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans.

[2][verification needed] E. faecalis has been frequently found in reinfected, root canal-treated teeth in prevalence values ranging from 30% to 90% of the cases.

[5] E. faecalis is a nonmotile microbe; it ferments glucose without gas production, and does not produce a catalase reaction with hydrogen peroxide.

It catabolizes a variety of energy sources, including glycerol, lactate, malate, citrate, arginine, agmatine, and many keto acids.

[10][13] E. faecalis contains a tyrosine decarboxylase enzyme capable of decarboxylating L-DOPA, a crucial drug in the treatment of Parkinson's disease.

[16][17] Treatment options for vancomycin-resistant E. faecalis include nitrofurantoin (in the case of uncomplicated UTIs),[18] linezolid, quinupristin, tigecycline[15] and daptomycin, although ampicillin is preferred if the bacteria are susceptible.

Ampicillin- and vancomycin-sensitive E. faecalis (lacking high-level resistance to aminoglycosides) strains can be treated by gentamicin and ampicillin antibiotics.

[26] This damage tolerance depends, in part, on the two protein complex RexAB, encoded by the E. faecalis genome, that is employed in the recombinational repair of DNA double-strand breaks.

[26] The ability of E. faecalis to form biofilms contributes to its capacity to survive in extreme environments, and facilitates its involvement in persistent bacterial infection, particularly in the case of multi-drug resistant strains.

[29] In 2013, a combination of cold denaturation and NMR spectroscopy was used to show detailed insights into the unfolding of the E. faecalis homodimeric repressor protein CylR2.

[31] Glutamate racemase, hydroxymethylglutaryl-CoA synthase, diphosphomevalonate decarboxylase, topoisomerase DNA gyrase B, D-alanine—D-serine ligase, alanine racemase, phosphate acetyltransferase, NADH peroxidase,Phosphopantetheine adenylyltransferase (PPAT), acyl carrier protein, 3‐Dehydroquinate dehydratase and Deoxynucleotide triphosphate triphosphohydrolase are all potential molecules that may be used for treating EF infections.

Although this claim may sound plausible, there is currently little evidence that establishes the link between E. faecalis and human virus (or other pathogens) levels.

Although this result may not apply to all sand types, a tentative conclusion is that human shedding is a major non-point source of E. faecalis in recreational waters.