biofilm formation. Biofilm formation of E. faecalis strains D32, UW7709 and the internal controls V583, OG1RF and E. faecium strain 64/3 on a synthetic surface was investigated by using polystyrene plates. After incubation in TSB for 24 hours, produced biofilms of adherent bacteria were stained with crystal violet. Bars represent the mean values of six or three (D32) replicates ± SEM. *** significant P-value < 0.0005, unpaired two-tailed t-test.