Table 4.

Average optical densities of isolates and reference strains and cutoff points in each measurement of the biofilm formation assay

Isolates a	Averages
	24 h	48 h	72 h
Rhodo 1	0.087	0.143	0.271
Rhodo 2	0.065	0.073	0.223
Rhodo 3	0.072	0.082	0.092
Rhodo 4	0.091	0.067	0.07
R. equiATCC 6939	0.08	0.074	0.089
R. equi ATCC 33701 P+	0.052	0.061	0.128
R. equi ATCC 33701 P-	0.059	0.063	0.213
S. aureus ATCC 25923	0.082	0.138	0.295
Negative Control	0.049	0.056	0.055

^a The averages were calculated from the values observed in each well. For greater uniformity of values, the highest and lowest values from the wells of each strain were excluded on each measurement day. All clinical isolates were biofilm producers. The highest means for each isolate were observed at 72 h of the assay