Table 2.

Validation of the modified antimicrobial susceptibility testing assay employing the DNA binding fluoroprobe Syto9

Strainsa	Antibiotic	MIC (μg/mL)b
		Expectedc	Measured
			Standard assay	Modified assay
S. aureus ATCC 29213	Oxacillin	0.12–0.5	0.0625	0.5
	Cefotaxime	1–4	1–2	2
	Tetracycline	0.12–1	0.125–0.25	0.5
	Ciprofloxacin	0.12–0.5	0.25–0.5	0.5
E. faecalis ATCC 29212	Oxacillin	8–32	0.5–2	8–16
	Tetracycline	8–32	16	16
	Ciprofloxacin	0.25–1	0.5–1	2
E. coli ATCC 25922	Cefotaxime	0.03–0.12	0.125	0.125
	Tetracycline	0.5–2	1	2–4
	Ciprofloxacin	0.004–0.015	0.0156	0.0156
P. aeruginosa ATCC 27853	Cefotaxime	8–32	8	16
	Tetracycline	8–32	16	16–32
	Ciprofloxacin	0.25–1	0.25	0.5–1

^aDesignated ATCC quality control strains for antimicrobial susceptibility testing

^bShown are the values derived from two independent experiments each conducted in triplicate

^cAccording to Clinical and Laboratory Standards Institute M100-S22 for broth microdilution assay