TABLE 2.

Antimicrobial concentration ranges and breakpoints used in AST

Microorganism(s) and antimicrobial agent	MIC (μg/ml) range determined by method		Breakpointa (μg/ml)
	VITEK 2	Referenceb	Susceptible	Resistant
Staphylococcus spp.
Clindamycin	0.25-8	0.015-32	0.5	4
Erythromycin	0.25-8	0.015-32	0.5	8
Gentamicin	0.5-16	0.03-64	4	16
Norfloxacin	0.25-16	0.03-16	2	16
Oxacillin	0.5-8	0.03-64	2 (0.25c)	4 (0.5c)
Rifampin	0.5-32	0.015-32	1	4
Teicoplanin	0.5-32	0.015-16	8	32
Vancomicin	1-32	0.05-16	4	32
Enterococcus spp.
Ampicillin	2-32	0.015-32	8	16
Teicoplanin	0.5-16	0.015-16	8	32
Vancomycin	1-16	0.015-16	4	32
HC Gentamicin	120	500	500
HC Streptomycin	200	2,000	2,000
S. agalactiae
Ampicillin	0.25-32	0.015-32	0.25
Clindamycin	0.25-8	0.015-32	0.25	1
Erythromycin	0.25-8	0.015-32	0.25	1
Teicoplanin	0.5-16	0.015-16
Tetracycline	1-16	0.03-16	2	8
Vancomycin	1-16	0.015-16	1
S. pneumoniae
Penicillin	0.06-2	0.015-32	0.06	2
Cefotaxime	0.06-4	0.12-32	0.5	2
Erythromycin	0.06-1	0.015-32	0.25	1
Ofloxacin	1-8	0.03-16	2	8

^a Breakpoints as given in reference 14.\

^b Agar dilution.\

^c Breakpoint for CNS.