TABLE 4.

Antimicrobial susceptibility testing results

Antimicrobial	All isolates tested (n = 1,978)						USA100 isolates (n = 1,062)			USA100 isolates (n = 1,062)			USA300 isolates (n = 625)
	% in category			MIC range	MIC50	MIC90	% in category			MIC range	MIC50	MIC90	% in category			MIC range	MIC50	MIC90
	S	I	R				S	I	R				S	I	R
Chloramphenicol	57.0	42.6	0.4	<2->32	8	16	30.0	69.4	0.6	<2->32	16	16	97.0	3.0	0.0	4-16	8	8
Clindamycinb	36.8	0.0	63.2	≤0.25->16	≤0.25	≥16	1.2	0.0	99.9	≤0.25->16	≥16	≥16	91.0	0.0	9.0	≤0.25->16	≤0.25	≤0.25
Erythromycin	5.6	0.5	93.9	≤0.25->8	>8	>8	0.5	0.4	99.2	0.5->8	>8	>8	5.6	0.5	93.9	≤0.25->8	>8	>8
Daptomycin	99.6	0.0	0.4a	≤0.5-4	≤0.5	1	99.4	0.0	0.6a	≤0.5-4	≤0.5	1	99.7	0.0	0.3a	≤0.5-4	≤0.5	1
Doxycycline	98.3	1.7	0.1	≤1-16	≤1	≤1	99.2	0.8	0.0	≤1-8	≤1	≤1	99.5	0.5	0.0	≤1-8	≤1	≤1
Tetracycline	94.0	0.1	5.9	≤1->16	≤1	≤1	98.2	0.0	1.8	≤1->16	≤1	≤1	89.9	0.0	10.1	≤1->16	≤1	>16
Gentamicin	95.8	0.1	4.1	≤2->32	≤2	≤2	96.3	0.0	3.7	≤2->32	≤2	≤2	98.7	0.2	1.1	≤2->32	≤2	≤2
Levofloxacin	18.5	0.2	81.3	≤0.5->16	>16	>16	0.2	0.0	99.8	≤1-8	4	4	100.0	0.0	0.0	≤1-4	2	4
Linezolid	99.9	0.0	0.1a	≤1-8	2	4	99.9	0.0	0.1a	<4->128	<4	<4				<4->128	<4	<4
Mupirocinc				<4->128	<4	<4				≤0.5->8	≤0.5	≤0.5	97.3	1.0	1.8	≤0.5->8	≤0.5	≤0.5
Rifampin	97.3	0.7	1.9	≤0.5->8	≤0.5	≤0.5	97.2	0.8	2.1	≤0.5/9.5->8/152	≤0.5/9.5	≤0.5/9.5	99.4	0.0	0.6	≤0.5/9.5->8/152	≤0.5/9.5	≤0.5/9.5
Trimethoprim- sulfamethoxazole	94.5	0.0	5.5	≤0.5/9.5->8/152	≤0.5/9.5	≤0.5/9.5	98.7	0.0	1.3
Vancomycin	99.9	0.1	0.0	≤0.5-4	1	1	99.9	0.0	0.1	≤0.5-4	1	1	100.0	0.0	0.0	≤0.5-2	1	1

^aFor daptomycin and linezolid, these isolates are nonsusceptible.

^bResistant isolates include those with inducible clindamycin resistance: 17.3% (n = 342) of all isolates, 25.8% (n = 274) of USA100 isolates, and 2.7% (n = 17) of USA300 isolates.

^cCLSI breakpoints have not been established for mupirocin.