TABLE 1.

Antimicrobial susceptibilities of methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered from patients hospitalized in 48 Canadian hospitals, 1995 to 2008

Antimicrobial agent(s) or characteristic	Antimicrobial susceptibility of MRSA isolates												P valuea
	Overall (1995-2008)			1995-1999			2000-2004			2005-2008
	No. tested	MIC90 (μg/ml)	% resistant	No. tested	MIC90 (μg/ml)	% resistant	No. tested	MIC90 (μg/ml)	% resistant	No. tested	MIC90 (μg/ml)	% resistant
Erythromycin	7,942	>8.0	92	2,696	>8.0	94	2,006	>8.0	93	3,240	>8.0	89
Clindamycin	7,522	>4.0	79	2,276	>4.0	92	2,006	>4.0	83	3,240	>4.0	66	<0.001
Tetracycline	7,871	>16	18	2,616	>16	31	2,006	>16	14	3,207	≤2.0	8	<0.001
TMP-SMXb	7,942	>8.0	27	2,696	>8.0	55	2,006	>8.0	16	3,240	≤0.25	7	<0.001
Ciprofloxacin	7,942	>8.0	89	2,696	>8.0	91	2,006	>8.0	89	3,240	>8.0	87
Gentamicin	4,639	16	11	0			1,399	>16	14	3,240	2.0	8	<0.001
Rifampin	7,870	≤0.25	2	2,624	≤0.25	2	2,006	≤0.25	2	3,240	≤0.25	1
Vancomycin	7,942	1.0	0	2,696	1.0	0	2,006	1.0	0	3,240	1.0	0
Fusidic acidc	7,533	0.5	6	2,287	0.5	5	2,006	1.0	8	3,240	0.5	5
Mupirocind	7,870	16	5	2,624	16	2	2,006	32	7	3,240	16	6	<0.001
Tigecycline	1,953	0.5	0	0			0			1,953	0.5	0
Linezolid	5,105	2.0	0	0			1,865	2.0	0	3,240	2.0	0
Daptomycin	1,953	0.5	0	0			0			1,953	0.5	0
Ceftobiprole	1,953	1.0	0	0			0			1,953	1.0	0
Multidrug resistant	2,594		33	1,624		60	553		28	417		13	<0.001

^aTrends in proportions (percentage resistant) over time determined by the Cochrane-Armitage trend test.

^bTMP-SMX, trimethoprim-sulfamethoxazole.

^cResistance to fusidic acid defined as exhibiting an MIC of ≥2.0 μg/ml (9).

^dResistance (high level) to mupirocin defined as exhibiting an MIC of ≥512 μg/ml (23).