TABLE 1.

Comparison of the MRSA-Screen test and two phenotypic tests to classify 200 S. aureus clinical isolates as MRSA or MSSA^a

Test method	MRSA (mecA gene positive) (n = 80)			MSSA (mecA gene negative) (n = 120)		Sensitivity (%)	Specificity (%)
	True positive	False negative	Indeterminate	True negative	False positive
MRSA-Screen	80	0	0	119	1b	100	99.2
Oxacillin disk diffusion	49	20	11	116	4	61.3	96.7
Oxacillin-salt agar screen	66	14	0	118	2	82.5	98.3

^aDefined by the presence or absence, respectively, of the mecA gene. 

^bThis isolate, when retested, gave no agglutination.