TABLE 1.

Analysis of MRSA and MSSA ratio of isolates per patient from 1996 to 2001

Yr and strain type	All hospital unitsa			ICUsb			Non-ICUsc
	No. of:		Ratiod	No. of:		Ratiod	No. of:		Ratiod
	Patients	Isolates		Patients	Isolates		Patients	Isolates
1996
MRSA	144	298	2.07	42	94	2.24	102	204	2.00
MSSA	450	631	1.40	79	114	1.44	371	517	1.39
1997
MRSA	133	269	2.02	38	86	2.26	95	183	1.93
MSSA	455	613	1.35	81	120	1.48	374	493	1.32
1998
MRSA	143	236	1.65	48	76	1.58	95	160	1.68
MSSA	424	589	1.39	70	97	1.39	354	492	1.39
1999
MRSA	136	248	1.82	37	66	1.78	99	182	1.84
MSSA	391	515	1.32	53	78	1.47	338	437	1.29
2000
MRSA	112	195	1.74	29	53	1.83	83	142	1.71
MSSA	257	345	1.34	55	72	1.31	202	273	1.35
2001
MRSA	192	391	2.04	47	105	2.23	145	286	1.97
MSSA	390	514	1.32	52	83	1.60	338	431	1.26
All years
MRSA	860	1,637	1.90	241	480	1.99	619	1,157	1.87
MSSA	2,367	3,207	1.35	390	564	1.45	1,977	2,643	1.34

^aAnalysis of patients with S. aureus (both MRSA and MSSA) from all units in the hospital, including ICUs but not including outpatient clinics or 1-day surgery.

^bAnalysis of patients with S. aureus (both MRSA and MSSA) infection only from ICUs that included surgical ICUs, medical or trauma ICUs, burn units, pediatric ICUs, and neonatal ICUs.

^cAnalysis of patients with S. aureus (both MRSA and MSSA) from all units in the hospital, excluding the ICUs listed in columns 5 to 7.

^dThe ratio expressed is the number of isolates detected divided by the number of patients during the analysis period.