TABLE 1.

Prevalence of methicillin-resistant and methicillin-susceptible Staphylococcus aureus colonization and correlation of results according to the CURE CHROMagar and PETS broth-enrichment study protocols

Study group	S. aureus prevalence (no. positive [%])			Test sensitivity (%)		Test agreement		Sample size
	Jointa	CHROMagar	Broth enrichment	CHROMagar	Broth enrichment	Kappa (95% confidence interval)b	Kappa interpretationc (agreement)
MRSA
Enrollment visit
Subsetd,e	37 (40.7)	27 (29.7)	29 (31.9)	73.0	78.4	0.54 [0.35–0.72]***	Moderate	91
Index only	32 (40.5)	26 (32.9)	24 (30.4)	81.3	75	0.59 [0.40–0.78]***	Moderate	79
3-mo visit
Subsetd,e	12 (48.0)	12 (48.0)	10 (40.0)	100	83.3	0.84 [0.63–1.00]***	Almost perfect	25
Index only	29 (53.7)	22 (40.7)	26 (48.2)	75.9	89.7	0.63 [0.42–0.83]***	Substantial	54
MSSA
Enrollment visit
Subsetd,e	20 (22.0)	8 (8.8)	15 (16.5)	40	75	0.17 [-0.08–0.42]*	Slight	91
Index only	12 (15.2)	7 (8.9)	8 (10.1)	58.3	66.7	0.34 [0.00–0.67]**	Fair	79
3-mo visit
Subsetd,e	1 (4.0)	1 (4.0)	1 (4.0)	100	100	1.00 [1.00–1.00]***	Almost perfect	25
Index only	8 (14.8)	3 (5.6)	8 (14.8)	37.5	100	0.50 [0.15–0.86]***	Moderate	54

^aJoint prevalence combines test results from the CHROMAgar and broth-enrichment protocols and is positive if either protocol yielded the target organism (gold standard), and the sensitivity is calculated by dividing the number positive for the individual tests by the number positive according to the gold standard (17).

^b*, P ≤0.05; **, P ≤ 0.01; ***, P ≤ 0.001.

^cAccording to criteria by Landis and Koch (14).

^dSubset was all household members from the first 25 homes enrolled, of which 14 continued in the study at the 3-month visit.

^eNo lesion swabs were included in the subset analysis; the subset includes index participants in order to mimic whole-household testing.