Table 3. Phenotypic and molecular characteristics of S. aureus carriage among study participants by livestock exposure group, North Carolina, 2011.

	ILO		AFLO		Prevalence Ratio
	No. positive/	%	No. positive/	%	(95% CI)a
	Total		Total
S. aureus	41/99	41.4	42/105	40.0	1.0 (0.7, 1.5)
Worker	34/80	42.5	35/92	38.0	1.1 (0.8, 1.7)
Household Member	7/19	36.8	7/13	53.8
MRSA	3/41	7.3	3/42	7.1	1.0 (0.2, 6.0)
Worker	3/34	8.8	3/35	8.6	1.0 (0.2, 5.9)
Household Member	0/7	0.0	0/7	0.0
MDRSA	15/41	36.6	8/42	19.0	1.9 (0.9, 4.0)
Worker	13/34	38.2	8/35	22.9	1.7 (0.8, 3.5)
Household Member	2/7	28.6	0/7	0.0
Tetracycline-resistant S. aureus	19/41	46.3	1/42	2.4	19.5 (2.7, 140)
Worker	19/34	55.9	1/35	2.9	19.6 (2.7, 140)
Household Member	0/7	0.0	0/7	0.0
S. aureus CC398	13/41	31.7	1/42	2.4	13.3 (1.8, 98.7)
Worker	13/34	38.2	1/35	2.9	13.4 (1.8, 98.0)
Household Member	0/7	0.0	0/7	0.0
scn- negative S. aureus	17/41	41.5	6/42	14.3	2.9 (1.3, 6.4)
Worker	15/34	44.1	6/35	17.1	2.6 (1.2, 5.7)
Adult Household Member	2/7	28.6	0/7	0.0
scn- negative, tetracycline-resistant S. aureus CC398	11/41	26.8	0/42	0.0	– b
Worker	11/34	32.3	0/35	0.0	– b
Household Member	0/7	0.0	0/7	0.0
scn– negative MRSA CC398	2/41	4.9	0/42	0.0	– b
Worker	2/34	5.9	0/35	0.0	– b
Household Member	0/7	0.0	0/7	0.0
scn- negative MDRSA CC398	6/41	14.6	0/42	0.0	– b
Worker	6/34	17.6	0/35	0.0	– b
Household Member	0/7	0.0	0/7	0.0

ILO = industrial livestock operation.

AFLO = antibiotic-free livestock operation.

PR = prevalence ratio.

^aPR (95% CI) comparing carriage among ILO participants to AFLO participants.

^bNo estimate of the PR (95% CI) is provided due to no occurrence of the outcome of interest in at least one group.