. 2018 Dec 13;126(12):127005. doi: 10.1289/EHP3453

Table 4.

Associations between 101 industrial hog operation (IHO) workers’ habitual occupational activities over 4 months and biweekly nasal carriage of multidrug-resistant and livestock-associated Staphylococcus aureus outcomes by IHO workers’ 79 adult and minor household members, North Carolina, 2013–2014.

Characteristic		79 household members’ nasal carriage outcomes at 655 biweekly study visits
Characteristic	No. of biweekly study visits completed by household members with exposure	MDRSA $N = 63$		scn-negative S. aureus $N = 46$		Tetracycline-resistant S. aureus $N = 34$		Putative S. aureus CC398 or CC9 $N = 26$
Exposure of IHO worker(s) living in the household^a	$N = 655$	$n$ (%)	OR (95% CI)	$n$ (%)	OR (95% CI)	$n$ (%)	OR (95% CI)	$n$ (%)	OR (95% CI)
Average no. of pigs in contact with^b
$< 4,000$	398	29 (7)	Reference	6 (2)	Reference	6 (2)	Reference	4 (1)	Reference
$\geq 4,000$	257	34 (13)	2.16 (0.70, 6.70)	40 (16)	13.09 (4.03, 42.56)	28 (11)	7.92 (2.20, 28.52)	22 (9)	9.0 (1.62, 50.36)
Average no. of sows/farrow/wean/nursery pigs in contact with^b
$< 2,000$	312	18 (6)	Reference	13 (4)	Reference	3 (1)	Reference	2 (1)	Reference
$\geq 2,000$	343	45 (13)	3.03 (0.90, 10.18)	33 (10)	2.50 (0.58, 10.70)	31 (9)	10.39 (2.12, 51.05)	24 (7)	11.75 (1.31, 105.71)
Contact with feeder/finish pigs
Never	481	31 (6)	Reference	27 (6)	Reference	25 (5)	Reference	18 (4)	Reference
Ever	174	32 (18)	4.39 (1.37, 14.09)	19 (11)	2.80 (0.67, 11.74)	9 (5)	1.41 (0.26, 7.56)	8 (5)	1.79 (0.27, 11.87)
Handled sick pigs
Sometimes or never	508	59 (12)	Reference	45 (9)	Reference	33 (7)	Reference	24 (5)	Reference
Consistently	147	4 (3)	0.19 (0.07, 0.52)	1 (1)	0.07 (0.01, 0.50)	1 (1)	0.10 (0.01, 0.75)	2 (1)	0.30 (0.06, 1.39)
Handled dead pigs
Sometimes or never	391	41 (10)	Reference	30 (8)	Reference	18 (5)	Reference	10 (3)	Reference
Consistently	264	22 (8)	0.64 (0.18, 2.31)	16 (6)	0.69 (0.15, 3.25)	16 (6)	1.29 (0.30, 5.58)	16 (6)	2.52 (0.48, 13.08)
Pressure washed barns
Never	142	31 (22)	Reference	14 (10)	Reference	5 (4)	Reference	3 (2)	Reference
Ever	513	32 (6)	0.20 (0.06, 0.61)	32 (6)	0.50 (0.12, 2.11)	29 (6)	1.23 (0.37, 4.04)	23 (4)	1.57 (0.38, 6.52)
Used pesticides
Never	123	22 (18)	Reference	21 (17)	Reference	11 (9)	Reference	8 (7)	Reference
Ever	523	41 (8)	0.34 (0.10, 1.19)	25 (5)	0.16 (0.05, 0.56)	23 (4)	0.25 (0.06, 1.06)	18 (3)	0.25 (0.03, 1.73)
Gave pigs shots
Never	79	10 (13)	Reference	6 (8)	Reference	6 (8)	Reference	6 (8)	Reference
Ever	576	53 (9)	0.42 (0.07, 2.44)	40 (7)	0.54 (0.06, 5.28)	28 (5)	0.30 (0.03, 2.70)	20 (3)	0.19 (0.02, 1.70)
Frequency of coveralls use
Sometimes or never	203	36 (18)	Reference	25 (12)	Reference	23 (11)	Reference	16 (8)	Reference
Consistently	452	27 (6)	0.27 (0.09, 0.85)	21 (5)	0.38 (0.11, 1.23)	11 (2)	0.24 (0.06, 1.05)	10 (2)	0.34 (0.06, 1.92)
Frequency of face mask use
Sometimes or never	365	43 (12)	Reference	42 (12)	Reference	31 (8)	Reference	23 (6)	Reference
Consistently	290	20 (7)	0.67 (0.19, 2.44)	4 (1)	0.12 (0.04, 0.40)	3 (1)	0.14 (0.04, 0.53)	3 (1)	0.20 (0.05, 0.81)
Frequency of glasses/goggles use
Sometimes or never	576	59 (10)	Reference	46 (8)	Reference	34 (6)	Reference	26 (6)	Reference
Consistently	79	4 (5)	0.78 (0.10, 6.28)	0	^c	0	^c	0 (1)	^c
Average no. of hours worked per week at IHO^b
$< 40$	130	16 (12)	Reference	2 (2)	Reference	2 (2)	Reference	0	Reference
$\geq 40$	525	47 (9)	0.68 (0.17, 2.76)	44 (8)	5.48 (1.30, 23.03)	32 (6)	3.18 (0.75, 13.57)	26 (5)	^c

Note: OR effect measures were estimated using logistic regression models with a generalized estimating equation and an exchangeable correlation matrix to account for the non-independence of observations within the same household. ORs were adjusted for the age and sex of household members. CI, confidence interval; IHO, industrial hog operation; MDRSA, multidrug-resistant S. Aureus; OR, odds ratio.

^{^a}

IHO workers living in the household reported their occupational activities during the week prior at up to eight biweekly study visits. For dichotomous exposures expressed as “Sometimes or never” or “Consistently” (e.g., handled dead pigs), “Sometimes or never” refers to activities that an IHO worker reported at $\geq 0$ but $< 80 %$ of completed biweekly visits, and “Consistently” refers to activities reported at $\geq 80 %$ of completed biweekly visits. For continuous exposures expressed as “Sometimes or never” or “Consistently” (e.g., percent time used face mask), “Sometimes or never” refers to activities a worker reported doing $\geq 0$ but $< 80 %$ of the time, on average, across all completed biweekly visits, and “Consistently” refers to activities a worker reported doing $\geq 80 %$ of the time, on average, across all completed biweekly visits.

^{^b}

Cutoff is the median value of the average numbers reported by workers over the 4-month period, rounded to one significant digit.

^{^c}

OR could not be computed because at least one cell had a frequency of 0.