Face Mask Use and Persistence of Livestock-associated Staphylococcus aureus Nasal Carriage among Industrial Hog Operation Workers and Household Contacts, USA

BACKGROUND: Industrial hog operation (IHO) workers may persistently carry antibiotic-resistant, livestock-associated <em>Staphylococcus aureus</em> in their nasal cavities. It is unclear whether IHO work activities can alter IHO workers' and their household members' exposure to these bacteria. OBJECTIVE: Our objective was to investigate the relationship of IHO work activities with persistence of antibiotic-resistant, livestock-associated S. aureus nasal carriage among IHO workers and their household members. METHODS: At biweekly intervals over 4 months, IHO workers and their household members completed questionnaires and provided nasal swabs that were assessed for <em>S. aureus</em>, multidrug-resistant <em>S. aureus</em> (MDRSA), and livestock-associated markers (tetracycline resistance, <em>scn</em> absence, <em>spa</em> type). We examined the association between transient and habitual IHO work activities and <em>S. aureus</em> nasal carriage outcomes. RESULTS: One hundred one IHO workers and 79 household members completed 1,456 study visits. Face mask use (each 25% increase) was associated with reduced odds of nasal carriage of MDRSA (odds ratio [OR]: 0.65 [95% confidence interval (CI): 0.46, 0.92], tetracycline-resistant <em>S. aureus</em> [OR = 0.74 (95% CI: 0.56, 0.97)], and <em>S. aureus</em> clonal complex (CC) 398/CC9 [OR = 0.77 (95% CI: 0.60, 0.99)]. IHO workers who ever (vs. never) gave pigs injections had higher odds of these outcomes. Among household members, living with an IHO worker who consistently ([Formula: see text] of the time) versus sometimes or never used a face mask was associated with reduced odds of carrying <em>scn</em>-negative <em>S. aureus</em>, tetracycline-resistant <em>S. aureus</em>, and <em>S. aureus</em> CC398/CC9 (OR range: 0.12-0.20, all [Formula: see text]), and consistent IHO worker coveralls use was associated with reduced odds of household member MDRSA carriage only. Living with an IHO worker who habitually had contact with [Formula: see text] hogs (vs. [Formula: see text]) was associated with higher odds of household member livestock-associated <em>S. aureus</em> carriage. CONCLUSIONS: Consistent face mask use was associated with reduced exposure to antibiotic-resistant, livestock-associated <em>S. aureus</em> among IHO workers and their household members. https://doi.org/10.1289/EHP3453.