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1744
Staphylococcus aureus CC398 and pig-specific fecal Bacteroidales qPCR concentrations decline with increasing time away from work among industrial hog operation workers

Session: Poster Abstract Session: Public Health
Saturday, October 11, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
Background: In the US, knowledge of industrial hog operations (IHOs) as a reservoir of occupational and community exposure to Staphylococcus aureus, including drug-resistant and livestock-associated strains, is emerging. But the dynamics and sources of S. aureus exposure remain poorly characterized in part because of a lack of quantitative measures of exposure specificity and limited access to IHOs to sample during work. The present study, conducted among IHO workers at non-work locations, aimed to determine the utility of quantitative polymerase chain reaction (qPCR) measures of microbes with livestock and/or swine specificity in nasal swabs as markers of recent IHO work exposure to S. aureus. We also examined associations of qPCR estimates with time since last work shift stratified by the antibiogram and livestock-association of culture-based S. aureus isolates. 

Methods: 22 IHO workers collected 316 nasal swabs before and after an IHO work shift over 7 d and again 14 d after enrollment and recorded time since last IHO shift. Swabs were cultured for S. aureus presence and assessed for multidrug-resistance (MDR = resistant >2 antimicrobial drug classes), tetracycline-resistance, clonal complex (CC), and absence of the scn gene (marker of livestock association). femA, mecA, S. aureus CC398, and pig-specific fecal Bacteroidales (Pig-2-Bac) DNA per nasal swab were estimated by qPCR. 

Results: femA and mecA qPCR estimates remained stable in nose swabs with increasing time since last IHO work shift, whereas S. aureus CC398 and Pig-2-Bac qPCR estimates declined significantly. Declines of S. aureus CC398 and Pig-2-Bac qPCR estimates were strongest among persistent carriers of S. aureus as well as during periods of tetracycline-resistant, MDR, CC398, and scn-negative S. aureus nasal carriage. 

Conclusion: S. aureus CC398 and Pig-2-Bac qPCR declined with increasing time since last IHO shift, particularly among persistent S. aureus nasal carriers and during periods of drug-resistant, livestock-associated S. aureus nasal carriage. qPCR estimates of S. aureus CC398 and Pig-2-Bac appear to improve knowledge of IHO work as a source of drug-resistant, livestock-associated S. aureus exposure among IHO workers and warrant further consideration in studies of S. aureus transmission dynamics between IHO workers and household and community contacts.

Christopher Heaney, MS, PhD1, Nora Pisanic, PhD2, Maya Nadimpalli, MS3, Jessica Rinsky4, David Love, PhD5, Keeve Nachman, PhD5, Trish M. Perl, MD, MSc, FIDSA, FSHEA6, Steve Wing, PhD4 and Jill Stewart, PhD3, (1)Epidemiology and Environmental Health Sciences, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, (2)Epidemiology and Environmental Sciences, Johns Hopkins University School of Public Health, Baltimore, MD, (3)Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, (4)Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, (5)Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, (6)Medicine, Johns Hopkins Medical Institutions, Baltimore, MD

Disclosures:

C. Heaney, None

N. Pisanic, None

M. Nadimpalli, None

J. Rinsky, None

D. Love, None

K. Nachman, None

T. M. Perl, None

S. Wing, None

J. Stewart, None

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