Research Article
Livestock-Associated Methicillin and Multidrug Resistant Staphylococcus
aureus Is Present among Industrial, Not Antibiotic-Free Livestock Operation
Workers in North Carolina
Jessica L. Rinsky equal contributor, equal contributor Contributed equally
to this work with: Jessica L. Rinsky, Maya Nadimpalli
Affiliation: Department of Epidemiology, University of North Carolina,
Chapel Hill, North Carolina, United States of America
X Maya Nadimpalli equal contributor, equal contributor Contributed equally
to this work with: Jessica L. Rinsky, Maya Nadimpalli
Affiliation: Department of Environmental Sciences and Engineering,
University of North Carolina, Chapel Hill, North Carolina, United States of
America
X Steve Wing, Affiliation: Department of Epidemiology, University of North
Carolina, Chapel Hill, North Carolina, United States of America
X Devon Hall, Affiliation: Rural Empowerment Association for Community Help
(REACH), Warsaw, North Carolina, United States of America
X Dothula Baron, Affiliation: Rural Empowerment Association for Community
Help (REACH), Warsaw, North Carolina, United States of America
X Lance B. Price, Affiliation: Department of Environmental and Occupational
Health, George Washington University, Washington, District of Columbia, United
States of America
X Jesper Larsen, Affiliation: Microbiology and Infection Control, Statens
Serum Institut, Copenhagen, Denmark
X Marc Stegger, Affiliation: Microbiology and Infection Control, Statens
Serum Institut, Copenhagen, Denmark
X Jill Stewart, Affiliation: Department of Environmental Sciences and
Engineering, University of North Carolina, Chapel Hill, North Carolina, United
States of America
Affiliations: Department of Environmental Health Sciences, Bloomberg School
of Public Health, Johns Hopkins University, Baltimore, Maryland, United States
of America, Department of Epidemiology, Bloomberg School of Public Health, Johns
Hopkins University, Baltimore, Maryland, United States of America
Abstract
Objectives Administration of antibiotics to food animals may select for
drug-resistant pathogens of clinical significance, such as methicillin-resistant
Staphylococcus aureus (MRSA). In the United States, studies have examined
prevalence of MRSA carriage among individuals exposed to livestock, but
prevalence of multidrug-resistant S. aureus (MDRSA) carriage and the association
with livestock raised with versus without antibiotic selective pressure remains
unclear. We aimed to examine prevalence, antibiotic susceptibility, and
molecular characteristics of S. aureus among industrial livestock operation
(ILO) and antibiotic-free livestock operation (AFLO) workers and household
members in North Carolina.
Methods Participants in this cross-sectional study were interviewed and
provided a nasal swab for S. aureus analysis. Resulting S. aureus isolates were
assessed for antibiotic susceptibility, multi-locus sequence type, and absence
of the scn gene (a marker of livestock association).
Results Among 99 ILO and 105 AFLO participants, S. aureus nasal carriage
prevalence was 41% and 40%, respectively. Among ILO and AFLO S. aureus carriers,
MRSA was detected in 7% (3/41) and 7% (3/42), respectively. Thirty seven percent
of 41 ILO versus 19% of 42 AFLO S. aureus-positive participants carried MDRSA.
S. aureus clonal complex (CC) 398 was observed only among workers and
predominated among ILO (13/34) compared with AFLO (1/35) S. aureus-positive
workers. Only ILO workers carried scn-negative MRSA CC398 (2/34) and
scn-negative MDRSA CC398 (6/34), and all of these isolates were tetracycline
resistant.
Conclusions Despite similar S. aureus and MRSA prevalence among ILO and
AFLO-exposed individuals, livestock-associated MRSA and MDRSA
(tetracycline-resistant, CC398, scn-negative) were only present among
ILO-exposed individuals. These findings support growing concern about
antibiotics use and confinement in livestock production, raising questions about
the potential for occupational exposure to an opportunistic and drug-resistant
pathogen, which in other settings including hospitals and the community is of
broad public health importance.
snip...
The results reported here show that the proportion of S. aureus identified
as MDRSA and the proportion exhibiting phenotypic and molecular markers of
livestock association was elevated among individuals exposed to the ILO
environment compared to those exposed to the AFLO environment. Carriage of
scn-negative MRSA CC398 and scn-negative MDRSA CC398 was limited to individuals
with direct exposure to ILO production – all of these isolates were also
resistant to tetracycline. Whether or not these livestock-associated S. aureus
strains (including MRSA and MDRSA) pose a health risk to workers and the broader
public requires further investigation. Overall, our findings support growing
concern about antibiotic use and confinement in livestock production, and raise
questions about the potential for occupational exposure to an opportunistic and
drug-resistant pathogen which in other settings including hospitals and the
community is a major cause of morbidity and mortality in the United States [4],
[61] and globally [6], [7].
Citation: Rinsky JL, Nadimpalli M, Wing S, Hall D, Baron D, et al. (2013)
Livestock-Associated Methicillin and Multidrug Resistant Staphylococcus aureus
Is Present among Industrial, Not Antibiotic-Free Livestock Operation Workers in
North Carolina. PLoS ONE 8(7): e67641. doi:10.1371/journal.pone.0067641
Editor: Axel Cloeckaert, Institut National de la Recherche Agronomique,
France
Received: February 19, 2013; Accepted: May 20, 2013; Published: July 2,
2013
Copyright: © 2013 Rinsky et al. This is an open-access article distributed
under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited.
Funding: Funding for this study was provided by the North Carolina
Translational and Clinical Sciences Institute, North Carolina Occupational
Safety and Health Education and Research Center, the W.K. Kellogg Health
Scholars Program – Community Track, and a Gillings Innovation Laboratory award
from the UNC Gillings School of Global Public Health. CDH was supported by the
W.K. Kellogg Health Scholars Program – Community Track, JLR by the National
Institute of Environmental Health Sciences (NIEHS; award no. T32ES007018), and
MN by a Royster Society fellowship and an EPA Science to Achieve Results
fellowship. The funders had no role in study design, data collection and
analysis, decision to publish, or preparation of the manuscript.
Competing interests: SW provided pro bono testimony in legal proceedings
related to landfills and provided pro bono consultation on radiation and health
for two law firms that made gifts to the University of North Carolina and
another law firm that did not make a gift to the University of North Carolina.
He conducted research on epidemiologic investigation of symptoms reported by
neighbors of areas where sewage sludge is applied to land funded by the Water
Environment Research Foundation. This does not alter the authors' adherence to
all the PLOS ONE policies on sharing data and materials.
Wednesday, January 2, 2013
New MRSA ST398 superbug strain found in UK milk Occupational risk factor
Rapid communications
Thursday, March 1, 2012
Staphylococcus aureus CC398: Host Adaptation and Emergence of Methicillin
Resistance in Livestock
Thursday, February 9, 2012
Occurrence and distribution of Staphylococcus aureuslineages among zoo
animals
Tuesday, January 17, 2012
In-feed antibiotic effects on the swine intestinal microbiome
Thursday, June 9, 2011
New Superbug Found in Cows and People
Wednesday, May 11, 2011
Methicillin-resistant Staphylococcus aureus in Retail Meat, Detroit,
Michigan, USA
Monday, April 18, 2011
Multidrug-Resistant Staphylococcus aureus in US Meat and Poultry
that MRSA is some nasty stuff. damn near killed me in 2001 after one of my
neck surgeries. 8 weeks vancomycin via long PIC line. ...
TSS
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