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Swine Farming and MRSA
Tara C. Smith, PhD
University of Iowa
Center for Emerging Infectious Diseases
Tara Smith

Associate Professor of Epidemiology, University of
Iowa School of Public Health

Co-director, Center for Emerging Infectious
Diseases

Bachelor’s in biology, Yale University

PhD in microbial pathogenesis, University of Toledo

Post-doctoral training in molecular epidemiology, University
of Michigan

Current research investigates the epidemiology of antibioticresistant Staphylococcus aureus in rural and farming exposures

Has written books on Ebola, Group A streptococcus, and Group B
streptococcus
3
Tara Smith

We’ll be discussing some work we’ve done looking
at swine farming and methicillin-resistant
Staphylococcus aureus

Iowa is the No. 1 pig-producing state (there are
about six-times more pigs than humans in Iowa)

We’ll look at swine farming as a potential reservoir
of MRSA bacteria in the state
4
Section A
Introduction to MRSA
Introduction to MRSA

Methicillin-resistant
Staphylococcus aureus (MRSA)

Gram-positive bacterium

Leading cause of hospitalassociated infections
Source: CDC
6
Introduction to MRSA

Approximately 30 percent of the population carries a strain of S.
aureus

About 1.5 percent are colonized with MRSA

There were 18,000 deaths and 94,000 invasive infections from MRSA
in 2005
Sources: Graham, P. L. 3rd, Lin, S. X., & Larson, E. L. (2006). Ann Intern Med, 144, 5, 318–325;
Kuehnert, M. J., Kruszon-Moran, D., Hill, H. A., et al. (2006). J Infect Dis, 193, 2, 172–179; Gorwitz, R.
J., Kruszon-Moran, D., McAllister, S. K., et al. (2008). J Infect Dis, 197, 9, 1226–1234.
7
Introduction to MRSA

Not only a hospital problem anymore

Now throughout community
-  Schools
-  Prisons
-
General population
8
Introduction to MRSA
Source: Kazakova, Hageman, Matava, et al. (2005). N Engl J Med, 352, 5, 468–475.
9
Introduction to MRSA
Source: CNN. Retrieved from http://www.cnn.com/2007/HEALTH/10/26/bacteria.staph/index.html
10
Introduction to MRSA
Source: Sing, A., Tuschak, C., Hörmansdorfer, S. (2008). N Engl J Med, 358, 11, 1200–1201.
Photo: PublicPhoto.org. Public Domain.
11
Introduction to MRSA
Photos are US Government Public Domain
12
MRSA and Swine

First identified in the Netherlands,
2005

Girl of 6 months found to have MRSA
upon hospital admission

Family lived on pig farm

Parents also colonized
Source: Armand-Lefevre, L., Ruimy, R., and Andremont, A. (2005). Emerg Infect Dis, 11, 5, 711–714.
13
MRSA and Swine

Twenty-six pig farmers swabbed; six
(23%) tested positive for MRSA
-
A rate 760-times higher than in
the general population

Pigs cultured

Same strain in pig and family
(“ST398” or “non-typeable” MRSA)
14
MRSA and Swine

Swine-associated MRSA also found in
Denmark, Germany, Austria, France,
Canada, Spain, Italy, Belgium,
Sweden, Dominican Republic, China,
Malaysia, UK, Switzerland, Portugal,
Finland
15