Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in organic and confinement swine...

Abby L. Harper, MPHUniversity of Iowa

Center for Emerging Infectious Diseases

10-09-2009

Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in organic and confinement swine

operations in Iowa and Illinois

Introduction to MRSA

Methicillin-resistant Staphylococcus aureus (MRSA)

Gram positive bacterium

Leading cause of hospital-associated infections

Image: http://trouble.philadelphiaweekly.com/archives/MRSA220207_400x379%5B1%5D.jpg

Introduction to MRSA

Not only a hospital problem anymore

Reference: NEJM 2005;352:468-75NEJM 2008;358:11.

Images: : http://www.foodpoisonblog.com/dog_cat.jpg http://agebb.missouri.edu/commag/swine/pigs.jpghttp://www.smh.com.au/ffximage/2006/07/26/cattle26706_wideweb__470x313,0.jpg

MRSA and Swine

First identified in the Netherlands, 2005

Pig farmers: higher rate of colonization with methicillin-susceptible S. aureus (MSSA) and MRSA

Reference: EID 2005;11:1965-66

MRSA and Swine

Swine-associated MRSA also found in Denmark, Germany, Austria, France, Canada

USA?

Swine MRSA in the USA?

Iowa: #1 pork producing state in the USA

16 million hogs

= 25% of hogs raised in the U.S.

= $4 billion/year

Image: http://en.wikipedia.org/wiki/Iowa

MULTI-STATE STUDY

Images: http://en.wikipedia.org/wiki/Iowahttp://en.wikipedia.org/wiki/Minnesotahttp://en.wikicpedia.org/wiki/Ohiohttp://wonkette.com/340314/ongoing-wonkette-iowa-caucus-coverage/

Multi-state study 18 farms per investigator

24 animals tested per farm

Nasal + pharyngeal sampling, humans

17 farms tested

Summary – Results in Swine

No MRSA found to date on organic farms in Iowa

Overall prevalence, swine: 45/408 (11%) Confinement swine: 45/192 (24%)

Humans: 27/86 (31.4%)

Humans working in confinement: 27/61 (44.3%)

Confirmed as ST398; first identification in US

Summary – Results in Humans

Individuals exposed to swine, especially in confinement

operations, are at risk for MRSA carriage

Images: http://brhssupplies.com/db1/00097/brhssupplies.com/_uimages/P1011023.JPGhttp://cache.daylife.com/imageserve/05C1f8NfK3eZ5/610x.jpg

Confinements as amplifiers and reservoirs

1000s of animals in small space

Ventilation systems

Low-tech environmental sampling

All but 1 grew MRSA Map created by: Abby L. HarperSources: Abby HarperIowa Geologic Survey – DNR

Follow-up Environmental Sampling PhD student in

Industrial Hygiene

Anderson impact sampler

CFUs / volume of air

May indicate MRSA particle size

Source: http://www.teagasc.ie/research/reports/dairyproduction/3989/eopr-3989.asphttp://www.pacwill.ca/en/ProductsServices/6stage.htm

Summary MRSA is present in

U.S. swine and swine workers in confinement facilities

Potential to spread to larger community

Reservoir of resistance

Image: http://cuteoverload.com/2009/04/27/pucker-up-behbeh/

Future directions

More general study of MRSA in rural Iowa

Population prevalence & strain types

Animals other than swine

Role of antibiotics?

Co-authors and team membersTara Smith (PI)

Mike Male, Anne Dressler,Blake Hanson, Shylo Wardyn (MS students)

Jennifer Kroeger (PhD student)Phil Scheibel (undergraduate)

Loreen Herwaldt MD, Dan Diekema MD (UIHC)

http://www.public-health.uiowa.edu/CEID/abby-harper@uiowa.edu