MRSA and Other Drug-Resistant Bacteria in Wildlife a Threat to People?


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Other Documented Drug Resistance in Wildlife

Two eastern cottontail rabbits tested positive for MRSA at an Iowa wildlife hospital.
Photo credit: Robert Nunnally

As Dr. Smith suggested, MRSA is not the only concern for those monitoring antibiotic resistance in wildlife.

Antibiotic resistant Escherichia coli has been found in migratory birds in the Arctic and in northern elephant seal pups in California.

Multiple drug resistances were found in a variety of bacteria cultured from predatory marine fish sampled in Belize and along the East Coast of the US.

In the case of the elephant seals, exposure to freshwater outflows, which may bring terrestrial pathogenic bacteria to the ocean, is thought to be one source.

The birds in the Arctic may have been exposed somewhere else in the world, bringing the resistant bacteria to an area once considered pristine wilderness.

Sharks and other predatory fish, like migratory birds, often range over large areas, making it difficult to determine where the resistant bacteria may have originated.

There is also the possibility, as noted by the researchers in the Arctic, that some antibiotic resistance is natural resistance based on exposure to other substances in the environment which are similar to antibiotics.

Collaborative Effort Needed to Understand the Spread of Resistant Bacteria

MRSA was found in one lesser yellowlegs, a migratory shorebird admitted to an Iowa wildlife hospital. Photo credit: Ómar Runólfsson

There is still much more that needs to be done to better understand the role of wildlife in the spread of antibiotic resistant bacteria.  Additional areas of research might include surveying a wider range of wildlife hospitals, opportunistically obtaining cultures from animals in the wild being handled for other research purposes and surveying the staff at wildlife hospitals for the presence of MRSA.

Studying MRSA in Animals

An epidemiologist, Dr. Smith would ideally develop a comprehensive program to monitor the types of MRSA present in soil, water, people and animals in one place to understand which are shared and potentially get a better picture of the MRSAs’ sources of origin. As is often the case, limited funding restricts what she and her colleagues are able to accomplish right now.


Wardyn, S.E., Kauffman, L.K., and Smith, T.C. Methicillin-resistant Staphyloccocus aureus in Central Iowa Wildlife. (2012). Journal of Wildlife Diseases. 49 (4), 1069-1073. Accessed October 31, 2012.

Blackburn, J., Mitchell, M., Blackburn, M., Curtis, A., & Thompson, B. Evidence of Antibiotic Resistance in Free-Swimming, Top-Level Marine Predatory Fishes. (2010). Journal of Zoo and Wildlife Medicine. 41 (1), 7-16 DOI: 10.1638/2007-0061.1 Accessed online October 31, 2012.

Faires MC, Gehring E, Mergl J, Weese JS. Methicillin-resistant Staphylococcus aureus in marine mammals. (2009).Emerging Infectious Diseases. . Accessed online October 31, 2012.

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