MRSA found in Iowa meat

I’ve blogged previously on a few U.S. studies which investigated methicillin-resistant Staphylococcus aureus in raw meat products (including chicken, beef, turkey, and pork). This isn’t just a casual observation as one who eats food–I follow this area closely as we also have done our own pair of food sampling investigations here in Iowa, and will be doing a much larger, USDA-funded investigation of the issue over the next 5 years.

Let me sum up where the field currently stands. There have been a number of studies looking at S. aureus on raw meat products, carried out both here in North American and in Europe. In a study from the Netherlands, a large percentage of samples were found to harbor MRSA (11.9% overall, but it varied by meat type–35.3% of turkey samples were positive, for example). Most of there were a type called ST398, the “livestock” strain. This was also found in one Canadian study (5.5% MRSA prevalence, and 32% of those were ST398), but no ST398 were found in a second study by the same group.

Here in the US, prevalence has found to be lower than in that Dutch study (from no MRSA found, up to 5% of samples positive). Furthermore, in the previously-published studies, no MRSA ST398 was found in samples of US meat, though this paper did find plenty of methicillin-sensitive S. aureus (MSSA) ST398 strains. Instead, most of the MRSA isolates have been seemingly “human” MRSA types, like USA100 (a common hospital-associated strain) and USA300 (a leading community-acquired strain).

Why am I rehashing all of this? We have a new paper out examining S. aureus in Iowa meats–and did find for the first time MRSA ST398, as well as MRSA USA300 and MSSA strains including both presumptive “human” and “animal” types. This was just a pilot study and numbers are still fairly small, but enough to say that yes, this is here in the heart of flyover country as well as in the other areas already examined.

As I mentioned, this is one of two studies we’ve completed examining MRSA on meat; the other is still under review and much more controversial, but I will share that as soon as I’m able. And with the USDA grant, we’ll be working on better understanding the role that contaminated meats play in the epidemiology and transmission of S. aureus for the next several years, so expect to see more posts on this topic…

References

Hanson et al. Prevalence of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) on retail meat in Iowa. J Infect Public Health. 2011 Sep;4(4):169-74. Link.

Waters et al. Multidrug-Resistant Staphylococcus aureus in US Meat and Poultry . Clin Infect Dis. 2011 May;52(10):1227-30. Link.

Weese et al. Methicillin-resistant Staphylococcus aureus (MRSA) contamination of retail pork. Can Vet J. 2010 July; 51(7): 749-752. Link.

De Boer et al. Prevalence of methicillin-resistant Staphylococcus aureus in meat. Int J Food Microbiol. 2009 Aug 31;134(1-2):52-6. Link.

Pu et al. Isolation and characterization of methicillin-resistant Staphylococcus aureus strains from Louisiana retail meats. Appl Environ Microbiol. 2009 Jan;75(1):265-7. Link.

Bhargava et al. Methicillin-resistant Staphylococcus aureus in retail meat, Detroit, Michigan, USA. Emerg Infect Dis. 2011 Jun;17(6):1135-7. Link.

Comments

  1. #1 Ken
    November 9, 2011

    Dr. Smith,

    Thanks for the great blog.

    Do you plan to look at MRSA infections among people who handle meat as part of their job (who either acquired MRSA from the meat and/or who have transmitted MRSA to the meat)?

    Ken

  2. #2 Matt
    November 9, 2011

    Very good post I very much enjoyed reading it, keep at it as I hope to read more.

  3. #3 Justicar
    November 9, 2011

    That does it. I’m having tofurkey surprise for dinner tonight.

  4. #4 Tara C. Smith
    November 9, 2011

    Ken, no plans to look at that currently, but perhaps toward the end of the grant. I’m more interested in consumers right now. Plus, there are pros and cons of looking at those who work in meat handling. Pros–obviously lots of meat contact, BUT con–in theory are also trained to handle properly, use gloves and handwashing, etc. There was one previous study (here) that looked at that population for colonization, and found a low level.

  5. #5 Luke Thomas
    November 13, 2011

    MRSA enters the tiniest micro crack in the skin, people touch their noses after handling meat. Cutting up and preparing raw meat is no different than putting your hands on MRSA wounds of infected humans. Expect the USDA to cover up these facts because the meat industry is a multi-billion dollar business and for every single representative in Congress Senate and House the meat industry hires 100 lobbyists so to pay these law makers, so the meat industry can do whatever they like without any regard to the consequences of human safety. We are NOW entering into a new age where antibiotics are becoming ineffective. Antibiotic abuse on farm factories is the cause of that since most people do handle raw meat.

  6. #6 Luke Thomas
    November 13, 2011

    CBS news reported about half the meat sold in America is infected with superbugs like MRSA

    http://www.cbsnews.com/stories/2011/04/15/health/main20054211.shtml

  7. #7 Tara C. Smith
    November 13, 2011

    Luke, the USDA has no ability to review/censor what our findings are, and they were very interested in our proposed research. You might be surprised at what goes on behind the scenes. We’ve even had funding from the National Pork Board to do some of these studies.

    And the CBS story refers to the Waters paper which I cited above.

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