MRSA: Jumping from Pigs to Humans?

I think I was a little too optimistic about MRSA (methicillin resistant Staphylococcus aureus) in pigs staying in pigs and not spreading to humans. A recent study in the Netherlands found that people exposed to pigs were 1000 times (yes, one thousand) more likely to be MRSA carriers than the general population, and the MRSA strain was usually the ‘pig’ strain.

What does this mean? The authors conclude:

After introduction of the new MRSA risk category in a hospital [Mad Biologist: screening those in contact with farm animals], which is located in a region with a relatively high density of pig farms, the number of MRSA carriers immediately increased >300%. This challenges the Search and Destroy strategy. Part of this strategy is the screening of patients at risk of MRSA and isolating them until they are proven to be free of MRSA. If MRSA is present, isolation is continued until hospital discharge. The unexpected and sudden increase of the MRSA incidence in our hospital resulted in a shortage of isolation facilities. An additional problem is the treatment of carriers, which is also part of the Search and Destroy strategy. Pig and cattle farmers colonized with MRSA return to the source of MRSA after hospital discharge; this raises questions about treatment of carriers. Our findings indicate that, currently, this strain does not spread easily among humans, but more research on this aspect is needed. Although the increase in absolute numbers of MRSA carriers is obvious, the true impact for hospitals will depend on the virulence and transmissibility of this new clone.

This is not good.
Cited article: van Rijen MM, Van Keulen PH, Kluytmans JA. 2008. Increase in a Dutch hospital of methicillin-resistant Staphylococcus aureus related to animal farming. Clin Infect Dis. 2008 Jan 15;46(2):261-3.

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9 Responses to MRSA: Jumping from Pigs to Humans?

  1. Ken Shabby says:

    My money says these pigs have been eating feed laced with antibiotics since they began weaning. Other countries have abolished this practice, but I fear the US will never give it up, despite public opinion shifts. Big ag has a huge powerful lobby that dictates US domestic and foreign policy, while there is no such thing as a lobby for the public at large. (Congress was supposed to, sure, but that hasn’t been true for the last century.)

  2. I think you’ve missed a tag in your post.

  3. Pat Gardiner says:

    You have it right. Pigs are a major source of human MRSA.
    The current problem probably started in England in 1999. There was a mutation in a disease called PMWS and a very nasty epidemic which was hushed up. The pigs were fed massive quantities of antibiotic to get them to the slaughterhouse.
    The pigs are still sick, but in the meantime English pigs have been recklessly exported as breeding stock all over the world.
    You also have PMWS but “for PR reasons” somebody thoughtfully renamed it PCVAD and other varients. It is a Circovirus and very nasty. The major outbreaks of MRSA appear at the same places as large pig farms eg Ontario and Quebec, with PMWS.
    Regards Pat Gardiner

  4. Pat,
    The first recorded observations of this MRSA strain were in the Netherlands in 2003 (actually 2005, but the strains were isolated in 2003). I haven’t heard of any reports from England, particularly from before 2000. You might be right about other agricultural associated MRSA strains, though.

  5. Pat Gardiner says:

    You are correct. The Dutch were fast on the ball. Despite the Dutch making their findings available, both Britain and the US refuse to test pigs for MRSA. Seven other major countries, including Canada, do and have found MRSA.
    Why refuse? Because they know they have it.
    Britain can’t because it would open up a can of worms going back to 1999 and the infamous CSF and FMD epidemics.
    I’m not sure why the US is so relucatant to test.
    The areas where there have been serious outbreaks of PMWS (under other names too) also have serious human MRSA outbreaks.
    The current MRSA wave of epidemics started here in Norfolk England with a mutation back in 1999 and Britain tried to hush it up, feeding antibiotics to try to control the situation. They continued to export breeding stock and spread the disease.
    This gives a reasonably reliable history of PMWS in England
    This gives the British government position on testing pigs
    You will realise that this is in officialspek ;o)
    Regards Pat
    PS You have stumbled onto a biggy. I have 7000 documents, gave evidence to the House of Commons and OLAF the serious fraud squad of the EU. I’m not very popular.

  6. Pat,
    The U.S. doesn’t test because the National Antimicrobial Resistance Monitoring System doesn’t have the funds to do so. Some new legislation might fix that problem however….

  7. Pat Gardiner says:

    not before Rolex fix their watches, I suspect ;o)
    Have you ever noticed how the small things in the world attract all the passion?
    You could circumnavigate the world with bodies from MRSA and just get told to wash your hands.
    Oh dear.
    Regards Pat

  8. Hank Roberts says:

    Pat Gardiner, have you got a list of your 7000 references (the cites, not full text) collected, in one place?
    I’m just curious, not a farmer, but well aware that producing antibiotics in bulk for ag use is likely one of the stupidest things done yet.
    My guess is that most of the people in the business don’t believe in evolution, so can’t believe they could be doing anything wrong because they lack the mechanism to understand the problem.

  9. pat gardiner says:

    Hi Hank
    Sure, glad to help. First, I guess go to the above site and have a read of 16 very short chapters telling to the story of what happened in England back in 2000. It is an easy read. You will find it under “Stop the World.”
    The British government don’t like it too much. You will notice that straight away. I was talking about Britain, Ireland, Canada and the US. All counties I know and like.
    Way back in 2001 I went to a newsgroup to seek help.
    It is not a nice place, then or now, but in arguing the toss, I went all over the WWW collecting stuff and posting it up – suddenly I noticed some were being deliberately removed and my records was the only trace.
    I had created an off shore archive of stuff you were not supposed to see. All by accident.
    Long ago, I notice that piggy MRSA and other superbugs hitting humans followed outbreaks of PMWS (circovirus) hitting pigs IN THE SAME AREA after a time lag. That’s your source – a mutation in PMWS in England in 1999 treated by massive does of antibiotic – and covered up.
    The story is starting to break now.
    So use Google Groups to search “” Try “piggy MRSA” even today.
    Pat Gardiner

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