Bacterial Beasts in the Making

Since there has been a lot of talk recently about limiting the use of antibiotics in animal production, I thought I would focus on the interesting and controversial subject of MRSA.  It's funny because I just realized I wrote about this subject about one year ago, but this time I did a little more digging.

Honestly, the image above was about the least stomach curdling I could find on Google images. Go ahead, type in "MRSA" and see all the beauties that pop up.  MRSA is a horrendous infection that I hope none of you kind readers ever have to experience.  It kills over 18,000 Americans a year, a rate higher than AIDS.

MRSA stands for methicillin resistant Staphylococcus aureaus.  Staphylococcus usually starts as a skin infection but can proceed to infect internal organs and even cause death.  There are several strains of MRSA and indeed new ones are being found all the time.  Most MRSA is hospital-acquired, meaning that patients become infected with MRSA inside a medical facility.  Methicillin is a type of penicillin, but this staph is also usually resistant to oxacillin, amoxicillin, and sometimes other antibiotics such as tetracycline.  Now what does MRSA have to do with antibiotic use in animal agriculture?

There are two classifications for antibiotic use in animals- those used for non-therapeutic reasons and those used for therapeutic reasons.   Non-therapeutic use (sometimes referred to as 'sub-therapeutic') refers to continual, low-dosage antibiotics mixed in feed or drinking water.  Although it is not thoroughly understood, low-dosage antibiotics help promote growth in animals, probably by preventing infections that take energy to fight.  The vast majority of antibiotics used in livestock and poultry is for non-therapeutic uses.  An example of non-therapeutic use might be if a poultry farmer put coccidiostats in their broiler feed to prevent coccidiosis, an infection that can slow the growth and ultimately kill poultry.  Therapeutic antibiotics are prescribed, usually by a veterinarian, when an infection has been identified in an animal or herd.  An example might be if a sow who recently gave birth did not eject her entire placenta, causing an infection in her uterus with the potential to kill her.  An injection of a penicillin might save her life.  What MRSA points out is that bacteria can develop resistance to antibiotics.  What is not clearly established is whether or not the use of antibiotics in animal agriculture, in particular the non-therapeutic use, is increasing the number of drug-resistant bacteria such as staph.

MRSA has been identified in pigs and those working around pigs (farmers, family of farmers, veterinarians, etc.) in many countries including the Netherlands, Canada, Ireland, England, China, and the United States.  Infection in the Netherlands is so serious that hospitals now pre-emptively isolate pig farmers and veterinarians to test them for MRSA before they can release them into other parts of the hospital.  Published in 2005, one study in the Netherlands showed that pig farmers were 760 times more likely that the general Dutch population to carry MRSA.  The strain of MRSA that is showing up the most in swine and swine farmers is ST398.  This strain has been found to transmit between animals, animal to people, and people to people.  Some ST398 is resistant to tetracycline, a common antibiotic used extensively on pig farms.

A 2008 University of Iowa pilot study showed a 49% MRSA colonization rate in swine and 45% of workers carried it.  Interestingly, of the two large pig farms studied,  one had MRSA colonization while the other had none.  This study did not look thoroughly into why there might be differences between production systems that would lend themselves to more MRSA colonization among animals or workers.  The authors do recommend further study on this.  As a pastured-pig producer myself, I wonder if the high density of animals and indoor conditions in CAFOs are more conducive to the spread of MRSA.  I also wonder if outdoor animals with more overall exposure to a diversity of bacteria could develop more immunity to pathogenic bacteria.  That has been shown to some degree in humans, with children raised on farms having higher immunities than children raised in cities.

The European Union Food Safety Authority (EFSA) now takes MRSA so seriously that it is calling for monitoring of pigs and other food producing animals.  They are also asking for further research so that the reasons for differences in the prevalence of MRSA can be identified, and research into possible options or control measures.  Strangely, the US Department of Agriculture Food Safety Inspection Services does not call for any monitoring of MRSA at all. 

Even a 2008 study of raw meat samples in stores around Baton Rouge, Louisiana showed 5.6% of pork and 3.3% of beef samples had MRSA colonies.  Although pork is normally cooked thoroughly so eating pork will not give you MRSA, there is a concern that slaughterhouse workers and butchers handling raw pork might be at risk (or the home cook who does not wash their hands after handling raw pork).  Interestingly, the strains were not those normally found on pig farms and thus could have come from humans.

Although I do have some concerns about state and federal policy limiting the use of antibiotics in livestock and poultry (mostly because I want to make sure we can still use antibiotics when we need to save the life of an animal without having to fill out a bunch of paperwork or pay a fee), I think it is pretty telling when the founder of World Poultry, Pig Progress, and Poultry Processing magazine, Weibe van der Sluis, had this to say about the overuse of antibiotics in animal agriculture:

"Although most of the time MRSA is linked to pig production, it is also related to the veal and poultry industry. The industry, therefore, cannot shrug its shoulders and move on as if nothing was wrong. In this case it would be wise to redefine the term prudent use of antibiotics. Time is up for those who use antibiotics to cover up bad management, poor housing conditions or insufficient health care. The standard rule should be: Do not use antibiotics unless there is a serious health issue and no other remedy applies. Veterinary practitioners, who usually authorize producers to use antibiotics, should also take responsibility and prevent unnecessary antibiotic use and the development of antibiotic resistance in animals and humans."

Instead of getting to a point when we have a bunch of SuperBugs that are resistant to all our commercially-available drugs and a lot of people and animals die while scientists scramble to develop new drugs to fight them off, why don't we take a more cautioned approach? I know that doesn't make the pharmaceutical lobbyists happy, but why are we letting them decide our policy or the future of our health anyways?

While those that defend the move towards indoor pig production as one that has reduced the incidence of trichinosis and toxoplasma in American pigs, I wonder if the spread of drug-resistant bacteria such as MRSA in pig CAFOs will wipe out any public health gains we have made on other fronts.  These other diseases are not skin-infections either, so they cannot be transmitted with the same ease as MRSA.  I think MRSA is just the beginning of the development of drug resistant infections that will spread around these vast biological monocultures we see in CAFOs, where thousands of the same species and breed are packed together to the delight of a mutant bacterium in waiting.

For more interesting references and a new book about SuperBugs, see http://drugresistantstaph.blogspot.com

To learn more about the campaign to keep antibiotics effective, check out www.keepantibioticsworking.org

Comments

[Walter Jeffries]

"ublished in 2005, one study in the Netherlands showed that pig farmers were 760 times more likely that the general Dutch population to carry MRSA."

Unfortunately statistics like that confuse people because they don't show the whole picture. That was only 13 pig farmers if it is 760 in 10,000 - the study group. Poor use of numbers by the media like this confound the issue by confusing people. Unfortunate.

Furthermore, it fails to differentiate between pig farmers raising pigs in a confinement animal feeding operation (CAFO = Factory Farm) with antibiotic feeds vs pastured pig farms where the animals are raised naturally outdoors like we do without the antibiotic or other commercial feeds. This further confuses the public. Most unfortunate.

[Foodporncom]

This is a great post, thanks! I get my meat and eggs from you and boast proudly of that fact as much as I can.

My sister, at age 37, almost died of a systemic MRSA infection in 2004. We don't know how exactly she got it. It was contracted outside of the hospital somehow. She was in a coma for 6 weeks, had to have a heart valve replaced (that is where the infection took root). She was a miracle case. No one could survive that ordeal but we were lucky and she did.

6 years later the problem with non-hospital-borne MRSA is worse than ever.

Thanks for helping to bring this issue to the forefront.

[Matt Moore]

Just found your blog today and have been reading ever since. You provide a lot of very insightful commentary. People like myself, who are fairly new to eating local and seasonal need as much education as folks like you can provide. The knowledgeable comments to your posts are further enlightening. Keep up the good work.

[karl omelay]

who was it, maichael palin that said you are what you eat eats? i guess that includes injections too..

we know someone that had a downer bull and called us with a question--my wife has renowned google-fu. "what is the withdrawal time on (powerful antibiotic) because i need to take him to slaughter?" yikes, that bull has had huge quantities of (powerful antibiotic) and now it is probably being served at some school lunch.

http://omelays.blogspot.com

[Thistledog]

Very well written and researched post. I for one really appreciate the effort and care you put into your posts on this blog. Your voice is reasoned and informed as well as passionate. Thank you!

[Ulla]

My boyfriend's uncle went in for a operation and died from infection not the actual ailment. So sad. Great blog post hopefully there will more political will from the top to address this extremely dangerous threat we have brewing.

[Bryan - oz4caster]

Quite interesting. It's very telling that most infections occur in hospitals. Probably to people given drugs that suppress the immune system but don't kill the MRSA. Also, most of these people are probably vitamin D deficient and thus more susceptible to infection.

I've read that most antibiotics suppress the immune system. If the drug suppresses the immune system but doesn't kill the bacteria, you're in big trouble. It would be interesting to see how megadosing vitamin D compares to antibiotics in effectiveness on MRSA. This may be a sad testament to over-use of antibiotics and under-use of vitamin D. Of course vitamin D is not near as profitable as antibiotics. Another good reason to avoid hospitals if at all possible.