Organic Farming and Antibiotic Resistance

A recent article in Applied and Environmental Microbiology illustrates the effect that conventional farming, which uses a lot of antibiotics, has on the evolution of antibiotic resistance. The authors examined the difference in the frequency of resistance to antibiotics in the human pathogen Campylobacter. Resistance in bacteria from conventional raised poultry (actually, the carcasses) was much higher than in organic, non-antibiotic intensive farming:

  • for floroquinolones, which are commonly used in medicine (e.g., ciprofloxacin), less than two percent of isolates were resistant, compared to 46% and 67% of isolates from conventionally raised chicken and turkey, respectively.
  • conventionally raised turkeys had very high levels of resistance to other antibiotics: erythromycin (80%-commonly used in non-emergency clinical practice), clindamycin (64%-commonly used in non-emergency clinical practice, including MRSA), kanamycin (76%), and ampicillin (31%).
  • 81% of isolates from conventionally-raised turkeys were multidrug resistant.
  • regardless of where they came from, most isolates were resistant to tetracycline (which isn't surprising; nearly everything is resistant to tetracycline at this point).

Turkey: maybe it shouldn't be what's for dinner...

an aside: after looking at the NARMS data closely, I am never eating ground turkey. Ever.

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Great to see you at Scienceblogs, just made my bookmarks much shorter. I hope you can bring over some of your old posts to the new site.

With regard to this post I must say I am not surprised by there being a difference but the magnitude is astounding. I assume this is explained by the increased selection pressure,(the abstract does not say and I don't have a subscripton)and wonder if you would have predicted this great a difference?

By CanuckRob (not verified) on 09 Jun 2006 #permalink

CR,

Glad you showed up. I'm not surprised by a difference, but the magnitude was shocking. Although what really surprised me was how rare resistance was in the organic farms. Often we see contamination, etc. so resistance, particularly to the more commonly used antibiotics, is higher, even when antibiotics are used. It gives me some small hope.

Would it be a long shot to consider that antibiotic use in farming in Iraq could have contributed the drug resistance of MDR Acinetobacter Baumannii coming from there?
I have been asking about how a bacteria could become so resistant to antibiotics in a county that supposedly had so few drugs under the years of embargoes.
The dirt particles in the air tested at one location I know of consisted of 50% animal feces.

By Marcie Hascall Clark (not verified) on 10 Jun 2006 #permalink

Marcie,

I don't know if antibiotics are/were widely used in Iraqi farming. Many antibiotics are relatively inexpensive and were not embargoed in Iraq, as they were viewed as humanitarian aid. Because AR (antibiotic resistance) genes in Acinetobacter are often physically linked, selection for a cheap, older antibiotic can often bring along lots of other AR genes. Also, AR genes are also linked to heavy metal resistance genes which could also provide another 'target' for selection. That's how I think MDR Acinetobacter evolved.

Another thing to keep in mind is that bacteria can become airborne and travel. Right now, much of the Middle East is suffering from an Acinetobacter epidemic (Israel, Kuwait, and Saudi Arabia are the countries I know of). Israel has been hit especially hard (or it might simply be that Israel has a very good surveillance system). To view this as an Iraqi problem isn't the best way to look at it.

Finally, Acinetobacter baumannii is found world-wide, including France which has also had significant MDR A. baumannii. About 6-7% of pneumonia cases in the U.S. are due to A. baumannii (compared to ~10-15 years ago when less than two percent were due to A. baumannii). A. baumannii has always been a problem, particularly in the tropical developing world where it actually acts as a contagious pneumonial agent. This problem didn't start during the Iraq War; it's been a chronic problem for a long time.

I hope this answers your question.

Mike
Thanks for the very enlightening, thought provoking, and also scary response. It has taken nearly three years of asking about the AB's antibiotic resistance to learn this and I really do appreciate it.
Several Israeli's suggested had suggested heavy metal and/or exposure to byproducts of the oil industry. I knew they were dealing with AB also but didn't realize it was the same AB that our soldiers are bringing home. They have been helpful regarding the leishmaniasis as well.
I have to say our dealings with this AB and the way the doctors prescribed antibiotics to treat it should be considered negligent. The civilian ID doc had him on two different antibiotics that it was already resistant too.
Thanks again for such an informative answer.

By Marcie Hascall Clark (not verified) on 11 Jun 2006 #permalink

hello, nice site

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