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Straight Talk About Feeding Antibiotics to Animals

It is time for some straight talk about the risks of using massive amounts of antibiotics in livestock and poultry.  I don’t know one infectious disease expert who would disagree that there are direct links between antibiotic use in food animals and antibiotic resistance in people.  Period.

If you don’t believe me just ask Rear Admiral Ali Kahn, Assistant Surgeon General and Acting Deputy Director for the Center for Disease Control and Prevention’s National Center for Emerging and Zoonotic Infectious Disease.

Just this summer, during a hearing before the House Energy and Commerce Committee, Dr. Kahn testified that, “there is unequivocal evidence and relationship between [the] use of antibiotics in animals and [the] transmission of antibiotic-resistant bacteria causing adverse effects in humans.”

Knowing this, I continue to be frustrated with the fact that Agriculture Secretary Tom Vilsack does not publically recognize that the industrial food animal production system is a leading contributor to the increase of antibiotic resistance in pathogens that infect people and animals.

Earlier this month at a National Cattlemen’s Beef Association meeting, Vilsack reportedly responded to a question about the Preservation of Antibiotics for Medical Treatment Act (PAMTA) by saying the, “USDA’s public position is, and always has been, that antibiotics need to be used judiciously, and we believe they already are.”

That quote had me scratching my head when I read it in a New York Times Op-Ed a couple of weeks ago.  The Times’ editors interpreted the statement as saying Vilsack believes there is no need to change antibiotic use policy among food animal producers.  That contradicts the positions of both the FDA and CDC.  The Times pointed out that while neither regulatory agency is doing enough to address the problem both, at least, recognize that current antibiotic use should change.

U.S. Rep. Louise Slaughter (D-NY) and Sen. Dianne Feinstein (D-CA), the primary sponsors of PAMTA, which calls for limits on the non-therapeutic use of certain antibiotics in livestock production, were perplexed with Secretary Vilsack’s comment, too.

They recently requested that Vilsack clarify his stance on the issue.  In a letter, Slaughter and Feinstein wrote, “Media reports suggest that you may have mischaracterized our legislation and made statements that run contrary to previous positions taken by Department officials. We hope that you can provide us with reassurance that your off-the-cuff remarks were taken out of context, and that you remain committed to protecting human and animal health.”

I called the Secretary’s office for a clarification myself.  A USDA spokesperson sent me the following statement:

“USDA believes that antibiotic use should be used judiciously to slow the development of resistance in animals. USDA believes livestock producers are good stewards, use antibiotics judiciously, but there are some bad actors, and continued use can develop resistance.   USDA wants to be a partner with Congress, producers and other federal partners to address this important issue.”

This statement does little to address the issue at hand.

The problem does not lie with a few rogue producers. Rather, there is an industry standard of feeding livestock and poultry low concentrations of antibiotics and other antimicrobials, like arsenicals, in their feed to promote growth. (All of which is approved by the FDA, by the way.) Considering industry produces more than 10 billion food animals a year (the majority chicken and hogs) the amount of antibiotics used in food animals is astronomical.

Case in point, researchers at Johns Hopkins Bloomberg School of Public Health estimate that the amount of antibiotics North Carolina hog producers use in their swine feed every year exceeds the total amount of antibiotics used to treat infections in people nationwide.  It is estimated that as much as 70 percent of the antimicrobial drugs used in the US are administered to animals not to treat disease, but to purportedly promote growth or prevent the spread of pathogens among livestock and poultry living in intensive confinement.

All uses of antibiotics contribute to drug resistance.  While human medicine plays a large role in the antibiotic drug resistance problem, new research is clearly showing that resistant bugs from food animals are starting to show up in people more and more.

Johns Hopkins Bloomberg School of Public Health and Hershey Medical Center researchers recently published a study that confirms other research indicating that hospitals are no longer the main source of exposure for methicillin resistant Staphylococcus aureus or MRSA.  And researchers in Europe have published evidence that livestock production is increasingly becoming a major source for the Super Staph bug.

The reason why PAMTA is focusing on the non-therapeutic use of antibiotics in animals is that it is contrary to everything we have known for 70 years about preserving these drugs.  The amounts of antibiotics used in animal feeds are low and are not intended to kill bacteria.  That creates a problem first recognized by the inventor of penicillin, Alexander Fleming, who warned in 1945 that, “the greatest possibility of evil in self-medication is the use of too small doses so that instead of clearing up infection, the microbes are educated to resist penicillin.”

Many infectious disease experts believe that we may very well be close to a post-antibiotic era, which could mean a return to a time when a simple bacterial infection could cause your child, your parents or you serious health problems or even death.

In their letter to Vilsack, Feinstein and Slaughter tried to clear up what they call common misperceptions about their legislation:

“The Preservation of Antibiotics for Medical Treatment Act does not ban the use of antibiotics.  And in fact we share your belief banning all uses of antibiotics would be counterproductive.  Instead, the Preservation of Antibiotics for Medical Treatment Act addresses usage of seven antibiotics that are critical in human medicine, phasing them out for non-therapeutic uses in livestock production.”

I respectfully suggest that the common misconception about PAMTA Feinstein and Slaughter should focus on is the misguided belief by many people that their bill would ban the use of antibiotics to treat sick food animals.  The legislation allows veterinarians to authorize proper use of antibiotics to treat or prevent disease.  .

While I support the proposed legislation to limit antibiotic use in food animals, I have continually made it clear that the current language in PAMTA should be stronger. I believe the concession to focus only on the so-called “seven antibiotics that are critical in human medicine” weakens the bill.  If we are going to be up front with the public, we must make it clear that bacteria don’t differentiate between types of antibiotics, whether they are approved for human medicine or not.

Dr. Ellen Silbergeld, professor of environmental health sciences at the Johns Hopkins Bloomberg School of Public Health, recently testified before Pennsylvania’s state Legislature regarding its own proposed legislation to limit antibiotic use in food animals.  She warned that, “bacteria respond to chemical structures,
not brand names, and resistance to one member of a pharmaceutical class results in cross resistance to all other members of the same class.”

For example, she noted that resistance in Campylobacter (a nasty bug that the USDA says is the second most frequently reported cause for foodborne illness) to the antibiotic enrofloxacin (an antibiotic approved for pets and other domestic animals, commonly called Baytril) results in resistance to the very important human therapeutic antibiotic ciprofloxacin.  Both antibiotics are two of more than 30 variations of the fluroquinolone class of antibiotics. As Silbergeld explains, when bacteria develop resistance to one member of that class of antibiotics, they can be resistant to all.

Authors made certain that language in PAMTA would ensure that any “derivative of a drug that is used in humans or intended for use in humans to treat or prevent disease or infection caused by microorganisms” would be banned from being used as a growth promoter in food animals. But–and this is a big “but”–the bill does not address the fact that the use of any antibiotic can lead to a pool of resistance that can affect every antibiotic class–important to both human and animal medicine.

Silbergeld has long warned that antibiotic resistant bacteria can share the genes (bits of DNA) that code for resistance with other bacteria in the environment and therefore readily transfer antibiotic resistance.  Sharing genes between bacteria is almost as easy for these organisms as forwarding an email to a friend; only bacteria are exchanging genetic code information.  Resistance genes for multiple classes of antibiotics can be shared in the same “email,” or what scientists call plasmid “cassettes.”

For instance, some isolates of Salmonella and Campylobacter have been found to have taken up a “cassette” of resistance genes that protect them from as many as 17 different antibiotic drugs.

What this means is that not only can bacteria share resistance genes within the same class of antibiotics such as the fluoroquinolines class antibiotics containing enrofloxacin (restricted for veterinary use) and ciprofloxacin (critical to human medicine), but also bacteria have the capability of exchanging resistance genes between different classes of antibiotics like we’ve seen in Salmonella and Campylobacter.

Allowing the non-therapeutic use of any antibiotic in food animals, regardless of whether it is defined as important to human medicine or not, could still lead to the development of bacteria that are resistant to an antibiotic that you and I may one day depend on.

The concept behind PAMTA is an important one.  We must stop wasting one of medicine’s most important lifesaving discoveries simply as a way to increase the growth of food animals and subsequently profit for the food industry.  If PAMTA is not passed this year I hope that the next version would follow more closely the recommendations from the Pew Commission on Industrial Farm Animal Production’s final report, which calls for “the phasing out and then banning the non-therapeutic use of [ALL] antimicrobials in food animal production.”

© Food Safety News
  • chris

    I’d be genuinely interested to learn what impact similar legislation to that proposed above has had on antibiotic use in the EU. Anecdotally, I understand there has been a considerable increase in the therapeutic use of antibiotics to combat veterinary health problems, which also has implications for animal welfare.
    Also, I think your leading statement “I don’t know one infectious disease expert who would disagree that there are direct links between antibiotic use in food animals and antibiotic resistance in people. Period.” is simplistic. The real question is does antimircobial use in food animals lead to antimicrobial resistance in bacteria and does that resistance result in negative impacts on human health.

  • richard raymond, MD

    Editor Flynn, you really should not have let this misleading article be published. The author is either really misled himself and unsuspectingly repeating garbage, or he is intentionally trying to mislead the public to promote his own agenda.
    There have been some studies saying antibiotic use in animals may lead to antibiotic resistant bacteria that could be harmful to humans. There are some experts in the field that would even argue with that watered down statement. But to say that the use of antibiotics in food animals “is a leading contributor to the increase in antibiotic resistance” is taking one giant step for PETA and HSUS, not for truth and honesty.
    Also, he does not clarify when he talks about the “massive” use of antibiotics in food animals, that most of those drugs are for veterinary use only, many are for parasites such as coccidiomycosis, and are not affecting human health whatsoever, except that the meat we eat is much less likely to be contaminated with Trichinella, Brucellosis, Diptheria, Tuberculosis, Toxoplasmosis, etc. Many parasitic diseases spread by tapeworms and their eggs remain in the developing countries where animals are not routinely treated with “antibiotics” and the diseases affect human health.For example, Cysticercosis is the leading cause of epilepsy in the world, and is caused by eating contaminated pork, but do we hear of Cysticercosis in the US lately?
    The author also implies the FDA is doing nothing but talking about the need for restrictions on antibiotic use in food animals, and goes on to expound that the approval of the use of Enrofloxicin (misspelled), or otherwise known as Baytril, is endangering our lives because it could lead to Ciiprofloxin resistant pathogens including Camylobacter commonly found in poultry. What he DOES NOT SAY is that the FDA removed Enrofloxicin (sp?) from the list of drugs apprioved for use in food animals, including poultry, way back in 1995. It is only approved now for dogs, cats and other pets and must be prescribed by a DVM. Some countries eat their pets, but most of us in the US do not. The FDA took corrective action without legislation to protect human health. Why did the author attempt to mislead us on this particular issue? Only he can answer.
    Lastly, physicians, for decades, myself include, have been prescribing antibiotics when they were not indicated (viral illnesses, fevers of unknown origin, etc, and parents for decades have stopped making their children choke down awful tasting medicine once the fever broke, the ear pain left, or they slept thru the night. These practices lead to antibiotic resistance. Perhaps the author would like to consider also banning antibiotic use in humans?
    The issue is of great importance, and must be examined carefully with responsible actions taken. Rhetoric like in this article does nothing to promote healthy discussions, nor does rhetoric from PHARMA saying there is NO problem.

  • Wednesday, April 14, 2010
    FSIS National Residue Program for Cattle Audit Report 24601-08-KC March 2010

  • Doc Mudd

    Nice article – not. A distorting screed from the same silly activists who brought us the “Meatless Monday” farce. Yesterday must have been “BS Wednesday” here at Food Safety News.
    Who is Mr. Loglisci and his biased activist organization?
    This article definitely does not pass the smell test.

  • dangermaus

    Considering how many countries sell antibiotics over-the-counter, and how many of the people in those countries use them in ways Dr. Raymond mentioned, the risk of bovine strain of bacteria gaining antibiotic resistance from feed, and then that resistance somehow getting transferred to a strain of that bacteria that attacks humans seems remote in comparison.
    I think the problem is consumers don’t care about how their food is produced, and will buy the cheapest thing on the shelf, and don’t really care how it’s produced. It never occurs to them that the .$89/dz eggs they’re eating were only possible because the chickens were doped their whole lives. Not that I have a solution to that problem, unfortunately. If we can figure THAT out, as a country, I’m sure our trade deficit will benefit, too, because we’ll also stop using credit to buy crap from China that we don’t need…
    Dr Raymond, it’s not fair to lump people with a distaste for raising food animals in ways that requires preemptive chemical intervention with PETA. I think the idea of animal rights is laughable at best, but I also think one can only have so much insight into chaotic systems, like human physiology under the lights Nutrition and Toxicology. As a result, we should probably eat organisms that were healthy their whole lives, and are eaten in a minimally-processed form.

  • dangermaus

    While I almost always take the other side as the guys who posted the previous comments, I’ve gotta agree… This is fear-mongering and little else. It uses concepts from Bacteriology that are nebulous, but extremely powerful and wondrous, to lead the reader to a vision of a world without effective antibiotics…
    Nice word, “screed”. Punchy, emotive… Gotta use that one more!

  • Nate A

    @ Richard Raymond,
    Many problems with your response:
    – “There are some experts in the field that would even argue with that watered down statement.”
    You don’t talk to too many epidemiologists, do you? This statement doesn’t do justice either to the growing body of evidence or to the gravity of the consequences.
    – “Also, he does not clarify when he talks about the “massive” use of antibiotics in food animals, that most of those drugs are for veterinary use only…”
    Completely irrelevant, even if it were true (I’d love to see a citation, by the way). As I’m sure you know, and as was pointed out in the article, resistance is developed across classes of drugs. It doesn’t matter that Baytril isn’t used in humans, for example; it’s overuse in animals is widely accepted to pose a risk of creating resistance to many other fluoroquinolones.
    – “..many are for parasites…”
    Again, completely irrelevant. You spent a whole paragraph extolling the virtues of anti-parasitics, as though it somehow justifies massive sub-therapeutic antibiotic use on factory farms.
    – “…the FDA removed Enrofloxicin (sp?) from the list of drugs approved for use in food animals, including poultry, way back in 1995.”
    This is false. Approval of sub-therapeutic Enro in poultry continued until 2005, and its use in other food animals (notably cows) continues to this day. The Baytril case certainly does demonstrate the FDA’s slothful take on the issue. This info is readily available, and I find it troubling that you so readily accuse the author of lying, when your own assertions are so blatantly false.
    – “Lastly, physicians, for decades, myself include, have been prescribing antibiotics when they were not indicated…”
    That you admit to, and seem to defend, irresponsible use of antibiotics causes me to question whether you take this issue seriously at all.
    – “Perhaps the author would like to consider also banning antibiotic use in humans?”
    This is a straw man in the making. Putting aside the absurdity of your suggestion, sensible regulatory approaches are currently being validated. In Norway, doctors such as yourself who carelessly prescribe antibiotics face penalties, and their regulatory regime has so far resulted in a drastic decline in MRSA infections in that country.