March 15, 2010

AVMA leadership missing key facts on antibiotics in food animals

Dave Love

Dave Love

Associate Scientist, Public Health & Sustainable Aquaculture Project

Johns Hopkins Center for a Livable Future

Dr. Ron DeHaven, CEO and Executive VP of the American Veterinary Medical Association (AVMA)*, spoke last week to the pork industry in Kansas City, MO. DeHaven opposes legislation to ban the use of non-therapeutic (growth promoting) antibiotics and antibiotics with human uses from food animal production. DeHaven used this opportunity to spread misinformation about the reality and consequences of non-therapeutic antibiotic use and food safety.

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Early MRSA infections. http://www.jiujitsuforums.com/wiki/File:Mrsa7.jpg

DeHaven seems to understand the biological basis for antibiotic resistance, by saying “antimicrobial resistance is caused by widespread use of antimicrobials in food production systems, and hence the more we expose microorganisms to antibiotics the more likely they are to develop that resistance.” The problem arises in his dismissal of the impacts of using antibiotics in food animals—a practice that experts recognize as a public health threat (Silbergeld et al., 2008).

In his talk DeHaven said, “there really is no scientific evidence to confirm just how, if, and to what extent that exposure represents a risk to human health… there has been really no case of human infection with resistant bacteria that has been proven to be caused by the use of antimicrobials in food animals.” This statement is disingenuous and does not acknowledge published findings to the contrary (Voss et al., 2005; Huijsdens et al., 2006) demonstrating MRSA (Methicillin-resistant Staphylococcus aureus) transmission from pigs to a pig farmer, and between pig farmers and their family.

Reported cases of disease are only the tip of the iceberg, therefore we expect that many more cases of community associated (i.e. non-hospital) antibiotic resistant bacterial diseases have originated from factory farms. A recent study in the Journal Emerging Infectious Diseases shows that community associated diseases are increasing at an alarming rate— over 33% increase annually for MRSA in the US from 1999 to 2006 (Klein et al., 2009). While all cases of MRSA may not originate on factory farms, we can’t rule out factory farms and as one source of MRSA (Nunan and Young 2007).

In addition to MRSA, resistant E. coli have been detected in cattle and pigs given antimicrobial drugs (Alexander et al., 2008; Rosengren et al., 2008). When antibiotics are given to food animals, as much as 75% of those drugs are excreted in waste, which contributes to the environmental burden of antibiotic residues and the development of resistant bacteria in the environment (Chee-Sanford et al., 2009). Regulations to reduce or ban antibiotics used in food animals appears to be one clear way we can reduce one source of resistant bacteria.

At the end of his talk, DeHaven takes a stance in support of greater oversight of drug delivery to animals by veterinarians. This would be laudable, except for a giant loop-hole he introduces when saying “veterinary involvement needs to be consistent or proportionate with the risk of those antibiotics.” This insinuates that continuing the practice of selling antibiotics over-the-counter (OTC) in feed to farmers, with no veterinary oversight, is acceptable. The AVMA is investigating other ways of relaxing food animal veterinary oversight, with increased involvement of veterinary technician and electronics prescriptions of antibiotics. With region-specific shortage of mixed animal veterinarians in the US, can you blame the AVMA for feeling squeamish about its options for taking care of the burgeoning numbers of food animals?

I encourage the AVMA not to take the easy way out, and not allow OTC antibiotics to replace hands-on food animal health care. The positive benefits of increase veterinarian involvement coupled with decreased use of growth promoters will have far-reaching, positive effects on and off the farm.

– Dave Love

[image attribution: Early MRSA infections. http://www.jiujitsuforums.com/wiki/File:Mrsa7.jpg]

* The AVMA represents its membership of US veterinarians, serving as an information channel, accrediting body for veterinary professional education, and advocating body for policy development and comment of relevance to the profession. The organization represents 80,000 members nationwide.

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