March 17, 2009
Hats off to New York Times Columnist Nicholas Kristof for his recent stories (“Pathogens in Our Pork” & “Our Pigs, Our Food, Our Health” ) spotlighting the serious public health risks of overusing antibiotics in industrial farm animal production. If you haven’t read them, you should. I don’t want to downplay the importance of Mr. Kristof’s reports, but in the public health and animal agriculture worlds the issue has long been a point of contention. Organizations like the American Medical Association, American Public Health Association and Keep Antibiotics Working sounded the alarms years ago regarding antibiotic resistance and the need to end the practice of adding antibiotics to animal feed simply to promote growth. Lawmakers have been trying to pass the Preservation of Antibiotics for Medical Treatment Act (PAMTA) for the past few years, which calls for an end to the practice. This year, it looks like it has a good chance of passing. Feedstuff’s Washington Correspondent, Sally Shuff, reports New York Congresswoman Louise Slaughter plans to introduce PAMTA 2009 today along with the CEO of Chipotle restaurants. Now that the animal feed issue is prominently placed in the public eye, I wanted to shine a light on another potential source of antimicrobial resistance, ethanol production.
That’s right, according to the USDA antibiotics like penicillin and virginiamycin are often used in ethanol production to keep bacteria from interfering with the fermentation process. According to a joint research project proposal, “Studies to Develop a Biosensor for Controlled Antibiotic Use During Ethanol Production from Corn,” by Southern Illinois University Edwardsville, the National Ethanol Research Center, the USDA Fermentation Biochemistry Research Unit, the Illinois Department of Commerce and Economic Opportunity, and a division of Emerson Electric Company, the use of antibiotics in corn to fuel ethanol production poses a “…risk of generating new antibiotic resistant strains of bacteria.” The byproduct of ethanol production is called Dried Distillers Grain (DDG). The project report claims that in the U.S. 80% of all Dried Distillers Grain with Solubles (DDGS), which is made from DDG, is used in dairy and beef feed as a protein supplement. The remainder, the project authors go on to say, is used in swine and poultry feed.
The amount of DDGS produced next year could top 11 million tons. The project authors claim, “The scale of dry grind corn to ethanol fermentation is so large and the use of antibiotics so widespread, the possibility of antibiotic resistance induction is high.” It’s assumed that the drying temperatures used to prepare DDGS will destroy all antibiotic residues, but the authors say that has never been proven.
There are several USDA studies that focus on the use of antibiotics in ethanol production, but there is very little information on antibiotic resistance in DDG or DDGS. I did, however, find a study that found dried distillers grain (DDG) can increase the shedding of E.coli O157:H7 and Salmonella in cattle. I also found an article in a 2007 Food and Nutrition Research Briefs that reported scientists are trying to find a way to make flour for human consumption with DDG.
I spoke with a top antibiotic resistance researcher at the CDC regarding the potential of penicillin residue getting into animal feed combined with DDGS. He told me that it would concern him, particularly because penicillin can lead to resistance to a number of other antibiotics still considered highly effective in human medicine.
It looks like some ethanol industry leaders are concerned about the imprudent use of antibiotics. I stumbled across a 2005 Ethanol Producer Magazine article that says “The medical field has already suffered the effects of antibiotic misuse and reached a critical stage where particular strains simply cannot be controlled using antimicrobial therapy. As an industry, we should take notice and learn from the past mistakes of others.”
By the way, that biosensor project proposal was accepted. The authors received $600,000 from the National Science Foundation. It should be completed by next January.