By TIM ALEXANDER

Illinois Correspondent

NORMAL, Ill. — Feeding animals with dried distillers grains (DDGs) containing antibiotic residues could contribute to the emergence of drug-resistant organisms that can “potentially” affect humans who consume meat from animals fed DDGs as part of their nutrient plan, the U.S. Food & Drug Administration (FDA) announced in May.

This was the topic of a May 14 Chicago Tribune article which also trumpeted a new report by advocacy group the Institute for Agriculture and Trade Policy (IATP), which suggested DDGs contain levels of penicillin, erythomycin and other antibiotics that could develop crossover immunity in humans.

But nothing in the FDA’s pronouncement, the IATP report or the Tribune article changes the fact that no reports of crossover bacterial immunity from animals consuming DDGs to humans has ever been scientifically confirmed, according to Dr. Paul Walker, a professor with the Illinois State University Department of Agriculture’s Animal Science division.

“We know that overuse of any antibiotic will stimulate bacteria to develop resistance or immunity to that antibiotic. Whether or not it results in crossover immunity, i.e. those bacteria then affecting humans’ resistance to those same antibiotics, (has) never been documented,” said Walker.

“One study is not decisive. We’ve never had an instance of crossover immunity at this point in time. There is no real evidence to suggest that antibiotic usage at either the therapeutic or subtherapeutic level in livestock causes crossover immunity to occur.”

Though the Tribune article named penicillin and erythomycin as two antibiotics that could be linked to crossover immunities – as they are also used as human antibiotics – the most common antibiotic used by ethanol producers in DDGs was not mentioned in the article, Walker said.

“The primary antibiotic used by ethanol producers is Virginiamycin, and that is not a pharmaceutical used in humans. So the buildup of disease resistance, if it did occur to Virginiamycin, would have almost zero effect on crossover immunity to bacteria in humans,” he said.

Very little Virginiamycin is blended into DDGs by ethanol producers – around 0.5 part per million, according to Walker. “The FDA has chosen not to regulate that. The FDA acknowledges their GRAS (generally recognized as safe) status,” he said.

“Most of the times antibiotics are used to keep disease at bay. We’re pretty prudent about not using these (excessively) in agriculture. First, it’s too darned expensive to put in the feed.”

The FDA began requiring ethanol and DDGs producers gain approval for antibiotic residue in the ethanol co-product after discovering them in 2008. Its study of 12 antibiotics used in 42 ethanol plants revealed that only one or two plants produced DDGs containing slight reactive residual properties, Walker said.

The FDA announcement in May included the intention to explore possible regulatory oversight of the use of antibiotics in the ethanol production process when the co-products are used for animal feed, according to the Tribune.

The article further noted some distillers opt for “antimicrobial methods that do not leave possible antibiotic residue in grain” – a claim Walker respectfully challenged.

“Actually, they do (often retain antibiotic residue) to some extent,” he said. “Some (ethanol) plants use a kind of a pasteurization method, and some use a preheating method to destroy bacteria prior to fermentation. But sometimes there may be higher levels of bacteria present in corn than those methods can handle.”

Charles Staff of the Distillers Grain Technical Council also took exception to the IATF study and FDA pronouncement, telling the Tribune: “We are talking about (antibiotic residue) parts per billion that is potentially present.

“(Ethanol producers) have better control (since the 2008 FDA analysis) and the antibiotic companies have established technical service and people who go out to the ethanol plants and monitor how they are using it.”

The issue gained national attention after U.S. Sens. Edward J. Markey (D-Mass.) and Louise Slaughter (D-N.Y.) sent a letter to the FDA in May asking how it could better regulate antibiotic residues in DDGs, and questioning why no further public information had been released since the 2008 study.

Walker sees no need for stepped-up FDA monitoring of antibiotic use by ethanol producers or farmers. “I’m not sure there is a need for increased FDA regulation at this point in time,” he said, while allowing that continued FDA monitoring of antibiotic levels in DDGs is reasonable.

DDGs replaced 914 million bushels of traditional corn feed used in the beef, dairy, swine and poultry industries in the 2010-11 production year, the IATP report stated.