Source: Michael Fielding, MEATINGPLACE, 12/7/11

It’s not months, but years, that it takes for bacteria to lose their resistance to antibiotics. This, according to a new study by Canadian researchers who found that bacteria in pigs remained largely resistant to two antibiotics more than two years after farmers discontinued their use.

The news comes just weeks after the Food and Drug Administration rejected two petitions to ban antibiotics from being used in food animal production.

Since most farm screens have traced resistance only in pathogenic bugs — a small percentage of those that live in pigs — there has been little data to help the industry combat the rest of the microbes, Martin Chénier told Science Now on Dec. 2. The assistant professor in the Department of Food Science and Agricultural Chemistry is one of three researchers who set out to assess the occurrence of chlortetracycline and tylosin resistance at the Swine Complex of McGill University in Quebec, Canada, which banned all antibiotics in January 2007.

They monitored gut bacterial populations in 10 pigs by examining the presence of antibiotic-resistant bacteria in their waste and found that the bacteria remained particularly resistant to both chlortetracycline and tylosin even after 2-1/2 years.

The issue remains a controversial one, though.

In September the Government Accountability Office concluded there has not been sufficient data to study a link between antibiotic use in food animals to antibiotic resistance in humans.

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