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News 260 views last update:6 Aug 2012

Antibiotic resistance remains issue

Despite declines of in-feed antibiotics, totally in the EU and partly in the US, resistancy issues are still a problem, according to scientists and livestock industry members.

The 2005 DANMAP report from the Danish government's programme for surveillance of European antimicrobial resistance, the most recent statistics available, says: "Antimicrobial consumption in food animals is still low compared to the total consumption before the cessation of growth promoter use." A chart in the report also says antimicrobial use in animals levelled in 2004 and 2005. At the same time, the use of antibiotics in humans has held about steady from 1997 through 2005, the DANMAP report showed.

US cuts back on antibiotics
The US Food and Drug Administration (FDA) says about 70% of infection-causing bacteria are resistant to at least one of the drugs most commonly used to treat infections in humans. The FDA site does not say where these bacteria acquired their resistance, but says use of antibiotics in animal feed can cause microbes to become resistant to drugs used to treat human illness.

In the US, sub-therapeutic antibiotic use, or below the level required to cure a sick animal, in livestock and poultry feed has declined in the last three years, according to Ron Phillips, vice president of legislative and public affairs for the Animal Health Institute. Antibiotics are being removed from animal feeds because consumers want them removed. In July 2005, the FDA removed its approval for Baytril for use in chicken feed because of its similarity to human antibiotics and concerns about resistant diseases. "These trends correspond to an increase in therapeutic use to treat a higher numbers of sick animals or birds. It "is precisely what is taking place in Europe," Philips added.

Farmers and veterinarian response
A Western Kansas veterinarian with a large cattle feedlot practice said many of his clients continue to use low-dose antibiotics as growth promoters because they work and because there are no comparable human drugs in use. In essence, it wouldn't matter if the animal's bacteria developed resistance to these drugs, because the bacteria still would be susceptible to human drugs, he said.
An Iowa veterinarian also said there is talk among pig producers of cutting back on antibiotics in feed, but "it's a necessary part of production." They are fed not only as a growth promoter but to prevent pneumonia and scours, or diarrhoea, he said.
As if to underscore this need, the FDA recently approved another antibiotic for feed use in pigs, although it is to be done by "veterinary directive" only, the Iowa veterinarian said.
The biggest issues in the cattle industry are whether or not cattle feeders will be allowed to continue to feed tylosin phosphate (to prevent liver abscesses) and/or monesin (to prevent coccidiosis, an intestinal disease in cattle)," said Gary Smith, Colorado State University professor of meat sciences.

The answer: Few and effective
According to Michael Hansen, senior scientist at the Consumers Union, which publishes Consumer Reports, the ideal rule-of-thumb is to keep livestock away from antibiotics unless they are needed, and then to treat as few as possible with an effective dose.

External links:
FDA
Consumers Union

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