Row over animal drug risk to people

By Mark Metherell
November 25, 2004

A Federal Government agency will ban the use of an animal antibiotic as a growth promoter but has stopped short of a total ban, despite a finding that the drug has the potential to trigger severe resistance to antibiotics in humans.

After a four-year review of the drug, virginiamycin, the Australian Pesticides and Veterinary Medicines Authority has found a "very low" risk of it generating antibiotic resistance in animals that could be spread to humans in infected meat.

But an authority spokesman, Martin Holmes, said that if the antibiotic resistance did spread to vulnerable patients, the "likely impact on people requiring treatment with related antibiotics would be severe".

Virginiamycin has been used to boost growth in cattle, pigs and poultry. Under the new rules it will be prescribed by veterinarians only for livestock diseases. The drug is in the same class of antibiotics as medicines "of last resort" - when humans suffer infections resistant to more common antibiotics.

The European Union banned its use in animals in 1999 and it is under review in the US because of the human resistance concerns.

A long-time critic of routine antibiotic dosing of animals, Peter Collignon, has described the authority's green light to its continued use as "disconcerting". He said it highlighted a flaw in the regulatory process, where a government agency dealing with agricultural chemicals made decisions with implications for human health.

Professor Collignon, an infectious disease specialist at Sydney University and the Australian National University, said the decision would still mean that huge volumes of the antibiotic would be used in food animals, despite no convincing evidence that it lowered animal mortality.

The decision would still mean its widespread use. "This will lead to increasing numbers of resistant bacteria in the foods we all eat, and potentially also jeopardise export trades in meat," he said.

However, the deputy chairman of a panel that advised the authority on human antibiotic resistance, John Turnidge, said risks to humans from virginiamycin use, "as far as we could judge, would be negligible". He said the veterinary agricultural regulators were "highly tuned" to human health considerations.

The distributor of virginiamycin in Australia, Phibro Animal Health, said it had already stopped selling the product as a growth promoter and its use in Australia had been reduced substantially in recent years.