Antibiotic resistance: the livestock link

Dr Collignon, an infectious diseases physician associated with the Australian National University, is a vocal campaigner for the necessity of fighting antibiotic resistance.

Antibiotics are a “miracle drug”, he told BeefEx, one of the few drugs that actually cures people instead of merely preventing them from succumbing further to an illness.

But resistance is rapidly eroding the effectiveness of antibiotics. Once the current classes of drug become ineffective, there are few options left.

Dr Collignon thinks that by necessity, campaigning against resistance means campaigning against the overuse of antibiotics in food animals.

Around the world, between 70-80 per cent of all antibiotics used are applied to livestock.

Careful regulation has meant Australia has some of the lowest levels of resistance in the world - for some classes of antibiotic, the lowest levels - even though we have among the highest levels of antibiotic use in the world.

Elsewhere, antibiotic resistance is rising rapidly. In Europe, several countries are contending with more than 50 per cent resistance to the isolates that cause blood stream infections like septicaemia. Even where there are relatively low levels of resistance, as with the Scandanavian countries, resistance rates are still at 5-10 per cent, which is a marked increase from a decade ago.

But Dr Collignon’s worst nightmares lie in developing countries, where a combination of poor regulation and polluted water - water is a major vector for antibiotic-resistant bacteria - are becoming irredeemable.

In India, where E. coli is the most common cause of urinary tract infections, “to all intents and purposes, about half those E. coli are untreatable”.

In India and Pakistan, there are varieties of pathogen that “are resistant to everything, including the last-line antibiotics”.

This isn’t a problem that will stay on the sub-continent, Dr Collignon said. Some of these “superbugs” have already travelled to the United Kingdom, where they are causing acute problems in hospitals.

His team attempt to treat a patient who contracted some virulent pathogens during elective surgery in India. The bugs proved immune to all antibiotics including some new experimental drugs.

“These organisms are rare here; they aren’t rare in places like India and China,” Dr Collignon said. He argues for a “one health” approach to antibiotic resistance that takes in all sectors, in all countries.

That includes the livestock sector. Dr Collignon noted that there is ample evidence that antibiotic use in animals affects humans.

Australia has never approved flouroquinolones, an antibiotic to treat E. coli, for use in livestock: as a result, it has the lowest level of human resistance to the drug in the world.

In Spain, chickens have a 90 per cent resistance to flouroquinolones, and children 22 per cent resistance - even though the drug isn’t prescribed to children because it affects their bones.

Australia’s prudent use of antibiotics is commendable, Dr Collignon told the conference, but the drugs are so profoundly important that we need to go further.

His personal view is that antibiotics should not be used as livestock growth promotants - a practice that “causes resistance for marginal benefit”.

Prophylaxis - continuous preventative use of antibiotics - has the same effect. We need to find other ways to prevent disease through vaccines, feed formulations or management, Dr Collignon said. If we don’t devise those practices now, he argues that we’ll have to do it eventually anyway because of resistance.

And he wants certain critical last-resort antibiotics to be always held in reserve from human and livestock use, as a last line of defence.

Done well, Dr Collignon told the conference, restricting antibiotic use in livestock will not only lower the risk of incurable infections in people, but potentially provide another marketing advantage for our food exports.

He points to the recent example of Perdue Chickens in the United States, producer of about a billion chickens a year. Perdue has decided not to routinely use antibiotics in its hatching sheds, where it would inject eggs with a vaccine and antibiotic before hatching.

“That company has reduced antibiotic use by 95 per cent, and its staying competitive,” Dr Collignon said.

If Australia wants to retain some of the lowest antibiotic resistance levels in the world, we need to be very careful about the foods we import, Dr Collignon said.

“I think we should have rules about the quality of our water and drugs in food animals - but there is absolutely no point in then letting imports come in that don’t follow those rules or we don’t do any testing to ensure they comply.”

For instance, in China, apples are sometimes sprayed with a potent antibiotic that remains active even if it is autoclaved. Australia imports apples from China without testing for antibiotic residues.

“They tell us they don’t use the antibiotic: we believe them,” Dr Collignon said. “I have a slightly less sanguine view. We’re giving our own country a competitive disadvantage.”

But so far, he said, he has lost this particular battle with the federal government.