The use of antibiotics as growth promoters in animals is being made a scapegoat for the rise of the superbug, a survey of leading medical microbiologists has suggested.
The survey of the opinions of 20 professors of medical microbiology or clinical medicine in the United Kingdom, continental Europe and the United States, was published yesterday at an international conference in Washington DC.
It runs counter to growing concern that the use of antibiotics to promote growth in farm animals is making a big contribution to the creation of drug-resistant superbugs in humans.
However, some experts rejected the survey results and said the practice should be curbed further.
The survey carried out by Robin Bywater, a consultant with strong industry links, and Mark Casewell, emeritus professor of medical microbiology at Guy's, King's and St Thomas's School of Medicine in London, suggests that a number of leading experts in the field believe the threat is being exaggerated.
Dr Bywater told the meeting on antimicrobial resistance, organised by the Royal Society of Medicine, that the research showed that, in the experts' opinion, less than 4 per cent of the overall human antibiotic resistance problem is likely to come from animals.
He said: "It is concluded that antibiotic use in animals, including for growth promotion, should be prudent and subject to risk assessment, but that the use in animals appears to have received a disproportionate amount of attention as a potential contributor to human resistance."
The survey ranked 20 disease-causing bacteria according to the perceived significance of their impact on human health and the extent to which drug resistance was thought to be affecting treatment.
Methicillin-resistant Staphylococcus.aureus, a potentially deadly wound infection that circulates in hospitals, was judged top of this league table, while just four bugs considered to be linked to use in animals were in ninth place and lower.
However, Rosamund Williams, coordinator of the World Health Organisation's drug-resistance surveillance, said that while much of the problem stemmed from the improper use of human medicines, animal use was still a major contributor. "We have to recognise about half of the total tonnage of antibiotics used in the world is not in human medicine," she said. She questioned whether it was possible to put figures on the contribution that animal or human use make to the problem.
The WHO is in the first stages of creating a global disease alert network to post warnings of outbreaks, including drug resistance.