Rise of superbugs linked to antibiotics in animal feed

Life-threatening bacteria, such as enterococcus faecalis (right), are proving immune, reports Roger Dobson
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The Independent Online
STRAINS of three life-threatening superbugs are now known to be immune to all antibiotics - and dozens more are resistant to a growing number of drugs.

In at least one case, the resistance has been traced to an antibiotic contained in animal feed used by farmers that proved to be almost identical to a drug used in humans.

A report to be published soon will also show that the incidence of a strain of salmonella - DT104 - is rapidly increasing and is again linked to the use of antibiotics in animals.

It is now estimated that about half of all antibiotic production goes into animals. Last week the House of Commons agriculture committee proposed that use of the drugs for promoting growth in farm animals be banned. A House of Lords committee has also recommended more prudent use of antibiotics in the face of growing bacterial resistance.

Leading specialists say that some strains of three forms of bacteria are already beyond the reach of antibiotics. These are strains of enterococcus faecalis, which can cause blood poisoning and wound infections, pseudomonas aeruginosa, which is linked to blood poisoning and pneumonia, especially in people with cystic fibrosis, and mycobacterium tuberculosis, which causes TB.

Professor Stuart Levy, president of the International Alliance for the Prudent Use of Antibiotics, said: "These strains of bacteria are all capable of causing life-threatening illnesses andincurable infections. We are already seeing a rise in the death rates from some diseases, such as TB."

Antibiotics have been used to control infection since the 1940s, when penicillin arrived on the market as the miracle drug of its day. Since then generations of antibiotics have been developed and used. But the problem with the use of antibiotics is that bacteria follow the Darwinian principle of the survival of the fittest. Some eventually become resistant and those resistant bacteria thrive and slowly become dominant, while the drug kills off their competitors.

The risk of resistance is highest when the antibiotics are used in low doses, either when patients do not complete their course of treatment, or when the drugs are given to animals as growth promoters.

"We know that around half the production of antibiotics goes into animals and there is very good scientific evidence that antibiotic-resistant bacteria can be found in animals," says Alan Jones, a scientist in the antibiotic reference laboratory of the Public Health Laboratory Service.

"We think that these organisms can transfer from animals to humans either via the food chain or by direct contact."

The PHLS stores some of the most resistant strains of bacteria found in the UK, including some that are completely resistant, and is currently involved in an intelligence-gathering operation to assess the scale of the resistance problem in the UK.

Dr Jones said: "It is a worrying problem. There are these strains of these three organisms which are resistant to all drugs and there are others that are resistant to six or seven different antibiotics.

"We need to cut down on the use of antibiotics, both in humans and in animals."

Salmonella is another problem that has been linked to the use of antibiotics in animals. Multi-drug resistant salmonella has increased tenfold in the past six years.

A report expected to be published shortly in the New England Journal of Medicine is expected to show that there has been another big increase in cases of the DT 104 strain.