30 May 1997

Resistant bugs move from farm to man

INCREASING resistance to antibiotics in humans in England and Wales is linked to overuse of antibiotics in farm animals, according to a public healthscientist.

Bernard Rowe, from Londons central public health laboratory, told an international conference on human antibiotic resistance, organised by the Wellcome Trust, that the main factor responsible for the spread and persistence of antibiotic resistant bacteria in humans in England and Wales was the overuse of antibiotics in farm animals.

And he said the UK had ignored World Health Organisa-tion advice that the routine inclusion of antibiotics in some livestock production systems should be discouraged.

In a report in 1994, addressing the growing problem of antibiotic resistance, the WHO stressed that antibiotics should not be used as a substitute for adequate hygiene in livestock production.

Dr Rowe said that while the overuse of antibiotics in human medicine was an important factor in the emergence and spread of multi-resistant salmonella in developing countries, the same was not true in Britain. Most cases of salmonella in this country were a consequence of food poisoning with the disease passed from food animals to humans.

About 80% of one strain of the bacterium Salmonella typhimurium was resistant to a range of antibiotics and could be related back to cattle infection, Dr Rowe said.

The particular strain causing concern, phage type DT 104, had now spread to poultry and pigs and was found in a wide range of human foods. Human infections had increased from 71 cases in 1990, to 4006 in 1996.

Human resistance to the antibiotic fluoroquinolone, used to treat other forms of salmonella infections, linked to poultry, had also increased dramatically. Before 1993, when the antibiotic was first licensed for use in livestock, fluoroquinolone resistance in humans was rare. Now resistance, at rates of up to 60%, were seen.

But Tony Mudd, representing European animal health manufacturers group, FEDESA, suggested antibiotic use on farms was not to blame.

A more likely explanation, he believed, was farm hygiene and the mixing of livestock by dealers.

Shelley Wright