Concerned about growing human resistance to antibiotics that are used to promote growth in livestock and poultry, San Francisco physicians are planning to push Congress and federal regulators to limit use of the lifesaving drugs in agriculture. The physicians contend the drugs should be administered only to fight disease when used on foodborne animals.

To spread their message, leaders of the San Francisco Medical Society held a conference of experts that examined the connection between the widespread use of common antibiotics on farms and evidence that their continued presence in foods can make many common disease-causing microbes resistant to the drugs designed to kill them.

According to Dr. Rolland Lowe, former president of the California Medical Association, leaders of the statewide organization already are mobilizing doctors all over California as well as more than 60 community health organizations to spread knowledge of two aspects of the problem: unnecessary prescribing for minor illnesses and overuse in the farm animal industry as "the pharmaceutical industry overwhelms you with confusing facts."

That the facts are confusing was made clear by wide disagreement between two groups of advocates. On one side, for example, was Margaret Mellon, food and environment program director of the Union of Concerned Scientists, who says her advocacy organization estimates that the beef, swine and poultry industries use more than 50 million pounds of antibiotics a year, with more than 25 million pounds a year just to promote growth in animals or for other "non-therapeutic" purposes.

On the other side, a recent survey by the Washington-based Animal Health Institute, which represents the major pharmaceutical companies producing antibiotics and other veterinary drugs, maintains that less than 20 million pounds of antibiotics are used in animals, with 17 million pounds for treating diseases and only 2.8 million pounds for "improving feed efficiency and enhancing growth."

However, Dr. B. Joseph Guglielmo, professor of clinical pharmacy at UCSF, reminded the conference that doctors themselves are prescribing far too many antibiotics indiscriminately for treating minor infections – often because patients demand them. Other physicians agreed that overprescribing might still be a major contributor to bacterial resistance to antibiotic drugs.

Dr. Randy Singer, an epidemiologist at the University of Illinois College of Veterinary Medicine, says "the harsh reality is that resistance to antibiotics occurs because of overuse in humans," and that using antibiotics in animals raised for food has proved important in keeping those animals healthy.

"Antibiotics used to improve animal growth and feed efficiency can reduce subclinical disease and improve productive performance and overall health," he says.

"There is definitely abuse of antibiotics in the livestock and poultry industries," Singer adds, "but the question is: How do you balance the need for animal health with the problem of persistence of antibiotics in the environment, and the increase of resistance to antibiotics?"

The San Francisco Medical Society, led by its president, Dr. George P. Susens, recently persuaded the California Medical Association to pass a resolution condemning unregulated use of antibiotics in the livestock and poultry industries.

And only three weeks ago in Chicago, the powerful American Medical Association adopted the California policy by voting for a resolution that declared, in part: "The spread of bacterial resistance arises not only from unnecessary clinical use in human medicine, but also from massive use in animal agriculture, with increasing evidence that resistance developed in animals is spreading to human pathogens."

The AMA also opposed use of the drugs in animals except to treat or prevent diseases and declared that nontherapeutic use in animals of antibiotics that are also used in humans should be terminated or phased out by regulation "based on scientifically sound risk assessment."