Doctors, of course, know that. If the worst of the illness is over in a few days, the antibiotic may get the credit, when in fact it had no effect on the virus that caused the illness. Researchers at the Centers for Disease Control and Prevention have estimated that a third of the 150 million outpatient prescriptions written were unnecessary. Hospitals, too, use antibiotics in ways being called inappropriate. Lieberman cites a Health Care Financing Administration study that found 63 percent of vancomycin orders were inconsistent with CDC guidelines.
Antibiotics given to human beings make up only half the antibiotic use in the United States.
Farmers use the other half, to prevent or to treat diseases in animals, to promote their growth and efficiency at turning feed into meat, and even to spray fruit trees and vegetables to prevent blemishes due to blight. A controversy has gone on ever since, and there have been studies by the dozens. Harvard Medical School researchers found that antibiotic-resistant genes in bacteria infecting humans were identical to some found in bacteria infecting animals. A team from the CDC linked an outbreak of resistant Salmonella infections in humans to beef cattle that had been fed chlortetracycline for growth. In 1984 the Natural Resources Defense Council petitioned the FDA to ban penicillin and tetracyclines in animal feed, but the Department of Health and Human Services said the NRDC had not proved that their use constituted an imminent hazard to the public health.