06/10/2009 - Ellen Silbergeld, Eng '72 (PhD), recalls that she did not want to go to the seminar. She was a professor of epidemiology at the University of Maryland School of Medicine in 1999 when her department's chairman needed an audience for the seminar's presenter, a candidate for a faculty position. Silbergeld recalls the chairman saying, "Please, just sit in the room. You can come to lunch." So she sat in the room, and something caught her attention. The seminar was on hospital-acquired infections, but the presenter mentioned in passing that some drug-resistant infections came from food. That seemed odd. Silbergeld knew you could pick up Salmonella from, say, tainted chicken salad. But how would that Salmonella have become resistant to antibiotics? She turned to a colleague and asked. Because, he said, factory chicken farms routinely feed antibiotics to their flocks, to accelerate growth, and the drugs generate resistance.
Ten years later, Silbergeld, now a professor of environmental health sciences at the Bloomberg School of Public Health, is one of several researchers at Johns Hopkins and around the world assembling evidence that the industrial farming of chickens, pigs, and cattle is cultivating more than poultry and livestock — it's cultivating bacteria that medicine is losing the ability to fight. Antimicrobial drugs, including antibiotics like penicillin, ciprofloxacin, and methicillin, kill pathogenic bacteria. But they simultaneously drive the resistance that is bacteria's defense, especially when administered in low, subtherapeutic doses. Scientists estimate that 50 percent to 80 percent of all antimicrobials in the United States are not used by doctors to treat sick people or animals but are added to farm animal feed, mostly in such subtherapeutic dosages. Public health researchers like Silbergeld are convinced that this nontherapeutic use of antimicrobials is building dangerous genetic reservoirs of resistance. If they are right, industrial agriculture is fostering and dispersing drug-resistant bacteria that impair medicine's ability to protect the public from them.
Industrial agriculture, known variously as factory farming, concentrated-animal feeding operations (CAFOs), and industrial farm animal production (IFAP), has produced an abundance of affordable steaks, pork chops, and broilers for grocery shelves over the last 65 years or so. It grew out of chicken farms on the Delmarva Peninsula, Midwestern pork processing plants, and cattle feedlots in Kansas and elsewhere. In 2008, the Pew Charitable Trusts and the Bloomberg School produced a report titled "Putting Meat on the Table: Industrial Farm Animal Production in America," that outlined how, after the conclusion of the Second World War in 1945, farm mechanization and the Green Revolution's program of genetic selection, irrigation, and chemical fertilizers combined to produce grain, soybean, and especially corn harvests of extraordinary abundance. With all that available corn, if you could feed it to livestock, you didn't need to raise animals in pastures. You could concentrate them in barns or feedlots and raise far more animals on far less land.
Read the full article Farmacology on the Johns Hopkins Magazine Web site.