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By Tom Scheck
September, 2000
Part of MPR's Fighting the Superbug series
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RealAudio 3.0 |
The Centers for Disease Control, the World Health Organization and epidemiologists throughout the world are calling for more prudent use of antibiotics. Ever since doctors started using penicillin to kill bacterial infections in the 1940s, researchers have worried some bacteria would become resistant to antibiotics. Their fears are now coming true as scientists discover antibiotic-resistant germs. They say so-called "superbugs" will leave doctors defenseless against some illnesses.
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Michael Osterholm heads a Web site that provides infectious disease information to health care professionals. He's also the former state epidemiologist with the Minnesota Department of Health. Osterholm says eventually all bacteria develop resistance to antibiotics. But excessive use speeds up the process.
"What the antibiotic-resistance problem of today really presents us with is a turn back to those days when you couldn't treat those infections, because the old infections couldn't work anymore and it is something as a society we're not really prepared for," he says.
Osterholm says there are several ways to limit antibiotic use. First, he says physicians should stop prescribing antibiotics for illnesses incurable by antibiotics, such as colds or bronchitis. A study by the Centers for Disease Control says up to 40 percent of antibiotic prescriptions are unnecessary. Osterholm says patients with the sniffles or a sore throat should stop demanding antibiotics. And then, there's the agricultural use of antibiotics.
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In "subtherapy," farmers mix low levels of antibiotics into poultry and livestock feed. Dennis Swan, a southwest Minnesota beef-cattle rancher, says low levels of antibiotics keep his animals healthy.
"If you didn't do it, you'd have a lot more pulls and you have to feed the individuals a lot heavier doses of it," Swan says. "It would cut my pulls (pulling them into a sick pen) 50 percent."
Subtherapy is so common, the Food and Drug Administration says 50 percent of U.S. produced antibiotics are used on the farm. And in some cases the drugs used in farm feed are the same antibiotics used to treat human illnesses. Since bacteria develop resistance to bacteria over time, scientists fear that exposing germs to low levels of antibiotics will dramatically speed up the resistance process. And since the bugs are developing on the farm, scientists worry "superbugs" will get into the food supply and become a threat to farm workers.
On his Dodge County farm in 1984, Mike Noble used a variety of antibiotics to treat an e-coli outbreak among his hogs. The strain survived six different antibiotics. Each day, Noble's family would round up the hogs and deliver the antibiotics orally.
Noble's six-year-old son helped. One night the child developed a high fever and stomach pains. Doctors suspect a resistant strain of e-coli had entered the boy's body. Noble says his son's illness wouldn't respond to any treatment. "I'm sitting here with an only child and I'm running a system that hasn't been working for me and actually is endangering the lives of my family. No one ever told me that that's a possibility," he said.
Noble's son is healthy now. But he wonders why the FDA has waited so long to address antibiotic use. Scientists have called for a ban on the use of certain antibiotics on the farm since the 1970s. The FDA refused to implement the ban, deciding there wasn't enough scientific evidence to support it. Scientists now believe they have proof that agricultural use of antibiotics contributes to human health problems.
In a lab at the Minnesota Department of Health, epidemiologists test antibiotics effectiveness on certain strains of bacteria. In petri dishes, a moss-colored film fills the container. The film is living bacteria. In some dishes, a clear circle surrounds a tablet. In others, the film envelops the tablet. Those circles around the pill mean the antibiotic has killed the bacteria. In the others, the antibiotic has no effect on the bugs. These bugs have become resistant.
Kirk Smith is a state epidemiologist. Last year, he and Michael Osterholm published the first major paper in the United States linking antibiotic use on the farm to the dinner plate. Smith says they tested camplyobacter, the most common form of food-borne illness in the United States.
For years, doctors prescribed flouroquinolones to fight the bacteria. But Smith says the drug has lost some of its effectiveness. In 1992, 1.2 percent of the camplyobacter cases in Minnesota were resistant to the drug. In 1998, camplyobacter resistance jumped to 10 percent. Smith says the increase in resistance is directly linked to the 1995 FDA approval of the drug for use by farmers to treat respiratory infections in chickens.
"The resistant strains that we found in chickens in grocery stores basically had identical DNA fingerprints as the resistant strains recovered from humans that were acquired here in Minnesota," says Smith.
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"It is something as a society we're not really prepared for."
- Dr. Michael Osterholm ( Hear more) | |
Flouroquinolones is commonly used to treat many stomach disorders. Resistance to the drug means doctors have to experiment with other antibiotics. As result, stronger antibiotics are used to combat common infections. Over time, those stronger antibiotics will lose their effectiveness.
The Food and Drug Administration is under pressure to act.
Dr. Steven Sundlof, the director of the Center for Veterinary Medicine at the Food and Drug Administration, says the FDA has developed a preliminary set of regulations on agricultural antibiotic use. Sundlof says the agency is considering a mandatory resistance testing for all new human and animal antibiotics. He says antibiotics used in both animals and humans will also receive scrutiny. Sundlof says a ban on antibiotics that show bacterial resistance is possible.
"The general scientific community is in agreement that there is a problem," he says.
Much of the agricultural industry opposes any new guidelines. They say restricting antibiotics use will threaten the food supply and increase production costs for farmers. The FDA will take public comment on the proposed regulations next month and expects to unveil the new policy early next year.
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