The evidence has been building, all pointing to the same critical public health problem. Several dangerous bacteria have become resistant to antibiotics -- largely because we demand the drugs from our doctors. Evidence also is emerging that antibiotics are overused in treatment of animals, too.

Yet, there's hope on the horizon, experts say. The CDC has launched a nationwide campaign aimed at informing the public about appropriate use of antibiotics. And the FDA has taken unprecedented action to pull antibiotics from use in treating -- and fattening -- livestock.

"We applaud the FDA's action," Margaret Mellon, PhD, director of the Food and Environment program at the Union of Concerned Scientists, tells WebMD. "We think this is a turning point for the agency in its handling of the antibiotic issue."

How did we get to this point?

Half of all Americans have mistaken beliefs about antibiotics, according to a study reported last year at the International Conference on Emerging Infectious Disease.

Before antibiotics became available in the 1940s, not much could be done to cure life-threatening bacterial infections. But antibiotics have been so successful in curing these infections that many people now believe -- erroneously -- that they can cure virtually any disease.

"We estimate that at least 40% of antibiotics used in doctors' outpatient offices across the country are being prescribed for conditions that are largely viral -- for which antibiotics have no effect," says Richard Besser, MD, pediatric and medical epidemiologist in the National Center for Infectious Diseases at the CDC.

"There seems to be this feeling by the general public that if you're coughing up something green or if it is coming out of your nose, you need an antibiotic," Besser tells WebMD. "That's just not true."

Physicians get pressure from patients -- and they're giving in to it, Besser says. "It's clear that clinicians are more likely to prescribe antibiotics if the patient wants one," he says. "If you look at the pressures on clinicians -- the amount of time it takes to explain the difference between viral and bacterial infections -- yet they have less and less time to spend with patients."

Some of the data:

Each year, 160 million antibiotic prescriptions are written for 275 million U.S. residents, but half of those prescriptions are unnecessary, according to a recent editorial in The New England Journal of Medicine.
　　Many people expect doctors to prescribe antibiotics for a bad cold -- and believe that those antibiotics help them get better faster, according to another study in NEJM. Many people think they can prevent more serious illnesses by taking antibiotics.
　　A CDC study of 366 family physicians and pediatricians in Georgia showed that although 97% thought that overly prescribed antibiotics were responsible for the development of resistant organisms, 86% prescribed antibiotics for bronchitis regardless of the duration of symptoms, 42% used them for colds, and 55% wrote antibiotic prescriptions for children with nonspecific upper respiratory infections to prevent ear infections -- largely because of parents' beliefs.

Even when parents know that antibiotics won't help their child's cold, they give in to pressure from day care workers, according to another study presented at last year's International Conference on Emerging Infectious Disease. Few day care providers knew that antibiotics would not end a cold more quickly or prevent it from spreading to other children, the study showed. The vast majority of these workers said they would keep children with colds in day care if they were taking antibiotics, but would send children home if they were not.

Common household soaps and detergents may even be contributing to the problem, according to researchers at Colorado State University in Fort Collins. Their study last year showed that exposure to the antiseptic triclosan, commonly used in these products, caused bacteria to gradually become resistant to several common antibiotics. In some cases, this increased their resistance as much as 500-fold. In some germs, resistance to triclosan translates into resistance to the drug used to treat tuberculosis; this is known as cross-resistance.

The fact that antibiotics are routinely used to fatten up cows, chickens, and pigs caught headlines recently. A report from the Union of Concerned Scientists, a nonprofit group, said that antibiotic use in livestock has jumped 64% since 1980. That's more than 25 million pounds per year, contrasted against about 3 million pounds of antibiotics used to treat humans yearly, the report said.

The result of all this overuse: increased numbers of antibiotic-resistant infections.

In fact, there's been a significant increase in the number of streptococcal -- strep -- infections resistant to multiple antibiotics, according to a CDC study published in the NEJM. "We're greatly concerned about that data," Besser says.

"That bacterial strain is responsible for bacterial meningitis [an infection of the lining of the brain], pneumonia, and is the leading cause of ear infections in children," he says. "It's responsible for an enormous amount of disease. It's a serious public health problem."

There's also been a significant rise in Salmonella food poisoning with strains resistant to the drug most commonly used to treat children with severe Salmonella infections. Numerous infections caused by the bacteria Campylobacter have been found resistant to a common class of antibiotics called fluoroquinolones, used to treat infections in chickens.

A "supergerm" form of the bacteria Enterococcus -- which invades surgical wounds, causing potentially deadly abdominal, urinary tract, and heart valve infections -- also has developed. Although the bacteria are resistant to virginiamycin, an antibiotic also widely used in the treatment of food-producing animals for about 26 years, some of these infections can be treated with another antibiotic, vancomycin.

It's a frightening issue -- but progress is being made to bring things under control.

About 30% fewer pediatricians are writing antibiotic prescriptions for children's infections, Besser tells WebMD. "That corresponds with increased awareness across the country of the problem of antibiotic resistance." Besser heads the CDC's nationwide campaign aimed at appropriate use of antibiotics.

One company -- Abbott Laboratories -- has voluntarily withdrawn a fluoroquinolone antibiotic for use in poultry, Mellon says. "We're hoping that Bayer [producer of Baytril, the other fluoroquinolone used in poultry] will do the same," she says.

Such actions have significant implications for this whole serious problem, Mellon tells WebMD. "It says that the FDA, after a 20-year hiatus, is back in action in animal antibiotics," she says. "We're delighted. Our hope, of course, is that this is the beginning of their efforts -- not the only cancellation that the agency undertakes."

The FDA also has proposed that labels on antibiotics contain information about the emergence of drug-resistant bacterial strains -- as a reminder to physicians to use them only when a bacterial infection is either "proven or strongly suspected."

Also, new antibiotics are being developed -- and old antibiotics are being redesigned.

Two new antibiotics -- called telithromycin and Zyvox -- have been approved by the FDA in recent months and are targeted at killing some drug-resistant supergerms as well as standard infections like pneumonia, chronic bronchitis, sinus infections, and strep throat.

Zyvox also has been FDA approved for the treatment of "superinfections" and should be "saved only for situations when there is no other choice," according to the FDA. An antibiotic called Synercid (approved in 1999) and others remain the first line of defense, according to the FDA.

And microarray, or "gene chip" technology, looks promising in allowing researchers to develop antibiotics that put different, very selective pressures on the bacteria as they attempt to dodge antibiotic bullets.

Yet, another approach is to take an old drug and redesign it, Stuart B. Levy, MD, director of the Center for Adaptation Genetics and Drug Resistance at Tufts University School of Medicine, tells WebMD. His company, called Paratek Pharmaceuticals in Boston, currently is involved in revamping one of the early antibiotics, tetracycline.

"Gene technology does give us a new approach to new antibiotics," Levy says. "But I do think there's merit in taking an old drug like tetracycline and restructuring it ... to redesign an antibiotic so it's not subject to resistance."

© 2001 WebMD Corporation. All rights reserved.