About half of antibiotics prescribed are unnecessary or inappropriate, the agency says, and overuse has helped create bacteria that don't respond, or respond less effectively, to the drugs used to fight them.
"Antibiotics are a shared resource that has become a scarce resource," said Dr Lauri Hicks, a medical epidemiologist at the CDC. She's also medical director a of new programme, Get Smart: Know When Antibiotics Work. "Everyone has a role to play in preventing the spread of antibiotic resistance," Hicks said.
The stakes are high, said Dr Arjun Srinivasan, CDC's associate director for health care-associated infection prevention programmes. Almost every type of bacteria has become stronger and less responsive to antibiotic treatment, he said.
Superbugs becoming more common
Most strains of antibiotic-resistant bacteria are still found in health care settings, such as hospitals and nursing homes. Yet superbugs, including MRSA (methicillin-resistant staphylococcus aureus) are increasingly found in community settings, such as health clubs, schools, and workplaces, said Hicks.
Community-associated MRSA (CA-MRSA), a strain that affects healthy people outside of hospitals, Hicks said that "people who would normally be treated with an oral antibiotic are requiring more toxic medications or, in some instances, admission to a hospital. We've seen this with pneumonia, too, and I worry we'll start to see it with other types of infections as well."
Other infections that resist antibiotic treatment include:
- E. coli. A new strain, ST131, was a major cause of serious resistant infections in the US in 2007, a study published this year in Clinical Infectious Diseases found. If the strain gains one more resistance gene, the study said, it may become almost untreatable.
- Gonorrhoea. Only one last class of antibiotics - cephalosporin - is recommended to treat this sexually transmitted disease.
- XDR-TB (extensively drug-resistant tuberculosis). While many TB strains resist at least one antibiotic used to treat them, XDR-TB is resistant to virtually all of them.
Just as antibiotic resistance is rising, the antibiotic arsenal is shrinking. The FDA has approved just 10 new antibiotics since 1998. "But in our opinion, it's as important to improve [antibiotic] use as it is to develop new drugs," said Srinivasan.
Antibiotic resistance has two main causes, said Philip Tierno, director of clinical microbiology and immunology at New York University's Langone Medical Center. The first is overprescribing.
"About six billion prescriptions are written annually in this country, about half of them for antibiotics," he said. "Of those written for antibiotics, the CDC thinks about half are improper."
Second, food animals such as chickens, cattle and hogs are given massive amounts of antibiotics, mainly to spur growth. "Of the 25 million pounds of antibiotics given to livestock per year, only three million pounds are given to treat disease," said Tierno. Earlier this year, concerns about antibiotic resistance led the FDA to recommend that farmers stop using antibiotics to promote growth in livestock.
To protect antibiotics' effectiveness, the CDC recommends the following:
- Take the antibiotic exactly as prescribed, and finish it even if you start to feel better. That way, bacteria can't survive and re-infect you.
- Throw out leftover antibiotics.
- Don't ask your doctor for an antibiotic if you have a cold or the flu. They're caused by viruses, so antibiotics won't help.
- If you think you have strep throat, ask to be tested. Only a test can tell if your sore throat is caused by a bacterial infection and thus requires an antibiotic.
- Don't take an antibiotic prescribed for someone else. Taking the wrong medicine may delay the right treatment and allow bacteria to multiply.
- If your child has an ear infection, watch and wait. This method is the best way to treat childhood ear infections, which are often caused by a virus, according to a new study published this week the Journal of the American Medical Association .
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