NEW YORK — U.S. doctors are prescribing enough antibiotics to give them to four out of five Americans every year — an alarming pace and the latest piece of evidence suggesting the drugs are being overused, according to a new government study.
Overuse is one reason antibiotics are losing their punch, making infections harder to treat and encouraging the rise of “superbugs” resistant to the drugs.
The Wednesday report also yielded the first look at antibiotic prescriptions by state, finding them highest in the South and Appalachia.
There is no scientific consensus on an appropriate level of antibiotic use. But some experts said the new study's results were disturbing and said that rates were probably excessive even in the lowest-use states.
Antibiotics have been commonly available since the 1940s and have worked wonders at saving patients with infections ranging from pneumonia to sexually spread diseases. But bacteria, meanwhile, have increasingly developed the power to shrug off antibiotics, leading to a sort of microscopic arms race.
The problem is magnified, experts say, when a patient doesn't take all the antibiotics prescribed or takes them for the wrong reasons, encouraging bacteria to survive the assault and adapt.
The U.S. Centers for Disease Control and Prevention is now tracking at least 20 strains of drug-resistant bacteria.
It was CDC researchers who conducted the latest study, analyzing a national prescription drug database for 2010. The findings were published in Thursday's New England Journal of Medicine.
It is the first study to examine antibiotic use among all Americans, not just specific groups such as Medicare patients.
All told, doctors prescribed 258 million courses of antibiotics in 2010. That's for a population of nearly 309 million, which translates to 833 prescriptions per 1,000 people.
But the rate was much higher in West Virginia, Kentucky and Tennessee — about 1,200 per 1,000 people. On the low end were Alaska, Oregon and California, at 600 or below.
Nebraska, at 948, and Iowa, at 871, were in the upper-middle range.
Why the differences?
One possibility is Southerners suffer more infections. Southern states have the highest rates of obesity and diabetes, which tend to be accompanied by more infections, said the CDC's Dr. Lauri Hicks, one of the researchers. “So some of that prescribing may be warranted,” she said.
On the other hand, the South also has higher rates of certain respiratory infections, including bronchitis, and the study found the most often prescribed antibiotic was azithromycin, commonly used for bronchitis symptoms. But that's a problem because bronchitis is usually caused by a virus — impervious to such antibiotics.
So “some of the prescribing may not be warranted,” Hicks said.