Updated

A new study suggests that doctors in many hospitals are unnecessarily prescribing multiple antibiotics for several days when just one would do the job.

Health officials say overuse of antibiotics is helping to breed dangerous bacteria that are increasingly resistant to treatment.

Faced with an unknown infection, hospital doctors often prescribe a couple of antibiotics. But once the bug is identified, doctors are supposed to drop any unnecessary second antibiotic.

The research found that didn't happen in three-quarters of the 500 hospitals included in the research.

The Centers for Disease Control and Prevention released the paper Wednesday. The authors call it the first national study to look at the issue.