Beware of magical discoveries: They generally require careful use lest the magic wear off.

Antibiotics, at one point seen as miracle drugs providing cures for previously fatal illnesses, are among the discoveries that have been used too carelessly, giving rise to an era of resistant infections. Scientists have been concerned about these resistant bacteria for many years. But doctors have continued to prescribe antibiotics unnecessarily for illnesses such as colds that are caused by viruses, not bacteria.

So the report on resistant infections released last week by the national Centers for Disease Control and Prevention didn’t reveal startling new information as much as it solidified understanding of the toll taken by these infections. It should serve as a wake-up call to the medical profession, and especially to Congress, to move more swiftly to preserve the usefulness of antibiotics.

The livestock industry alone consumes some 80 percent of the antibiotics in this country — not to treat illness in the animals but to promote growth and prevent infections from sweeping through crowded pens.

It’s true that antibiotics help produce food more cheaply. But society as a whole is picking up the growing tab in the form of resistant bacteria. The tally according to the CDC: 2 million Americans sickened each year, 23,000 deaths, $23 billion a year in added medical costs and $35 billion in lost productivity. And the numbers are expected to worsen.

The Food and Drug Administration is offering only guidelines for the agriculture industry, not regulations, and experience has shown that the industry does not respond to voluntary restrictions. Congress, which has rejected more stringent rules on antibiotic use for more than a decade, must act while most antibiotics still retain their power to cure.