ATLANTA – Calling up to half of antibiotic use in humans and much of antibiotic use in animals “unnecessary,” the Centers for Disease Control and Prevention is recommending steps to slow the development of antibiotic resistant bacteria. A new report from the C.D.C. said more than 2 million people in the United States get infections that are resistant to antibiotics and at least 23,000 people die as a result.

“Antibiotic resistance is rising for many different pathogens that are threats to health,” said Tom Frieden, M.D., director of the C.D.C. “If we don’t act now, our medicine cabinet will be empty and we won’t have the antibiotics we need to save lives.”

Antibiotics are commonly used in food-producing animals to prevent, control, and treat disease, and to promote growth. As in humans, the C.D.C. said it is important to use antibiotics in animals responsibly. To help ensure that medically important antibiotics are used judiciously in food-producing animals, the Food and Drug Administration recently proposed guidance describing a pathway for using the drugs only when medically necessary and targeting their use to only address diseases and health problems.

“Every time antibiotics are used in any setting, bacteria evolve by developing resistance,” said Steve Solomon, M.D., director of the C.D.C.’s office of antimicrobial resistance. “This process can happen with alarming speed. These drugs are a precious, limited resource — the more we use antibiotics today, the less likely we are to have effective antibiotics tomorrow.”