But what public health advocates want to see is a decline, as has happened with young children, once the group most likely to use antibiotics.
“It’s hard to feel heartened about a plateau when overuse remains so prevalent,” said Dr. Caleb Alexander, co-director of the Johns Hopkins Center for Drug Safety and Effectiveness. “It’s as perennial as the grass.”
Antibiotic overuse contributes to a serious public health threat by creating drug resistance, as infectious bacteria adapt to the medications. Drugs then lose their effectiveness, forcing doctors to resort to more toxic, less potent, often costlier options. Two million Americans get antibiotic-resistant infections annually, the C.D.C. has reported, and 23,000 die from them.
Moreover, antibiotics interact badly with many of the other drugs older adults take, including such widely used medications as statins, blood thinners, kidney and heart medications. “The number of potential drug-drug interactions with antibiotics are vast,” Dr. Alexander cautioned.
Some antibiotics also have dismaying, even alarming, side effects in themselves. In 2013, the F.D.A. issued a warning about azithromycin, which in rare cases leads to dangerous heart arrhythmias.
But for more than a decade, the agency’s most frequent target has been fluoroquinolones.
It has warned that this class of antibiotics (including Cipro and Levaquin) increases the risk of tendinitis and tendon rupture, particularly in older adults; that it can cause the nerve damage called peripheral neuropathy; and that it can lead to hypoglycemia (low blood sugar).
“One of the most common problems for older adults are changes in mental status — getting anxious, getting loopy,” said Dr. Sara Cosgrove, medical director of the Johns Hopkins Hospital’s Adult Antimicrobial Stewardship Program. “These drugs get into the brain.” The F.D.A. also warned of the problem in July.