As the United Nations General Assembly (UNGA) meets in New York this week, one of the topics the global leaders will discuss is antibiotic overuse and the growing problem of microbes—so-called superbugs—that are resistant to the current antibiotics available today.

It’s only one of a handful of times the UNGA has discussed a health issue, but the growing problem is concerning enough that some leaders see it as a threat to economic and social stability.

The problem is a familiar one, but the challenge is to find ways to address it. In a new study published in JAMA Internal Medicine, researchers highlight just how daunting that challenge is.

In the first and most comprehensive look at how hospitals in the U.S. use antibiotics, the scientists report that between 2006 and 2012, rates of antibiotic use haven’t changed much among more than 300 hospitals, despite the fact that awareness of antibiotic resistance was emerging during that time, especially in the form of resistant bugs such as C. difficile and S. aureus. Each year in the U.S., two million people are infected with bacteria that can’t be treated with existing antibiotics, and 23,000 of them die.

“This is the first time we have national estimates for what is going on in hospitals,” says Dr. Arjun Srinivasan, associate director of health care associated infection prevention programs at the Centers for Disease Control and Prevention and one of the co-authors of the study.

And what the data is showing is disturbing. The fact that use of antibiotics remains the same and isn’t declining is concerning enough, since it hints that doctors are still prescribing drugs at the same rate as they have in the past, despite recent studies showing that many prescriptions aren’t necessary and are for the wrong types of infections for which antibiotics don’t work.

Even more worrisome, the study found that the types of antibiotics being used more often are the third and fourth generation drugs that are typically considered last resort medications to treat infections resistant to other classes of antibiotics. Use of older antibiotics went down during the study period while prescriptions of newer, broad spectrum antibiotics increased anywhere from three times to 18 times, depending on the class.

The study didn’t analyze why these drugs were being prescribed more, but one reason could be that doctors are trying to treat more difficult infections that won’t respond to the older drugs. “We now know what the problem is: use of the these agents has gone up. The question now is, ‘Why?’” says Srinivasan of the last-resort antibiotics. “How much of the increase in use is because doctors are treating harder-to-treat infections? How much is fear of a hard-to-treat infection that isn’t actually there? How much is even misunderstanding that they’ve heard of resistant infections, and think they need to use a stronger drug, but don’t actually need to?”

Those answers will have to come from future research, he says, as well as more detailed information on how recently adopted efforts to control overuse of antibiotics are working. Since the study ended in 2012, more intensive programs to regulate doctors who prescribe antibiotics, as well as monitor hospital use of the drugs, have been in put in place around the country. New guidelines for helping hospitals and doctors adopt more stringent antibiotic practices have also been available, and new calls for stronger stewardship from the government, including a National Action Plan and a White House summit, have also raised awareness and accountability surrounding the issue.

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