According to a CDC report, the use of broad-spectrum antibiotics is on the rise in U.S. hospitals, even as concerns of antibiotic-resistant bacteria grow. The study’s findings were published in the Journal of the American Medical Association Internal Medicine Sept. 19.

The authors wrote that their findings could help inform new ways to identify specific bacterial threats and use targeted treatment approaches instead of broad-spectrum drugs that could contribute to evolving antibacterial resistance.

“Appropriate antibiotic prescribing improves patient safety, slows development of antibiotic resistance, and reduces wasted resources,” the authors pointed out.

The study examined 166 million patient days’ worth of hospital stays, a total of 34 million discharges recorded throughout 552 hospitals between 2006 and 2012. The data was gathered from the Truven Health MarketScan Hospital Drug Database.

The researchers found that overall, there was not a significant increase in use of antibiotic use in hospitals in the six years. It was the increased use of broad-spectrum antibiotics that was especially concerning, the authors wrote.

In total, the found that about 55 percent of patients received an antibiotic at some point during their hospital stay. For 1,000 patient days, there was an average of 755 days of antibiotic therapy nationally. Overall, days of antibiotic use per patient days only increased about 5.6 days over the six years.

But certain antibiotics did show high increases in therapy days per patient days, and they are the antibiotics that could be contributing most to antibiotic resistance. Third- and fourth-generation cephalosporins saw an increase of 10.3 days of therapy per patient days in the six years, macrolides saw a 4.8-day increase, glycopeptides saw a 22.4-day increase, β-lactam/β-lactamase inhibitor combinations saw an increase of 18 days, carbapenems had 7.4 more therapy days per patient days at the end of the six years and tetracyclines had an increased use of 3.3 therapy days per patient days between 2006 and 2012.

The study called for ongoing monitoring of this kind of antibiotic use and antibiotic use in hospitals in general as public and private players in the healthcare industry work to reduce the speed and even try to reverse some types of antibiotic resistance.

The authors wrote, “Because inappropriate antibiotic use increases the risk of antibiotic resistance and other adverse patient outcomes, continued monitoring of antibiotic use is critical to future improvements in patient safety.”