• Posted April 20, 2026

Extra Antibiotic Doesn't Reduce Infection Risk During Surgery To Fix Complex Fractures, Trial Finds

Adding an extra antibiotic powder doesn’t further reduce a person’s risk of infection during surgery to repair complex bone fractures, a new study says.

People had about the same rate of post-surgery infections whether doctors sprinkled one or two antibiotic powders into their surgical wound, researchers reported April 15 in the Journal of the American Medical Association.

“Surgeons should not expect benefit from this combination approach in routine practice,” researcher Nathan O’Hara, an associate professor of orthopedics at the University of Maryland, said in a news release.

Doctors currently sprinkle vancomycin powder into the surgical site of people with high-risk leg fractures, to reduce their risk of deep infections, researchers said in background notes.

But vancomycin only targets gram-positive bacteria that are seen commonly in surgical infections, researchers said.

It does nothing to prevent infection from gram-negative bacteria, which can also cause an infection after broken bones.

That led researchers to test whether adding tobramycin powder – which targets gram-negative bacteria – might further reduce infection risk.

For the clinical trial, researchers recruited more than 1,500 patients from 39 U.S. trauma centers, and randomly assigned them to receive vancomycin powder alone or the combination of vancomycin and tobramycin powders.

Results showed that infection rates between the two groups were not significant – 7.4% for those who received the combination versus 6.6% for those who got vancomycin alone.

“We specifically tested the common belief that adding an aminoglycoside like tobramycin would cut down gram-negative infections,” said principal investigator Dr. Robert O’Toole, chief of orthopedics at the University of Maryland’s R Adams Cowley Shock Trauma Center.

“That simply didn’t bear out,” he said in a news release. “Vancomycin alone remains a solid option for reducing gram-positive infections, but our data do not support routinely adding tobramycin powder.”

Infections following bone surgery “can lead to repeat operations, prolonged antibiotics, delayed healing and long-term disability, so infection control remains tantamount,” Dr. Mark Gladwin, dean of the University of Maryland School of Medicine, said in a news release.

“This well-designed study, drawing from diverse trauma centers nationwide with its high protocol adherence and follow-up, provides practical guidance for infection prevention protocols in orthopedic trauma,” Gladwin said.

More information

The U.S. Centers for Disease Control and Prevention has more on preventing surgical site infections.

SOURCE: University of Maryland, news release, April 15, 2026