Findings suggest powder may reduce rate of S aureus

Research presented at the Orthopaedic Trauma Association 2015 annual meeting provides "provocative evidence" that topical vancomycin powder may alter the bacteriology of surgical site infections (SSIs), and may thus play an important role in preventing infection after fracture fixation surgery, according to Robert V. O'Toole, MD, the study's senior author.

"SSI remains a big problem in orthopaedic trauma," said Dr. O'Toole. "Retrospective studies in the spine literature have hinted that applying topical vancomycin powder might be a way to reduce SSI, but no large studies on using vancomycin powder to prevent SSI in orthopaedic trauma have yet been completed.

"Our study doesn't prove topical vancomycin powder is effective in reducing the overall incidence of SSI," emphasized Dr. O'Toole, "but it does indicate that vancomycin seems to affect the bacteriology."

Conducting the study
The retrospective review focused on fracture fixation patients with positive intraoperative cultures who received topical intrawound vancomycin powder. The patients were treated at a single academic medical center between October 2012 and November 2014. A total of 91 patients (99 distinctive injuries) met the inclusion criteria.

Dr. O'Toole; lead study author Rabah Qadir, MD; and their colleagues defined deep infections using criteria established by the Centers for Disease Control and Prevention. They identified baseline rates of Staphylococcus aureus from a recently published control group (n = 214) treated at the same institution prior to the use of topical vancomycin powder. In addition, they determined the baseline rate of deep infection in high-energy pilon, plateau, and calcaneus fractures from a recently published control group (n = 116) at the same institution.

The researchers, who used the Fisher exact test to compare categorical values, found a significantly lower rate of S aureus in patients who received vancomycin powder compared to infections in the cohort of patients before vancomycin powder was used (12.5 percent versus 58 percent, P = 0.03). They also identified a trend for a lower rate of methicillin-resistant S aureus (0 percent versus 32 percent, P = 0.06) and a lower infection rate in the 34 calcaneus, pilon, and/or plateau fractures treated with vancomycin powder compared to control group patients (0 percent versus 13 percent, P = 0.02).

Drawing conclusions
"We were pleased to see the rate of S aureus decrease in the patient cohort that received vancomycin powder," said Dr. O'Toole. "There was also a significant finding indicating that the powder reduced the rate of methicillin-resistant S aureus. This seems to indicate that vancomycin affects the bacteriology of SSI, and perhaps lowers the incidence of SSI."

Dr. O'Toole acknowledged that this study was not designed to answer the question of whether vancomycin powder reduces the overall infection rate, as it was neither randomized nor large enough. He noted, however, that a large, randomized trial is currently being performed by the Major Extremity Trauma Research Consortium in an effort to answer that question. It will be some years, however, before the results of that research are available.

"Like a lot of other investigators, we are really excited about the potential for topical vancomycin powder to reduce the incidence of SSI in orthopaedic trauma," he said. "Our findings—which need to be confirmed in larger, randomized, controlled trials—give more credence to the idea that vancomycin powder may do something important to reduce the incidence of SSIs after fracture fixation surgery."

Coauthors for "Topical Vancomycin Powder Decreases the Incidence of Staphylococcus aureus" with Drs. O'Toole and Qadir are Timothy Costales, BS; Max Coale, BA; Timothy Zerhusen, BS; and Manjari Joshi, MD. The authors' disclosure information can be accessed at www.aaos.org/disclosure

Bottom Line

• This retrospective review of surgically treated fracture fixation patients with positive intraoperative cultures found that patients who received topical intrawound vancomycin powder had a significantly lower rate of S aureus bacteria than patients who did not receive vancomycin. There was also a trend for a lower rate of methicillin-resistant S aureus bacteria in vancomycin-treated patients.
• In addition, the researchers also found a lower infection rate in 34 high-energy calcaneus, pilon, and/or tibial plateau fractures treated with vancomycin powder compared to previous controls treated without vancomycin powder.
• The findings suggest that vancomycin affects the bacteriology of SSI and may lower its incidence.