Nancy A. Melville

May 21, 2015

Washington, DC — The use of intrawound vancomycin powder shows efficacy in the prevention of spinal surgical site infections, with the greatest benefit in high-volume institutions, according to a meta-analysis.

"The evidence for the use of vancomycin powder is still developing, but we found the greatest impact appears to be in high-volume spinal surgery institutions with high baseline infection rates and among patients with higher-risk factors, such as obesity, diabetes, or having large intermittent procedures," said first author Nickalus R. Khan, MD, from the University of Tennessee Health Sciences Center in Memphis.

Their findings were presented here at the American Association of Neurological Surgeons (AANS) 83rd Annual Meeting.

The meta-analysis included 355 spinal surgery studies and focused on 9 studies that included control groups with patients who were not treated with vancomycin powder.

Eight of the studies included level III evidence, and one study was a randomized controlled trial with level II evidence.

In total, the control groups had approximately three times the rate of infection compared with the treatment groups: 95 infections among 2424 cases (3.9%) in the control groups compared with 28 infections (1.1%) among 2368 cases treated with vancomycin (P < .01).

Patients who had implants showed a significantly greater risk reduction for surgical site infection with vancomycin powder (P = .023) compared with noninstrumented spinal operations (P = .226).

"We found in this meta-analysis of nine studies with over 2000 patients in both the treatment and control groups that the use of intrawound vancomycin powder in open spine surgery decreased the overall risk of surgical site infection by one third, with no reported complications, Dr Khan said.

With a recent report of 100,449 surgical site infections now surpassing central line, urinary tract, and other infections, the findings are important, Dr Khan added. "Up to $10 million a year is spent in fighting surgical site infections," he said.

"The current protocol of preoperative antibiotics has been shown to provide coverage for fewer than half staphylococcal organisms found in hospitals," he added.

Intravenous vancomycin has not been shown to be more effective than intravenous cyclosporine in treating surgical site infections. Vancomycin powder, meanwhile, is attractive for having low systemic toxicity.

He added, however, that the benefit is still not clear for widespread use in all spinal operations.

In looking at additional trends for vancomycin use, Dr Khan and his team found that centers with infection rates greater than 10% in the control group showed statistically significant reductions in infection associated with vancomycin use, while those with lower infection rates did not show this difference.

"Based on the findings, we hypothesize that the indiscriminate application of vancomycin in any patient undergoing a spinal operation is probably not appropriate."

Susan Goobie, MD, an assistant professor of anesthesia at Harvard Medical School and senior assistant in Perioperative Anesthesia, at Children's Hospital, in Boston, Massachusetts, agreed that the findings suggest the best use in high-risk patients.

"The number needed to treat (36) is high, so I probably would only support giving this in high-risk cases, and not idiopathic," she told Medscape Medical News.

Otherwise, she added that "this is a very well done meta-analysis with pretty good results to support vancomycin. There is only one prospective randomized study, however, which is the gold standard."

The authors and Dr Goobie have disclosed no relevant financial relationships.

American Association of Neurological Surgeons (AANS) 83rd Annual Meeting. Abstract 672. Presented May 4, 2015.

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