Preop nasal screening for S. aureus significantly lowered postop spine infection rates

Spinal patients who underwent screening had a 0.7% surgical Staph infection rate vs. 1.5% of the unscreened group

AUSTIN, Texas — Using a novel preoperative nasal screening protocol may significantly decrease the rate of postoperative Staphylococcus aureus infections in patients undergoing spinal procedures, according to a study presented here.

David Shapiro, MD, and colleagues at Northwestern University Feinberg School of Medicine, Chicago, compared rates of postoperative surgical Staphylococcus aureus infections between two patient groups who underwent major spinal surgery. The study included 673 patients who received preoperative nasal screening using real-time polymerase chain reaction (PCR) testing and 699 patients who received surgery before the screening protocol was implemented.

Of the PCR-tested group, 29% were positive for S. aureus and subsequently were treated with mupirocin for 5 days before surgery.

Postoperatively, investigators found an overall surgical S. aureus infection rate of 0.7% among patients screened preoperatively compared to 1.5% for the non-screened group.

"PCR is a cost-effective way and [an] easy way to decrease the rate of postoperative Staph infections," said Shapiro, in a presentation at the North American Spine Society 22nd Annual Meeting. "Real-time PCR allows for prompt initiation of therapy and demonstrates a statistically significant improvement in the rate of postoperative Staph infections."

Investigators obtained two preoperative nasal swabs from patients in the PCR group. "One swab was placed into a bacterial lysis solution containing achromopeptidase, while the other was saved for culture and sensitivity testing, and strain testing," Shapiro said.

"The DNA liberated from the swab was used as a template for real-time PCR with primers to detect [S. aureus]," he said.

PCR testing magnifies the DNA for bacterial identification without waiting several days for culture incubation, Shapiro noted.

"This is the first time, to our knowledge, that this test has been put to the use for preoperative nasal screening for [S. aureus]," he said. "It was developed at our hospital and it is not FDA approved."

For more information:
Shapiro D, Peterson L, Shapiro G. Use of a real-time PCR assay to detect Staphylococcus Aureus as part of a successful nasal screening program for major spine surgery. Paper #60. Presented at the North American Spine Society 22nd Annual Meeting. Oct. 23-27, 2007. Austin, Texas.