Background: Postoperative spinal wound infections are relatively common and are often associated with increased morbidity and poor long-term patient outcomes. The purposes of this study were to identify the common bacterial flora on the skin overlying the lumbar spine and evaluate the efficacy of readily available skin-preparation solutions in the elimination of bacterial pathogens from the surgical site following skin preparation.
Methods: A prospective randomized study was undertaken to evaluate 100 consecutive patients undergoing elective lumbar spine surgery. At the time of surgery, the patients were randomized to be treated with one of two widely used, and Food and Drug Administration (FDA)-approved, surgical skin-preparation solutions: ChloraPrep (2% chlorhexidine gluconate and 70% isopropyl alcohol) or DuraPrep (0.7% available iodine and 74% isopropyl alcohol). Specimens for aerobic and anaerobic cultures were obtained prior to skin preparation (pre-preparation), after skin preparation (post-preparation), and after wound closure (post-closure). A validated neutralization solution was used for each culture to ensure that the antimicrobial activity was stopped immediately after the sample was taken. Positive cultures and specific bacterial pathogens were recorded.
Results: Coagulase-negative Staphylococcus, Propionibacterium acnes, and Corynebacterium were the most commonly isolated organisms prior to skin preparation. The overall rate of positive cultures prior to skin preparation was 82%. The overall rate of positive cultures after skin preparation was 0% (zero of fifty) in the ChloraPrep group and 6% (three of fifty) in the DuraPrep group (p = 0.24, 95% confidence interval [CI] = 0.006 to 0.085). There was an increase in positive cultures after wound closure, but there was no difference between the ChloraPrep group (34%, seventeen of fifty) and the DuraPrep group (32%, sixteen of fifty) (p = 0.22, 95% CI = 0.284 to 0.483). Body mass index (BMI), duration of surgery, and estimated blood loss did not a show significant association with post-closure positive culture results.
Conclusions: ChloraPrep and DuraPrep are equally effective skin-preparation solutions for eradication of common bacterial pathogens on the skin overlying the lumbar spine.
Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.
1Departments of Orthopaedic Surgery (J.W.S., B.M.W., M.T.N., and M.H.H.) and Neurological Surgery (P.A.S., J.C.L., and J.K.S.), Northwestern University Feinberg School of Medicine, 676 North St. Clair Street, Suite 1350, Chicago, IL 60611