Surgical Site Infections following Spine Surgery for Non-idiopathic Scoliosis

Background: Surgical site infections (SSIs) following spine surgery in children and adolescents with nonidiopathic scoliosis are associated with increased morbidity and health care costs. Potentially modifiable risk factors for SSIs merit additional study in this population. Methods: A single-center, retrospective cohort study was performed from August 2008 through December 2013 in children and adolescents undergoing surgery for nonidiopathic scoliosis to determine the trends in SSI rate and causative microorganisms. A standardized perioperative antimicrobial prophylaxis regimen was developed from September-October 2008. Potential risk factors for SSIs were assessed by multivariable analysis using Poisson regression models. Fusion procedures and growing construct procedures were analyzed separately. Results: In all, 268 patients underwent 536 surgical procedures of whom 192 underwent 228 fusion procedures, 89 underwent 308 growing construct procedures, and 13 underwent both procedures during the study period. Twenty-one SSIs (3.9% of surgical procedures and 7.8% of patients) occurred within 90 days of surgery, 17 SSIs occurred after fusion procedures (4.5% of procedures and 8.9% of patients), and 4 SSIs occurred after growing construct procedures (1.3% of procedures and 4.5% of patients). There were 9 polymicrobial SSIs (42.9%). Of the 31 bacterial pathogens isolated, 48% were Gram-negative organisms. Among patients undergoing fusion procedures, SSIs were associated with underdosing of preoperative cefazolin [relative risk (RR)=4.99; 95% confidence interval (CI), 1.89-17.43; P=0.012] and tobramycin (RR=5.86; 95% CI, 1.90-18.06; P=0.002), underdosing of intraoperative (RR=5.65; 95% CI, 2.13-14.97; P=0.001) and postoperative (RR=3.86; 95% CI, 1.20-12.40; P=0.023) tobramycin, and any preoperative or intraoperative underdosing (RR=4.89; 95% CI, 1.70-14.12; P=0.003), after adjustment for duration of surgery. No factors were associated with SSIs in those undergoing growing construct procedures. During the study period, the SSIs rate declined (P<0.0001). Conclusions: Underdosing of tobramycin and preoperative cefazolin were associated with an increased SSI risk among patients undergoing fusion procedures. Future multicenter studies should further investigate the generalizability of these findings. Level of Evidence: Level II - retrospective study.