Study design: Retrospective case control study.
Objective: To determine prevalence and risk factors for intraoperative bacterial contamination in posterior spinal deformity surgery.
Summary of background data: The prevalence of deep surgical site infection in pediatric spinal deformity surgery varies from 1% to 14%. Little evidence exists about the incidence and role of intraoperative bacterial contamination.
Methods: A total of 114 cases of pediatric posterior instrumented deformity surgery were retrospectively identified. All patients received preoperative and every 4-hour intraoperative antibiotics and 3M Ioban 2 Antimicrobial Incise Drape. Preoperative photographs of patients' backs were used to correlate presence of back acne with contaminant bacteria. Laboratory cultures were obtained from paraspinal muscle debrided before closure.
Results: Of the 114 cultures obtained, 26 (23%) were positive in 21% of idiopathic, 37% of neuromuscular (P = 0.02), and 14% of congenital patients. Contaminant bacteria included Propionibacterium acnes (69%), Staphylococcus (23%), Coryneform (4%), and Clostridium (4%). P. acnes was seen only in children 11 years or older (P = 0.02) and only with back acne (P < 0.0001). Eight of 19 (42%) patients with pelvic fusion had positive cultures (P = 0.04) and all 8 were neuromuscular patients. Eighty-one percent of culture-positive patients were older than 11 years (P = 0.01). Three of 114 (2.7%) patients developed an early deep surgical site infection, all with positive cultures (P = 0.01).
Conclusion: Neuromuscular patients fused to the pelvis, children older than 11 years, and surgery duration greater than 6 hours were associated with positive cultures. Back acne is a preventable risk factor for P. acnes seeding. Intraoperative bacterial contamination indicates a need to consider the type of surgery and patient age to determine prophylactic antibiotics and other modalities to prevent infection.