Retrospective analysis of culture-negative versus culture-positive postoperative spinal infections

Retrospective analysis. This study aimed to investigate the characteristics, clinical features, and outcomes of culture-negative (CN) and culture-positive (CP) postoperative spinal infections (PSIs). Causative organism cultures and the use of adequate antibiotics are essential for treating postoperative spinal wound infections. However, managing infected surgical sites with negative wound culture results is a common clinical problem. Although the outcomes of microbiologically confirmed PSIs have been well studied, the outcomes and clinical characteristics of CN PSIs have not been previously published. Between January 1995 and December 2014, 69 patients diagnosed with PSIs were enrolled. Enrolled patients were classified into 2 groups: CN (28 patients) and CP (41 patients). Baseline data, clinical manifestations, specific treatments, and treatment outcomes were compared with the groups. The overall rate of CN PSI was 40.6% (28/69). Baseline data and clinical manifestations were similar between the 2 groups. There were no significant differences in the duration of parenteral antibiotic use between the CN and CP groups. Revision surgery was required less often for the CN group (64.3%) than for the CP group (87.8%) (P = .020). Revision surgeries were repeated 0.82 times/case in the CN group and 1.34 times/case in the CP group (P = .014). Treatment outcomes, such as poor radiologic findings, need for additional anterior surgery, extension of fusion to adjacent segment surgery, and total length of hospital stay, were not different between groups. Revision surgery was performed less often for the CN group than for the CP group. From the perspective of revision surgery, CN PSIs have better prognosis than CP PSIs. However, clinical presentations and radiologic prognoses were not different between the two groups. We suggest that CN PSIs may be treated in the same way as CP PSIs.