The significance of the initial inflammatory marker levels on isolating a causative organism in patients with pyogenic spinal infection

Objective Pyogenic spinal infection (PSI) is an increasingly common presentation to spinal units in the UK. Its investigation and diagnosis is often delayed. The purpose of this study was to determine the prognostic significance of the inflammatory marker levels on admission on achieving a positive microbiological diagnosis in patients with PSI. Study design Retrospective case series review of all patients presenting with PSI to our unit. Subjects Clinical data were collected on 96 consecutive patients diagnosed with a PSI over a 7-year period. Patient < 18 years at time of presentation or who had previous spinal surgery were excluded. Outcome Measures Positive blood and/or tissue culture, and requirement for surgery. Continuous data were compared using the Wilcoxon rank-sum test∗∗ and logistical regression remodelling was assessed using the Spearman correlation∗. Categorical data was analysed using Fisher's exact test. ∗∗∗ Results The C-reactive protein was statistically significant for; duration of preceding symptoms (p=0.0003)∗, isolation of a causative organism (p< 0.0001)∗∗, positive biopsy culture (p=0.0016)∗∗ and requirement for surgery (p=0.031)∗∗. The White Blood Cell (WBC) count was statistically significant for; duration of preceding symptoms (p< 0.0001)∗, isolation of a causative organism (p = 0.0003)∗∗, positive biopsy culture (p=0.0023)∗∗. The majority of patients who had a positive tissue culture had a positive blood culture (p< 0.0001)∗∗∗. Conclusion The inflammatory marker levels on admission are a useful prognostic marker for isolating a causative organism in patients with PSI and help guide treating surgeons to whether proceeding to biopsy is likely to be a helpful investigation. Tissue biopsy in patients with PSI is only marginally superior to blood culture alone.