Risk Factors Preventing Identification of the Microorganism Causing Vertebral Osteomyelitis.

Study design: Retrospective study.

Objective: To elucidate the factors influencing the identification of causative microorganisms in vertebral osteomyelitis (VO) and the effectiveness of different culture methods in increasing the identification rate.

Methods: A total of 252 patients diagnosed with and treated for VO at a single hospital were enrolled. The results of various culture methods were reviewed along with the clinical data of the patients retrospectively.

Results: Microbiological diagnosis was achieved in 210 out of 252 patients (83.3%). Diagnostic percentages of blood cultures, CT-guided drainage, fluoroscopic disc biopsy, and intraoperative specimens were 73.6%, 73.9%, 27.6%, and 50.8%, respectively. Staphylococcus aureus was the most common pathogen (85 cases, 40.5%). Higher White Blood Cell (WBC) count, lower serum albumin (ALB) level, epidural abscess, and absence of prior antibiotic exposure were significant predictors of positive culture results across all culture methods. Prior antibiotic exposure was the most significant predictor of negative outcomes (OR 0.24). Blood culture results correlated with body temperature, C-reactive protein (CRP), ALB, and prior antibiotic exposure. A shorter duration of antibiotic administration before culture was associated with an increased likelihood of positive blood culture results.

Conclusions: This study demonstrated that laboratory findings indicating a high inflammatory response (elevated WBC count, CRP level, and body temperature), lower ALB level, presence of epidural abscess, absence of prior antibiotic exposure, and shorter duration of antibiotics were significant predictors of positive culture results. Blood cultures should be conducted in the presence of high inflammation levels to improve microorganism identification rates.