Abstract and Introduction
Study Design: Prospective cohort study.
Objective: We aimed to determine the 2-year survival and to identify clinical and microbiological characteristics of patients with native vertebral osteomyelitis (VO) as compared to postoperative VO to find further strategies for improvement of the management of VO.
Summary of Background Data: A relevant subgroup (20%–30%) of patients with VO has a history of spine surgery. Infection in these patients might be clinically different from native VO. However, clinical, microbiological, and outcome characteristics of this disease entity have not been well studied as most trials either excluded these patients or are limited by a small cohort and short observation period.
Methods: Between 2008 and 2013, patients who presented at a tertiary care center with symptoms and imaging findings suggestive of VO were reviewed by specialists in infectious diseases, clinical microbiology, and orthopedics to confirm the diagnosis and followed prospectively for a period of 2 years. Statistical analysis for group comparisons, survival analysis, and uni- and multivariable Cox regression models were performed.
Results: Thirty percent of the patients with VO (56/189) reported a history of spine surgery in the same segment. Patients with postoperative infection had a lower ASA score (American Society of Anesthesiologists) (P = 0.01) and were less likely to suffer from comorbidities compared to native cases (P = 0.003). Infections caused by coagulase-negative staphylococci (33.3 vs. 6.5%, P < 0.001) and other bacteria of the skin flora (15.2 vs. 0%, P = 0.002) were more prevalent in postoperative patients. Suffering from native VO increased the 2-year mortality risk 3-fold, also when adjusted for the remaining risk factors ASA score and number of comorbidities (hazard ratio 2.916 [95% confidence interval 1.215 –6.999], P = 0.017).
Conclusion: Beside clear microbiological differences, the significant better 2-year survival supports the concept of postoperative VO presenting a distinct disease entity. The subtle disease presentation of patients with postoperative VO should not attenuate clinical suspicion of physicians.
Level of Evidence: 3
Infections of the vertebrae and intervertebral disc—known as pyogenic vertebral osteomyelitis (VO) or spondylodiscitis—are rare. The increasing incidence of VO during the last years[1,2] might be attributed to an ageing society with chronic debilitating diseases, a growing number of immunocompromised individuals, and invasive medical procedures as well as to a higher diagnostic awareness and yield.[1–3]
A relevant subgroup of 20% to 30% of patients with VO has a history of previous spine surgery.[4,5] Although native vertebral osteomyelitis (NVO) is typically the result of hematogenous spread of pathogens from a distant infectious focus, the direct inoculation of pathogens and a spread of infection per continuitatem seems to be the more relevant pathogenetic mechanism in patients with postoperative vertebral osteomyelitis (PVO).[3–5] Furthermore, infection in these patients is more likely to be caused by coagulase-negative staphylococci[3–8]—a fact prompting that other disease characteristics might also differ.
However, most reports addressing VO either excluded patients with a history of spine surgery, mix them with patients with post-traumatic infection or are limited by a small cohort and short observation period.[4,5,9] Controversy especially exists over the outcome in these patients ranging from a good prognosis to severe and long-lasting disability.
The goal of this study was to determine the 2-year survival and to identify clinical and microbiological characteristics of patients with native as compared to postoperative VO to find further strategies for improvement of the management of VO.
Spine. 2020;45(20):1426-1434. © 2020 Lippincott Williams & Wilkins