1447. Retrospective Study Comparing the Characteristics of NTM Vertebral Osteomyelitis and Tuberculous Vertebral Osteomyelitis

Abstract Background Nontuberculous mycobacteria (NTM) species rarely cause vertebral osteomyelitis (VO). The clinical characteristics and radiological findings of NTM VO are not well described since the number of cases are limited. Here we present the clinical characteristics of culture positive NTM VO, compared to those of tuberculous (TB) VO. Methods We performed a retrospective, multicenter study at 5 hospitals. Patients with radiologic findings consistent with VO, and positive NTM or TB cultures on biopsy were included. Demographic characteristics and symptoms were collected, along with laboratory, radiologic, and pathologic findings. Results Nineteen patients with NTM VO and 105 patients with TB VO were included. M. intracellulare (52.6%) and M. abscessus (26.3%) were the most common NTM pathogens. The mean age of patients was significantly older in the NTM VO group (68.0 vs. 58.5 years, P = .01). Previous steroid or immunosuppressant use was more frequent in the NTM VO group (21.1% vs. 2.9%, P = .01; 15.8% vs. 2.9%, P = .046, respectively), as was a history of vertebral surgery (47.4% vs. 13.3%, P < .001). Symptoms and laboratory findings were similar between the 2 groups, although the proportion of patients with positive interferon-gamma release assays (IGRA) was significantly higher in the TB VO group (14.3% vs. 86.4%, P < .001). Radiologic findings were also similar, with lumbar involvement being the most common (57.9% and 44.8%, respectively). Chronic granulomatous inflammation was more frequently seen in TB VO patients (33.3% vs. 64.0%, P = .04), while inflammation alone was more common in NTM VO. Although there was no significant difference in survival after 1 year, survival at last follow-up (median, 24 months) was significantly lower in the NTM VO group (75.0% vs. 98.8%, P = .02). Conclusion NTM VO should be considered in older patients with a history of immunosuppression or previous vertebral surgery. The pathologic findings and radiologic findings of NTM VO were similar to that of TB VO. Granulomatous inflammation and positive IGRA tests were more common in TB than NTM VO. Disclosures All Authors: No reported disclosures.