Clinical and Microbiological Features of Native Vertebral Osteomyelitis (NVO) in Adults: a Retrospective Analysis from a Private Hospital of Mendoza, Argentina

Background: NVO in adults is often due to hematogenous seeding.Due to its insidious presentation, the diagnosis is often delayed and may initially be mismanaged as a degenerative process. Staphylococci are the most frequent involved microorganisms. Reports from Argentina are scarce. We describe the demographics, clinical presentation and microbiology of a cohort of adult patients with NVO of a private hospital of Mendoza, Argentina. Methods & Materials: Retrospective review of medical records of patients diagnosed of NVO, as stated in ID department records, between 2005-2017, was done. Patients with tuberculosis, brucellosis andpostoperative spondylodiscitis were excluded. Immunodeficiency was defined as prednisone > 20 mg/d for > 2 weeks, chemotherapy during last year, HIV infection and/otransplantation. Results: A total of 20 patients were registered. Five patients were excluded due to incomplete data. Thus, 15 patients were included for further analysis. Mean age was 60.73 years, female 53% (n = 8). Associated comorbidities: immunodeficiency (40%), obesity (20%),hemodialysis(13.3%), diabetes mellitus (6.6%). Bacteremia was present in 7 patients (46.6%); all bacteremic patients had a distant focus of infection: endovascular (26.6%), soft tissue (13.13%) and lower respiratory tract (6.6%). Fever (66.6%) and pain (60%) were the most common presenting features. The time from onset of symptoms to diagnosis was 58.18 days (1-171 days). ERS was accelerated in 60%, elevated WBC in 46.6%. Eleven of 15 patients (73.3%) had an MRI done, which was diagnostic in all cases. All patients had blood cultures done (7 were positive). Three patients had CT-guided needle biopsy done (1 was diagnostic). Eight patients (53.3%) had microbiological diagnosis (7 by blood culture and 1 by CT-guided needle biopsy). MSSA (n = 5, 33.3%) was the most frequent agent. Other isolations were Streptococcus spp. (n = 1), Enterococcus faecalis (n = 1) and Klebsiella pneumoniae (n = 1). Seven patients did not have etiological diagnosis, and were diagnosed by MRI. Conclusion: In the present cohort of patients, NVO typically presented with back pain. The most common organism isolated was Staphylococcus aureus. It is important to emphasize that the delay time between onset of symptoms and diagnosis was 2 months, remarking the lack of initial suspicion of NVO.