Impact of Culture Status on Outcomes in Vertebral Osteomyelitis: A Retrospective Cohort Study of 206 Patients.

Study DesignRetrospective cohort study.ObjectivesTo compare clinical features and outcomes between culture-positive and culture-negative vertebral osteomyelitis (VO), describe empirical antimicrobial regimens used for culture-negative VO, and identify independent predictors of 1-year recurrence and mortality.MethodsWe retrospectively reviewed 252 consecutive patients treated for VO at a tertiary center (2010-2023). Finally, 206 patients were analyzed (173 culture-positive, 33 culture-negative). Demographics, comorbidities, laboratory and imaging findings, microbiology, antimicrobial regimens, and surgical treatment were collected. Antimicrobials were generally administered for ≥6 weeks. Primary outcomes were initial treatment failure, recurrence, 1-year all-cause mortality, and infection-related mortality.ResultsCulture-negative VO showed lower temperature, C-reactive protein, and white blood cell count; higher albumin; and fewer epidural abscesses than culture-positive VO, consistent with a milder phenotype. Initial treatment failure and recurrence occurred in 24/206 (11.7%) and 3/206 (1.5%) patients, respectively. All recurrences occurred in the culture-positive group. One-year all-cause mortality was 17% (29/173) in culture-positive and 24% (8/33) in culture-negative patients (p=0.305); infection-related mortality was 13% and 18%, respectively (p=0.424). Among culture-negative patients, outcomes did not differ between cefazolin-based versus other empirical regimens. Multivariable analysis identified older age, higher Charlson Comorbidity Index, hypoalbuminemia, and absence of surgery as independent predictors of mortality, whereas culture status was not.ConclusionsIn this cohort with high microbiological yield (84%), culture-negative VO presented with milder clinical features and had recurrence and 1-year mortality comparable to culture-positive VO when treated with ≥6 weeks of antimicrobials. Prognosis was driven primarily by host factors rather than culture status.