Mulett, Sergio L Alvarez

Abstract Background Native vertebral osteomyelitis (NVO) is a life-threatening spinal infection with rising incidence and significant morbidity. Despite its growing burden, long-term data on clinical characteristics, management trends, and outcomes remain limited. Methods We conducted a 26-year multicenter retrospective cohort study of adults (≥18 years) diagnosed with NVO at Mayo Clinic sites between 1999 and 2024. Demographic, microbiologic, treatment, and outcome data were analyzed across five time periods. Predictors of treatment failure were assessed using a multivariable competing risk model. Results Among 1255 patients (median age 67; 66% male), lumbosacral involvement was most common (65%), and 21% had multilevel involvement. Pathogens were identified in 77%, most commonly Staphylococcus aureus (49%; Methicillin-susceptible S. aureus 37%, methicillin-resistant S. aureus 13%). Over time from 1999–2004 to 2020–2024, Gram-negative bacilli increased from 6% to 14% (P = .048). Comorbidities including chronic kidney disease (10% to 21%), active chemotherapy (6% to 11%), and immunosuppression (8% to 17%) increased significantly. Additionally, 1-year treatment failure declined (16% to 10%). In multivariable analysis, diabetes mellitus (subdistribution hazard ratio [sHR] 1.92, 95% CI 1.18–3.13) and multilevel involvement (sHR 1.67, 95% CI 1.17–2.38) were associated with increased incidence of treatment failure, while concurrent infections (sHR 0.57, 95% CI 0.37–0.87) and higher Charlson Comorbidity Index (sHR 0.62, 95% CI 0.43–0.90) were associated with lower failure. Conclusions This large multicenter cohort highlights increasing host complexity, shifting microbiology, and predictors of failure, emphasizing the importance of early risk stratification and tailored strategies, such as multidisciplinary evaluation and close follow-up of high-risk patients to improve outcomes.

Abstract Background Hematopoietic cell transplantation (HCT) is associated with a net state of immunosuppression to enable graft acceptance and mitigate graft-versus-host disease risk1. Most of these patients require multiple prophylactic antimicrobials to prevent opportunistic infections during the post-transplant course2, including central nervous system (CNS) infections3. Brain abscesses are a form of CNS infection with a high incidence of morbidity and mortality4 Methods We conducted a retrospective cohort study of adults diagnosed with brain abscess following HCT between January 2009 and December 2024, including patients from all Mayo Clinic sites (Arizona, Florida, and Minnesota). The study was approved by our institutional review board with a protocol number 24-011428. The data was extracted from the electronic medical records into a secure database in REDCap. Statistical analyses were conducted using R version 4.4.1 (R Foundation for Statistical Computing). Results We identified 22 patients with brain abscess diagnosis following HCT. 50% of patients had leukemia. 81.8% of them received prior chemotherapy. 16 patients had prior allogeneic HCT, and 54.5% received a myeloablative conditioning regimen (table 1). 21 patients had neuroimaging available. More than one cerebral lobe was involved in 42.9% of the cases. 14 patients had extra-axial infection, the lung being the most frequently affected organ. Nocardia accounted for 40.9% of the brain abscesses (table 2). 45.5% underwent surgical intervention, and most of our patients were treated with a combination of intravenous and oral antimicrobials, many of them followed by long-term suppression. 54.5% of the brain abscesses resolved, with a median time to resolution of 156 days. All-cause mortality was 59.1%, with a median time to death of 540 days after brain abscess diagnosis (table 3). Conclusion Although rare, brain abscess is a devastating complication of HCT, with high morbidity and mortality. The most common pathogen encountered was Nocardia species. The required treatment is usually extensive, and these patients often need long-term suppression. Further investigation is required to determine risk factors for specific pathogen infection, non-resolution, and mortality. Disclosures All Authors: No reported disclosures

Abstract Background Native vertebral osteomyelitis (NVO) is a life-threatening spinal infection with considerable clinical burden. Although increasing literature has described its features and associated treatment failure, large-scale cohorts with long-term follow-up remain limited. Herein, we evaluated a large cohort of patients with NVO to characterize the clinical manifestations, management, and long-term outcomes, and to further explore factors associated with treatment failure.Table 1.Baseline characteristics of patients with native vertebral osteomyelitisTable 2.Treatment, failure rates, and mortality in patients with native vertebral osteomyelitis Methods We conducted a retrospective multicenter cohort study of adults (≥18 years) with NVO across Mayo Clinic sites between 1999 and 2024. Data on demographics, clinical manifestations, antimicrobial therapy, and surgical intervention were collected. Cumulative incidence of treatment failure was estimated as a function of follow-up accounting for the competing risk of death. Independent predictors of treatment failure were evaluated in a multivariable Cox regression model with time-dependent covariates.Table 3.Multivariable predictors of treatment failure in patients with native vertebral osteomyelitisFigure 1.Cumulative incidence of death and treatment failure following diagnosis of native vertebral osteomyelitis(A) Short-term (12-month) cumulative incidence of death and treatment failure (magnified view of the first year from panel B).(B) Long-term (up to 7 years) cumulative incidence of death (dotted orange line) and treatment failure (solid blue line). Results Among 1,255 patients included (median age 67 years; 66% male), lumbosacral involvement was most common (65%), with multilevel vertebral involvement ( >2 levels) in 21%. Epidural abscesses were present in 43%, paravertebral abscesses in 42%, and psoas abscesses in 20%. Pathogens were identified in 77%, most commonly S. aureus (50%; MSSA 37%, MRSA 13%), followed by Streptococcus species (22%), and Gram-negative bacilli (11%) (Table 1). The median total antibiotic duration was 59 days (IQR, 42–132). Surgical intervention was performed in 13% after a median of 2 days (IQR, 1-5). Treatment failure occurred in 162 patients during a median follow-up of 2.8 years (6-month and 5-year cumulative incidence were 11% and 14%, respectively), with the median time to failure of 3.1 months. Cumulative mortality was 12% at 6 months and 33% at 5 years (Table 2, Figure 1). Diabetes (HR 1.90, 95% CI 1.16–3.12), multilevel vertebral involvement (HR 1.75, 95% CI 1.22–2.51), and MRSA infection (HR 2.11, 95% CI 1.06–4.18) were independently associated with increased risk of treatment failure (Table 3). Conclusion This 25-year study highlights the persistent burden of treatment failure in NVO and associated risk factors, underscoring the importance of early recognition of high-risk features to optimize outcomes. Disclosures All Authors: No reported disclosures