Postoperative spinal infection after spinal arthrodesis: incidence, microbiology, risk factors, and outcomes in a tertiary-care hospital cohort.

BACKGROUND

Postoperative spine infection (PSI) is a major complication of spinal arthrodesis, associated with substantial morbidity and healthcare burden. Evidence remains fragmented, with limited multivariable analyses and scarce South American data. This study evaluated PSI incidence, characteristics, management, outcomes, and factors associated with infection and treatment failure in a tertiary-care hospital.

METHODS

This single-centre retrospective cohort included patients undergoing spinal arthrodesis from January 2018 to December 2023. PSI was defined according to adapted European Bone and Joint Infection Society criteria. Bivariate and exploratory multivariable analyses evaluated factors associated with PSI and treatment failure.

RESULTS

Among 150 patients, 30 (20.0%) developed PSI, predominantly early infections (96.7%). Microbiological identification was achieved in 56.7% of cases. Staphylococcus aureus was the most frequently isolated pathogen (47.1%), while Gram-negative bacilli constituted the main aetiological group (58.8%). In multivariable analysis, alcohol consumption (odds ratio [OR] 3.29, 95% confidence interval [CI] 1.11-9.71) and body mass index ≥25 kg/m² (OR 3.89, 95% CI 1.42-10.69) were associated with increased odds of PSI, while non-β-lactam prophylaxis showed lower odds (OR 0.35, 95% CI 0.14-0.92). Treatment failure occurred in 36.7% and was associated with late infection, persistent pain, reinterventions, and plastic wound reconstruction.

CONCLUSIONS

PSI showed high incidence and severity, with substantial Gram-negative bacilli contribution. Body mass index ≥25 kg/m², alcohol consumption and antimicrobial prophylaxis strategy were factors associated with PSI, supporting tailored prevention based on local epidemiology.