Microbial Etiology of Postoperative Spinal Fusion Infections and Factors Associated with Gram-Negative Infections, United States, 2021-2022.

Accurate knowledge of microbial etiology is essential for optimizing spinal fusion surgical site infection (SSI) management, yet contemporary national data in the United States, particularly prevalence and factors associated with gram-negative infections, remain poorly understood. We conducted a cross-sectional analysis of US data reported to the Centers for Disease Control and Prevention National Healthcare Safety Network (2021-2022) to characterize the microbiology of spinal fusion SSI and identify factors associated with gram-negative infection. Among 7,187 cases, gram-negative organisms caused 31.5% (n = 2,265) of SSIs. Older age, female sex, higher body mass index, longer operative times, higher American Society of Anesthesiologists class, lumbar involvement, inpatient surgery, and emergent and trauma surgeries were independently associated with gram-negative infections relative to monomicrobial Staphylococcus aureus infections. Our findings might inform future studies focusing on high-risk cohorts as targets for expanded gram-negative prophylactic regimens. Clinicians can use risk profiles to guide empiric gram-negative antibiotic coverage in treating SSIs.