Predictors of Mortality in Staphylococcus aureus Bacteremia: A Retrospective Cohort Study from a Tertiary-Care Center

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Introduction: Staphylococcus aureus bacteremia (SAB) remains a serious infectious condition associated with substantial early mortality despite advances in antimicrobial therapy.This study evaluated clinical, laboratory, and management-related factors associated with 28-day mortality among adults with SAB. Materials and Methods:A total of 151 adult patients with clinically significant SAB identified by blood culture between January 1, 2023, and October 24, 2024, were retrospectively analyzed.The primary outcome was 28-day all-cause mortality.Univariable and multivariable logistic regression analyses were performed to identify independent predictors of mortality.Model discrimination was assessed using the area under the receiver operating characteristic curve (AUC). Results:The median age of the cohort was 67 years (interquartile range, 55-78), 60% of patients were male, and 33% were managed in the intensive care unit (ICU).Overall mortality was 54.3%, and 28-day mortality was 40.7%.Compared with 28-day survivors, non-survivors were older and more frequently had ICU admission, neurological comorbidities, healthcare-associated infection, an elevated neutrophil-to-lymphocyte ratio, and higher serum lactate levels, whereas fever and chills were more frequent among survivors.Source control and infectious disease (ID) consultation within the first 24 hours were also more frequently provided to survivors.In multivariable analysis, advanced age [odds ratios (OR), 1.04; 95% confidence intervals (CI), 1.00-1.09],ICU admission (OR, 6.37; 95% CI, 1.85-24.2),and higher serum lactate levels (OR, 1.55 per mmol/L; 95% CI, 1.08-2.56)were independently associated with increased 28-day mortality.Source control and early ID consultation demonstrated protective trends after adjustment.The final model showed good discriminatory performance (AUC, 0.85; 95% CI, 0.75-0.95). Conclusion:This study suggests that early mortality in SAB is driven primarily by host characteristics and disease severity rather than by microbiological resistance patterns alone.Advanced age, ICU admission, and elevated serum lactate were the strongest independent predictors of early mortality, whereas source control and early ID consultation demonstrated protective trends that did not reach statistical significance after adjustment.These findings support a standardized, multidisciplinary approach to SAB management that extends beyond antimicrobial therapy and emphasizes timely optimization of modifiable clinical care processes.