Impact of a standardized management protocol and antimicrobial stewardship intervention on mortality and quality of care in Staphylococcus aureus bacteremia: a before-after study

Abstract

Purpose Staphylococcus aureus bacteremia (SAB) is associated with substantial morbidity and mortality. This study aimed to evaluate changes in quality-of-care indicators and clinical outcomes following implementation of a standardized SAB management protocol combined with an antimicrobial stewardship intervention. Methods This single-center, quasi-experimental before-and-after study included adult patients with SAB. Patients diagnosed in 2024 constituted the pre-intervention cohort, whereas those assessed between January and September 2025 constituted the post-intervention cohort. During the post-intervention period, cases were proactively evaluated at the bedside by infectious diseases specialists following laboratory notification, using a structured checklist addressing follow-up blood cultures, echocardiography, source assessment and control, and definitive antimicrobial agent selection. Results Overall, 143 patients were included: 88 in the pre-intervention and 55 in the post-intervention cohort. Baseline characteristics and measured indicators of disease severity and infection complexity were comparable between groups. Adherence to the minimum evaluation bundle increased from 47.7% to 69.1% (p = 0.012), echocardiographic evaluation from 65.9% to 92.7% (p < 0.001), follow-up blood cultures obtained within 24-48 h from 36.4% to 72.7% (p < 0.001), and guideline-concordant definitive antimicrobial agent selection from 65.9% to 87.3% (p = 0.005). Seven-day mortality was 13.6% in the pre-intervention cohort and 3.6% in the post-intervention cohort (p = 0.050), while 28-day mortality was 33.0% and 16.4%, respectively (p = 0.029). In the multivariable Cox proportional hazards model, the post-intervention period was associated with a lower hazard of 28-day mortality (adjusted HR 0.46, 95% CI 0.22-0.97; p = 0.040), whereas higher Charlson Comorbidity Index (adjusted HR 1.17 per point, 95% CI 1.04-1.31; p = 0.008) and ICU admission (adjusted HR 4.10, 95% CI 2.14-7.81; p < 0.001) were associated with higher mortality. Conclusion Implementation of a standardized, infectious diseases-led SAB management protocol incorporating antimicrobial stewardship was associated with improved quality-of-care processes and lower 28-day mortality. These findings support the potential clinical value of a structured, proactive approach to SAB management, although the before-and-after design precludes causal inference.