Evaluating the influence MRSA Co-infection on 28-day mortality among sepsis patients: insights from the MIMIC-IV database

Background Sepsis remains a leading cause of mortality in intensive care units (ICUs), with methicillin-resistant Staphylococcus aureus (MRSA) infections presenting significant treatment challenges. The impact of MRSA co-infection on sepsis outcomes necessitates further exploration. Methods We conducted a retrospective observational cohort study using the Medical Information Mart for Critical Care IV (MIMIC-IV-2.2) database. This cohort study included sepsis patients, scrutinizing baseline characteristics, MRSA co-infection, antimicrobial susceptibility, and their relations to mortality through Cox regression and Kaplan-Meier analyses. Results Among 453 sepsis patients analyzed, significant baseline characteristic differences were observed between survivors (N = 324) and non-survivors (N = 129). Notably, non-survivors were older (70.52 +/- 14.95 vs. 64.42 +/- 16.05, P < 0.001), had higher lactate levels (2.82 +/- 1.76 vs. 2.04 +/- 1.56 mmol/L, P < 0.001), and higher SOFA scores (8.36 +/- 4.18 vs. 6.26 +/- 3.65, P < 0.001). Cox regression highlighted SOFA score (HR = 1.122, P = 0.003), body temperature (HR = 0.825, P = 0.048), and age (HR = 1.030, P = 0.004) as significant predictors of 28-day mortality. MRSA co-infection was found in 98.7% of cases without a significant effect on 28-day mortality (P = 0.9). However, sensitivity to cephalosporins, meropenem, and piperacillin/tazobactam was associated with reduced mortality. The area under the ROC curve for the combined model of age, SOFA, and body temperature was 0.73, indicating a moderate predictive value for 28-day mortality. Conclusion While MRSA co-infection's direct impact on 28-day sepsis mortality is minimal, antimicrobial sensitivity, especially to cephalosporins, meropenem, and piperacillin/tazobactam, plays a critical role in improving outcomes, underscoring the importance of antimicrobial stewardship and personalized treatment strategies in sepsis care.