Comparison of Clinical Characteristics and Outcomes Between MRSA and MSSA Infections Among Patients in Intensive Care Units

Staphylococcus aureus infections are an important cause of morbidity and mortality among patients in intensive care units (ICUs), particularly those with multiple comorbidities and critical conditions. Methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains differ in resistance, clinical behavior, and prognoses, making it important to understand their effects on clinical outcomes. Comparing clinical outcomes of MRSA and MSSA infections is important. This retrospective cohort study analyzed ICU patients with confirmed S. aureus infections at a quaternary care hospital. Demographic, clinical, and comorbidity data were collected. Poisson regression was used to analyze 7-day mortality and identify adjusted risk factors. Seven-day mortality was higher in patients with MSSA than MRSA infections, with an adjusted relative risk for MRSA of 0.380 (95% confidence interval: 0.15–0.95; p = 0.039). Independent risk factors for mortality included lack of an infectious disease consultation, vascular comorbidities, such as peripheral vascular disease and cerebrovascular events, chronic kidney disease, and inotropic support requirement. Patients with MRSA infections required significantly longer ventilatory support (mean 43.5 days vs. 13 days for MSSA; p = 0.019). Staphylococcus aureus infections in ICU patients were associated with poor outcomes, particularly in patients without infectious disease consultation and those with vascular comorbidities. Mortality differences between MRSA and MSSA highlight the importance of appropriate empiric therapy and standardized protocols incorporating infectious disease consultation to improve outcomes in critically ill patients.