Predictors of mortality in <i>Staphylococcus aureus</i> infections: The role of C-reactive protein, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio

Objective<i>Staphylococcus aureus</i> causes infections ranging from mild skin conditions to life-threatening diseases such as endocarditis. The incidence of <i>S. aureus</i> infections is increasing due to the rise in invasive procedures and immunosuppression. Inflammatory markers such as C-reactive protein level, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio are useful for monitoring disease severity. This study aimed to identify the clinical and laboratory predictors of mortality in patients with <i>S. aureus</i> infections.MethodsThis retrospective observational study included patients aged >18 years with <i>S. aureus</i> growth who were treated at a tertiary hospital between 1 November 2013 and 1 February 2022. Infections were classified as pneumonia or infections of the bloodstream, bone and joint, and skin and soft tissue.ResultsUnivariate analysis revealed that age >73 years, emergency department admission, and methicillin resistance were significant mortality risk factors. Multivariate analysis showed that age >73 years, pneumonia, and C-reactive protein level >86 mg/L increased the mortality rate by 3.5-, 7.6-, and 4.4-fold, respectively.ConclusionC-reactive protein level, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio are accessible, cost-effective markers that aid in predicting mortality. Integrating these biomarkers with clinical parameters such as advanced age and pneumonia can improve early risk stratification in patients with <i>S. aureus</i> infections.