Clinical and microbiological characterization of bacteremia by Staphylococcus aureus

Abstract

Introduction: Staphylococcus aureus is a frequent cause of bacteremia and the increase in resistance rates makes initial treatment difficult. The incidence of bacteraemia due to methicillinresistant S. aureus (MRSA) has increased, mainly in infections acquired in the hospital environment. This study aims to clinically characterize patients with S. aureus bacteremia detected in a Medellín hospital and to define their microbial resistance profile. Methods: retrospective cohort in a tertiary hospital. Patients ?16 years with isolation for Staphylococcus aureus in peripheral blood were included. Information related to the episode, the acquisition site, the microbiological classification and the clinical characteristics were recorded. Results: Of 775 reports of blood cultures positive for S. aureus, 698 patients were finally admitted to the study. The median age was 58 years (RIQ = 42-69), 383 were men (54.9%). In 354 patients (50.7%) the bacteremia was of nosocomial origin and 26.2% (n = 183) were MRSA. In 123 (17.6%) bacteremia acquired in the community, the frequency of MRSA was 33.3% (n = 41). The most frequent antecedent was to have a vascular catheter in 321 patients (46%). Empirical therapy was initiated in 67.2% of the cases (n = 469). Regarding severity, the SOFA score median was 4 (RIQ = 1-5), APACHE II of 15 (RIQ = 10-19) and mortality was 24.9% (n = 174). Conclusions: although the majority of bacteremia are of nosocomial origin, the most frequent report was MSSA in both the nosocomial and community groups. Despite this, mortality in the nosocomial bacteremia group was lower compared with that of the community.