[Bacteremia by Staphylococcus aureus: analysis of 311 episodes]

Area of Science:

• Infectious Diseases
• Bacteriology
• Clinical Microbiology

Context:

• Staphylococcus aureus bacteremia presents distinct epidemiological and clinical features depending on acquisition source (nosocomial vs. community-acquired).
• Methicillin-resistant S. aureus (MRSA) poses a significant challenge, particularly in nosocomial settings.
• Endocarditis is a serious complication of S. aureus bacteremia, with specific risk factors identified.

Purpose:

• To delineate differences between nosocomial and community-acquired S. aureus bacteremia.
• To identify patient characteristics associated with a high risk of developing endocarditis.
• To characterize patients with MRSA bacteremia.

Summary:

• Nosocomial S. aureus bacteremia occurred in 63% of cases, often in older patients with comorbidities and invasive procedures, leading to higher mortality.
• Endocarditis was observed in 19% of bacteremia episodes, predominantly in intravenous drug users (IDU) (64% risk vs. 3% in non-IDU).
• MRSA accounted for 45% of nosocomial cases, while community-acquired bacteremia in non-IDU patients had lower mortality and no MRSA cases.

Impact:

• Findings highlight the critical need for distinct management strategies for nosocomial versus community-acquired S. aureus bacteremia.
• Identifying high-risk groups, such as IDU and patients with valvular disease, can guide targeted prevention and treatment of endocarditis.
• Understanding MRSA prevalence in different settings informs antibiotic stewardship and infection control measures.