Polymicrobial Staphylococcus aureus bacteremia: Frequency, distinguishing characteristics and outcome

Area of Science:

• Infectious Diseases
• Microbiology
• Clinical Medicine

Background:

• Staphylococcus aureus bacteremia (SAB) is typically monomicrobial (M-SAB).
• Understanding polymicrobial SAB (P-SAB) is crucial for patient outcomes.
• Previous data on P-SAB incidence and characteristics are limited.

Purpose of the Study:

• To compare the incidence, sources, and outcomes of P-SAB versus M-SAB in adults.
• To identify specific clinical settings associated with P-SAB.
• To analyze the impact of polymicrobial involvement on mortality in SAB.

Main Methods:

• Retrospective review of adult SAB cases over a 13-year period.
• Comparison of P-SAB (93 cases) and M-SAB (1444 cases) based on clinical data.
• Analysis of infection sources, microbial characteristics, and mortality rates.

Main Results:

• P-SAB accounted for 6.1% of all SAB cases.
• P-SAB was significantly associated with necrotizing soft tissue infections/decubiti (20.7%), femoral intravascular catheters (10.9%), and healthcare-associated pneumonia (11.2%).
• P-SAB demonstrated a substantially higher mortality rate (50.5%) compared to M-SAB (24.2%).

Conclusions:

• Polymicrobial Staphylococcus aureus bacteremia is infrequent but associated with specific severe infections.
• P-SAB presents a significantly increased risk of mortality across various sources.
• Further investigation into the role of S. aureus in polymicrobial infections is warranted.