Firstline - Clinical Decisions

Diagnosis

Clinical Assessment

Presence of Methicillin Sensitive Staphylococcus aureus (MSSA) or Methicillin Resistant Staphylococcus aureus (MRSA) in blood
Bacteremia can be secondary to a primary S. aureus infection elsewhere such as skin and soft tissue, bone and joint, pneumonia or vascular catheter
S. aureus bacteremia can also result in subsequent seeding and infection of a sterile site such as heart valves or prosthetic devices
It is imperative to look for sources and metastatic sites of infection in the setting of S. aureus bacteremia

Further Diagnostic Evaluation

Thorough clinical assessment should be performed to identify potential sources and metastatic sites of infection, for example:

Blood Cultures

Blood cultures should be drawn 48h after initial positive cultures and as needed thereafter until clearance is demonstrated

Uncomplicated Bacteremia

Positive blood cultures AND the following:

Exclusion of endocarditis via echocardiogram
No implanted prosthesis (i.e. prosthetic heart valves or vascular grafts)
Follow-up cultures performed on specimens obtained 2-4 days after initiating IV therapy and source control do not grow S. aureus
Defervescence within 72 hours of initiating effective therapy (IV antistaphylococcal therapy and removal of presumed focus of infection (i.e. debridement of soft tissue infection or IV catheter removal)
No evidence of metastatic sites of infection

Complicated Bacteremia

Positive blood cultures AND the following:

Infective endocarditis
Implanted prosthesis
Follow up cultures performed on specimens obtained 24 days after initial set that grow MRSA
Persistent fevers within 72 hours of initiating effective therapy
Evidence of metastatic sites of infection

Source Control

Drainage of abscess (if present)
Removal of seeded devices (i.e. vascular catheters, prosthetic material, or orthopedic hardware)

Reference