Sepsis and Bacteremia

DEFINITION
Bacteremia—defined as the presence of bacterial organisms in the bloodstream
Sepsis—systemic response to bacterial infection (e.g., fever, hypotension)
Terms are not synonymous, although often used interchangeably

PATHOPHYSIOLOGY
Shedding of bacterial organisms into the bloodstream—may occur transiently, intermittently, or continually
The most critical host response for elimination of bacteremia—provided by mononuclear phagocyte system of the spleen and liver; activation leads to release of numerous cellular mediators (cytokines), some of which are beneficial and others detrimental; may lead to death of the host
Neutrophils—relatively more important for defense against extravascular infection
Bacteremia—transient, subclinical event or may escalate to overt sepsis when the immune system is overwhelmed; generally of more pathologic significance when the bloodstream is invaded from venous or lymphatic drainage sites