Blood is cultured to detect and identify bacteria or other cultivable microorganisms (yeasts, filamentous fungi). The presence of such organisms in blood is called bacteraemia or fungaemia, and is usually pathological. In healthy subjects, the blood is sterile. However, there are a few exceptions: transient bacteraemia often occurs shortly after a tooth extraction or other dental or surgical manipulation of contaminated mucous membranes, bronchoscopy, or urethral catheterization. This type of transient bacteraemia is generally due to commensal bacteria and usually resolves spontaneously through phagocytosis of the bacteria in the liver and spleen.
Septicaemia is a clinical term used to describe bacteraemia with clinical manifestations of a severe infection, including chills, fever, malaise, toxicity, and hypotension, the extreme form being shock. Shock can be caused by enodotxin produced by Gram-negative rods.