What type of sample do blood cultures typically require?

Blood cultures typically require whole blood samples because the test is designed to detect the presence of microorganisms, such as bacteria or fungi, in the bloodstream. Whole blood allows for the direct analysis of the living organisms, which are vital to diagnosing infections.

When whole blood is collected, it contains all the components necessary for detection, including red blood cells, white blood cells, platelets, and plasma. These components work together to facilitate the growth of pathogens in a culture medium, thereby allowing for accurate identification and sensitivity testing.

In contrast, serum and plasma samples, which are obtained after blood has been processed to remove cells, would not provide viable microorganisms, as the components necessary for growth in culture may be absent. Bone marrow samples are used for different clinical indications, such as hematological disorders, rather than for blood culture purposes.

Using whole blood ensures that the blood culture can accurately reflect the status of a patient's bloodstream, which is critical for effective treatment of infections.