Blood culture

Blood culture is microbiological culture of blood. It is employed to detect infections that are spreading through the bloodstream.

Method

About 30 ml of blood is taken through venipuncture and injected into two "blood bottles" with specific media for aerobic and anaerobic organisms.

Care needs to be taken that the bottles are not contaminated with bacteria from staff members or other patients. To that end, the patient's skin and the top of the blood bottles are rubbed with denaturated alcohol.

To maximise the diagnostic yield of blood cultures, multiple samples are often taken from different veins.

Uses

Any infection causing fever may prompt hospital physicians to request blood cultures. Identifying the agent may aid in choosing the correct antibiotic and addressing particular risk factors.

Blood culture is essential in the diagnosis of infective endocarditis. In this elusive disease, blood cultures may have to be repeatedly taken during febrile episodes, when bacteria are shed from the heart valves into the bloodstream (bacteremia).

History

Blood cultures were pioneerd in the early 20th century. Gustav Mahler, the composer, was diagnosed with infective endocarditis close to the end of his life, but as this was before the introduction of antibiotics, it contributed to his (early) death.

See also

• Microbiological culture