Blood culture is a microbiological culture of blood to check for foreign invaders in a patient’s blood. The practice of taking blood cultures to detect infections in the bloodstream was established in the early 20th century. Blood cultures remain the primary and most trusted test for the diagnosis of bacteremia and septicemia. As blood is a sterile environment, culturing can show the presence of a systemic infection. If the culture tests positive, the contributory micro-organism can usually be identified. Conventionally, two cultures are collected: an aerobic bottle, for favored growth of aerobic and facultative anaerobic microbes, and an anaerobic bottle, allowing favored growth of strict anaerobic bacteria.