A blood culture is a laboratory test used to detect the presence of bacteria or fungi in the bloodstream. This test helps diagnose infections that may be affecting the body, such as sepsis. During the procedure, a healthcare professional collects a sample of blood, which is then placed in a special culture medium to encourage the growth of any microorganisms present. If bacteria or fungi grow in the culture, further tests can identify the specific type of organism and determine the most effective treatment. Blood cultures are essential for guiding appropriate therapy and improving patient outcomes in cases of serious infections.