AFB cultures are used to diagnose active M. tuberculosis infections, infections due to another member of the Mycobacterium family, or to determine whether TB-like symptoms are due to another cause. They are used to help determine whether the TB is confined to the lungs (pulmonary disease) or has spread to organs outside the lungs (extrapulmonary disease). AFB cultures can also be used to monitor the effectiveness of treatment and can help determine when a patient is no longer infectious.
Blood cultures are used to detect the presence of bacteria or yeasts in the blood, to identify the microorganism(s) present, and to guide treatment. Two or more blood cultures are typically ordered and collected as consecutive samples. Often, a complete blood count (CBC) is ordered along with or prior to the blood culture to determine whether the person has an increased number of white blood cells, indicating a potential infection. Sometimes other testing is also performed, such as a chemistry panel to evaluate the health status of a person's organs, or a urine, sputum, or cerebrospinal fluid (CSF) culture to help identify the source of the original infection. This is especially true when a person has symptoms associated with a urinary tract infection, pneumonia, or meningitis.
Fungal (mycotic) cultures are microbiology laboratory tests to detect or rule out the presence of fungi (plural of fungus) in specimens taken from patients, animals, and the environment. The laboratory uses optimal conditions to grow and identify any fungus present in the specimen while attempting to eliminate or identify contaminants. The specimen is cultured by spreading a small portion of it on various agar media (inoculation). The media are then incubated in a warm, moist environment and examined regularly to detect growth of any organisms. The isolated fungus is identified primarily by its colony morphology and microscopic structures.