Mycobacterium avium is a type of bacteria that belongs to the Mycobacterium genus. It is commonly found in soil, water, and dust, and can also be present in domestic and wild animals. This bacterium is known for causing infections, particularly in individuals with weakened immune systems, such as those with HIV/AIDS or other immunocompromising conditions. In healthy individuals, Mycobacterium avium typically does not cause disease. However, in vulnerable populations, it can lead to a condition known as pulmonary disease, which affects the lungs, or disseminated disease, where the bacteria spread throughout the body. Treatment usually involves a combination of antibiotics over an extended period.