Nocardiosis is a disease caused by bacteria found in soil and water. It can affect the lungs, brain, and skin.

It is most common in people with weakened immune systems who have difficulty fighting off infections (for example, people with cancer or those taking certain medications such as steroids). Antibiotic treatment might be given for several months to get rid of the infection.

Stained photomicrograph of a tissue sample of a mycetoma excised from a patient's thorax ill with nocardiosis.