Mycobacterium chelonae is a member of the rapidly growing mycobacteria. It is an aerobic gram-positive organism that grows on most nutrient media as a straight or slightly curved bacillus which may develop branching filaments. It has variable acid-fast staining characteristics. The colonies are small, round, and smooth colonies but may be rough or wrinkled. It has been isolated from water, soil, and dust. They can cause a hypersensitivity pneumonitis in metalworking fluids. It is associated with nosocomial outbreaks or pseudo outbreaks due to rapidly growing mycobacteria.