Strictly aerobic, gram +ve rods, catalase +ve Stain weakly Acid-Fast (due to mycolic acids in the cell wall) Found in the soil Not part of the human normal flora Two species are pathogenic for humans: Nocardia asteroides [Worldwide] and Nocardia brasiliensis [Central America] Form thin filaments (confused with fungus) Can grow on most non-selective media (slow, 3-5 days)