Lung abscess caused by Legionella micdadei.

We describe a case of lung abscess caused by sporadic infection with Legionella micdadei in a patient with AIDS. L micdadei infection can be very difficult to diagnose because the organism stains only weakly Gram negative, requires special culture media, and is not detectable with some direct fluorescent antibody tests that are directed only at Legionella pneumophila. Since it can stain acid fast, it may be confused with mycobacteria. The abscess was successfully treated using antibiotics and percutaneous catheter drainage.