The use of tracheal and pulmonary aspiration to diagnose Legionella micdadei pneumonia.

Legionella micdadei (Pittsburgh pneumonia agent) pneumonia was diagnosed in three patients by transtracheal aspiration and in a fourth patient by percutaneous lung aspiration on two occasions. The organism was identified by direct fluorescent antibody staining and by culture in each case. Diagnosis by aspiration of the respiratory tract was rapid, specific, and safe. This allowed early institution of specific antimicrobial therapy in a group of severely ill, immunocompromised patients. These techniques should be considered whenever the diagnosis of L micdadei pneumonia is likely.