Legionella pneumophila lung abscess in a patient with systemic lupus erythematosus.

Lung abscess is an infrequently reported complication of Legionella pneumophila pneumonia associated with a high mortality rate. The risk factors, natural course, optimal method of diagnosis, and optimal therapy of this complication are not well defined. One case of Legionella pneumophila lung abscess occurring in a patient with systemic lupus erythematosus is described, and the reports of 26 other cases are reviewed. This complication is usually hospital-acquired and occurs predominantly in transplant recipients and systemic lupus erythematosus patients treated with corticosteroids with or without a cytotoxic drug. The time interval between the onset of immunosuppressive therapy and infection is usually of several weeks. Progression from pneumonia to abscess formation may be rapid, more commonly within an upper lobe. Transthoracic aspiration within the abscess cavity may be diagnostic, thus obviating the need for open lung biopsy. The prompt institution of erythromycin 4 gm daily intravenously followed by oral therapy for at least 4 weeks is associated with a high survival rate. Adequate drainage from the abscess cavity must be maintained. Radiologic healing may be slow. Long-term survival without relapse does occur. That the clinical spectrum of Legionella pneumophila infection includes lung abscess has not been sufficiently emphasized. This agent should be considered early in the differential diagnosis of lung abscess.