대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Legionella Pneumonia

Radiologic Findings

Plain chest radiograph taken at admission shows diffuse ground glass opacities and reticular opacities in the bilateral lungs, which were not present on chest film 5 months ago. Chest CT shows ground glass opacities in the bilateral lungs, particularly in the BLL. The lesions mainly occur in the posterior portion of the lung. He underwent urine legionella antigen test, which revealed that the disease is legionella pneumonia. After receiving antibacterial medication with levofloxacin, the symptom improved and returned back to home.

Brief Review

The most common legionella species causing human disease is L. pneumophila. This organism can cause both community-acquired pneumonia and nosocomial pneumonia.

The prevalence of legionella pneumonia is 12.5%, the second most frequent cause of pneumonia. Besides, legionella pneumonia occurs more frequently in the immunocompromised patients suffering from various diseases such as AIDS, kidney transplant, and steroid therapy, DM, age older than 50 and so on.

Although legionella pneumonia does not have specific radiologic features, the most common findings are peripheral patchy consolidations, which usually spreads rapidly. It usually involves more than one lobe and often the bilateral lungs as the disease progresses.

On CT, according to Kim et al뭩 study, legionella pneumonia can be manifested as multiple pulmonary infiltrates such as lobar consolidation, lobular consolidation mixed with GGOs, and purely GGOs involving the bilateral lungs. Lobar consolidations were fairly common in immunocompromised hosts. Furthermore, cavities commonly occur in patients with high-dose steroid therapy. Whereas, multiple GGOs without consolidations are usually seen in immunocompetent patients.

To diagnose L. pneumophila infection, specific laboratory tests are needed; culture with special selective media, direct florescent antibody test (DFA), serologic tests, DNA probe, and urinary antigen test. The drug of choice for this disease is erythromycin. With appropriate therapy, complete recovery occurs in approximately 80% to 90% of cases, particularly if there is no underlying illness.

References

1.Sopena N, Sabri?M, Pedro-Botet ML, et al. Prospective study of community-acquired pneumonia of bacterial etiology in adults. Eur J Clin Microbiol Infect Dis. 1999;18:852-858.

2. Kim KW, Goo JM, Lee HJ et al. The Chest radiographic and CT findings of Legionella pneumonia. J Comput Assist Tomogr. Submitted.

Keywords

Lung, Infection, Bacterial infection,