Lung
Infectious
Bacterial
Legionella
Author: Elliot Weisenberg, M.D.
Last author update: 1 September 2011
Last staff update: 24 December 2020
Copyright: 2003-2023, PathologyOutlines.com, Inc.
PubMed search: Legionella pneumophila [title] OR Legionnaires disease [title] pulmonary
Table of Contents
Clinical features | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | Cytology images | Positive stains | Electron microscopy images | Additional referencesCite this page: Weisenberg E. Legionella. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungnontumorlegion.html. Accessed October 3rd, 2023.
Clinical features
- Initial public attention after epidemic in Philadelphia, Pennsylvania (US) convention of American Legion
- Caused by Legionella species, a short, Gram negative bacillus (Wikipedia)
- Retrospective review disclosed sporadic cases since early 1900s
- Pontiac fever is caused by same bacteria, but without pneumonia, and often subclinical
- Hilar lymph nodes infected in 50% of cases at autopsy; 25% have spread to other organs
- Causes: contaminated water in water cooling tanks, drinking water conduits, air conditioning systems and other contained indoor water storage systems
- Immunosuppressed patients, especially organ transplant recipients, are especially vulnerable to severe disease
- Interaction with macrophages and dendritic cell subtypes appears to be important for resolution (Front Microbiol 2011;2:126)
Treatment
- Erythromycin or other antibiotics, but high mortality in immunocompromised
Microscopic (histologic) description
- Extensive bronchopneumonia to lobar pneumonia with intra-alveolar neutrophils, macrophages, fibrin; often with leukocytoclastic neutrophilic infiltrate, small vessel vasculitis and necrosis
Microscopic (histologic) images
Images hosted on other servers:
Gram stain
Immunofluorescence staining
Cytology images
Images hosted on other servers:
Impression smear from lung
Positive stains
- Dieterle silver stain, monoclonal fluorescent reagent
Electron microscopy images
Images hosted on other servers:
Legionella pneumophila
