Author:  Gretchen Hinson, MD Educational Pearls:   Legionnaires disease refers to a severe pneumonia caused by Legionella pneumophilia and occurs typically at the extremes of age Associated gastrointestinal symptoms (nausea/vomiting/diarrhea) may be present Hyponatremia is a common laboratory finding Legionella urinary antigen can be a convenient test to identify the infection Treatment is with fluoroquinolones, macrolides and/or tetracyclines     References Pierre DM, Baron J, Yu VL, Stout JE. Diagnostic testing for Legionnaires’ disease. Annals of Clinical Microbiology and Antimicrobials. 2017;16:59. doi:10.1186/s12941-017-0229-6. Cunha BA, Cunha CB. Legionnaire's Disease and its Mimics: A Clinical Perspective. Infect Dis Clin North Am. 2017 Mar;31(1):95-109. doi: 10.1016/j.idc.2016.10.008. Review.