ABSTRACT
Legionella pneumophila has been found to be a common cause of community-acquired pneumonia in patients who
required intensive care unit (ICU) admission. In many studies, the clinical manifestations
for Legionnaires' disease were more severe and the mortality was higher when compared
with pneumonias of other etiology. However, this may be due to delay in diagnosis
and suboptimal antibiotic therapy, rather than enhanced virulence of L. pneumophila. A syndromic approach using high fever, diarrhea, mental status changes, hyponatremia,
etc., may be useful in suggesting the correct diagnosis in patients with severe pneumonia,
but this remains to be validated. The availability of Legionella diagnostic microbiology
testing in-house (rather than being sent to an outside reference laboratory) maximizes
the ability to correctly diagnose Legionnaires' disease. All patients with community-acquired
pneumonia admitted to an ICU should undergo Legionella testing using the urinary antigen
and culture on selective media. Moreover, we recommend routine cultures of the hospital
water supply once a year (regardless of whether a case of nosocomial Legionnaires'
disease has ever been diagnosed). If Legionella is found in the water supply, all
patients with nosocomial pneumonia should undergo diagnostic tests for Legionella;
empiric anti-Legionella antibiotics should be administered pending definitive diagnosis.
KEYWORD
Legionnaires' disease -
L. pneumophila, nosocomial pneumonia - community-acquired pneumonia - intensive care unit
