Legionella are aerobic, gram-negative, intracellular bacteria

-it is typically acquired through inhalation of aerosols

-it can cause a self-limited febrile illness or/and a pneumonia 

-it is often associated with contamination of water supplies in large facilities such as hospitals, air conditioning cooling towers and apartment complexes 

Symptoms & Signs

fever, nausea, vomiting, diarrhea, confusion, changes in mental status, hyponatremia, elevated hepatic transaminases, elevated C-reactive protein levels, failure to respond to treatment for pneumonia with beta-lactam monotherapy

Diagnosis 

PCR, respiratory tract sample culture, detection of Legionella antigen in urine 

Treatment Macrolides (Azithromycin, clarithromycin), Fluoroquinolones (levofloxacin), tetracyclines, Trimethoprim-sulfamethoxazole, rifampin, and telithromycin