Legionella pneumonia

8% of severe CAP, with encephalopathy, LFT derangement, bradycardia, diarrhoea and acute kidney injury.
Etiology Legionella pneumophilia - obligate aerobe, Gram negative rod
Epidemiology outbreaks including within hospitals
seasonal pattern
2-10 day incubation
Symptoms Fever, productive cough, pleuritic chest pain
CNS: GBS, ADEM
GI: diarrhoea
Diagnosis and investigations Diagnostic: urinary antigen (false positive with other Gram neg bacteria)

Also: culture (gold standard), immunofluorescence of respiratory specimens
Serology not very helpful
Signs: Hyponatraemia
GI: deranged LFTs
Renal: rhabdo, AKI
Radiology Lobar consolidation with rapid progression
"ground-glass opacification that may have a subtle crazy-paving appearance" - septal thickening
Management: Fluoroquinolones eg levofloxacin, macrolides