Legionella Flashcards
what is the biology of legionella pneumophila?
- Small gram negative rods poorly staining*
- Facultative intracellular *
inside what cell does legionella pneumophila live?
macrophages
where can we find a reservoir of legionella?
in water that is:
- Parasitize protozoa in streams, rivers
- contaminates waterlines
- Air-conditioning cooling towers *
- Hot water heaters *
- Hot-tubs *
- Grocery store produce sprayers *
how does legionella spread?
INHALATION of aerosols *
who is more at risk of acquiring legionella pneumophila?
- Individuals over 55 yrs who smoke and drink alcohol
- Elderly debilitated
- Chronic lung disease, immunocompromised
what does legionella do Inside the phagosome?
Legionella uses Type 4 Secretion Systems (T4SS) to inject proteins * into the cytosol to burst the phagosomal membrane.
what does legionella inhibit?
phagolysosome fusion
where does legionella replicate?
inside vacuoles
what causes the host cells to be killed?
proteolytic enzymes produced by legionella
what immunity helps us combat legionella infection?
Immunity to disease is primarily cell mediated *(humoral immunity plays a small role)
what diseases does legionella cause?
- Severe infection – Legionnaire’s disease*
- Mild infection – Pontiac fever
who gets legionnaire’s disease?
Immunosuppressed patients
Smokers over 55 yrs with high alcohol intake
who can get Pontiac fever with legionella infection?
healthy individuals
in pontiac fever, does the disease reach the lungs?
there is no pulmonary involvement
what symptoms are seen in legionnaire’s disease?
- Atypical pneumonia*
- Acute lobar pneumonia + major confusion + diarrhea *
- dry, NON-PRODUCTIVE COUGH*
- Gram stain of sputum – neutrophils but no bacteria *
