Legionella Flashcards Preview

Microbiology Block 3 > Legionella > Flashcards

Flashcards in Legionella Deck (18):
1

what is the biology of legionella pneumophila?

  • Small gram negative rods poorly staining*
  • Facultative intracellular *

2

inside what cell does legionella pneumophila live?

macrophages

3

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 *

4

how does legionella spread?

INHALATION of aerosols *

5

who is more at risk of acquiring legionella pneumophila?

  • Individuals over 55 yrs who smoke and drink alcohol
  • Elderly debilitated
  • Chronic lung disease, immunocompromised

6

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. 

7

what does legionella inhibit?

phagolysosome fusion

8

where does legionella replicate?

inside vacuoles

9

what causes the host cells to be killed?

proteolytic enzymes produced by legionella

10

what immunity helps us combat legionella infection?

Immunity to disease is primarily cell mediated *(humoral immunity plays a small role)

11

what diseases does legionella cause?

  •  Severe infection – Legionnaire’s disease*
  •  Mild infection – Pontiac fever

12

who gets legionnaire's disease?

Immunosuppressed patients 

 

Smokers over 55 yrs with high alcohol intake

 

13

who can get Pontiac fever with legionella infection?

healthy individuals

14

in pontiac fever, does the disease reach the lungs?

there is no pulmonary involvement

15

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 *

     

16

what staining techniques can be used to diagnose legionnaire's disease?

since it is a poorly stain gram negative

  • DFA (direct fluorescent antibody) staining of specimens
  • Dieterle silver-stain

17

what other test can be used to diagnose legionnaire's disease?

Urine Antigen detection  - rapid, sensitive *

18

what is the treatment for legionella?

Macrolide – Azithromycin, clarithromycin

Newer quinolone – Levofloxacin, gatifloxacin