Legionella pneumophila

Question 1

Physical description of Legionella

Answer 1

• G negative

- rods

Question 2

Length and growth of Legionella

Answer 2

• length is highly variable; pleomorphic

- require Fe and cysteine, high humidity

Question 3

Clinical presentation of legionella

Answer 3

• most asymptomatic
• Pontiac fever; highly infectious and mild flu-like malaise
• Legionnaires disease; acute pneumonia with high fever, consolidation and fibrin deposition in multiple foci in lower lungs

Question 4

Risk factors for legionnaires disease

Answer 4

• smoking, emphysema, lung cancer, bronchitis

- immunosuppressant drugs

Question 5

Similarity between Legionella and H. influenzae

Answer 5

-both are leading causes for Community acquired pneumonia

Question 6

Epidemiology of Legionella

Answer 6

• freshwater and soil everywhere
• invade and parasitize ameoba and flagellated protozoa
• films form in areas of continual standing water

Question 7

Contracting legionella

Answer 7

• mechanically aerosolized droplets

- not transmissible

Question 8

Pathogenesis of legionella

Answer 8

• macrophage specific adhesion pili
  1. type 2 and type 4 secretion systems
• T4SS secretes AnkB that interferes with microtubules based transport, no lissome fusion to phagosome
  2. pathogen mediated endocytosis
• macrophage invasion potentiator
• macrophage coils around
  3. grow in macrophages by preventing fusion
  4. can release blebs of LPS

Question 9

Control of legionella

Answer 9

• detect by urine antigen test
• decontaminate with bleach
• TNFalpha blockers and increased risk

Question 10

Medication for legionella

Answer 10

erythromycin/azithromycin and sometimes with flurorquinolones