Lecture 5 Part 1: Legionella and Coxiella

Question 1

What is the shape and Gram classification of Legionella pneumophila?

Answer 1

Slender, pleomorphic Gram (-) rods

Question 2

What are the key characteristics of Legionella pneumophila?

Answer 2

1. Slender, pleomorphic Gram(-) rods
2. Obligate aerobe with specific growth requirements (L-cysteine, ferric ions)
3. Non-fermentative, oxidizes amino acids
4. Ubiquitous in water and soil
5. Strong tropism for the lungs, infects alveolar macrophages
6. Intracellular infection in macrophages
7. Protozoal parasite, infects amoebas

Question 3

What type of aerobe is Legionella pneumophila?

Answer 3

Obligate aerobe

Question 4

What specific growth requirements does Legionella pneumophila have?

Answer 4

L-cysteine, ferric ions

Question 5

What type of metabolism does Legionella pneumophila exhibit?

Answer 5

Non-fermentative, oxidize amino acids

Question 6

Where is Legionella pneumophila commonly found?

Answer 6

Ubiquitous in water and soil

Question 7

**

What is the strong tropism of Legionella pneumophila?

Answer 7

Strong tropism for the lung (alveolar macrophages)

This indicates a preference for infecting lung tissue, specifically alveolar macrophages.

Question 8

What type of infection does Legionella pneumophila cause?

Answer 8

Intracellular macrophage infection

Question 9

What type of parasite is Legionella pneumophila associated with?

Answer 9

Protozoal parasite (amoebas)

Question 10

What are the virulence factors of Legionella pneumophila?

Answer 10

1. LPS is less toxic than LPS from other bacteria (e.g., Enterobacteria)

**2. Type IV secretion system **delivers over 200 proteins (many unknown)

3. Inhibits phagolysosome fusion, remains in vacuoles
   - produces proteolytic enzymes

4. Recruits ribosomes, mitochondria and ER components into
a phagosomal compartment
** - LCV – Legionella-containing vacuole

5. At later stages, produces pore-forming toxins to escape the LCV and the macrophage**

Question 11

What clinical disease is caused by Legionella pneumophila?

Answer 11

Causes destructive pneumonia, it rarely spreads outside the lungs

Question 12

Name another clinical disease is caused by Legionella pneumophila

Answer 12

Pontiac fever which is an influenza-like illness

Question 13

Name anotherr clinical disease is caused by Legionella pneumophila

Answer 13

Legionnaires’ disease is a severe form of pneumonia caused by Legionella pneumophila,
2-10 day incubation period
can lead to necrotizing multifocal pneumonia