RT Pathogens

Question 1

What are the differences in the upper and lower respiratory tract?

Answer 1

Upper is non sterile. Lower is sterile

Question 2

What are common pathogens in the RT from upper to lower?

Answer 2

Bordetella pertussis
Corynebacterium diphtehriae
Neisseria meningitidis
Strep pyogenes
Staph aureus
Strep pneumoniae
Haemophilus influenzae
Mycoplasma pneumoniae
Pseudomonas aeruginosa
Legionella penumophila
Mycobacterium tuberculosis (true pathogen)

Question 3

What does Legionella pneumophila cuase?

Answer 3

Legionnaire’s disease and pontiac fever

Question 4

Describe the motility and metabolism of mycobacterium

Answer 4

Non motile, aerobic

Question 5

What is unique about Mycobacterium?

Answer 5

Lipid-rich cell wall–resists antimicrobials, disinfectants and stainings

Question 6

What kind of stain identifies Mycobacterium?

Answer 6

Acid fast

Question 7

What kind of diseases do mycobacteria cause?

Answer 7

Mycobacterium tuberculosis-tuberculosis
Mycobacterium leprae-leprosy
Mycobacterium avium complex (MAC)-pulmonary disease in mostly immunocompromised

Question 8

Where is trehalose dimycolate found, and what does it do?

Answer 8

in cell wall of mycobacterium tuberculosis

makes caseating granulomas (necrosis, inflammation)

Question 9

What are the reservoirs for Mycobacterium tuberculosis?

Answer 9

Humans only

Question 10

How does a healthy person get M. tuberculosis?

Answer 10

From close exposure for long time with someone who has active tuberculosis

Question 11

HOw is M. tuberculosis transmitted?

Answer 11

inhalation, taken up by phagocytic cells

Question 12

What makes someone with active TB infectious?

Answer 12

Have lots of TB in their sputum

Question 13

What are the symptoms of active TB?

Answer 13

Malaise
Weight loss
COUGH
NIGHT SWEATS

Question 14

What is characteristic of latent TB?

Answer 14

granuloma (area of activated immune cells)

Question 15

What are the symptoms of latent TB? What do you see on CXRs?

Answer 15

usually none, no signs of lesion on CXR and sputum normal

Question 16

How can you tell the difference from a primary infection with TB as opposed to that caused by reactivation of latent infection?

Answer 16

Hard to tell

Question 17

What is the gold standard for ID of M tuberculosis?

Answer 17

Positive culture (however, grows slowly)

Question 18

What ID tests can you do for M tuberculosis?

Answer 18

PPD
Quantiferon assay (using bacterium's secreted antigens, detects IFN released from blood cells)

Question 19

How is mycobacterium leprae spread?

Answer 19

Inhalation

Question 20

How can you differentiate the two main types of leprosy?

Answer 20

Tuberculoidal leprosy follows a strong cell mediated immune response and weak humoral response. The opposite is true for lepromatous leprosy

In tuberculoidal, few erythematous plaques; not infectious

In lepromatous, many erythematous plaques, very infectious

Question 21

What is treatment like in general for Mycobacteria?

Answer 21

Difficult in treating; needs multiple antibiotics and lengthy treatments

Question 22

Describe the stain and shape, any other features of Legionella

Answer 22

Gram negative (but stain poorly) bacilli, single flagella

Question 23

Metabolism of Legionella

Answer 23

Obligate aerobes

Question 24

Where does Legionella infection start?

Answer 24

Lungs

Question 25

Which of the following are opportunistic pathogens? Pseudomonas aeruginosa, Legionella pneumophila, Mycobacterium tuberculosis

Answer 25

Pseudomonas aeruginosa and Legionella pneumophila

Question 26

What is unique about the metabolism of Legionella?

Answer 26

gets most energy from breaking down amino acids instead of carbs

Question 27

What is the major Legionella species causing disease in humans?

Answer 27

Legionella penumophila serogroup I

Question 28

Where are Legionellea commonly found?

Answer 28

water, living in amoeba

Question 29

How are Legionella able to infect humans?

Answer 29

inhalation, NOT by drinking water. no transmission between people

Question 30

Pathogenesis of Legionella

Answer 30

Intracellular pathogen, replicates within phagocytic cells Makes virulence factors (many-cytotoxins, hemolysins, proteases, endotoxins, lipases) Type IV secretion system that ejects things into macrophage cytosol Prevents phagosome-lysosome fusion

Question 31

What are the symptoms of Legionaire's disease?

Answer 31

Pneumonia, cough, fever, chest pain

Question 32

Pontiac fever symptoms

Answer 32

Flu-like (fever, chills, malaise)

Question 33

Stain and shape of Pseudomonas

Answer 33

gram negative rods, flagella

Question 34

Where are Pseudomonas commonly found?

Answer 34

water and soil, biofilms on catheters

Question 35

Metabolism of Pseudomonas aeruginosa

Answer 35

oxidase positive! oxidize various carbs

Question 36

Hemolysis ability of Pseudomonas aeruginosa?

Answer 36

hemolytic on blood agar plates

Question 37

What are special pigments made by Pseudomonas aeruginosa?

Answer 37

Pyoverdin and pyocanin--help resist ox stress and give it green color on agar

Question 38

What is the phenotype of Pseudomonas aeruginosa in CF patients?

Answer 38

mucoid

Question 39

What enables Pseudomonas aeruginosa to make biofilms and microcolonies?

Answer 39

polysaccharide capsule

Question 40

What changes do you see in CF patients with age with respect to Psuedomonas aeruginosa infection?

Answer 40

Non-mucoid to mucoid bacteria

Question 41

Pathogenesis of Pseudomonas aeruginosa

Answer 41

Lots of different virulence factors! makes adhesins makes polyshaccharide capsule alginate cover that causes mucoid phenotype makes endotoxin-can cause shock pyocyanine and pyochelin cause oxygen radicals to be released from host cells exotoxins injected into host cells makes proteases

Question 42

Where do Pseudomonas live in the host?

Answer 42

extracellular

Question 43

How can Psuedomonas infect a human?

Answer 43

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