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Flashcards in RT Pathogens Deck (43):
1

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

Upper is non sterile. Lower is sterile

2

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

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

3

What does Legionella pneumophila cuase?

Legionnaire's disease and pontiac fever

4

Describe the motility and metabolism of mycobacterium

Non motile, aerobic

5

What is unique about Mycobacterium?

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

6

What kind of stain identifies Mycobacterium?

Acid fast

7

What kind of diseases do mycobacteria cause?

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

8

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

in cell wall of mycobacterium tuberculosis
makes caseating granulomas (necrosis, inflammation)

9

What are the reservoirs for Mycobacterium tuberculosis?

Humans only

10

How does a healthy person get M. tuberculosis?

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

11

HOw is M. tuberculosis transmitted?

inhalation, taken up by phagocytic cells

12

What makes someone with active TB infectious?

Have lots of TB in their sputum

13

What are the symptoms of active TB?

Malaise
Weight loss
COUGH
NIGHT SWEATS

14

What is characteristic of latent TB?

granuloma (area of activated immune cells)

15

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

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

16

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

Hard to tell

17

What is the gold standard for ID of M tuberculosis?

Positive culture (however, grows slowly)

18

What ID tests can you do for M tuberculosis?

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

19

How is mycobacterium leprae spread?

Inhalation

20

How can you differentiate the two main types of leprosy?

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

21

What is treatment like in general for Mycobacteria?

Difficult in treating; needs multiple antibiotics and lengthy treatments

22

Describe the stain and shape, any other features of Legionella

Gram negative (but stain poorly) bacilli, single flagella

23

Metabolism of Legionella

Obligate aerobes

24

Where does Legionella infection start?

Lungs

25

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

Pseudomonas aeruginosa and Legionella pneumophila

26

What is unique about the metabolism of Legionella?

gets most energy from breaking down amino acids instead of carbs

27

What is the major Legionella species causing disease in humans?

Legionella penumophila serogroup I

28

Where are Legionellea commonly found?

water, living in amoeba

29

How are Legionella able to infect humans?

inhalation, NOT by drinking water. no transmission between people

30

Pathogenesis of Legionella

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

31

What are the symptoms of Legionaire's disease?

Pneumonia, cough, fever, chest pain

32

Pontiac fever symptoms

Flu-like (fever, chills, malaise)

33

Stain and shape of Pseudomonas

gram negative rods, flagella

34

Where are Pseudomonas commonly found?

water and soil, biofilms on catheters

35

Metabolism of Pseudomonas aeruginosa

oxidase positive! oxidize various carbs

36

Hemolysis ability of Pseudomonas aeruginosa?

hemolytic on blood agar plates

37

What are special pigments made by Pseudomonas aeruginosa?

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

38

What is the phenotype of Pseudomonas aeruginosa in CF patients?

mucoid

39

What enables Pseudomonas aeruginosa to make biofilms and microcolonies?

polysaccharide capsule

40

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

Non-mucoid to mucoid bacteria

41

Pathogenesis of Pseudomonas aeruginosa

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

42

Where do Pseudomonas live in the host?

extracellular

43

How can Psuedomonas infect a human?

cystic fibrosis
eye (contact lenses for long time)
burns
UTI
wound
can cause bacteremia and endocarditis