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Medical Microbiology > L19 > Flashcards

L19 Flashcards

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Biology 101 flashcards USMLE® Step 1 flashcards
1
Q

True or False: Non-bacterial agents (viral) are responsible for majority of URI

A

True

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2
Q

Bronchitis, Bronchiolitis, and Pneumonia are infections of the ___
A. URT
B. LRT

A

B. LRT

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3
Q

True or False: Oral and nasal cavities have natural flora, but the URT is sterile

A

False - while oral/nasal cavities have NF, the LRT is sterile

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4
Q

Which two pathogens can cause URT infection in the throat – specifically 1) Strep throat and 2) Diptheria?

A

1) Strep throat - S. pyogenes

2) Diptheria - Corynebacterium diptheria

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5
Q

True or False: Pneumonia, Whooping Cough, and Tb or LRT infections

A

True

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6
Q

True or False: Mycobacterium tuberculosis causes: TB or Chronic pneumonia

A

True

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7
Q

Mycoplasma,
Ureaplasma, and Chlamydia, Legionella are all atypical pneumonias, which can cause __ infection
A. URT
B. LRT

A

B. LRT

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8
Q

Bordetella pertussis can cause which LRT infection?
A. Pneumonia
B. Whooping Cough
C. Strep

A

B. Whooping Cough

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9
Q

What is the #1 bacterial agent of pharyngitis?
A. Mycoplasma
B. Streptococcus pyogenes
C. Cutibacterium acnes
D. Strep aureus

A

B. Streptococcus pyogenes
- Group A Strep
- Gram-positive cocci, chains

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10
Q

Which three adhesions (microbial surface components recognizing adhesive matrix molecules) are used by S. pyogenes for virulence?

A
  1. M protein
  2. Fibronectin and Collagen binding protein
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11
Q

Which three strategies are used by S. pyogenes to evade host immune
response?

A
  1. Capsule (contains HA)
  2. M Protein (antigenic variation)
  3. C5a Peptidase
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12
Q

True or False: S. pyogenes uses toxins (SPE) and enzymes (e.g - Streptolysin S and O; Streptokinase)

A

True

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13
Q

What is the function of Streptolysin S and O + Streptokinase in S. pyogenes?

A

Streptolysin S and O = Lyse RBC

Streptokinase = Activates plasminogen to plasmin to dissolve clots

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14
Q

True or False: In addition to causing strep, S. pyogenes can cause Scarlet Fever + Necrotizing Fascitis

A

True

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15
Q

What happens if you don’t treat pharyngitis (aka - secondary sequlae)?

A
  1. Scarlet Fever - SPE
  2. Rheumatic Fever
  3. AGN
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16
Q

If pharyngitis goes untreated, Rheumatic fever could develop, leading to “molecular mimicry” in which Abs for GAS cross-react
with the host ___ tissue

A

Cardiac

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17
Q

Deposition of antigen-Abs for GAS in the
glomerular basement membrane activate
complement and induces inflammation. This can result when ___ is not treated

A

Pharyngitis

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18
Q

Complications of S. pyogenes infection?

A
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19
Q

S. pyogenes lab diagnosis?

A
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20
Q

Chart

A
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21
Q

True or False: Immunization is important for avoiding Corynebacterium infection

A

True

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22
Q

True or False: Corynebacterium diptheria occurs in palisades and is a gram (+) pleomorphic rod

A

True

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23
Q

C. diptheria uses an AB toxin. B binds to ___ while A is ___ portion/inactivates ___

A

receptor/heparin-binding epidermal GF (heart and nerves); enzymatic; EF-2

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24
Q

True or False: C. diptheria uses toxin carried on a bacteriophage; regulated by iron

A

True

25
Q

Under what conditions will C. diptheria not transcribe toxin genes?

A

When there’s enough Fe
- Both Fe/DtxR will bind to toxin operator

26
Q

True or False: Under low Fe conditions, there is release of DtxR (diptheria toxin repressor) – which allows for transcription of toxin gene

A

True

27
Q

Why is C. diptheriae infection associated with painful swallowing?

A
  • Leads to pseudomembrane formation (bacteria, plasma cell, dead cells)
28
Q

Which test can be used to dx C. diptheria?

A

Elek Test

29
Q

True or False: In bronchiolitis, airway becomes obstructed from swelling of bronchiole walls

A

True

30
Q

Which gram (-) cococobacilli is the causative agent of Pertussis/Whooping cough? Where does it adhere?

A

Bordetella pertussis
- Adheres to: ciliated epithelial cells in trachea

31
Q

True or False: Pertussis/Whopping Cough mostly affects trachea and bronchi

A

True

32
Q

What MOA is used by B. pertussis to cause airway swelling?

A

Makes A-B5 type toxin that binds to G-alpha inhibitory subunit

Increases cAMP and mucous production, as well as death/sloughing of infected cells

33
Q

What is the most contagious stage of Pertussis?
A. Common Cold
B. Paroxysmal cough
C. Convalescent stage

A

A. Common Cold

34
Q

Stages of Pertussis?

A

Common Cold, Paroxysmal Cough, and Convalescent Stage

35
Q

How do organisms enter lung to cause pneumonia?

A

1) Aspiration - S/K pneumo
2) Inhalation of aerosols
3) Hematogenous - S. aureus

36
Q

Pneumonia is associated with necrotic/apoptotic type _ cells

A

1

37
Q

Which two extracellular bacteria cause Typical pneumonia (lobar)?

A

K/S Pneumoniae

38
Q

Which two agents cause Host-compromised Pneumonia (cancer)?

A

Nocardia + P. aero

39
Q

Atypical (interstitial) pneumonia can be caused by which three agents?

A
  1. Legionella
  2. Mycoplasma
  3. Chylamydia
40
Q

Chronic pneumonia is caused by which 2 anaerobes?

A

1) Fungi
2) M. tuberculosis

41
Q

Consolidation/Lobar Pneumonia is associated with which Gram positive bacteria?

A

S. pneumo

42
Q

Which gram (+) bacteria is the major cause of community-acquired pneumonia? Why are epidemics unlikely in this case?

A

S. pneumo
- Due to aspiration (not contagious!)

43
Q

S. pneumo features?

A

Gram (+)
Lancet shape
Encapsulated diplococci
Catalse/coag (-)

44
Q

What is major virulence factor used by S. pneumo?

A

Capsule polysaccharide
- basis of vaccine

45
Q

Rusty colored sputum suggets ___ pneumonia

A

Lobar/Consolidation

46
Q

S. pneumo dx?

A
47
Q

True or False: Atypical Pneumonias are fastidious, grow slow, and lack peptidoglycan layer

A

True
- also, most cause destruction of ciliated respiratory epithelium

48
Q

True or False: M. pneumo and U. urealyticum are extracellular pathogens while Chlamydia are obligate intracellular

A

True

49
Q

True or False: Only M. pneumo and C. pneumo are transmitted person to person – U. urealyticum and C. trachomatasis are transmitted vertically

A

True

50
Q

True or False: M. tuberculosis is associated with chronic pneumonia

A

True
- Note: AFB (+)

51
Q

True or False: M. tuberculosis do NOT have gram stain and do NOT grow on blood agar – there cell contains mycolic acid

A

True

52
Q

True or False: Mycobacteria are often referred to as acid-fast bacilli (AFB)

A

True
- rod shaped
- resistant to decolorization by acid

53
Q

What primary stain can bind to mycolic acid in mycobacteria?

A

Carbolfuschin

  • decolor = acid OH
  • counter = meth blue
54
Q

Which two virulence factors are used by mycobacteria (M Tb)?

A
  1. mycolic acid
  2. cord factor
    - glycolipid found in cell wall
55
Q

True or False: M Tb is INTRACELLULAR BACTERIA + primary defense is cell mediated ( T cell )

A

True

56
Q

True or False: M Tb induces hypersensitivity + it can replicate/survive in macrophages (facultative intracellular)

A

True

57
Q

Blood sputum suggests __

A

Tb

58
Q

Tb dx?

A

Medical Microbiology (31 decks)

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