ID 2 Flashcards

1
Q

Why can’t you stain mycobacteria?

A

cell wall has high lipid content

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2
Q

why can’t you stain mycoplasma/ureaplasma?

A

no cell wall

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3
Q

Why can’t you stain chlamydia?

A

primarily intracellular + lacks classic peptidoglycan because of decreased muramic acid.

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4
Q

What other bugs can’t you stain and why?

A

Intracellular like Legionella, rickettsia, chlamydia, bartonella, ehrlichia, anaplasma

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5
Q

Giemsa staining for

A
Chlamydia
Borrelia
Rickettsia
*Trypanosomes
*Plasmodium
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6
Q

What does PAS stain?

A

Glycogen, mucopolysaccharides

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7
Q

other name for Ziehl-Neelsen

A

carbol fuchsin

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8
Q

What else can you use Ziehl-Neelsen for

A

1) acid-fast bacteria (nocardia)

2) protozoa (cryptosporidum oocysts)

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9
Q

Alternative stain for acid-fast bacteria to Ziehl-Neelsen and characteristics of test?

A

Auramine-rhodamine for screening (cheep, more sensitive but less specific)

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10
Q

Mucicarmine affect?

A

stains thick polysaccharide capsule of cryptococcus red

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11
Q

what else do you use silver stain for?

A

1) coccidoides
2) legionella
3) H pylori

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12
Q

What can you stain viruses with?

A

Fluorescent antibody stain

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13
Q

Example of selective media

A

Thayer-Martin (contains antibiotics)

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14
Q

significance of differential/indicator media?

A

yields a color change in response to metabolism of certain organisms

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15
Q

example of indicator differential media?

A

MacConkey (contains a pH indicator)

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16
Q

culture requirements for H influenza?

A

Factors V (NAD+) and X (hematin)

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17
Q

n meningitides media?

A

Thayer-Martin

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18
Q

How does Thayer-Martin agar work?

A

1) inhibits gram positives with vancomycin
2) inhibits gram negatives (except neisseria obviously) with trimethoprim and colistin
3) inhibits fungi with nystatin

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19
Q

what does Regan-Lowe medium contain?

A

Charcoal, blood, antibiotic

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20
Q

tb culture?

A

Lowenstein-Jensen agar

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21
Q

M pneumonia media?

A

Eaton agar. Requires cholesterol.

22
Q

Effect on MacConkey agar?

A

Used for lactose-fermenting enterics. Fermentation produces acid, causing colonies to turn pink.

23
Q

e coli medium?

A

eosin-methylene blue (EMB) agar

24
Q

affect of EMB agar

A

colonies with green metallic sheen

25
Q

legionella agar

A

charcoal yeast extract buffered with cysteine and iron

26
Q

What do you stain fungi with?

A

Sabouraud’s agar

27
Q

Aerobes?

A

Nocardia
Pseudomonas
Mycobacterium tuberculosis

28
Q

anaerobes?

A

Clostridium
Bacteroides
Fusobacterium
Actinomyces

29
Q

Anaerobe characteristics

A

1) susceptible to oxidative-damage (don’t have catalase or superoxide dismutase)
2) foul smelling (short-chain fatty acids)
3) hard to culture
4) produce gas in tissue (CO2 and H2)
5) normal flora in GI tract but pathogenic elsewhere

30
Q

Why are ahminoglycosides ineffective against anaerobes?

A

ahminoglycosides require O2 to enter into bacterial cells.

31
Q

obligate intracellular bugs

A

Rickettsia
Chlamydia
Coxiella

32
Q

why are certain bugs obligate intracellular?

A

rely on host ATP production

33
Q

facultative intracellular bugs?

A
Salmonella
Neisseria
Brucella
Mycobacterium
Listeria
Francisella
Legionella
Yersinia
34
Q

immunologic response to encapsulated bacteria?

A

Opsonized, then cleared by spleen.

35
Q

what vaccines do asplenics need?

A

1) s pneumo
2) h flu
3) n menigitidis

36
Q

why are vaccines conjugated to a carrier protein?

A

promotes T-cell activation and class switching

37
Q

what is the pneumococcal vaccine?

A

1) Pneumococcal conjugate vaccine (PCV), ie Prevnar

2) PPSV, pneumococcal polysaccharide vaccine with no conjugated protein, i.e. Pneumovax

38
Q

Other conjugate vaccines?

A
  • H influenza type B

- meningococcal vaccine

39
Q

Urease action

A

hydrolyzes urea to release ammonia + CO2, thus increasing pH.

40
Q

Urease-positive organisms

A
Proteus
*cryptococcus
H pylori
Ureaplasma
*Nocardia
Klebsiella
*S epidermidis
S saprophyticus
41
Q

catalase MOA

A

Degrades H2O2 into H2O and bubbles of O2. This prevents H2O2 from being converted to microbicidal products by myeloperoxidase.

42
Q

Catalase positive organisms?

A
Nocardia
Pseudomonas
Listeria
Aspergillus
Candida
E coli
Staphylococci
Serrate
B cepacia
H pylori
43
Q

s aureus pigment?

A

yellow (aureus is latin for gold)

44
Q

pseudomonas pigment?

A

blue-green

45
Q

Other biofilm-producing bug?

A

*Nontypeable H influenza

46
Q

What does nontypeable mean?

A

Unencapsulated

47
Q

Contact-lens associated keratitis caused by?

A

pseudomonas

48
Q

s aureus virulence factor?

A

protein A; prevents opsonization and phagocytosis

49
Q

bugs that have an IgA protease?

A

1) S pneumonia
2) H flu type B
3) Neisseria

50
Q

Function of M protein?

A

prevents phagocytosis.

51
Q

autoimmune response to ARF MOA?

A

M protein of group A strep shares similar epitopes to human cellular proteins (molecular mimicry).