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Flashcards in ID 2 Deck (51):
1

Why can't you stain mycobacteria?

cell wall has high lipid content

2

why can't you stain mycoplasma/ureaplasma?

no cell wall

3

Why can't you stain chlamydia?

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

4

What other bugs can't you stain and why?

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

5

Giemsa staining for

Chlamydia
Borrelia
Rickettsia
*Trypanosomes
*Plasmodium

6

What does PAS stain?

Glycogen, mucopolysaccharides

7

other name for Ziehl-Neelsen

carbol fuchsin

8

What else can you use Ziehl-Neelsen for

1) acid-fast bacteria (nocardia)
2) protozoa (cryptosporidum oocysts)

9

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

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

10

Mucicarmine affect?

stains thick polysaccharide capsule of cryptococcus red

11

what else do you use silver stain for?

1) coccidoides
2) legionella
3) H pylori

12

What can you stain viruses with?

Fluorescent antibody stain

13

Example of selective media

Thayer-Martin (contains antibiotics)

14

significance of differential/indicator media?

yields a color change in response to metabolism of certain organisms

15

example of indicator differential media?

MacConkey (contains a pH indicator)

16

culture requirements for H influenza?

Factors V (NAD+) and X (hematin)

17

n meningitides media?

Thayer-Martin

18

How does Thayer-Martin agar work?

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

19

what does Regan-Lowe medium contain?

Charcoal, blood, antibiotic

20

tb culture?

Lowenstein-Jensen agar

21

M pneumonia media?

Eaton agar. Requires cholesterol.

22

Effect on MacConkey agar?

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

23

e coli medium?

eosin-methylene blue (EMB) agar

24

affect of EMB agar

colonies with green metallic sheen

25

legionella agar

charcoal yeast extract buffered with cysteine and iron

26

What do you stain fungi with?

Sabouraud's agar

27

Aerobes?

Nocardia
Pseudomonas
Mycobacterium tuberculosis

28

anaerobes?

Clostridium
Bacteroides
Fusobacterium
Actinomyces

29

Anaerobe characteristics

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

Why are ahminoglycosides ineffective against anaerobes?

ahminoglycosides require O2 to enter into bacterial cells.

31

obligate intracellular bugs

Rickettsia
Chlamydia
Coxiella

32

why are certain bugs obligate intracellular?

rely on host ATP production

33

facultative intracellular bugs?

Salmonella
Neisseria
Brucella
Mycobacterium
Listeria
Francisella
Legionella
Yersinia

34

immunologic response to encapsulated bacteria?

Opsonized, then cleared by spleen.

35

what vaccines do asplenics need?

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

36

why are vaccines conjugated to a carrier protein?

promotes T-cell activation and class switching

37

what is the pneumococcal vaccine?

1) Pneumococcal conjugate vaccine (PCV), ie Prevnar
2) PPSV, pneumococcal polysaccharide vaccine with no conjugated protein, i.e. Pneumovax

38

Other conjugate vaccines?

- H influenza type B
- meningococcal vaccine

39

Urease action

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

40

Urease-positive organisms

Proteus
*cryptococcus
H pylori
Ureaplasma
*Nocardia
Klebsiella
*S epidermidis
S saprophyticus

41

catalase MOA

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

42

Catalase positive organisms?

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

43

s aureus pigment?

yellow (aureus is latin for gold)

44

pseudomonas pigment?

blue-green

45

Other biofilm-producing bug?

*Nontypeable H influenza

46

What does nontypeable mean?

Unencapsulated

47

Contact-lens associated keratitis caused by?

pseudomonas

48

s aureus virulence factor?

protein A; prevents opsonization and phagocytosis

49

bugs that have an IgA protease?

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

50

Function of M protein?

prevents phagocytosis.

51

autoimmune response to ARF MOA?

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