Flashcards in ID 2 Deck (51)
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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
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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.
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