LEC3 - General Methods for Examination of Fungi Flashcards
1
Q
fungi Incubation is at
A
21°C-30°C
2
Q
- If suspected for dimorphic fungus, cultures should also be incubated
at what temperature
A
37 * C
3
Q
fungi cultures are maintained for how many weeks
A
4-6 weeks
4
Q
Record the ff upon culturing;
A
✓Number of days required to see fruiting structures
✓Mold or yeast
✓Media used
✓Temperature
✓Morphology of colonies
5
Q
texture of colonies
A
velvety
cottony
powdery
hairy
6
Q
what are the things to consider in Colony Morphology
A
- Texture
- Growth Measurements
- Center and Margin of Culture
- Sulcation
- Exudates
- Reverse Colony
- Any soluble pigments
7
Q
- General medium
- Most commonly use
A
Sabouraud Dextrose Agar (SDA)
8
Q
Sabouraud Dextrose Agar (SDA)
____% dextrose and an acidic pH
A
4%
9
Q
pH of Sabouraud Dextrose Agar (SD
A
acidic
10
Q
Sabouraud Dextrose Agar (SDA)
A
❖ Chloramphenicol
❖ Gentamicin
❖ Cycloheximide
11
Q
Sabouraud Dextrose Agar (SDA)
modifications
A
- Emmon’s Modification
- Mycosel Agar
12
Q
Sabouraud Dextrose Agar (SDA)
Modifications:
- Emmon’s Modification
describe the dextrose percentage and ph
A
2% DEXTROSE in neutral pH
13
Q
Sabouraud Dextrose Agar (SDA)
Modifications:
Mycosel Agar
describe what is modified
A
SDA + Chloramphenicol and Cycloheximide
14
Q
- Enrichment agar
A
Brain Heart Infusion (BHI) Agar
15
Q
Brain Heart Infusion (BHI) Agar is used in
A
Recovery of Cryptococcus neoformans and dimorphic transitions of
Sporothrix schenckii and Paracoccidioides brasilliensis
16
Q
Brain Heart Infusion (BHI) Agar are can be in what type of agar
A
tube or plates
17
Q
Brain Heart Infusion (BHI) Agar
modifications
A
- BHI Broth + Penicillin
- BHI + Gentamicin + Chloramphenicol
18
Q
Brain Heart Infusion (BHI) Agar
modifications :
BHI Broth + Penicillin
what is being isolated
A
growth of Zygomy
19
Q
Brain Heart Infusion (BHI) Agar
modifications :
BHI + Gentamicin + Chloramphenicol
what is being isolated
A
Cryptococcus neoformans from
contaminated specimens
20
Q
- Enriched selective medium
A
Inhibitory Mold Agar
21
Q
Inhibitory Mold Agar
contains what substances
A
inorganic salts, chloramphenicol and gentamicin
22
Q
- Primary recovery of pathogenic fungi
A
Inhibitory Mold Agar
23
Q
- General purpose medium
A
Sabouraud Dextrose + BHI (SABHI)
24
Q
- Addition of blood increases isolation of dimorphic fungi
A
Sabouraud Dextrose + BHI (SABHI)
25
Promotes conversion to the yeast stage
Sabouraud Dextrose + BHI (SABHI)
26
* Enhance growth of dermatophytes in cutaneous specimens and
inhibit other fungi and bacteria
Dermatophyte Test Medium
27
Dermatophyte Test Medium inhibitors
* Cycloheximide, Chloramphenicol and Gentamicin
28
Selective and differential for presumptive identification of genus
Candida from primary plates
CHROMagar Candida
29
isolation of Candida albicans specifically for the
growth of Chlamydospores
Cornmeal Tween 80 Agar
30
Cornmeal Tween 80 Agar
Addition of ____ to provide contrasting
background for observing morphologic features
of yeast
trypan blue
31
Christensen’s Urea Agar composition
Composed of 2% Urea, Phenol
32
Christensen’s Urea Agar is used in the isolation of
Cryptococcus, Trichosporon and Rhodotorula sp
33
agar used in * Differential identification of
Aspergillus spp
Czapek’s Agar
34
Czapek’s Agar components
Sodium nitrate, sucrose and yeast
extract
35
medium used for * Identification of Cryptococcus
neoformans
Niger Seed Agar/Birdseed Agar/Staib’s
Medium
36
Niger Seed Agar/Birdseed Agar/Staib’s
Medium composition
Potassium nitrate, peptone, meal
extract, sulfanilic acid, N,N-dimethyl1naphthylamine
37
Enhances pigmentation and sporulation of
dermatophytes
Potato Dextrose Agar
38
Potato Dextrose Agar composition
Potato extract, D-glucose
39
used in Differentiation of Microsporum canis (yellow pigment) to Microsporum auduinii (rice
grains turn brown)
Rice Medium
40
rice medium composition
White rice extract, polysorbate 80
41
medium used for Detection of Cryptococcus spp, differentiation of Trichophyton
mentagrophytes from Trichophyton rubrum
Urea Agar
42
component of urea agar
Peptone, dextrose, sodium chloride,
monopotassium phosphate, urea and
phenol red
43
positive result of urea agar
Pink
44
used for the Conversion of mold to yeast form of Blastomyces dermatitidis
Cottonseed Agar
45
Indirect Microscopic Examination through
Culture
things needed to observe
* Septate versus sparsely septate hyphae
* Hyaline or phaeoid hyphae
* Fruiting structures
* Type size, shape and arrangement of conidia
46
* Microscopic characteristics that should be observed:
* Septate/Aseptate
* Hyaline/Phaeiod
* Fruiting Structures
* Types, size, shape and arrangement of conidia
47
Methods for microscopic examination
* LPCB Tease Preparation (acto-phenol cotton blue)
* Scotch Tape/Adhesive/Cellophane Preparation
* Riddell/Microculture Technique
48
LPCB (Lactophenol Cotton Blue) Tease Mount
* Teasing needles are used to remove a portion of the mycelium from
the ____of the colony
middle third
49
Disadvantage of LPCB (Lactophenol Cotton Blue) Tease Mount
disruption of conidia during the teasing process
50
* gently touching a piece of clear tape, sticky side down, to the surface
of the colony and then removing it.
Cellophane Tape/Scotch Tape Preparation
51
The tape is placed onto a drop of LPCB on a slide and examined
Cellophane Tape/Scotch Tape Preparation
52
Advantage of Cellophane Tape/Scotch Tape Preparation
retention of conidial arrangement
53
Disadvantage of Cellophane Tape/Scotch Tape Preparation
potential contamination of the colony, should be read within 30 minutes and then discarded
54
Useful for demonstrating the natural morphology of fungal structure
Slide Culture Technique/Riddell Technique
55
Direct Microscopic Examination perks
* Directly from clinical specimen
* Rapid report to the physician
* Provides clue to the genus of the organism
* Might provide evidence of infection despite negative cultures
56
* Most common routine test
10-20% Potassium Hydroxide (KOH) Test
57
10-20% Potassium Hydroxide (KOH) Test sample sources
Nail scrapings, hair, skin scales, thin slices of tissue
58
* Presumptive test for fungal infections
10-20% Potassium Hydroxide (KOH) Test
59
Upon collection of sample, 10-20% KOH is added to the slide, wait for
__, then look for yeast or hyphae.
15-30 minutes
60
-rapid breakdown of cellular debris
without the need for heating
DMSO (Dimethyl sulfoxide)
61
Uses a fluorescence dye
KOH with Calcofluor White Stain
62
KOH with Calcofluor White Stain
In need of a ____ microscope to
visualize formation of yeast and hypha
fluorescence
63
Superior to KOH test
KOH with Calcofluor White Stain
64
india Ink/Nigrosin Stain
what sample is needed
csf sample
65
India Ink/Nigrosin Stain
* CSF sample is used to examine presence of ___
Cryptococcus neoformans
66
In india ink/nigrosin ink, what is the appearance of yeast
Yeast surrounded by a halo (capsule) against a black background.
67
periodic acid schiff color of fungal element
magenta in pink or green background
68
gomori methenamine silver color of fungal element
black in green background
69
giemsa color of fungal element
purple blue yeast with clear halo or capsule in pink-purple background
70
india ink color of fungal element
yeast with clear halo in black background
71
KOH color of fungal element
REFRACTILE
72
KOH - cakcofluor white
fluorescent
73
masson-fontana color of fungal element
brown in pink-purple background
74
Sterile 5- to 10-mm hair fragments are floated on sterile water
supplemented with a few drops of sterile 10% yeast extract
Hair Perforation T
75
Differentiate T. mentagrophytes from T. rubrum -
5-day ____test at
room temperature
Urease Test
76
urease test uses what agar
Christensen urea agar
77
Single most useful nutritional test for dermatophytes
Thiamine Requirement
78
Only ____ are identified to be
germ tube positive
Candida albicans and Candida dubliniensis
79
7 different ____ number 1 through 7 are
used to determine the nutritional requirements of the
Trichophyton spp
Trichophyton agars
80
can
be used as an alternative in Germ Tube Production
Brain Heart Infusion Broth, Trypticase Soy Broth, Nutrient Broth
81
Germ Tube Production
* Incubated at 37°C and must be read not beyond_
3 hrs
82
Assimilation tests identify which carbohydrates a yeast can use
aerobically as a sole carbon source
Carbohydrate Assimilation
83
Serological Test
* Use of blood samples
* Complement Fixation
* Agglutination
84
* Complement Fixation
* Histoplasma capsulatum
* Coccidioides immitis
* Blastomyces dermati
85
Agglutination
Cryptococcus neoformans
* Other dimorphic fungi
86
Molecular Detection
* PCR
* Use the DNA of fungi as a confirmatory in identification
87
Positive for Urease
* Cryptococcus and Rhodotorula
* Most strains of Trichosporon spp
88
Negative for Urease test
* Candida spp
89
Temperature Studies of Cryptococcus spp
*
Weak growth at 35°C, no growth at 42°C, optimal growth at 25°C
90
Temperature Studies of * Candida sp
* Most can grow up to 45°C
* Candida dubliniensis cannot grow at 45°
91
Potassium Nitrate Assimilation
*___ (positive control)
Cryptococcus albidus
92
Potassium Nitrate Assimilation
__ (negative control)
Candida albicans
93
accurate method to determine the ability of yeast to use nitrate as
the sole source of nitrogen
Potassium Nitrate Assimilation
94
Potassium Nitrate Assimilation
Positive test result turns the medium __, if negative it turns ;__
blue; yellow
