Lecutre 6 - Laboratory ID methods: Mycology
Study these flashcardsFree · spaced repetition · iPhone, Android, Mac & web
All cards
1
What are the 2 types of diagnostic testing?
Classic and Newer
2
What are the 2 types of classic diagnostic testing?
Microscopy examination (numerous staining techniques)
Culture.
Culture.
3
What are the 4 types of new diagnostic testing?
1. antigen & antibody testing
2. NAAT (nucleic acid amplification tests)
3. MALDI-TOF MS <- more for yeasts
4. Micro scan, Vitex, Phoenix
2. NAAT (nucleic acid amplification tests)
3. MALDI-TOF MS <- more for yeasts
4. Micro scan, Vitex, Phoenix
4
What is the main type of wet mount used for microscopic examination?
KOH Wet Mount
5
What stains are used in the clinical lab?
GRAM STAIN, MODIFIED ACID FAST STAIN, WRIGHT STAIN, GIEMSA STAIN
6
What stains are used for pathology lab?
Periodic Acid-Schiff, H&E, Gomori's Methenamin Silver (GMS)
7
What the most used staining for mycology sections for ID?
Lactophenol cotton blue
8
Which stain makes hyphae elements glow?
Calcofluor white
9
What is KOH wet mount made out of?
10% Potassium hydroxide + specimen
10
What is the purpose for KOH wet mount?
to dissolve away the non-fungal elements in a specimen to better see if any fungus is present
11
What is the purpose for India Ink?
to identify encapsulated yeast (cryptococcus spp.)
12
What TYPE OF SPECIMEN is india ink usually used for?
CSF specimen
13
What does "phenol" in Lectophenol Cotton Blue do ?
kills the organisms
14
What does "lactic acid" in Lectophenol Cotton Blue do ?
preserves fungal structures
15
What does "cotton blue" in Lectophenol Cotton Blue do ?
Stains the chitin found in the fungal cell walls
16
How do you set up a slide with Lactophenol cotton blue stain?
use tape method or tease mount "teasing" and mix into stain on slide
17
What does calcofluor white bind to?
polyysaccharides of chitin in fungal cell walls 
18
What stain is this??
Gram stain
19
What stain is this??
Gomori's Methenamine Silver
20
What stain is this??
Periodic Acid-Schiff
21
What stain is this??
Giemsa Stain
22
Which laboratory testing is THE GOLD STANDARD AND WHAT DOES IT PROVIDE?
CULTURE; often provides the definitive diagnosis
23
What can you examine from culture?
microscopic and macroscopic morphology
24
What is it called when the specimen is first placed onto the agar plate?
primary inoculation (specimen onto agar plate) 25-35oC; hold 4 weeks
25
What is it called when you transfer a colony onto a new type of media?
Secondary isolation (colony onto new type of media) - selective/differntial agar can help ID organism)
26
Which instrument is mostly used for rapid yeast ID?
Microscan; vitek phoenix instruments 
27
What does MALDI-TOF stand for?
MATRIX
ASSISTED
LASER
DESORPTION/
IONIZATION
T IME
OF
FLIGHT
ASSISTED
LASER
DESORPTION/
IONIZATION
T IME
OF
FLIGHT
28
What type of molecular testing is done?
PCR Testing or DNA probes
29
What is another type of molecular testing done? besides PCR
DNA PROBES (AccuProbe)
30
What is the "principle" behind DNA Probes?
Nucleic acid hybridization
31
What are the 3 types of antigen testing done?
Aspergillus Antigen Testing
B-D-glucan (Fungitell)
Antigen screen for Cryptococcosis
B-D-glucan (Fungitell)
Antigen screen for Cryptococcosis
32
What is immunodiffusion? (serologic testing)
antibodies from patient's serum bind to antigens in well of gel agar, form line of precipitation (qualitative test) 
33
How long does IgM seroconversion last?
1-3 weeks
34
How long does IgG seroconversion last?
2-28 weeks, not lifelong
35
What is another serologic testing (AB), besides immunodiffusion?
Complement fixation
36
How is this different from other tests?
No hemolysis = positive aka no reaction = positive
37
Is complement fixation qualitative or quatitative?
Quantitative
38
how does complement fixation work?
If antibodies to specific fungal pathogen testing is present in patient’s blood, complement will NOT lyse the rcbs b/c it will instead bind to antigen
39
What is the purpose of antifungal susceptibility testing?
produce MIC (minimum inhibitory concentration) values that may be used to guide patient therapy, inform epidemiological studies, and track rates of antifungal drug resistance.
40
When do physicians want antifungal susceptibility testing?
fungal infection is invasive
• when acquired drug resistance is suspected
• when the patient is unexpectedly failing therapy
• when acquired drug resistance is suspected
• when the patient is unexpectedly failing therapy
41
What are examples of antifungal susceptibility tests?
Disk diffusion; gradient diffusion; broth dilution
42