2 LAB IDENTIFICATION OF FUNGI Flashcards
The standard microdilution method for molds that cause invasive and
cutaneous infections
CLSI document M38-A2
What are the predominant culture sites for recovery of Sporotrichosis?
- Respiratory
- Tissue
- Skin
- Mucus
GRAM STAIN is an example of _______.
a. PERMANENT MOUNTS
b. WET MOUNT
c. TEASE MOUNT
d. MICROSLIDE CULTURE METHOD
a. PERMANENT MOUNTS
_______ and _______ are risk group 3 pathogens and requires biosafety level 3.
Coccidioides spp. and H. capsulatum
What is the media used to isolate Dermatophytic Fungi?
Sabouraud Dextrose Agar
What is the recommended battery of media?
- Media with and without CYCLOHEXIMIDE
- Media with and without an antibacterial agent
These bacteria grows slowly (>10 days). Enumerate.
- B. dermatitidis
- H. capsulatum
- P. brasiliensis
______ describes the various elevations of the colony on the agar plate
COLONY TOPOGRAPHY
______ is useful for demonstrating internal details
Stain fungal elements well; hyphae of yeasts and molds can
be readily distinguished
PERIODIC-ACID SCHIFF STAIN
TRUE OR FALSE
H&E slides are not required to be restained in PERIODIC-ACID SCHIFF STAIN if fungus wall is invisible
FALSE (H&E slides may be restained with this method if fungus wall is invisible)
This is a type of colony topography wherein elevations have furrows that radiate out from the center
Rugose
GRAM STAIN, also known as ________ , is an example of permanent mount.
HUCKER MODIFICATION
GERM TUBE TEST is used as a presumptive identification of _____ or _______
C. albicans or C. dubliniensis
What type of tubes should be used for culture media?
SCREW-CAPPED TUBES
this stain fungal elements well; hyphae of yeasts and molds can
be readily distinguished
PERIODIC-ACID SCHIFF STAIN
What are the different pathogenic fungi partially or completely inhibited by Cycloheximide?
- C. neoformans complex
- Candida krusei and other Candida spp.
- Trichosporon spp.
- P. boydii
- Aspergillus spp.
PERIODIC-ACID SCHIFF STAIN attaches to polysaccharides in the fungal wall and stains ______
PURPLISH RED = MAGENTA
What stain does gram stain employs?
CRYSTAL VIOLET and AMMONIUM OXALATE
Determine what type of COLONY’S TEXTURE is being described.
high aerial mycelium that appears slightly matted down
WOOLY
What is the requirement for Emmons’ modification of Sabouraud Dextrose Agar?
a. Antibacterial antibiotics should be included
b. Less glucose with a pH of 6.8–7.0
c. Should contain no antibacterial or antifungal agents
d. pH of 5.5–5.6
b. Less glucose with a pH of 6.8–7.0
This is the test specifically used to identify C. albicans
GERM TUBE TEST
This document covers requirements for use of the broth microdilution
method
CLSI document M27-A3
What are the different specimens for RESPIRATORY SECRETIONS?
- Sputum
- Induced sputum
- Bronchial washings
- Bronchoalveolar lavage
- Tracheal aspirations
TRUE OR FALSE
All fungi are Gram(+)
TRUE
This type of permanent mount is useful for the detection of yeast
GRAM STAIN (HUCKER MODIFICATION)
(1-3)-β-D-glucan activates the coagulation cascade in _______.
LIMULUS AMEBOCYTE LYSATE
Determine what type of COLONY’S TEXTURE is being described.
Loose, high aerial mycelium
COTTONY
_____ direct smear and culture (CHROMagar Candida and Candida ID)
Oropharyngeal candidiasis
Reference Method for Broth Dilution Antifungal Susceptibility
Testing of Yeasts
CLSI document M27-A3
Give at least 3 organisms included in CLSI document M38-A2 for evaluation.
Aspergillus spp., Fusarium spp., Rhizopus oryzae (R. arrhizus), Pseudallescheria boydii, Scedosporium prolificans, Sporothrix schenckii (mycelial form), Dermatophytes (Epidermophyton, Microsporum, and Trichophyton)
This is a type of colony topography wherein elevations are furrowed or convoluted.
Umbonate = slightly raised in the center
Verrucose
What bacteria grows fast, typically less than 4 days in a medium?
Mucorales
Determine what type of COLONY’S TEXTURE is being described.
Dense, powdery, resembling sugar granules
GRANULAR
________ preserves fungal structures
LACTIC ACID
Reference Method for Broth Dilution Antifungal Susceptibility
Testing of Filamentous Fungi
CLSI document M38-A2
Sabouraud Dextrose Agar is used to isolate _______.
Dermatophytic Fungi
What is the required pH for Sabouraud Dextrose Agar?
a. 5.1–5.1
b. 5.3–5.4
c. 5.5–5.6
d. 5.7–5.8
c. pH of 5.5–5.6
Method for antifungal disk diffusion susceptibility testing of yeasts
(Candida spp.)
CLSI document M44-A2
All of the following are temporary mounts EXCEPT:
a. CALCOFLUOR WHITE STAIN
b. 10-20% KOH
c. HEMATOXYLIN & EOSIN STAIN
d. INDIA INK OR NIGROSIN
c. HEMATOXYLIN & EOSIN STAIN
In LCB, ____ serves as the killing agent
PHENOL
TRUE OR FALSE
Inoculation and manipulation of mould colonies should always be performed in a BIOLOGICAL SAFETY CABINET CLASS III
FALSE
- Inoculation and manipulation of mould colonies should always be performed in a BIOLOGICAL SAFETY CABINET CLASS II
EXOANTIGEN TEST uses identification through __________ .
ANTIGEN-ANTIBODY REACTION
Give at least 2 GENERAL CONSIDERATIONS FOR THE IDENTIFICATION OF YEASTS.
- COLONIAL MORPHOLOGIC FEATURES
- MICROSCOPIC MORPHOLOGIC FEATURES
- PHYSIOLOGIC STUDIES
- RAPID COMMERCIAL YEAST IDENTIFICATION TESTS
This is constricted germ tubes and is a characteristic of C. tropicalis
PSEUDO–GERM TUBES
This is a type of colony topography wherein elevations are slightly raised in the center.
Umbonate
Determine what type of COLONY’S TEXTURE is being described.
Smooth surface with no aerial mycelium
GLABROUS
TRUE OR FALSE
In respiratory secretions, ANTIBACTERIAL ANTIBIOTICS should be included in the battery of media
TRUE
In temporary wet mounts, ________ is the most widely used method of
staining.
LACTOPHENOL COTTON BLUE
Determine what test is being asked?
Antibody developed against particular mycelial antigens will react specifically in a GEL IMMUNODIFFUSION PRECIPITIN TEST
EXOANTIGEN TEST
CLSI document M27-A3 is approved for the testing of _____ and _____
Candida spp. and C. neoformans
Method for antifungal disk diffusion susceptibility testing of
nondermatophyte filamentous fungi
CLSI M51-A
Determine what type of COLONY’S TEXTURE is being described.
Low aerial mycelium resembling a velvet cloth
VELVETY
_____ is the type of media used for DERMATOPHYTE culture
MYCOBIOTIC OR MYCOSEL AGAR
What is the purpose of ANILINE BLUE in LCB?
a. preserves fungal structures
b. stains fungal structure
c. killing agent
b. stains fungal structure
What are the different commercial yeast ID systems?
- API-20C yeast system
- API Yeast-Ident system
- Uni-Yeast Tek system
- AutoMicrobic system
- Abbott Quantum II system
_________ present in the cell wall of most yeasts and molds, including
Pneumocystis, except ________ molds
(1-3)-β-D-GLUCAN DETECTION ; mucoraceous
All of the following are permanent mounts EXCEPT:
a. PAPANICOLAOU STAIN
b. GRAM STAIN (HUCKER MODIFICATION)
c. GIEMSA AND WRIGHT STAIN
d. LACTOPHENOL COTTON BLUE (LPCB)
d. LACTOPHENOL COTTON BLUE (LPCB)
The Incubation requirement for DERMATOPHYTE culture is _______.
MINIMUM OF 21 DAYS AT 30°C
For respiratory secretions, is it necessary to include CYCLOHEXIMIDE in at least one of the culture media?
YES
What type of test is being asked?
- Requires the use of serum or plasma
- substrate is inoculated and then incubated at 35° C for 3 hours
GERM TUBE TEST
VAGINAL SPECIMEN should be transported to laboratory within _____ of collection using culture transport swabs
24 hours
This involve gently touching a piece of clear tape, sticky side down, to the surface of the colony
CELLOPHANE (SCOTCH) TAPE METHOD
Candida glabrata appears ______ in CHROMagar Candida
VELVET
TRUE OR FALSE
CSF Media should contain no antibacterial or antifungal agents
TRUE
In CSF, 1 drop of the concentrate = _____ or _____ for Cryptococcus
INDIA INK PREPARATION or LATEX AGGLUTINATION
Enumerate the 3 Automated Blood Culture Systems (yeast):
- BACTEC
- BacT/ALERT
- VersaTREK
TRUE OR FALSE
All specimens (TISSUE, BONE MARROW, AND STERILE BODY FLUIDS) should be cultured 2 hrs after collection to ensure the recovery of fungi
FALSE (All specimens should be cultured ASAP)
What do you examine for Abscess Fluid and Wound Exudates specimens?
the presence of granules
This appears STEEL BLUE in CHROMagar Candida.
Candida tropicalis
_____ used for the detection of C. neoformans in CSF through negative staining to demonstrate ________ .
INDIA INK OR NIGROSIN ; POLYSACCHARIDE
CAPSULE
The required days of incubation for respiratory, bone marrow, and blood pathogens, and for specimens in which a dimorphic fungus is suspected is ____________________
28 days
For skin specimens,
- submitted as scrapings or cuttings
- scraped from the outer edge of a surface lesion
a. both statements are true
b. only statement 1 is true
c. only statement 2 is true
d. both statements are false
c. only statement 2 is true
What is the incubation period for vaginal specimens?
30°C for 7 days
What is the disadvantage of Wet Mount?
characteristic arrangement of spores is disrupted.
______ is the preferred method for microscopic examinations. This also binds to the ______ in the walls of fungal cells.
CALCOFLUOR WHITE STAIN ; CHITIN
CSF specimens should be processed promptly but if not possible
should be kept FROZEN.
FALSE ( CSF spx should be kept at RT or in incubator at 30°C if processing promptly is not possible)
Used for the detection of Nocardia and B. dermatitidis
ACID FAST STAIN
Used for the detection of H. capsulatum and C. neoformans from blood
or bone marrow specimens
GIEMSA AND WRIGHT STAIN
For permanent mounting in TEASE MOUNT, an addition of _____ is necessary.
10% PVA
_____ is recommended for disseminated fungal infections
BLOOD
Optimal temperature for fungal blood cultures:
30°C
TRUE OR FALSE
CSF Cultures should be examined weekly
False ( CSF Cultures should be examined DAILY)
What are the advantages and disadvantages of CELLOPHANE (SCOTCH) TAPE METHOD?
Advantage: conidial arrangement is retained
Disadvantages:
- potential contamination of the colony
- temporary nature of this preparation
Candida krusei appears _____ in CHROMagar Candida
ROSE
What is the disadvantage of TEASE MOUNT?
Disruption of conidia
Considered to be the best stain for the detection of fungi in histologic
sections
GOMORI’S METHENAMINE SILVER STAIN
Specimens incubated for _____ days detect the presence of yeast in mouth, throat, or vaginal specimens
7 days
Used for Nocardia
AURAMINE-RHODAMINE STAIN
This type of stain demonstrate melanin or melanin-like substances in the lightly pigmented agents of PHAEOHYPHOMYCOSIS
MASSON-FONTANA STAIN
Cytotechnologist can detect fungal elements using this method
PAPANICOLAOU STAIN
Specimens incubated for _____ days detect fungal pathogens in tissues and sterile body fluids other than blood
21 days
In PAPANICOLAOU STAIN, fungal elements stain _____.
pink to blue
MASSON-FONTANA STAIN identifies the presence of _______ and the
differentiation of melanin and hemosiderin pigments
PHAEOID FUNGI
Fungal Blood Cultures System:
- BIPHASIC BHIA- BROTH (Isolator)
- LYSIS-CENTRIFUGATION SYSTEM (Septi-Chek)
a. both are true
b. only 1 is true
c. only 2 is true
d. both are false
d. both are false
- BIPHASIC BHIA- BROTH (Septi-Chek)
- LYSIS-CENTRIFUGATION SYSTEM (Isolator)
(+) Result of GOMORI’S METHENAMINE SILVER STAIN: ______
Black
What is the color of C. albicans in CHROMagar Candida?
GREEN
Used for studying the host reaction and for determining
whether a fungus is hyaline or dematiaceous
HEMATOXYLIN AND EOSIN (H&E) STAIN
TISSUE, BONE MARROW, AND STERILE BODY FLUIDS
Incubation: _________
30°C for 21 days
The preferred specimen for urine is __________.
FIRST-VOIDED MORNING URINE SPECIMEN
Suggested incubation time for blood is ______ .
21 days
The media used for MICROSLIDE CULTURE METHOD is _____.
Potato dextrose agar or other fungal medium
What species are POSITIVE in HAIR PERFORATION OR BAITING TEST?
T. mentagrophytes(+) and Microsporum canis(+)
This is the single most useful nutritional test for dermatophytes
THIAMINE REQUIREMENT
ACRIDINE ORANGE is used for __________________.
TINEA VERSICOLOR
________ measures the ability to produce NITRATE REDUCTASE
cell wall is dissociated with benzalkonium chloride to
reduce nitrate to nitrite.
RAPID NITRATE REDUCTASE TEST
CORNMEAL AGAR FOR YEAST IDENTIFICATION
- Candida albicans demonstrate ______ and ______
- Cryptococcus spp. demonstrate _______.
- hyphae and chlamydospores
2. blastoconidia
________ ability of yeast to use nitrate as the sole source of nitrogen
POTASSIUM NITRATE ASSIMILATION
What is the (+) and (-) results in POTASSIUM NITRATE ASSIMILATION?
(+) result = turns the medium BLUE
(-) result = turns the medium YELLOW
What species are NEGATIVE in HAIR PERFORATION OR BAITING TEST
T. rubrum(-) and M. equinum(-)
_______ turns the rice grains brown in GROWTH ON RICE GRAINS METHOD
M. audouinii
Cryptococcus spp.
optimal temperature is _____
weak growth at _____
no growth at _____
optimal temperature: 25° C
weak growth: 35° C
no growth: 42° C
What is the (+) and (-) QC of POTASSIUM NITRATE ASSIMILATION?
Cryptococcus albidus (+) C. albicans (-)
This is used to differentiate T. mentagrophytes(+) from T. rubrum(-)
UREASE TEST
Determine what is being asked:
In UREASE TEST,
Media: ___________
Incubation: ________
Media: Christensen Urea Agar
Incubation: 5 days at RT
In LEVODOPA-FERRIC CITRATE TEST, C. neoformans produce the enzyme _______ which when made to react with DIHYDROXYPHENYLALANINE in the presence of ______ forms a dark pigmented compound = MELANIN.
PHENOL OXIDASE ; FERRIC CITRATE
Positive result in RAPID UREASE TEST is _______.
PINK TO PURPLE COLOR
(+) result of RAPID NITRATE REDUCTASE TEST ________.
RED COLOR
______ yeast ID system is the most commonly used ID systems in CARBOHYDRATE UTILIZATION OR ASSIMILATION TEST
API 20C
Growth in TRICHOPHYTON AGARS is scored on a scale of _______
1 to 4
TRUE OR FALSE
Tubes of media with and without thiamine are inoculated with a tiny,
medium-free portion of the colony and observed for growth after 10 to 15 days
FALSE (Observation for growth is after 10 to 14 days)
