Lab Diagnosis Flashcards
Reagent used to demonstrate FUNGAL HYPHAE
10% KOH
Purpose of gentle heating using 10% KOH
Increase rate of clearing
Most commonly used test/reagent in the Laboratory
Lactophenol Cotton Blue (LPCB)/Aman’s Medium
Lactophenol Cotton Blue. Give the Components and its purpose for each
Lactic acid - preserves fungal structure
Phenol - killing agent
Aniline Blue - staining fungal structures
Reagent used for Negative Staining
KOH with Fountain Pink
True or False. Negative Staining Result
Pink - Fungal Structures
Colorless - Fungal Organism
False.
Pink - Fungal Organism
Colorless - Fungal Structures
Test used to detect infection of the hair or scalp, which organisms glow that would help locate the infected area
Wood Lamp Illumination Method
Detects Candida Infection/Thrush
Saliva/Spit Test
Positive Result in Saliva Test
Strings of the saliva resembling a jellyfish and a cloudy saliva at the bottom of glass with cloudy specs.
Result of India Ink Method
Positive: Fungal organism take up the stain in a dark background and transparent capsule surrounding the organism.
Frequently added component in culture media
Chloramphenicol - inhibits growth of bacteria
Cycloheximide - inhibits growth of saprophytic fungi.
This allows growth of fastidious dimorphic fungi
5-10% SRBCs
General medium for isolation of Fungi
SDA - Saborauds Dextrose Agar
Screening Medium for Dermatophytes
DTM - Dermatophytes Test Medium
Positive Result in DTM
Red color change from Amber
Indicator used in DTM
Phenol Red
Culture media to recover Blastomyces and Hiostoplasma
Sauboraud BHI
BHIA
used to recover DIMORPHIC fungi
Added agent in SDA to enhance growth recovery of dermatophytes
Thiamine
Demonstrate Pigment production
PDA
Demonstrate for Chlamydospore production
Cornmeal Agar
Media used for presumptive identification of Candida species
Cornmeal Agar with Tween 80 & Trypan Blue
Used for differentiation of Aspergillus species
Czapek’s Agar
Birdseed Agar
Identification of Cryptococcus neoformans
Pigment produced by C. neoformans in Birdseed agar that indicates presence of Phenol oxidase
Brown Pigment
True or False.
Rice Agar: Differentiates Trichophyton mentagrophytes from Trichophyton rubrum
Urease Agar/Test Medium: Differentiates Microsporum audonii and Microsporum canis.
False.
Urease Agar/Test Medium: Differentiates Trichophyton mentagrophytes from Trichophyton rubrum
Rice Agar: Differentiates Microsporum audonii and Microsporum canis.
Result to Differentiate Tricophyton
Trycophyton mentagrophytes - Rapid utilization
Trycophytoin rubrum - Late utilization
Result to Differentiate Microsporum
Microsporum audonii - Negative
Microsporum canis - Positive
Standard method for Microslide Culture Technique
Ridell Culture Method
Modified Ridell Method
Remel Culture Method
This method contains two plastic molded blocks containing sporulating agar.
Remel Culture Method
Incubation of Culture in Incubator
30C
Incubation of Culture in Room Temp.
25C
Maximum incubation period
4 weeks
Incubation period for Candida Infections
5 days
8 weeks
Incubation for Dimorphic fungi and before it is reported as negative
A special test used for identification of Trycophyton mentagrohytes
Hair perforation Test
Special test for identification of C. albicans
Germ Tube Test
Specimen used in Germ Tube Test
Serum or Fetal Bovine serum
Results in Germ Tube Test
Positive: Tube like Formation without constrictions ( C. albicans)
Negative: Budding cells/Pseudohyphae (C. tropicalis)
Special Tests
Hair Perforation Test
Germ Tube Test
Chemical Reaction Test
Levodopa Ferric Citrate Test
Rapid Urease Test
Rapid Nitrate Reduction Test
Rapid identification for Cryptococcus neoformans
Levodopa-Ferric Citrate Test
Enzyme present in C. neoformans
Phenol oxidase
Positive Result for L-DOPA Ferric Citrate Test
Dark Pigmented Compound (Melanin)
Positive Result in Rapid Urease Test
Pink-Red Color
True or False. Urease test Result
C. neoformans - Negative
C. albicans - Positive
False.
C. neoformans - Positive
C. albicans - Negative
Principle in Nitrate Reduction Test
Benzalkonium chloride is used to dissociate the cell wall to release nitrate reducatse and addition of N-naphthyl-ethylenediamine and sulfanilic acid
Positive Result in Nitrate Reduction Tes
Red Color
In nitrate Reduction Test, this is added when color didn’t appear after 10 minutes.
Zinc dust
General Test for Cryptococcus
Nitrate Reduction Test
A simultaneous ID and AST of yeasts for identification and antifungal susceptibility test containing 24 reaction wells
Yeast ID Test
Interpretation in Yeast ID
Red - Yellow
Red - Orange
No Color Change
Red - Yellow: Growth of yeast
Red - Orange: Slow Growth of yeast
No Color Change: No growth
Interpretation in Yeast AST
Red - Yellow
Red - Orange
No Color Change
Red - Yellow: Resistant
Red - Orange: Intermediate
No Color Change: Susceptible
Chromogenic well that is a color based distinction for C. albicans and C. tropicalis
No.13 CHR
True or False. Interpretation of No. 13 CHR
Green Color - C. tropicalis
Purple - C. albicans
False.
Green Color - C. albicans
Purple - C. tropicalis
All of the following are examples of appropriate
specimens for the recovery of fungi except:
A. Tissue biopsy
B. CSF
C. Aspirate of exudate
D. Swab
A: D. Swab
Rationale: Generally, swabs are inadequate
for the recovery of fungi because they are easily
contaminated by surrounding skin flora
For which clinical specimens is the KOH direct
mount technique for examination of fungal
elements used?
A. Skin
B. CSF
C. Blood
D. Bone marrow
A. Skin
Rationale. 10% KOH is used for contaminated
specimens such as skin, nail scrapings, hair, and
sputum to clear away background debris that may
resemble fungal elements
The India ink stain is used as a presumptive test
for the presence of which organism?
A. Aspergillus niger in blood
B. Cryptococcus neoformans in CSF
C. Histoplasma capsulatum in CSF
D. Candida albicans in blood or body fluids
B. Cryptococcus neoformans in CSF
What is the first step to be performed in the
identification of an unknown yeast isolate?
A. Gram stain smear
B. India ink stain
C. Catalase test
D. Germ tube test
D The true germ tube
An isolate produced a constriction that was
interpreted as a positive germ tube, but Candida
albicans was ruled out when confirmatory tests
were performed. Which of the following fungi is
the most likely identification?
A. Candida tropicalis
B. Cryptococcus neoformans
C. Candida glabrata
D. Rhodotorula rubra
A. Candida tropicalis
Rationale. C. tropicalis forms pseudohyphae that resemble true germ tubes by producing a constriction at the point of origin of the yeast cell.
