Analytic procedures for mycology are essential for accurately diagnosing fungal infections in clinical laboratories. This article provides a comprehensive overview of laboratory techniques used to detect, identify, and classify fungi. Key methods include direct microscopic examination, potassium hydroxide (KOH) preparations, special stains such as lactophenol cotton blue, and culture on selective media like Sabouraud dextrose agar. Advanced diagnostics, including antigen detection and molecular assays, help in confirming fungal pathogens rapidly. This resource is designed for medical laboratory professionals and students preparing for international certifications like ASCP MLS, AMT MLT/MT, AIMS, CSMLS, IBMS, HAAD/DOH, DHA, and MOH exams.
85 MCQs (1476-1560):
- Which stain is most commonly used to visualize fungal elements in direct microscopic examination?
a) Gram stain
b) Lactophenol cotton blue stain
c) Wright-Giemsa stain
d) Ziehl-Neelsen stain - What is the primary purpose of using KOH (potassium hydroxide) preparation in fungal diagnostics?
a) To enhance fungal spore germination
b) To dissolve host tissue elements, leaving fungal structures visible
c) To stain fungal hyphae blue
d) To enhance bacterial detection - Sabouraud dextrose agar is commonly used for fungal culture because:
a) It contains high lipid content for fungal growth
b) Its acidic pH inhibits most bacteria
c) It selectively isolates dermatophytes only
d) It enhances bacterial colony pigmentation - Which test helps differentiate Candida albicans from other Candida species?
a) Urease test
b) Germ tube test
c) Coagulase test
d) Oxidase test - Which of the following best describes dimorphic fungi?
a) They can only grow as yeast at any temperature
b) They switch between yeast and mold forms depending on temperature
c) They are only visible under electron microscope
d) They require specific stains for identification - The India ink preparation is primarily used for the identification of:
a) Cryptococcus neoformans
b) Candida tropicalis
c) Aspergillus fumigatus
d) Histoplasma capsulatum - What is the role of cycloheximide in fungal culture media?
a) It enhances fungal sporulation
b) It inhibits saprophytic fungi and many bacteria
c) It stains fungal hyphae for easy identification
d) It accelerates germ tube production - Which mycological test involves detection of chlamydospore formation on cornmeal agar?
a) Slide culture technique
b) Germ tube test
c) Sporulation test
d) Cornmeal agar morphology test - What is the preferred method to confirm mold identification in the laboratory?
a) Observation of colony pigmentation alone
b) Direct inoculation onto blood agar
c) Microscopic examination of reproductive structures
d) Gram staining and catalase testing - A mycological specimen showing septate hyphae with dichotomous branching at 45° angles is most consistent with:
a) Mucor species
b) Candida species
c) Aspergillus species
d) Cryptococcus species - Which fungal structure is commonly used for microscopic identification of molds?
a) Endospores
b) Conidia
c) Capsule
d) Flagella - The preferred specimen for diagnosing dermatophyte infections is:
a) Urine sample
b) Skin scrapings and hair
c) Blood sample
d) Nasal swab - Which temperature range is optimal for most pathogenic fungal cultures?
a) 4°C
b) 25–30°C
c) 37–40°C
d) 50°C - Which test detects urease production by yeast isolates?
a) Germ tube test
b) Urease test on Christensen’s agar
c) Sugar fermentation test
d) Slide agglutination test - A positive germ tube test after 2–3 hours in serum indicates:
a) Cryptococcus neoformans
b) Candida albicans
c) Aspergillus fumigatus
d) Histoplasma capsulatum - The best method for preserving fungal morphology for microscopic identification is:
a) Wet mount with saline
b) Lactophenol cotton blue mount
c) Gram stain
d) Ziehl-Neelsen stain - Which mycological culture method allows observation of fungal colony morphology and sporulation patterns on a slide?
a) Slide culture technique
b) Streak plate method
c) Broth enrichment culture
d) Cold enrichment technique - Which stain is most useful for detecting fungal elements in histopathological tissue sections?
a) Giemsa stain
b) Periodic acid-Schiff (PAS) stain
c) Gram stain
d) Safranin stain - Which rapid test detects Cryptococcus antigen in cerebrospinal fluid (CSF)?
a) Latex agglutination test
b) Germ tube test
c) Coagulase test
d) Catalase test - Which medium enhances sporulation of molds for microscopic identification?
a) Blood agar
b) Potato dextrose agar
c) MacConkey agar
d) Thayer-Martin agar - A fungus that grows as yeast at 37°C and mold at 25°C is called:
a) Thermophilic fungus
b) Dimorphic fungus
c) Opportunistic mold
d) Dermatophyte - Which reagent clears tissue debris, making fungal elements more visible in direct smears?
a) Ethanol
b) Potassium hydroxide (KOH)
c) Sodium chloride
d) Sulfuric acid - Which fungal test uses carbohydrate assimilation patterns to differentiate yeasts?
a) Urease test
b) Germ tube test
c) Sugar assimilation test
d) Chlamydospore formation test - India ink negative staining primarily demonstrates:
a) Fungal cell walls
b) Capsules surrounding yeast cells
c) Hyphal septation
d) Conidial arrangement - Which fungal structure is associated with Aspergillus identification?
a) Sporangium
b) Conidiophore with vesicle and phialides
c) Pseudohyphae only
d) Chlamydospores exclusively - The primary method to diagnose Histoplasma capsulatum in tissue sections is:
a) Acid-fast stain
b) Direct Gram staining
c) Giemsa or PAS staining for intracellular yeasts
d) Lactophenol cotton blue staining - Dermatophytes are best differentiated based on:
a) Blood culture results
b) Microscopic morphology on specialized media
c) Gram reaction and motility
d) Antigen detection in CSF - Which method is recommended for safe handling and minimizing spore aerosol exposure during mold identification?
a) Open bench culture handling
b) Working inside a biological safety cabinet
c) Incubating in ambient air without cover
d) Using only slide culture without protection - Calcofluor white stain is used in fungal microscopy because it:
a) Stains fungal elements red
b) Fluoresces fungal cell wall chitin under UV light
c) Dissolves tissue background
d) Selectively kills bacteria in samples - A direct fungal smear shows broad, ribbon-like, non-septate hyphae. The most likely causative agent is:
a) Candida albicans
b) Mucor species
c) Aspergillus species
d) Cryptococcus neoformans - The term “fungal dimorphism” refers to:
a) Production of two types of spores simultaneously
b) Ability to switch between yeast and mold forms depending on environment
c) Growth in aerobic and anaerobic conditions equally
d) Morphological changes during antifungal treatment - Which laboratory method best demonstrates fungal viability and morphology simultaneously?
a) Gram staining
b) Culture on Sabouraud dextrose agar
c) Direct saline wet mount
d) Heat-fixed smear with acid-fast stain - Which procedure is used to induce chlamydospore production for yeast identification?
a) Growth on cornmeal agar
b) Urease testing on Christensen’s agar
c) Germ tube test in serum
d) Latex agglutination test - A fungal culture from blood grows as a yeast-like colony that produces urease and encapsulated cells on microscopy. This is most consistent with:
a) Candida albicans
b) Cryptococcus neoformans
c) Aspergillus fumigatus
d) Histoplasma capsulatum - The major advantage of using chromogenic agar for Candida species is:
a) It eliminates all bacterial growth
b) It differentiates species based on colony color
c) It speeds up spore germination
d) It enhances hyphae formation in molds
- A mold colony shows black pigment and septate hyphae on culture. Which genus is most likely?
a) Rhizopus
b) Aspergillus niger
c) Candida glabrata
d) Cryptococcus gattii - The use of molecular methods in mycology primarily helps with:
a) Morphological identification under microscope only
b) Rapid and precise identification of fungal species and resistance genes
c) Increasing fungal sporulation
d) Enhancing fungal pigment production - Which clinical sample is most appropriate for diagnosing pulmonary aspergillosis?
a) Hair sample
b) Nail clippings
c) Sputum or bronchoalveolar lavage
d) Urine specimen - In mycology, exoantigen testing is mainly used for:
a) Detecting fungal capsules
b) Identifying specific fungal species based on secreted antigens
c) Observing hyphae branching patterns
d) Enhancing spore formation in culture - Which of the following fungi is known to produce germ tubes and chlamydospores?
a) Candida albicans
b) Cryptococcus neoformans
c) Mucor species
d) Aspergillus flavus - Which safety level is recommended for handling systemic pathogenic fungi?
a) BSL-1
b) BSL-2
c) BSL-3
d) BSL-4 - Fungal serological tests detect:
a) Bacterial toxins
b) Host antibodies or fungal antigens in patient serum
c) Viral RNA
d) Mycotoxins in food only - Which morphological feature distinguishes Rhizopus from Mucor species microscopically?
a) Presence of conidiophores
b) Presence of rhizoids opposite sporangiophores
c) Capsule production
d) Yeast cell budding pattern - A rapid method to detect Aspergillus galactomannan antigen in serum is useful for:
a) Detecting dermatophyte infections
b) Diagnosing invasive aspergillosis
c) Identifying dimorphic fungi
d) Determining fungal pigment production - Which yeast grows on bird droppings and is identified by urease production and capsule detection?
a) Candida krusei
b) Cryptococcus neoformans
c) Candida parapsilosis
d) Trichosporon beigelii - Which fungal genus produces macroconidia that are spindle-shaped with thin walls and multiple septa?
a) Microsporum
b) Candida
c) Cryptococcus
d) Rhizopus - Which fungal test differentiates Candida albicans from Candida glabrata based on sugar fermentation and assimilation profiles?
a) Germ tube test
b) Carbohydrate assimilation test
c) Urease test
d) Cornmeal agar morphology test - Which fungal genus is characterized by producing arthroconidia in culture?
a) Coccidioides
b) Cryptococcus
c) Histoplasma
d) Blastomyces - The use of saline wet mounts in mycology primarily helps with:
a) Visualizing motile fungal spores
b) Observing the natural arrangement of fungal elements without distortion
c) Enhancing pigmentation of fungal colonies
d) Promoting rapid germ tube formation - Which of the following is the most reliable criterion for mold identification in the laboratory?
a) Colony pigmentation alone
b) Hyphal width measurement
c) Microscopic structure of reproductive spores and conidiophores
d) Growth rate on Sabouraud agar - The major features by which molds are routinely categorized are:
a. Macroscopic growth characteristics and microscopic morphology
b. Biochemical reactions and microscopic morphology
c. Macroscopic characteristics and selective media
d. Specialized sexual reproductive cells and phialides - A sputum specimen from a patient with a known Klebsiella pneumoniae infection is received for fungus culture. The proper procedure is to:
a. Reject the specimen and request a repeat when the bacterium is absent
b. Incubate cultures at room temperature to inhibit the bacterium
c. Use media with cycloheximide and chloramphenicol to inhibit bacteria/saprophytic fungi
d. Perform a direct PAS stain; if no fungi are seen, reject the specimen - Many fungal infections are transmitted via inhalation. Which is usually contracted this way?
a. Sporothrix schenckii
b. Trichophyton rubrum
c. Malassezia furfur
d. Histoplasma capsulatum - A wet preparation of skin tissue reveals fluorescent septate hyphae under a fluorescent microscope. The smear uses:
a. Acridine orange
b. Calcofluor white
c. Gomori methanamine silver
d. Periodic acid-Schiff - Germ tube formation presumptively identifies:
a. Candida tropicalis
b. Candida parapsilosis
c. Candida glabrata
d. Candida albicans - An HIV-positive patient with meningitis has CSF cultures revealing a budding, encapsulated yeast. The organism is:
a. Candida glabrata
b. Cryptococcus neoformans
c. Paracoccidioides braziliensis
d. Sporothrix schenckii - Caffeic acid media shows brown pigment production with a yeast isolate. This identifies:
a. Candida albicans
b. Candida glabrata
c. Saccharomyces cerevisiae
d. Cryptococcus neoformans - The characteristic identifying Cryptococcus neoformans is:
a. Yellow colonies
b. Positive urease test
c. Presence of a capsule
d. Positive phenol oxidase test - A urine yeast isolate is gram-positive, catalase-positive, and fails to produce germ tubes. To identify it, perform:
a. Polymyxin B susceptibility
b. Novobiocin susceptibility
c. Oxidase test
d. Beta-lactamase test - Recovery of some molds/yeasts may be compromised if media contains:
a. Cycloheximide
b. Gentamicin
c. Chloramphenicol
d. Penicillin - A neonatal blood culture grows a yeast with buds on a broad base. Growth is enhanced around olive oil discs. The organism is:
a. Candida tropicalis
b. Malassezia furfur
c. Candida lipolytica
d. Cryptococcus gattii - Medium used to verify purity of a yeast isolate from blood culture is:
a. Sabouraud dextrose agar
b. Potato dextrose agar
c. Cornmeal agar
d. CHROMagar™ - Yeast grown in rabbit plasma shows germ tubes. The identification is:
a. Candida tropicalis
b. Candida krusei
c. Candida albicans
d. Candida glabrata - The most sensitive initial test for cryptococcal disease is:
a. India ink
b. Gram stain
c. Cryptococcal antigen
d. Giemsa stain - To confirm an unknown mold is a pathogenic dimorphic fungus, use:
a. Animal inoculation
b. Conversion from yeast to mold form
c. Demonstration of sexual/asexual reproduction
d. Molecular testing - Laboratory workers should use a biological safety hood when handling cultures of:
a. Streptococcus pyogenes
b. Staphylococcus aureus
c. Candida albicans
d. Coccidioides immitis - Structures important in identifying Coccidioides immitis are:
a. Barrel-shaped arthrospores
b. Tuberculate macroconidia
c. Thick-walled sporangia
d. Pyriform microconidia - The most useful morphological feature for identifying Histoplasma capsulatum mycelial phase is:
a. Arthrospores in every other cell
b. 2–5 μm microspores
c. 8–14 μm tuberculate macroconidia
d. 5–7 μm nonseptate macroconidia - A mold at 25°C has conidiophores with oval conidia; at 37°C, it produces cigar-shaped yeast cells. The organism is:
a. Histoplasma capsulatum
b. Sporothrix schenckii
c. Blastomyces dermatitidis
d. Acremonium falciforme - Which is a dimorphic fungus?
a. Blastomyces dermatitidis
b. Candida albicans
c. Cryptococcus neoformans
d. Aspergillus fumigatus - A white, cottony mold from a bronchial washing shows septate hyphae with conidial heads. The fastest identification method is:
a. MALDI-TOF mass spectrometry
b. Animal inoculation
c. Exoantigen test
d. Slide culture - A mold from a bone marrow culture produces a red pigment. It should be suspected as:
a. Blastomyces dermatitidis
b. Aspergillus niger
c. Talaromyces marneffei
d. Rhizopus species - The most useful microscopic structures for identifying dermatophytes are:
a. Septate and branching hyphae
b. Racquet and pectinate hyphae
c. Chlamydospores and microconidia
d. Macroconidia and microconidia - A dermatophyte with racquet hyphae, pectinate bodies, and salmon-pink reverse is:
a. Epidermophyton floccosum
b. Microsporum canis
c. Microsporum audouinii
d. Trichophyton rubrum - A dense grayish growth filling the container like “cotton candy” on day 3 is likely a:
a. Dermatophyte
b. Dimorphic mold
c. Zygomycete
d. Dematiaceous mold - Talaromyces species are separated from Aspergillus fumigatus by:
a. Production of conidia on phialides
b. Optimum growth temperature
c. Presence of rhizoids
d. Lack of vesicle - A mold resembling Talaromyces with long, tapering phialides bending away from the axis is:
a. Exophiala
b. Acremonium
c. Cladosporium
d. Paecilomyces - A corneal isolate grows white/violet on Sabouraud agar and shows slender sickle-shaped macroconidia. It is:
a. Acremonium
b. Aspergillus
c. Fusarium
d. Geotrichum - A common cause of eumycotic mycetoma in the USA is:
a. Pseudallescheria boydii
b. Nocardia brasiliensis
c. Coccidioides immitis
d. Aspergillus fumigatus - A slow-growing black mold with cladosporium, phialophora, and fonsecaea sporulation is:
a. Fonsecaea pedrosoi
b. Pseudallescheria boydii
c. Phialophora verrucosa
d. Cladosporium carrionii - The greatest risk for coccidioidomycosis is in:
a. Missouri cattle ranchers
b. Wyoming rabbit ranchers
c. Central Valley California migrant workers
d. Pregnant women with house cats - Medium most helpful for yeast morphology is:
a. Cornmeal agar with Tween 80
b. Brain-heart infusion medium
c. Potato dextrose agar
d. Urea agar - A mold with “salt and pepper” colonies at 2 days and LPCB stain showing sporangiophores is:
a. Aspergillus
b. Cunninghamella
c. Fusarium
d. Rhizopus - A dematiaceous mold from a foot wound with chaining macroconidia (longitudinal/horizontal septations) is:
a. Alternaria
b. Curvularia
c. Paecilomyces
d. Scopulariopsis - An encapsulated yeast from the environment using glycine in canavanine-glycine-bromothymol blue agar is:
a. Candida krusei
b. Cryptococcus gattii
c. Cryptococcus neoformans
d. Rhodotorula species
Answer Key
Answer Key:
- Lactophenol cotton blue stain
- b) To dissolve host tissue elements, leaving fungal structures visible
- b) Its acidic pH inhibits most bacteria
- b) Germ tube test
- b) They switch between yeast and mold forms depending on temperature
- a) Cryptococcus neoformans
- b) It inhibits saprophytic fungi and many bacteria
- d) Cornmeal agar morphology test
- c) Microscopic examination of reproductive structures
- Aspergillus species
- b) Dimorphic fungus
- b) Potassium hydroxide (KOH)
- c) Sugar assimilation test
- b) Capsules surrounding yeast cells
- b) Conidiophore with vesicle and phialides
- c) Giemsa or PAS staining for intracellular yeasts
- b) Microscopic morphology on specialized media
- b) Working inside a biological safety cabinet
- b) Fluoresces fungal cell wall chitin under UV light
- b) Mucor species
- c) BSL-3
- b) Host antibodies or fungal antigens in patient serum
- b) Presence of rhizoids opposite sporangiophores
- b) Diagnosing invasive aspergillosis
- b) Cryptococcus neoformans
- a) Microsporum
- b) Carbohydrate assimilation test
- a) Coccidioides
- b) Observing the natural arrangement of fungal elements without distortion
- c) Microscopic structure of reproductive spores and conidiophores
- b. Malassezia furfur
- d. CHROMagar™
- c. Candida albicans
- c. Cryptococcal antigen
- b. Conversion from yeast to mold form
- d. Coccidioides immitis
- a. Barrel-shaped arthrospores
- c. 8–14 μm tuberculate macroconidia
- b. Sporothrix schenckii
- a. Blastomyces dermatitidis
- c. Central Valley California migrant workers
- a. Cornmeal agar with Tween 80
- d. Rhizopus
- a. Alternaria
- b. Cryptococcus gattii
- b) Conidia
- b) Skin scrapings and hair
- c) 37–40°C
- b) Urease test on Christensen’s agar
- b) Candida albicans
- b) Lactophenol cotton blue mount
- a) Slide culture technique
- b) Periodic acid-Schiff (PAS) stain
- a) Latex agglutination test
- b) Potato dextrose agar
- b) Ability to switch between yeast and mold forms depending on environment
- b) Culture on Sabouraud dextrose agar
- a) Growth on cornmeal agar
- b) Cryptococcus neoformans
- b) It differentiates species based on colony color
- b) Aspergillus niger
- b) Rapid and precise identification of fungal species and resistance genes
- c) Sputum or bronchoalveolar lavage
- b) Identifying specific fungal species based on secreted antigens
- a) Candida albicans
- a. Macroscopic growth characteristics and microscopic morphology
- c. Use media with cycloheximide and chloramphenicol to inhibit bacteria/saprophytic fungi
- d. Histoplasma capsulatum
- b. Calcofluor white
- d. Candida albicans
- b. Cryptococcus neoformans
- d. Cryptococcus neoformans
- c. Presence of a capsule
- a. Polymyxin B susceptibility
- a. Cycloheximide
- a. MALDI-TOF mass spectrometry
- c. Talaromyces marneffei
- d. Macroconidia and microconidia
- d. Trichophyton rubrum
- c. Zygomycete
- d. Lack of vesicle
- d. Paecilomyces
- c. Fusarium
- a. Pseudallescheria boydii
- a. Fonsecaea pedrosoi
Top 8 Medical Laboratory Scientist (MLS) Exams:
Top 8 Medical Laboratory Scientist (MLS) Exams that are recognized globally and can help professionals validate their credentials and enhance their career opportunities:
1. ASCP – American Society for Clinical Pathology (USA)
- Exam Name: MLS(ASCP)
- Eligibility: Bachelor’s degree with clinical laboratory experience.
- Global Recognition: High
- Purpose: Certifies Medical Laboratory Scientists in the United States and internationally.
2. AMT – American Medical Technologists (USA)
- Exam Name: MLT(AMT) or MT(AMT)
- Eligibility: Academic and/or work experience in medical laboratory technology.
- Global Recognition: Moderate
- Purpose: Credentialing for medical technologists and technicians.
3. AIMS – Australian Institute of Medical and Clinical Scientists
- Exam Name: AIMS Certification Exam
- Eligibility: Assessment of qualifications and work experience.
- Recognition: Required for practice in Australia.
- Purpose: Certification and registration in Australia.
4. CSMLS – Canadian Society for Medical Laboratory Science
- Exam Name: CSMLS General or Subject-specific Exams
- Eligibility: Graduation from a CSMLS-accredited program or equivalent.
- Recognition: Canada
- Purpose: Entry-to-practice certification in Canada.
5. IBMS – Institute of Biomedical Science (UK)
- Exam Name: Registration and Specialist Portfolio Assessment
- Eligibility: Accredited degree and lab experience.
- Recognition: UK and some Commonwealth countries.
- Purpose: Biomedical Scientist registration with the HCPC (UK).
6. HAAD / DOH – Department of Health, Abu Dhabi (UAE)
- Exam Name: DOH/HAAD License Exam
- Eligibility: Degree in medical laboratory science and experience.
- Recognition: UAE (Abu Dhabi)
- Purpose: Licensure for medical laboratory practice in Abu Dhabi.
7. DHA – Dubai Health Authority (UAE)
- Exam Name: DHA License Exam for Medical Laboratory Technologists
- Eligibility: Relevant degree and experience.
- Recognition: Dubai, UAE
- Purpose: Professional license for clinical laboratory practice in Dubai.
8. MOH – Ministry of Health (Gulf Countries like UAE, Saudi Arabia, Kuwait)
- Exam Name: MOH License Exam
- Eligibility: BSc/Diploma in Medical Laboratory + experience.
- Recognition: Varies by country.
- Purpose: Required for practicing in public and private sector labs.
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