Micro 60 Flashcards

A neutropenic patient with sinusitis develops onychomycosis and necrotic lower-extremity lesions. Which fungus should be suspected?

A. Candida albicans

B. Cryptococcus neoformans

C. Fusarium species

D. Pneumocystis jirovecii

Why are clinical signs and symptoms alone usually insufficient for identifying a fungal infection?

A. Fungal diseases are always asymptomatic

B. Findings rarely distinguish the cause

C. Fungi never produce inflammation

D. Symptoms occur only after culture

Processing of which microbial specimen is generally least affected by a short delay?

A. Fungi

B. Viruses

C. Bacteria

D. Parasites

What is generally considered to be among the most rapid and cost-effective means of diagnosing fungal infections?

A. Antibody sequencing

B. Fungal genome mapping

C. Animal inoculation

D. Direct microscopic examination

Which stain binds fungal cell walls and produces fluorescence?

A. Calcofluor white

B. Giemsa stain

C. India ink

D. Gram stain

Calcofluor white improves fungal visualization through which effect?

A. Dissolves the fungal capsule

B. Stains intracellular iron

C. Makes cell walls fluoresce

D. Produces dark-field contrast

A bone marrow specimen contains suspected intracellular Histoplasma yeast. Which stain is especially useful?

A. Acid-fast stain

B. Giemsa stain

C. Calcofluor white

D. India ink

Which specimen can be examined with Giemsa for intracellular Histoplasma?

A. Nail clippings

B. Bronchoalveolar lavage

C. Peripheral blood smear

D. Cerebrospinal fluid only

Besides peripheral blood, Giemsa may detect Histoplasma in which specimen?

A. Stool culture

B. Bone marrow

C. Hair shafts

D. Corneal scrapings

Which preparation may also reveal Histoplasma yeast with Giemsa?

A. Touch preparation of tissue

B. Serum electrophoresis

C. Urine antigen strip

D. Nail potassium hydroxide mount

Which stain is commonly used to detect Pneumocystis jirovecii cysts?

A. Giemsa

B. India ink

C. Gomori methenamine silver

D. Acid-fast stain

GMS staining for Pneumocystis jirovecii is usually performed on which specimens?

A. Respiratory specimens

B. Nail specimens

C. Blood cultures

D. Skin scrapings

Which diagnostic method is generally considered most sensitive for fungal infection?

A. Clinical examination

B. Serum microscopy

C. Skin testing

D. Isolation in culture

Why is fungal culture diagnostically valuable?

A. It demonstrates fungal isolation

B. It detects host antibodies

C. It measures inflammatory cytokines

D. It stains fungal capsules

Fastidious dimorphic fungi commonly require which culture supplement?

A. Bile salts

B. Blood

C. Urea

D. Charcoal

Which organisms commonly require blood-containing fungal media?

A. Candida and Cryptococcus

B. Aspergillus and Fusarium

C. Histoplasma and Blastomyces

D. Mucor and Rhizopus

A nonselective fungal medium could best be described at supporting which organisms?

A. Dermatophytes

B. Rapid yeasts and molds

C. Fastidious dimorphic fungi

D. Rapid and slow-growing fungi

Why might a laboratory use nonselective fungal media?

A. It supports broad fungal recovery

B. It suppresses every opportunist

C. It identifies Candida by color

D. It prevents mold sporulation

What is the purpose of cycloheximide in fungal media according to the provided material?

A. Enhances fungal fluorescence

B. Prevents opportunistic fungal growth

C. Stimulates dimorphic conversion

D. Increases yeast pigmentation

Which medium assists with identification of different Candida species?

A. Blood agar

B. Sabouraud broth

C. CHROMagar

D. MacConkey agar

Most medically important fungi grow optimally within which temperature range?

A. 4°C to 10°C

B. 15°C to 20°C

C. 37°C to 42°C

D. 25°C to 30°C

A culture produces smooth, pasty, opaque colonies. Which fungal form is most likely?

A. Dermatophyte mold

B. Yeastlike fungus

C. Mucorales mold

D. Filamentous basidiomycete

Which colony appearance most strongly indicates a mold?

A. Small translucent colonies

B. Smooth mucoid colonies

C. Large filamentous colonies

D. Pasty opaque colonies

Mold colonies can vary substantially in which characteristics?

A. Texture, color, and topography

B. Capsule, motility, and flagella

C. Hemolysis, odor, and spores

D. Antibody, antigen, and genome

PNA FISH can rapidly distinguish individual yeast species from which specimen?

A. Fixed skin tissue

B. Blood culture

C. Nail scraping

D. Bronchoalveolar lavage

PNA FISH differentiates yeast species by targeting which molecules?

A. Cell-wall glucans

B. Capsular proteins

C. Specific RNA sequences

D. Membrane ergosterol

What is the first major step of MALDI-TOF fungal identification?

A. Extract fungal proteins

B. Amplify fungal DNA

C. Stain fungal capsules

D. Measure serum antibodies

After protein extraction during MALDI-TOF, what occurs next?

A. Proteins enter animal tissue

B. Specimen is cultured indefinitely

C. Antibodies are added

D. Specimen is spotted with matrix

What does MALDI-TOF generate from the fungal proteins?

A. Fluorescent cell-wall image

B. Mass spectral pattern

C. Viral RNA sequence

D. Antibody-titer curve

How is the MALDI-TOF spectrum used for identification?

A. Compared with reference spectra

B. Tested for erythrocyte binding

C. Converted into fungal RNA

D. Examined for yeast budding

MALDI-TOF can be particularly helpful in identifying species from which genus?

A. Pneumocystis

B. Histoplasma

C. Aspergillus

D. Microsporum

Which fungal cell-wall marker can be measured in several invasive mycoses?

A. Galactomannan

B. 1,3-β-glucan

C. 1,3-α-glucan

D. Lipopolysaccharide

Detection of 1,3-β-glucan may support infection by which yeast?

A. Cryptococcus neoformans

B. Candida species

C. Malassezia furfur

D. Sporothrix schenckii

Detection of 1,3-β-glucan may support infection by which mold?

A. Rhizopus species

B. Mucor species

C. Aspergillus species

D. Fusarium species

Detection of 1,3-β-glucan may support which pulmonary infection?

A. Pneumocystis jirovecii pneumonia

B. Pulmonary cryptococcosis

C. Invasive mucormycosis

D. Pulmonary blastomycosis

Elevated serum D-arabinitol suggests which infection?

A. Pulmonary aspergillosis

B. Localized dermatophytosis

C. Disseminated candidiasis

D. Pulmonary histoplasmosis

In which specimen is D-arabinitol measured for disseminated candidiasis?

A. Serum

B. Sputum

C. Nail tissue

D. Cerebrospinal fluid

Elevated D-mannitol in bronchoalveolar lavage suggests which disease?

A. Disseminated candidiasis

B. Cryptococcal meningitis

C. Pulmonary aspergillosis

D. Cutaneous fusariosis

Which specimen is tested for D-mannitol during suspected pulmonary aspergillosis?

A. Serum

B. Urine

C. Bone marrow

D. Bronchoalveolar lavage fluid

A patient with diabetic ketoacidosis develops invasive fungal sinusitis. Which organism is most likely?

A. Candida albicans

B. Rhizopus species

C. Sporothrix schenckii

D. Malassezia furfur

Why is a short transport delay less harmful for fungal specimens?

A. Fungi replicate during transport

B. Fungi resist all temperature changes

C. Fungi remain viable at 4°C

D. Fungi require no living organisms

For how long may fungal specimens remain refrigerated without major viability loss?

A. A short period

B. Several months

C. One full year

D. Indefinitely

What is the preferred diagnostic approach for gastrointestinal fungal infection?

A. Serum antibody testing

B. Stool fungal culture

C. Urine antigen testing

D. Biopsy with histopathology

Which specimen is commonly obtained to diagnose Pneumocystis jirovecii pneumonia?

A. Bronchoalveolar lavage

B. Peripheral blood smear

C. Urine sediment

D. Nail scraping

Which invasive procedure may also diagnose Pneumocystis jirovecii infection?

A. Bone marrow aspiration

B. Skin punch biopsy

C. Lung biopsy

D. Lumbar puncture

Which stain commonly demonstrates Pneumocystis jirovecii cysts?

A. Mucicarmine stain

B. Methenamine silver stain

C. Acid-fast stain

D. India ink

Which antibody-based method can detect Pneumocystis jirovecii?

A. Fluorescent monoclonal antibody

B. Latex cryptococcal antigen

C. Heterophile antibody test

D. Direct Coombs test

Which stain detects Pneumocystis trophic and intracystic forms?

A. Mucicarmine stain

B. Calcofluor white

C. Giemsa stain

D. Gram stain

Mucicarmine staining is used to demonstrate which fungal structure?

A. Aspergillus conidia

B. Histoplasma yeast nuclei

C. Pneumocystis cyst walls

D. Cryptococcal capsular material

Which organism has a capsule highlighted by mucicarmine?

A. Cryptococcus neoformans

B. Rhizopus species

C. Candida glabrata

D. Sporothrix schenckii

Cycloheximide may be added to which fungal medium?

A. MacConkey agar

B. Brain heart infusion agar

C. Chocolate agar

D. Lowenstein-Jensen medium

What is the purpose of cycloheximide in fungal culture media

A. Promote capsule production

B. Detect antifungal resistance

C. Suppress rapid fungal contaminants

D. Induce yeast conversion

Cycloheximide particularly inhibits which contaminating organisms?

A. Rapid yeasts and molds

B. Fastidious dimorphic fungi

C. Intracellular Histoplasma yeast

D. Encapsulated cryptococcal yeast

Which organism requires olive oil for optimal culture recovery?

A. Candida albicans

B. Cryptococcus neoformans

C. Malassezia furfur

D. Pneumocystis jirovecii

CHROMagar may rapidly assess susceptibility to which antifungal drug?

A. Amphotericin

B. Fluconazole

C. Flucytosine

D. Caspofungin

What is the first step when identifying an unknown fungal isolate?

A. Distinguish yeast from mold

B. Perform antifungal susceptibility testing

C. Sequence the fungal genome

D. Measure serum fungal antigen

What is the classical method for identifying a mold isolate?

A. Colony odor

B. Serum antibody testing

C. Microscopic morphology

D. Urine antigen testing

Which test detects the cryptococcal polysaccharide capsular antigen?

A. Trehalose test

B. Latex agglutination test

C. Germ-tube test

D. Urease breath test

Latex agglutination for Cryptococcus detects which target?

A. Capsular polysaccharide antigen

B. Fungal ribosomal RNA

C. Cell-wall β-glucan

D. Yeast mitochondrial protein

Which specimens are commonly tested for Histoplasma antigen?

A. Sputum and stool

B. CSF and saliva

C. Urine and serum

D. Nails and hair

A patient with suspected disseminated histoplasmosis needs rapid antigen testing. Which specimen is appropriate?

A. Nail clipping

B. Urine sample

C. Corneal scraping

D. Hair shaft

Which hyphal morphology characterizes Mucor and Rhizopus?

A. Narrow septate hyphae

B. Broad nonseptate hyphae

C. Budding encapsulated yeast

D. Pseudohyphae with blastoconidia

How do Mucor and Rhizopus hyphae typically branch?

A. At acute angles

B. At narrow parallel angles

C. At wide irregular angles

D. Without visible branching

Which combined morphology suggests Mucorales infection?

A. Broad, irregular, nonseptate hyphae

B. Narrow, septate, acute branches

C. Encapsulated budding yeast

D. Intracellular tiny yeasts

Which fungus appears as cigar-shaped yeast at 37°C?

A. Blastomyces dermatitidis

B. Sporothrix schenckii

C. Histoplasma capsulatum

D. Coccidioides immitis

The cigar-shaped tissue form of Sporothrix develops at what temperature?

A. 20°C

B. 25°C

C. 30°C

D. 37°C

According to the cited study, MycAssay Pneumocystis was evaluated using which specimen?

A. Bronchoalveolar lavage

B. Serum

C. Urine

D. Bone marrow

Which test can detect Candida at 1 CFU/mL?

A. PNA FISH

B. T2Candida

C. CHROMagar

D. Latex agglutination