Mycology Flashcards
1
Q
Lactophenol Cotton Blue Wet Mount
A
- Most widely used method of staining and observing fungi
- Lactic acid and Glycerol preserves structures
- Slides can be made permanent
2
Q
ASPERGILLUS FUMIGATUS
A
- Starts with white growth becoming blue-green and eventually grayish-green with age.
- Columnar symmetry
- Uniserate phialides cover only 2/3 of the vesicle
- Thermophilic. Grows well at 45°C, sometimes higher.
- Causative agent of “Fungus Ball” or Aspergilloma and a type of pulmonary infection termed “Farmer’s Lung.”
3
Q
ASPERGILLUS NIGER
A
- Very large compared to many of the other Aspergillus sp.
- Dark brown/ Black in color.
- Biserate - Metulae and Phialides present.
- Radiate Symmetry - arrangement of the metulae and phialides covers the entire vesicle.
- Colonial appearance often begins as white, turning yellow and becoming black with age.
4
Q
ASPERGILLUS CLAVATUS
A
- Huge club-shaped vesicle (~ 200 x 40 um)
- Phialides are same size as those of other Aspergillus species, appears so small due to enormous size of vesicle
5
Q
ASPERGILLUS NIDULANS
A
- Typically smaller than most of the other Aspergillus sp. Due to its short conidiophore.
- Colonial Morphology is Dark green/olive buff with a purple or olive reverse.
- Columnar symmetry, biserate with a pale brown conidiophore.
- Round hülle cells produced
- Cleistothecia with RED ascospores
6
Q
ASPERGILLUS FLAVUS
A
- Common food-borne fungus
- Many strains produce aflatoxins
- Colony: yellowish-green (lime color) surface
- Microscopic: rough, spiny neck develops with age
7
Q
ASPERGILLUS TERREUS
A
Macroscopic: Cinnamon brown color
Microscopic: Columnar fruiting structure
Biseriate phialides
8
Q
ASPERGILLUS VERSICOLOR
A
Macroscopic: Colony mostly green or tan with spots of various colors
Microscopic: Biseriate phialides, loosely radiate, cover most of vesicle
Small conidial head resembling Penicillium
Hülle cells produced
9
Q
ASPERGILLUS GLAUCUS GROUP
A
- Macroscopic: Colony mostly green or tan with spots of various colors
- Microscopic: uniseriate phialides,
- Cleistothecia on sexual state (Eurotium herbariorum) release ascospores
- Grows best with 20% sucrose added to medium
- Seldom encountered clinically
- Worldwide in nature; prefers dry environment
10
Q
CANDIDA ALBICANS
A
- SAB DEX = Cream-colored, pasty, smooth
- CHOM AGAR = Green
- Microscopic Morphology
- SAB DEX
- Round to oval cells
- Cornmeal tween 80/ DALMAU PLATE
- Formation of pseudohyphae
- clusters of blastoconidia
- formation of clamydoconidia
- 25 degrees
- Positive germ tube
- growth at 42 degrees
- SAB DEX
11
Q
CANDIDA DUBLINIENSIS
A
- Pathogenicity
- oral candidiasis
- immunocompromised
- Fluconazole Resistantnce
- Growth rate
- 3 days
- Colony Morphology
- Sab Dex
- Cream colored, pasty, smooth
- Chrom agar
- Green
- Sab Dex
- Microscopic Morphology
- Sab Dex
- Round to oval cells
- Cornmeal tween 80/Dalmau Plate
- formation of pseudohyphae or hyphae
- clusters of blastocondia
- formation of chlamydoconidia/chlamydospores(pairs or clusters)
- Positive Germ tube test
- No growth at 42 degrees
- Sab Dex
12
Q
CANDIDA GLABRATA (tropulopsis glabrata)
A
- Pathogenicity
- Bloodstream
- UTI
- Reduced fluconazole Susc.
- found in healthy individuals
- Growth rate
- 3-5 days
- Cholesterol may enhance or depend on
- Colony Morphology
- Sab Dex
- Small, partly smooth
- White to cream-colored
- Chromagar
- Pink with darker center
- Smooth
- Sab Dex
- Microscopic Morphology
- Sab Dex
- oval cells
- Cornmeal Tween 80
- Small oval cells
- single terminal budding
- no Pseudohyphae
- Sab Dex
13
Q
CANDIDA KEFYR (Pseudotropicalis)
A
- Pathogenicity
- Infections in susceptible individuals
- Growth rate
- 3 days
- Colony Morphology
- Sab Dex
- Smooth
- White to cream-colored
- Chromagar
- Pink to Lavender
- Sab Dex
- Microscopic Morphology
- Sab Dex
- Round to oval cells
- Cornmeal Tween 80
- pseudohyphae with elongated blastoconidia that line up in parallel (logs in a stream)
- Sab Dex
14
Q
CANDIDA KRUSEI
A
- Pathogenicity
- susceptible individuals 2%
- Resistant to fluconazole
- Growth rate
- 3 days
- Colony Morphology
- Sab Dex
- cream colored, flat, dull, dry
- develop mycelial edge
- Chrom Agar
- Rough
- Pink centered and white border
- Sab Dex
- Microscopic Morphology
- Sab Dex
- Round oval or elongated cells
- Cornmeal Tween 80
- Pseudohyphae with elongate blastoconidia (matchsticks or trees)
- Sab Dex
15
Q
CANDIDA PARAPSILOSIS GROUP
A
- Pathogenicity
- infections in susceptible individuals 6%
- 2nd most common agent of fungal endocarditis
- Responsible for invasive infections in neonates
- Growth rate
- 3 days
- Colony Morphology
- Sab Dex
- Creamy, sometimes lacy appearance
- Chrom Agar
- White to pink
- Sab Dex
- Microscopic Morphology
- Sab Dex
- Ovoid Cells
- Cornmeal Tween 80
- Blastoconidia(single or small clusters) along pseudohyphae
- Pseudohyphae appear curved
- Sab Dex
16
Q
CANDIDA TROPICALIS
A
- Pathogenicity
- Known to cause infection in immunocomprimised patients 7%
- Virulent in combination with leukemia
- Found in patients without evidence of disease
- Growth rate
- 3 days
- Colony Morphology
- Sab Dex
- Creamy, may be wrinkled
- Chrom Agar
- Blue
- Sab Dex
- Microscopic Morphology
- Sab Dex
- Round to oval cells
- Cornmeal tween 80
- Forms blastoconidia singly or in groups along pseudohyphae
- True hyphae may be present
- Few teardrop chlamydospores rarely produced
- Negative germ test
- Sab Dex
17
Q
GEOTRICHUM CANDIDUM
A
- Pathogenicity
- role is uncertain
- normal flora
- pulmonary disease in immunocompromised
- Growth rate
- 4 days
- Colony Morphology
- 25 degrees
- early stages
- white, moist
- easily picked off media
- later stages
- submerged hyphae (ground glass)
- may develop short, white colony ariel mycelium
- early stages
- 37 degrees
- most strains will not grow
- some strains will have minimal surface growth and extensive subsurface growth
- 25 degrees
- Microscopic Morphology
- Course true hyphae ( No Pseudo)
- rectangular arthroconidia that germinate from one corner
- may become rounded
- no blastoconidia
18
Q
MALASSEZIA SPECIES
A
- Pathogenicity
- part of normal skin flora
- M. globosa, M. Sympodhalis
- agents of pityriasis (tinea) Versicolor, folliculitis, seborrheic dermatitis, catheter-associated sepsis
- Growth rate
- 5 days 30-35 degrees
- poor growth at 25 degrees
- growth requirements
- Cycloheximide
- Long-chain fatty acids (Olive oil)
- Colony Morphology
- Smooth, cream to yellowish brown
- often becomes dry, dull, brittle and wrinkled with age
- Microscopic Morphology
- yeast-like cells are phialides with collarettes
- cells are round at one end and blunt at another
- budlike structures form single at blunt end
- Hyphae are usually bent
19
Q
TRICHOSPORON SPECIES
A
- Pathogenicity
- causes invasive localized and disseminated disease
- immunocompromised neutropenic patients susceptible
- Some species cause white piedra
- Normal flora of skin, nail, and mouth
- Growth rate
- 5 -7 days
- Colony Morphology
- At first,
- cream-colored, moist, and soft
- With age, wrinkled and powdery or crum-like
- heaped center
- adherence to cracking of agar
- yellow-grey coloring
- At first,
- Microscopic Morphology
- cornmeal tween agar
- true and pseudohyphae formation
- blastoconidia single or in chains
- arthroconidia on older cultures
20
Q
Cryptococcus neoformans Clinical Significance
A
- Route of Infection
- AEROSOLIZATION
- INHALATION
- VIRULENCE FACTORS
- Polysaccharide Capsule
- Ability to grow at 37 C
- Phospholipase Enzymes
- Phenoloxidase Enzymes
- in dry environments,
- yeast is
- small enough to be inhaled into
- alveolar space
- Fungus can cause acute lung infection or no
- symptoms at all
- Reactivation in immunosuppressed persons
- (HIV/AIDS, especially CD4 <100)
- Meningitis is the most common presentation
- Cryptococcal infection
- CRYPTOCOCCOSIS
- Primary pulmonary infection in immunocompetent persons,
- commonly presents with fever and dry cough.
- Immunocompromised patients:
- Meningitis:headache,neck pain,fever, visual disturbance,confusion.
- Disseminated infection - kidneys, prostate, bone, and skin
21
Q
Cryptococcus neoformans ID
A
- Direct Examination/India Ink
- Culture and Identification
- Cytology and Histopathology
- Serology
- Moist colonial morphology,
- appears “runny”
- Very round yeast-like cells, with a narrow “Isthmus” between
- mother and daughter cell, almost an invisible attachment.
- Inositol Assimilation positive
- Urease positive
- Polysaccharide Capsules can be seen with India Ink.
- Melanin pigment is produced on “Birdseed”, “Caffeic Acid”,
- “Staib” or “Niger seed” Agars
- C. neoformans does NOT grow in the presence of Cyclohexamide.
- Specimen
- CSF
- Respiratory
- Tissue
- Blood
- Medias
- 10% KOH
- Calcofluor
- Gram’s Stain
- India Ink
- Histological
- H&E
- Mucicarmine
- PRIMARY ISOLATION
- SABOURAUD DEXTROSE
- INHIBITORY MOLD
- BHI
- ISOLATION FROM CULTURE
- DIFFERENTIAL MEDIA
- BIRD SEED AGAR
- CAFFEIC ACID AGAR
- GROWTH OF DARK
- BROWN TO BLACK
- COLONIES IN 2-5 DAYS
- Microscopic Morphology
- round, narrow budding yeasts with size variation
- no true hyphae
- pseudohyphae absent or rudimentary
- capsule
- Macroscopic Morphology
- soft, glistening to dull, smooth colony, usually mucoid
- cream, slightly pink, or yellowish-brown color
- growth at 25oC and 37oC
- NOTE: THIS CHARACTERISTIC SEPARATES C. NEOFORMANS FROM OTHER CRYPTOCOCCUS
- SPECIES, HOWEVER, SOME MUTANT STRAINS MAY NOT GROW AT 37oC
- Cryptococcus neoformans
- Germ tube (-)
- On Corn Meal-Tween 80
- Pseudohyphae (-)
- Chlamydoconidia (-)
- Large, round blastoconidia, often well-spaced because of
- the mucoid capsules (Looks like “frog eggs”)
- Antigen Detection
- Complement Fixation
- Latex Particle Agglutination
- Antibody Detection
- IFA, TA
- Enzyme immunoassay (EIA)
- Lateral flow assay (LFA)
22
Q
Cryptococcus gattii VS. C. neoformans
A
- Spherical yeast
- Has prominent polysaccharide capsule
- Replicates by budding
- Causes respiratory and CNS infections in humans and animals
- Positive for urea hydrolysis
- Negative for growth on cycloheximide containing media
- Produces phenol oxidase (brown on birdseed agar)
- C. gattii
- Nonimmunocompromised
- Associated with tree bark
- Causes large lesions in the lung
- &/or brain (
- Assimilates glycine; grows in
- the presence of L Canavanine
- C. neoformans
- Immunocompromised
- Associated with pigeons
- Does not usually cause
- Cryptococcomas
- No glycine assimilation; does
- not grow in the presence of
- L canavanine
23
Q
CHROMOBLASTOMYCOSIS
A
- Chronic disease of skin and subcutaneous tissue and is caused by a group of melanoid fungi
- In tissue, the fungal elements manifest as non budding, thick walled, pigmented, muriform cells
- Formation of verrucoid (rough), warty, cutaneous nodules, which may be
- raised 1 3 cm above the skin surface
- soil inhabiting fungi : enters hand or feet after trauma
- found primarily in the tropics or subtropics
- dull red or violet color on skin may resemble a ringworm lesion
- pruritus (itchiness) and papules may develop
- fungus gets under the skin (produces bumps)
- may spread to brain (life threatening in that case)
24
Q
Chromoblastomycosis ID
A
- Etiologic Agents
- Cladophialophora carrionii
- Phialophora verrucosa
- Rhinocladiella aquaspersa
- Fonsecaea compacta
- Fonsecaea pedrosoi
- Culture:
- Sabouraud’s dextrose agar.
- Interpretation: clinical history and direct microscopic evidence are considered significant.
- Culture identification is the only reliable means of distinguishing these fungi.
- Identification:
- Culture characteristics and microscopic morphology especially conidial
- morphology, the arrangement of conidia on the conidiogenous cell and the
- morphology of the conidiogenous cell.
*
25
Q
Cladophialophora carrionii
A
26
Q
Phialophora verrucosa
A
- an agent of chromoblastomycosis phaeohypomycosis
- other reported infections include endocarditis, keratitis, and osteomyelitis
- Pigmented septate hyphae
- Vase shaped phialides with flared, darker collarettes
- Clusters of conidia
27
Q
Rhinocladiella aquaspersa
A
- Sympodial conidia
- Conidiophores straight, upright, unbranched, thick walled, and dark brown.
28
Q
Fonsecaea compacta and Fonsecaea pedrosoi
A
- Fonsecaea pedrosoi
- Fonsecaea compacta
- dematiaceous (dark/brown) septate and loosely branching hyphae.
- conidia produced are pale brown or olivaceous in color
- In tissues, it appears as large (5 12 µm diameter), round, brownish
- and thick-walled bodies
- Can exhibit different morphotypes
- Cladosporium type
- Phialophora type
- Rhinocladiella type
- Conidiophores are long, septate
- Conidia produced from tips of condiophores but also along condiophore
- sides and directly from hyphae
30
Q
Malassezia furfur
A
- Tinea/Pityriasis versicolor
- M. furfur is a lipophilic yeast and normal skin flora
- May cause systemic infections in patients receiving prolonged infusions of lipids through central catheters
- Direct examination of skin scraping in 10% KOH prep
Round to oval cells in clusters, accompanied by short, angular hyphae (spaghetti and meatball) - Isolation and Culture M. furfur grows poorly on regular
- SAB
- Produce pinpoint colonies at first
- Grows well when overlaid with olive
- oil (lipophilic)
31
Q
Hortaea werneckii (Phaeoannelomyces werneckii and Exophiala werneckii)
A
- Superficial infection of the skin
- Primarily found in tropical regions of Central and
- South America and the Caribbean, and occasionally in humid regions of the US
- Causes dark brown/black patches on skin of palms and sometimes the soles of the feet
- Direct Microscopic Exam of Hortaea werneckii
- Skin scraping in 10% KOH and Parker ink or calcoflour white mounts
- Isolation and Culture of Hortaea werneckii
- Colonies are slow growing (3 weeks), shiny, olive to greenish black yeast-like colonies
- Two-celled cylindrical yeast-like cells that after 7 days colonies may develop a dark
- septate hyphae with annellation.
32
Q
Piedraia hortae
A
- Formation of hard black nodules on the
- shafts of the scalp, beard, mustache and groin
- Primarily in tropics – Central & South
- America, SE Asia & Africa
- Direct Microscopic Exam
- Hairs containing one or more black nodules are placed in 10-25% KOH, shows compact
- masses of dark, septate hyphae and round to oval asci containing ascospores
- Isolation and Culture
- Hair fragments implanted onto primary
- isolation media (SAB Dex agar)
- Colonies of Piedraia hortae are dark greenish,
- brown to black, glabrous or covered with very short aerial hyphae
- Closely septate hyphae, dark and thick walled, intercalary cells
33
Q
Trichosporon asahi
A
- White Piedra
- Fungal infection of hair shaft characterized by the presence of soft white, yellowish, beige or green nodules on hair shafts of face, axilla or genital area
- More common in South America, Africa and Asia
- Trichosporon ovoides- scalp hair white piedra
- Trichosporon inkin - most cases of pubic white piedra
- Characterized by irregular, soft, white to light brown nodules
- Direct Microscopic Exam
- Hair should be examined using 10% or 25%
- KOH or calcoflour white
- Look for irregular, soft, white or light brown
- nodules firmly adhering to the hairs
- Isolation and Culture
- Grows on SGA with antibiotics without cycloheximide, since this drug is inhibitory to some of the species
- Grows rapidly, white or yellowish to deep cream colored, smooth, wrinkled, velvety with a mycelial fringe
- Microscopic: True hyphae and pseudohyphae
- with blastoconidia singly or in short chains
38
Q
Blastomyces dermatitidis ID
A
- one-celled, smooth-walled conidia borne on short lateral to terminal hyphal branches
- Diagnosis
- Direct Exam
- See characteristic yeast form in tissues
- Fungal culture
- recovery of dimorphic fungus Blastomyces dermatitidis
- Exoantigen test
- DNA probe
- Direct Exam
- Cycloheximide in selective fungal media inhibits the yeast form of Blastomyces dermatitidis
- Definitive ID
- Conversion from mold phase to the yeast phase
- subculture mold form to a blood agar plate and incubate at 37 C –look for characteristic yeast forms (2-4 weeks !!!)
- Conversion from mold phase to the yeast phase
42
Q
*Histoplasma capsulatum var.
capsulatum ID*
A
- Microscopic morphology:
- “ tuberculate” macroconidia
- Exoantigen test:
- “h” antigen, “m” antigen
- Nucleic Acid probe:
- Ribosomal RNA:DNA hybrid “Accuprobe”, Gen-probe
- Culture: can be performed on tissue, blood, and other body fluids, but may take up to 6 weeks to become positive; most useful in the diagnosis of the severe forms of histoplasmosis. A commercially available DNA probe (AccuProbe, GenProbe Inc.) can be used to confirm.
- Microscopy: for detection of budding yeast in tissue or body fluids, low sensitivity, but can provide a quick proven diagnosis if positive.
- Direct Smear
- Sputum
- Wright’s stain, Gomori metheamine silver (GMS)
- Biopsy, stained with H&E, PAS,
- Culture
- Slow growth at 25C on Sabouraud medium
- –SCC (Sab + cycloheximide + chloramphenicol)
- Buff, fluffy, yellow, tan
- Tuburculate Macroconidia
44
Q
Sporothrix schenckii
A
- Thermally dimorphic fungus
- Mold form (at 25 C)
- Macroscopic –light colored (“dirty white”), moist, glaborous and yeast-like at first becoming fuzzier and darker (dark gray-brown mycelium)
- Microscopic
- Hyaline septate hyphae with rosettes and birds-on-a-wire conida
- Yeast form (at 37 C)
characteristic “cigar-shaped” yeasts
46
Q
Paracoccidiodes brasiliensis
A
- Thermally dimorphic fungus
- Direct Exam
- Fungal Culture
- Direct Exam of clinical material
- Sputum
- Biopsy material
- lymph node drainage
- Look for characteristic yeast having multiple buds resembling a “mariners wheel”
- use selective fungal media with
- chloramphenicol and cycloheximide
- P. brasiliensis grows very slowly
- (15 - 25 days @ 25 oC)
48
Q
Black Molds Dematiaceous fungi
A
- Black colonies
- Brown hyphae and spores
- Numerous species
- Difficult to identify
- All have one of four types of sporulation
- Rhinocladiella-like
- Cladosporium-like
- Phialophora-like
- Acrotheca-like
49
Q
Cladophialophora bantiana
A
- Major cause of cerebral phaeohyphomycosis all over the world
- Thermotolerant - Grows well at 42-45°C
- Produces long, branching acropetal chains of blastic conidia with truncate and pointed ends
- Connecting dark hila between cells inconspicuous
- Cactus Like Conidia
50
Q
Exophiala jeanselmei
A
- etiologic agent of eumycetoma, phaeohyphomycosis, and rarely chromoblastomycosis
- Early growth mucoid, yeast-like (anamorph: Phaeoannellomyces)
- Becoming velvety, olive-grey to black, producing annellated conidiogenous cells (anamorph: Exophiala)
51
Q
Exophiala dermatitidis
A
- old name Wangiella dermatitidis
- agent of cutaneous, deep-seated infection
- may be found as a colonizer in the lungs of cystic fibrosis patients
- MACRO: Black, moist, shiny, yeast-like.
- 2-3 weeks, olive-grey & velvety
- Microscopic:
- Abundant, budding yeast-like cells; few brown septate hyphae with ellipsoidal conidia accumulating in groups
- Apical phialides without a collarette produced from hyphae or on short branches; annellated pores or pegs on the sides of hyphae
52
Q
Aureobasidium pullulans
A
- mucoid to glabrous, white to black colony
- Yeast-like conidia (generally non-pigmented) arising in groups laterally from submerged hyphae
- Older hyphal cells become dark melanoid
- Rare cause of infection in immunocompromised host
53
Q
Phialophora verrucosa
A
54
Q
Alternaria alternata
A
- agent of cutaneous, deep-seated infection
- Muriform conidia in simple or branching acropetal (youngest at tip) chains
55
Q
Bipolaris australiensis
A
- Species of Bipolaris are agents of sinusitis and rarely deep-seated infections
- Holoblastic conidia, darkly pigmented, distoseptate (not partitioned side-to-side by septa), with non-protruding hila borne on geniculate (bent-knee) conidiophores
56
Q
Exserohilum rostratum
A
- Cause of subcutaneous infections, sinusitis, and keratitis
- Large, brown-pigmented, thick-walled, multi-celled conidia with disto-septa produced on geniculate conidiophores
- ASSOCIATED WITH COMPOUNDED PHARMACEUTICAL [STEROID] PRODUCTS CONTAMINATED WITH DUST/DIRT
- USED FOR INFECTIONS INTO LUMBAR SPINE AND KNEE JOINTS FOR PAIN MANAGEMENT
- MENINGITIS SPINAL ABSCESS
- SYNOVIAL INFECTIONS
57
Q
Curvularia lunata
A
- Major etiologic agent of keratitis, sinusitis, and deep infection especially in immuno-compromised patients
- Holoblastic conidia curved, occasionally straight, several-celled, smooth or verrucose, with protuberant hilum produced on geniculate conidiogenous cells
58
Q
Phaeoacremonium parasiticum
A
MACRO: cream-colored and velvety becomes grayish beige to olive-brown. clusters or aerial hyphae. Reverse is tan to brown
MICRO: Phialides along hyphae or on branched or unbranched conidiophores. Slightly tapering towards the apex. Basal septum and a collarette that is small and tubular or vaguely funnel shaped. Conidia are hyaline, oblong, some curved – gathered in clusters at end of phialide
59
Q
Chaetomium
A
- Respiratory sites
- Can cause nail and skin infection
- Severe cases – nervous system
- Can produce toxins
- Dematiceous
- Velvety texture (5 days growth), sandy in color; reverse tan or darker brown/black
- Microscopic: brown, septate hyphae, large fruiting body – perithecium, which develops to ostiole, release ascospores
60
Q
Phoma glomerata
A
- For subcutaneous nodules, surgery
- Itraconazole - excellent and used the most
- voriconazole and posaconazole
- Duration of therapy: 6 wk to > 12 months
- Amphotericin B is often ineffective
- For brain abscess, include surgical resection if possible.
- For brain abscess or disseminated infections, combination therapy (eg, with 2 or 3 drugs, at least one of which is an azole)
