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PATH 327 Exam 2 > Mycology > Flashcards

Mycology Flashcards

1
Q

What are the 4 asexual spores and 4 sexual spores? What is another term for “asexual” and “sexual” spores?

A

Asexual aka anamorph: sporiangiospres, aplanospores, zoospores, conidia

Sexual aka teliomorph: oospores, zygospores, ascospores, basidiospores

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2
Q

Fungi have cell walls. What are the three main components? What component does it NOT have and bacteria cell walls do?

A
  • chitin, mannan, cellulose (sometimes)
  • no peptidoglycan
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3
Q

What component of fungal cell wall is a great target for antifungals?

A

Ergosterol

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4
Q

What are hyphae? What is a mycelium?

A

Hyphae = microscopic filamentous threads
Mycelium = network of hyphae

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5
Q

Where do fungi get nutrients? Do they photosynthesize? What 4 exoenzymes help with food digestion?

A
  • gets nutrients from dead and decaying matter
  • no photosynthesis cuz lacks chlorophyll
  • hydrolase, lyase, oxido reductase, transferase
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6
Q

What are the 3 basic cell types that fungi produce?

A
  1. Yeast
  2. Hyphae
  3. Spores (sexual, asexual/conidia)
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7
Q

Yeast characteristics:
- unicellular or multucellular? Shape?
- asexual reproduction?
- sexual reproduction?
- colony texture and colour?

A
  • unicellular, ovoid or spherical
  • asexual reproduction: budding
  • sexual reproduction: ascospores, basidiospores
  • Colonies are soft, smooth, creamy, tan/pink/orange
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8
Q

Mold characteristics:
- shape?
- Spores?

A
  • shape: hyphae
  • spores are asexual or sexual (blastic and thalic conidiogenesis, sporangium)
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9
Q

What are the four main classifications of fungi?

A

Ascomycota
Basidiomycota
Deuteromycota
Zygomycota

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10
Q

What are the four main clinical mycoses classifications? What part of the body do they affect? Name examples for each.

A
  1. Superficial or cutaneous mycoses
    a. skin, hair, nails. Rarely invades deep tissue
    b. Dermatophytes, cutaneous candidiasis
  2. Subcutaneous mycoses
    a. subcutaneous tissue, rarely spreads systematically
    b. Mycetoma, chromoblastomycosis, phaeohyphomycosis, sporotrichosis
  3. Systemic/deep mycoses
    a. May become widely disseminated
    b. Blastomycosis, candidiasis
  4. Opportunistic mycosis
    a. ubiquitous saprophytes, predisposing conditions
    b. cryptococcosis
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11
Q

What are the 6 microscopic examination methods for fungal?

A
  1. KOH = dissolves keratin in hair/nail samples
  2. Calcoflour white = stain only fungus cell wall
  3. Gram stain
  4. Wright’s stain
  5. India Ink = capsule around yeast
  6. Toluidine Blue
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12
Q

What is the difference btwn primary and secondary isolation culture media?

A

Primary: used to grow species
Secondary: used to differentiate species

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13
Q

What laboratory techniques would you use to identify yeast (3)? How would you identify yeast?

A
  1. special media (candiselect, cornmeal-tween 80)
  2. C. albicans-germ tube test
  3. Commercial assays (MALDI-TOF, mlcr methods)
  • shape, presence of budding
  • site in body found
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14
Q

Two main approaches to identification of filamentous fungi?

A

Macroscopic examination (things can see with naked eye) and microscopic examination

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15
Q

What are the two main medically important species of yeast?

A

Candida spp and cryptococcus spp

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16
Q

What are the 5 main diagnostic features to identifying candida spp

A
  1. using various sample types (skin, swabs, body fluids)
  2. Microscopy (gram stain, special fungal fluorescent stain)
  3. Histologic findings
  4. Imaging studies
  5. Beta-D-glucan
17
Q

which fungal species is the most common fungal pathogen?

A

Candida spp

18
Q

Which fungi is associated with bird seedings and environmental bassidomyces

A

Cryptococcus spp

19
Q

Pathogenesis of cryptococcus spp?

A

inhalation of spores, thick capsule evades host immune system. Mostly affects immunocompromised patients

20
Q

Three main diagnosis features of cryptococcus spp?

A

o1. clinical
2. radiological
3. laboratory (latex agglutination, microscopy, culture, histopathology)

21
Q

Difference in clinical presentation of cryptococcus in terms of immunocompetent and immunocompromised individuals?

A

Immunocompetent: localized infection
Immunocompromised: systemic infection, involves CNS and lungs

22
Q

Treatment of cryptococcus infection (2)

A
  • Pulmonary: observation, drugs
  • Extrapulmonary/CNS: drugs, prolonged treatment
23
Q

Rhodotorula spp: description, type of infection, how to identify?

A
  1. ubiquitous, opportunistic infection
  2. catheter infections, mainly in patients with leukemia and AIDS
  3. salmon pink pigment, round/flat capsule, API sugar assimilation and urease test, grows at 37°C
24
Q

Saccharomyces cerevisiae: description, type of infection, how to identify?

A
  1. baker’s/brewer’s yeast
  2. rarely causes infection, only in immunocompromised
  3. smooth white colonies, round/oval with multilateral budding, forms distinctive ascospores
25
Q

Malassezia furfur: description, type of infection, how to identify?

A
  1. normal skin flora, “Russian doll appearance,” skin scrapings look like spaghetti and meatballs
  2. catheter-associated sepsis
  3. lipids required for growth, blood culture (gram stain, calcoflour)
26
Q

Geotrichum & Trichosporon spp: description, type of infection, how to identify?

A
  1. part of skin, nail, and mouth flora
  2. trichosporon: disseminated disease in immunocompromised, white piedra = hair infection
    geotrichum: doesn’t rly cause disease
  3. cornmeal agar. Both form true hyphae and arthroconidia.
27
Q

What type of fungi causes dermatophytosis? How is it transmitted and what common disease is associated with it?

A
  • filamentous fungi (ascomycota) that invades and degrades keratinized tissue
  • mode of transmission: direct or indirect contact with infected sites of humans, animals, or contaminated objects
  • Tinea aka ringworm disease (caused by fungi, not parasite)
28
Q

What are the four main types of dermatophytes that affect humans? What classifications are they associated with?

A

A = anthropophilic
Z = zoophilic
G = geophilic

  1. Microsporum (A, Z, G)
  2. Trichophyton (A, Z)
  3. Epidermophyton (A)
  4. Nannizia (G)
29
Q

What are the three main classifications of dermatophytes? Name and example of each.

A
  1. Anthropophilic: epidermophyton floccosum, trichophytum rubrum
  2. Zoophilic: Micosporum canis
  3. Geophilic: Nannizia gypsea, Microsporum gypseum
30
Q

Name 3 clinical presentations of dermatophytosis

A
  1. dry/scaly skin
  2. rings on scalp/cheek/genitals/face
  3. abnormal nail growth
31
Q

In the lab, how would you identify dermatophytes (5)

A
  1. bromcresol purple milk solids glucose agar
  2. trichophyton agars
  3. Sabouraud dextrose agar
  4. Wood’s lamp
  5. urease test, performation test
32
Q

Name 3 main characteristics of subcutaneous mycoses

A
  1. caused by soil saprophytes
  2. implantation mycoses, chronic localized infection of skin
  3. can cause global or endemic infections
33
Q

Name 3 main characteristics of mycetomas

A
  1. chronic, pus-forming infections of subcutaneous tissue
  2. painless nodules that ulcerate
  3. caused by Madurella, Acremonium, Leptosphaeria, etc.
34
Q

Name 3 main characteristics of chromoblastomycosis

A
  1. implantable mycoses caused by brown pigmented fungi
  2. similar to TB cuz involves chronic fibrotic & granulomatous reactions
  3. tissue proliferation produces crusty lesions
35
Q

Name 4 main characteristics of phaeohyphomycosis

A
  1. dematiaceous fungi
  2. subcutaneous: cystics lesions in adults
  3. Paranasal sinus: sinusitis, esp in patients with histroy of allergic rhinitis or immunosuppression
  4. Cerebral: cladophialophora bantiana
36
Q

Name 3 main characteristics of sporotrichosis

A
  1. chronic, tissue with nodular lesions
  2. mainly affects limbs, hands, fingers
  3. can also affect lymphatics and bones/joints
37
Q

Name 4 main characteristics of sporothrix schenckii

A
  1. ubiquitous, rapid growth
  2. colony morphology depends on temp of growth
  3. 25-30°C -> small white, narrow hyphae
  4. 35-37°C -> cream/tan, round/oval budding yeast
38
Q

Name 4 main characteristics of lobomycosis

A
  1. found in humans and dolphins
  2. chronic localized nodular lesions that can ulcerate
  3. massive lesions containing masses of spheroidal yeast-like organisms (Loboa loboi)
  4. organisms not yet culturable

PATH 327 Exam 2 (3 decks)

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