Introduction to Mycology Flashcards

1
Q

What is a fungus?

A

A eukaryotic, heterotrophic organism devoid of chlorophyll that obtains its nutrients by absorption, and reproduces by spores.
The primary carbohydrate storage product of fungi is glycogen.
Most fungi have a thallus composed of hyphae (sing. hypha) that elongate by tip growth

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2
Q

Characteristics of Fungi

A

Eukaryotic
Non-vascular organisms
Reproduce by means of spores, usually wind disseminated
Both sexual(meiotic) and asexual (mitotic) spores may be produced, depending on the species and conditions
Typically not motile, although a few(Chytrids) have a motile phase
Have alternation of generations like plants

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3
Q

More Characteristics of Fungi

A

Fungi are heterotrophic(“other feeding” must feed on preformed organic material)
Unlike animals(also heterotrophic), which must ingest, then digest, fungi digest then ingest
Fungi produce exoenzymes to accomplish this
Most store their food as glycogen like animals
Have cell membranes with unique sterol-ergosterol
Most have very small nuclei with little repetitive DNA
They synthesize chitin

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4
Q

Classification based on morphology

A
Yeast(unicellular)
Yeast like
Filamentous Mold(hyphae; mycelium)
Septate
Coenocytic (non septate)
Dimorphic
Yeast
Mycelium
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5
Q

Fungi Life Cycle

A

Asexual reproduction
Sexual reproduction
The end result of both sexual and asexual reproduction is the formation of spores

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6
Q

Types of Asexual Spores

A

Sporangiospores—they are formed in an enclosed sac called sporangium
Conidia—borne naked on specialized hy-phae
Arthrospores
Chlamydospores
Conidiospores
Blastospores

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7
Q

Arthrospores

A

are formed by the fragmentation of septate hyphae

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8
Q

Chlamydospores

A

thick walled spores formed within a hyphae

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9
Q

Conidiospores

A

Produced in chains at the end of a conidiophore, Unicellular conidiospores are called microconida

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10
Q

Blastospores

A

an asexual pore formed by budding by yeasts cells

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11
Q

Asexual spores (sporangiospores)

A

Zygomycota
- Have separate hyphae
- Have sporangiospores in sporangia
Formed within a sac (sporangium) at the end of an arield hypha called a sporangiospore

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12
Q

Macronconidia

A

Multicellular conida axsexual spores

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13
Q

Antifungal Agents

A
  • Polyene antibodtics
  • Flucytosine - 5 flurouracil in fungus
  • Imidazole derivatives
  • KI and NaI
  • Griseofulvin
  • terbinafine
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14
Q

Polyene antibodies

A

Bind ergosterol, destroying the osmotic intgrity of the fungal cell membrane
Amphotericin B, Nystatin etc

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15
Q

Flucytosine

A

Incorporated into fungal RNA errors in RNA synthesis

Ancobon, etc

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16
Q

Imidazole derivatives

A

derivatives—They affect cell membrane and cell wall functions
Ketoconazole, Fluconazole, Clotrimazole, etc

17
Q

Griseofulvin

A

effective against dermato-phytes

18
Q

Terbinafine

A

effective against dermato-phytes

19
Q

Classification of Fungal Disease

A
Superficial mycoses (Superfical layer of the skin) 
Cutaneous mycoses (The upper skin)
Subcutaneous mycoses (Called below the skin) 
Systemic mycoses (Any part of the body that has a potential to cause the disease) 
Opportunistic mycoses (Fungal agents that have the opportunity to cause disease) 
Mycotoxicoses
20
Q

Fungal Diagnosis Apparatus

A
Wood’s lamp (An ultraviolet lamp used to detect hairs that are infected with Microsporum fungi)
Wet mount (add 5% Potassium hydroxide) 
Skin test
Serology
Flourescent Antibody Test
Biopsy and histopathology
Culture
DNA
21
Q

Fungal Staining

A

Lactophenol cotton blue stain
Saburated glucose agar for culture isolation
Potassium Hydroxide

22
Q

Skin Testing

Dermal Hypersensitivity

A

Limited use:
Determines cellular defense mechanisms
Epidemiologic studies

23
Q

There are three types of Dermatophytes

A
  1. Trichophyton spp
  2. Epidermo-phyton spp
  3. Microsporum
    Infect the skin, nails, hairs and feathers
    Keratophilic an keratolytic
24
Q

All dermatophytes produce sepate hyphae

A

Macroconidia [Multicellular]
Microconidia [Unicellular]
and all dermatophytes cause ringworm

25
Sc hematic of Tissues Colonized by Dermatophytes
A: Stratum corneum B: Ectothrix arthrospores C: Endothrix arthrospores
26
Classification of Dermatophytes | Habitat
Geophilic—found in the soil Zoophilic—parasitic on animals Anthropophilic—parasitic on humans
27
Classification of Dermatophytes | Location of fungal arthrospores
Ectothrix—found on hair shaft | Endothrix—found inside hair shaft
28
Ringworm | Transmission
Highly contagious disease | Implantation of arthroconidia and/or hyphae
29
Ringworm | Pathogenesis
Fungal proteins incite strong host inflammatory reaction Fungi try to escape the inflammatory response, creating the classic “ring-like” reaction Self-limiting
30
Ringworm | Clinical Findings
``` Asymptomatic Classical ringworm lesions Nodular or tumor-like lesions [kerions] Secondary bacterial invasion S. aureus folliculitis and furunculosis Hypersensitivity reactions ```
31
Bovine Ringworm
Trichophyton verrucosum
32
Equine Ringworm
Tricophyton equinum
33
Canine Ringworm
Microsporum canis | Trichophyton mentagrophytes
34
Canine Ringworm | Snd Bacterial Infection
Pyogranulomatous dermatitis
35
Feline Rignworm
Microsporum canis
36
Avian Ringworm
Trichophyton gallinae (See avain ringworm in the wattles and combs causes by the Trichophyton gallinae also refers to faveus (the ringworm of the wattles and combs))
37
Ringworm in Humans
Microsporum canis and Microsporum audouinii Create a tumor-like nodules in Kerions
38
Laboratory Diagnosis of Ringworm
Wood light (M. Canis) KOH preparation Lactophenol Cotton Blue Stain Dermatophyte Test Medium