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Lecture 9 Flashcards

1
Q

Fungal kingdom characteristics

A

Mushrooms, yeast, moulds
Unicellular or multicellular
Eukaryotic
Cell wall
Heterotrophic - Saprotrophs
Non-motile

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2
Q

Fungal eukaryotic cell characteristics

A

Complex cell wall contains chitin
Distinct nucleus and membrane bound organelles
Some fungi have plasmid-like structures
Requires 400x – 1000x magnification to see individual cells

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3
Q

Yeast replicate how

A

Yeast are fungi that grow as unicellular organisms
Replicate by “budding”

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4
Q

Mould characteristics

A

Most fungi are multi-cellular organisms AKA mould
Multicellular fungi are more complex
Can have multiple structures, multiple life stages, more than one type of reproduction

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5
Q

2 life stages of mould

A

Vegetative state
Reproductive state

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6
Q

Vegetative stage of hyphae and mycelium

A

Vegetative fungal cells are arranged end-on-end to form long slender strands called hyphae
Can also branch
Hyphae can SPREAD
Cells at the tips undergo mitosis
The end of each cell is made up of an “endwall” and two endwalls form a septum
The septum contains small holes that allow for exchange of cytoplasmic materials between adjacent cells
Not all hyphae are septate
As hyphae continue to divide and branch a mycelium forms
Mycelium = the mass of hyphae that form the vegetative part of a fungus
Can form on surfaces, underground, in liquids

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7
Q

Describing macroscopic mycelia

A

When yeast or mycelium is large enough to see on a surface, it is referred to as a colony
Colony description:
Colour (may be different on top, bottom, centre, edges)
Texture (powdery, granular, woolly,…)
Size does not matter
Depends on age of culture and type of media (always indicate both)

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8
Q

Heterotrophs nutrition

A

Heterotrophs – All fungi require nutrition provided to them in the form of complex organic molecules

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9
Q

Saprophytes nutrition

A

Saprophytes – Almost all fungi acquire nutrients from dead or decaying organic matter

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10
Q

Parasitic nutrition

A

Parasitic – Some fungi can infect plants or animals to obtain nutrition

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11
Q

Exoenzymes are and steps in digestion

A

Cells in hyphae release exoenzymes
digestive enzymes released into environment→ digest organic matter in the environment → absorb digested materials into the cell

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12
Q

Fungal reproduction types

A

Asexual reproduction
Budding
Mycelium fragmentation
Producing spores
Sexual reproduction

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13
Q

Asexual reproduction in fungi

A

Through mitosis
The progeny cells are identical to the parent cell

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14
Q

Budding reproduction

A

Asexual reproduction in yeast
Bulge forms on side of the cell, cell contents replicate and fill the new bud, chromosomes undergo mitosis, new copy of genome also moves into bud
Single bud or chain of buds

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15
Q

Mycelium fragmentation reproduction

A

Pieces of hyphae break off
New section will continue to grow from tips via mitosis until new mycelium forms

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16
Q

Producing spores in reproduction

A

Most common form of asexual reproduction
Spore - a reproductive particle, usually a single cell, released by a fungus, that may germinate into another
Spore is identical to the parent cell
When the fungus is disturbed, spores are released from the parent and carried to a new location → Allows spread
Different types of spores can help to identify the fungus

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17
Q

Endospores reproduction

A

AKA Sporangiospores
Spores are unicellular
Contained in a capsule (sporangium), which will release the endospores when disturbed

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18
Q

Conidiospores reproduction

A

Unicellular or multicellular spores that are released directly from the tip or side of the hyphae
Only seen with microscope

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19
Q

Two forms of condinospores used to identify the fungus

A

Microconidia
Spore made up of a single cell
Macroconidia
Multicellular spore, the entire unit breaks off to form a new fungus

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20
Q

Microscopic difference b/w Microsporum and trichophyton based on macroconidia from culture

A

Microsporum
Macroconidia have pointy, elongated tips
Trichophyton
Macrocrocindina have rounded tips

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21
Q

Sexual reproduction is and why

A

Meiosis
Allows genetic variation
Triggered by changes in environmental conditions
Requires “Spore 1” and “Spore 2”
Spores can be from the same or different mycelium

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22
Q

3 Stages of Sexual Reproduction and what they entail

A

Plasmogamy - two haploid cells fuse and mix their cytoplasm and organelles
Results in one large cell with 2 nuclei
Karyogamy - the 2 haploid nuclei fuse to form a diploid (2n) nucleus
Meiosis – The chromosomes randomly sort into two different spores (n)

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23
Q

Fungal spores are

A

Spread easily in wind/air due to very small size
Very difficult to destroy
Resistant to all detergents, most chemical disinfectants, drying, heat and extreme cold
Standards of sterilization are designed to be able to destroy fungal spores and bacterial endospores

24
Q

Mycoses means

A

Fungal disease

25
Mycology means
Study of fungal disease
26
Fungal disease can be due to
Infection by the fungus Exposure to fungal toxins
27
Fungi are
Ubiquitous in the environment Most are saprophytic, non-pathogenic Many of the pathogenic species are transmitted via fomites e.g. dog inhales spores or hyphae while digging in soil Part of normal flora: Skin, ears Oral cavity GI tract Urogenital tract
28
4 types of mycoses
Superficial mycoses Dermatophytoses, “ringworm” Opportunistic mycoses Systemic mycoses Mycotoxicosis All have zoonotic potential and cause similar disease in people Be very cautious working with animals with mycoses
29
Anti fungals are, side effects, and work on
Drugs used to treat fungal infections More side effects because fungi are eukaryotic cells Drugs also act on animal cells Antifungals only work on replicating cells Cannot treat spores
30
Superficial mycoses is
Commonly seen Infection of the epidermis, hair, nails Rarely spread to underlying tissues Secrete extracellular enzymes that break down keratin Cattle, horses, cats, dogs, people
31
Fungal agents that cause superficial mycoses
Microsporum Trichophyton
32
Diagnostic tests for dermatophytes
Wood’s lamp Tape sample of skin and hair Fungal culture Dermatophyte test medium (DTM) Routine fungal culture (referred test)
33
How to use fluoresce to diagnose mycoses
Approx 50% of cases of Microsporum canis will fluoresce under long-wave ultraviolet light Never a definitive test, never the only test Lots of false negatives: 50% of Microsporum does not fluoresce Trichophyton never fluoresces Lots of false positives: Purulent discharge, certain dyes, conditioners fluoresce
34
Tape sample and examination
Scotch or packing tape Press over lesion; take skin and hair In-clinic microscopic examination with simple stain for spores on hair shaft
35
Prep to collect sample
WEAR GLOVES Wipe the affected area with a swab saturated with 70% alcohol, to remove surface bacterial contamination and medication. ALWAYS take samples from outer margins of lesion where the fungus is actively growing
36
Collecting hair for culture
Hairs should be pulled/plucked out (NOT cut) If Wood’s Lamp positive, take fluorescent hairs If there are broken hairs, take BROKEN HAIRS
37
Skin scrapes and crusts should be collected where and how
Collect any crusts Can also perform superficial skin scraping of the affected area From edge of lesions - from red border if present Use edge of blunted scalpel blade (No mineral oil)
38
Toothbrushing fore spore
Use new toothbrush (medium to hard bristles) Brush all over hairs to collect spores Submit whole toothbrush
39
Transport of samples
Place in DRY sterile container such as sealed envelope (tape shut, do NOT lick) or sterile container No plastic bags Moisture will cause any bacterial contamination to grow preferentially Room temperature
40
Dermatophyte test media can grow
Specific media designed to grow Trichophyton and Microsporum Produces easy-to-recognize colonies Contains a dye that turns red/pink in the presence of exoenzyme secreted by dermatophytes
41
How to inoculate DTM
Place hair and skin scrapings onto the surface of the media or press bristle of toothbrush onto surface of media Press gently to adhere to surface of media Must seal container so media does not dry out Leave at room temperature, dark Takes up to 3 weeks
42
What can supportive media grow
All types of fungi
43
Positive DTM test is
Media turns turns AND colonies are white and “fluffy” Minimum 9 days for positive culture on regular DTM Minimum 2 days for positive culture on rapid DTM Lots of false positives Negative cultures must wait 3 weeks
44
Preventing spread of ringworm
ZOONOTIC Wear gloves and lab coat/gown Wipe exam tables with DAMP CLOTH to prevent dispersal of spores Clean all in-contact instruments/equipment Use a disinfecting agent with fungicide claims Vacuum repeatedly, do NOT sweep Follow with mop with disinfectant
45
Opportunistic mycoses requires
Opportunistic requires either: Very large inoculum Immunosuppressed host
46
Aspergillus fungi are
Aspergillus fungi Common in the environment Not normal flora Opportunistic infection Not very pathogenic All species susceptible
47
Aspergillus most commonly infects
Lungs (Mycotic pneumonia) Nasal cavity (Nasal aspergillosis) Guttural pouch (Guttural Pouch Mycosis) Can also cause abortions and mastitis
48
Guttural pouch mycosis
Aspergillus colonize the pouch and can invade the cranial nerves and internal carotid artery
49
Candida is and infects where
Yeast Normal flora of the upper respiratory tract, GI tract, genital mucosa Opportunistic infection if immunocompromised or if antibiotics remove bacteria competing for same space Common sites of infection in dogs: Oral cavity, mucous membranes such as UGT Soft, white growth over surface Can also cause severe systemic infections
50
Malassezia is and commonly infects
Yeast Normal flora of skin and ears Opportunistic infection Overgrowth if moist and hot or antibiotic therapy removes bacteria Common infection in ears, skin, feet
51
Systemic mycoses is and what is most common in Saskatchewan
Infections of internal tissues/organs Transmission is usually by inhalation of spores Severe, difficult to treat, life-threatening Most common in Saskatchewan: Blastomycosis
52
Blastomycosis is and commonly causes
Infection caused by Blastomyces dermatitidis Fungus is endemic in N. America, Great Lakes area, prevalent around Regina Is found in both yeast and mycelium forms Mycelium and spores are located in the ground in decaying vegetation Dogs inhale when digging then spreads systemically Always found in yeast form in clinical samples Primary pathogen Zoonotic Most commonly causes pulmonary infection Can spread to skin, eyes
53
Mycotoxicosis is and can be gotten by
AKA Fungal toxicosis Fungi can produce toxins which either remain in the cell or are secreted into the environment Contamination of feed with mould Mushroom/compost ingestion Most are resistant to heat and chemicals Severe disease: GI effects, neurotoxins, cardiotoxins, hallucinogens, carcinogens, anaphylactic reactions
54
Moldy sweet clover is and poisons cattle how
Certain legumes (such as sweet clover) produces a chemical called coumarin Coumarin is converted by mould to dicoumarin If dicoumarin is ingested by cattle →binds Vitamin K → cannot use Vitamin K in clotting process→fatal risk of bleeding
55
Ergot is and cause
Disease caused by Claviceps purpurea Mould infects rye, barley, wheat, oats, grasses Mould produces toxins that cause disease when ingested Vasoconstriction most common decreases blood flow to tissues and tissue necrosis occurs Neurological disease Abortion

Microbio (11 decks)

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