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Microbio > Lecture 9 > Flashcards

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
Q

Mycology means

A

Study of fungal disease

26
Q

Fungal disease can be due to

A

Infection by the fungus
Exposure to fungal toxins

27
Q

Fungi are

A

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
Q

4 types of mycoses

A

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
Q

Anti fungals are, side effects, and work on

A

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
Q

Superficial mycoses is

A

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
Q

Fungal agents that cause superficial mycoses

A

Microsporum
Trichophyton

32
Q

Diagnostic tests for dermatophytes

A

Wood’s lamp
Tape sample of skin and hair
Fungal culture
Dermatophyte test medium (DTM)
Routine fungal culture (referred test)

33
Q

How to use fluoresce to diagnose mycoses

A

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
Q

Tape sample and examination

A

Scotch or packing tape
Press over lesion; take skin and hair
In-clinic microscopic examination with simple stain for spores on hair shaft

35
Q

Prep to collect sample

A

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
Q

Collecting hair for culture

A

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
Q

Skin scrapes and crusts should be collected where and how

A

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
Q

Toothbrushing fore spore

A

Use new toothbrush (medium to hard bristles)
Brush all over hairs to collect spores
Submit whole toothbrush

39
Q

Transport of samples

A

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
Q

Dermatophyte test media can grow

A

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
Q

How to inoculate DTM

A

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
Q

What can supportive media grow

A

All types of fungi

43
Q

Positive DTM test is

A

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
Q

Preventing spread of ringworm

A

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
Q

Opportunistic mycoses requires

A

Opportunistic requires either:
Very large inoculum
Immunosuppressed host

46
Q

Aspergillus fungi are

A

Aspergillus fungi
Common in the environment
Not normal flora
Opportunistic infection
Not very pathogenic
All species susceptible

47
Q

Aspergillus most commonly infects

A

Lungs (Mycotic pneumonia)
Nasal cavity (Nasal aspergillosis)
Guttural pouch (Guttural Pouch Mycosis)
Can also cause abortions and mastitis

48
Q

Guttural pouch mycosis

A

Aspergillus colonize the pouch and can invade the cranial nerves and internal carotid artery

49
Q

Candida is and infects where

A

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
Q

Malassezia is and commonly infects

A

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
Q

Systemic mycoses is and what is most common in Saskatchewan

A

Infections of internal tissues/organs
Transmission is usually by inhalation of spores
Severe, difficult to treat, life-threatening
Most common in Saskatchewan:
Blastomycosis

52
Q

Blastomycosis is and commonly causes

A

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
Q

Mycotoxicosis is and can be gotten by

A

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
Q

Moldy sweet clover is and poisons cattle how

A

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
Q

Ergot is and cause

A

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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