Fungi

Question 1

Problem of fungi being euk

Answer 1

Fewer antifungal reagents

Question 2

Classification

Answer 2

Traditionally on absence or presence and type of sexual spore

Question 3

Ascomycota

Answer 3

Septate hyphae

Eg candida, aspergillus

Question 4

Basidiomycota

Answer 4

Septate hyphae

Eg cryptococcus

Question 5

Zygomycota

Answer 5

Non-septate hyphae

Eg mucor, mortierella

Question 6

Chytridiomycota

Answer 6

Non-septate hyphae

Eg algal parasites

Question 7

Fungi and discrim of pathogenic fungi

Answer 7

Usually aerobes with optimum growth of 20-30 degrees. An indication of a pathogenic fungi would be the ability to grow at 37 degrees
Divided into yeasts moulds and dimorphs

Question 8

Yeasts

Answer 8

Unicellular but larger than bact
Oval/round G+ve
Repro by budding, can form spores
May form from a projection/germ tube from parent

Question 9

Mould

Answer 9

Filamentous
Grow parrallel and close to surface
Branches mat to form an interconnected or vegetative mycelium which can be cms long

Question 10

Hyphae

Answer 10

Septate or nonseptate
Septation often incomplete so have small central pore so organelles or nuclei can pass
Under certain conditions perpendicular hyphae produced. At tips of these conidiophores are formed cont conidia (asex spores)

Question 11

Dimorphism

Answer 11

Most pathogenic fungi
Transition between 2 forms dep on enviro:
Yeast in tissue/37 degrees
Mould outside host/lower temp

Question 12

CW struct

Answer 12

Cont chitin mannopto and beta glucans

Also have a plasmolemma (CM) cont sterol: ergosterol

Question 13

Condiophore

Answer 13

Specialised conidia prod hyphae

Question 14

Conidium

Answer 14

Asex spore form at tip and sides of hyphae

Question 15

Arthrospores

Answer 15

Asex spores form within hyphae

Question 16

Chlamydospores

Answer 16

Asex res thick walled spores

Question 17

Sporangium

Answer 17

Closed struct cont sporangiospores

Question 18

Blastoconidia

Answer 18

Buds that arise from yeast

Question 19

Types of fungal dis

Answer 19

Contag cut dis: ringworm caused by dermatophytes
Cut or muc infections
Systemic or tissue infections
Sensitization: allergic react to fungal product
Mycotoxic dis: ingest preformed toxic products

Question 20

Ringworm transfer

Answer 20

From one animal to another by conidiospore infection usually
Can be zoonotic
Some species show host spec others dont

Question 21

Basic ringworm tissue destruct

Answer 21

Fungi can hydrolyse keratin for growth and gen restricted to living in cornified non living keratin layer and appendages

Question 22

Ring worm caused by

Answer 22

Dermatophytes: mainly microsporum and trichophyton

Question 23

Ringworm host response

Answer 23

Causes lesions as much as fungi virulence factors
Causes spread of dermatophytes away from infectious focus toward normal hide/skin
Gives circular ring appearance

Question 24

Ring worm pathogenesis

Answer 24

Minor trauma key to infect intro
Conidia or hyphae fragments introduces to stratum corneum germinate and prolif
Hyphae
Invade wall of hair follicles and eventually emerge into follicular canal
Penetrate hair cortex
Hyphal prolif and conidia form in peripilat space and cortex

Question 25

Keratinase collagenase and elastase role in ringworm

Answer 25

Contrib to spread and damage to hairs

Question 26

Ringworm diagnosis

Answer 26

Microscopy or culture M canis most difficult and req culture to diagnose Many (not canis) can be diagnosed by fluorescence under UV light

Question 27

Hair plucking or scraping of ringworm preparation

Answer 27

Made using DMSO and KOH to digest pro debris and give clearer image then scrapings plated onto selective agar

Question 28

Candida albicans

Answer 28

Grows as budding yeast prod pseudohyphae in animal tissue | Present in small no on skin and muc surf

Question 29

Candida predisp factors to infection

Answer 29

Depression of normal flora | Nutrition, imm or management factors

Question 30

Candida thrush sysmptoms

Answer 30

Prod localised pyogenic lesions in mouth intestine or genital tract Infect on muc mem charct by white grey pseudomembranous inflam patches

Question 31

Candida virulence factors

Answer 31

Prod EC toxin and enz eg neuraminidase and proteases

Question 32

Candida other infections to thrush

Answer 32

``` Crop mycosis young chickens and turkeys Mastitis in cows Enteritis and mycotic stomatitis in young cats and dogs Genital infection in horses and primates Systemic infections rare ```

Question 33

Candida diagnosis

Answer 33

Suggestive lesion presence and direct microscopy | Soft creamy colonies on Sabouraud agar after 24-48hr and demo of large chlamydospores

Question 34

Cyrptococcus neoformans

Answer 34

Budding yeast of variable size Not produce pseudohyphae Dogs cats foxes horses ferrets guinea pigs and some birds potentially humans Have large capsule and prod shiny slimy colonies of Sabouraud agar initially white then dev a yellow brown tinge

Question 35

Cyrptococcus neoformans infection route and cause

Answer 35

Inhalation with 1o infect in resp syst, pharynx and paranasal sinuses Can dissem to CNS resulting in yeast like cells detected in CSF or in 1p infection pus

Question 36

Malassezia pachydermatis

Answer 36

Commensal on oily areas of dogs skin and ears Usually isolated alone or with certain bact as cause of canine otitis externa Yeast recog from lesions due to russian doll appearance Can also cause chronic dermatitis

Question 37

Systemic and tissue mycoses causes and found

Answer 37

Geograph isolated 1o pathogens Non in UK All dimorphic

Question 38

Dimorphic fungi appearance

Answer 38

Grow as mould with hyphae externally as saprophytes. Appears more stable form Yeast like internally

Question 39

Dimorphic fungi targets

Answer 39

Many target lungs but some have more gen spread | Some are highly contagious to humans

Question 40

Aspergillus pathogenic species

Answer 40

Fumigatus Niger Nidulans

Question 41

Aspergillus info and virulence factors

Answer 41

Ubiquitous soil saprophytes | Produce many EC toxins and enz causing virulence incl haemolysins and proteases

Question 42

Aspergillus diseases | Nasal aspergillosis

Answer 42

In dogs With persistant turbinate or sinus infect Fungal hyphae seen in turbinate surf during rhiniscopy Can dissem causing widespread granulomas

Question 43

Aspergillus diseases in cows

Answer 43

Mastitis Mycotic pneumonia Mycotic abortion: 0.5% of abortion, other cause mortierella wolfii

Question 44

Aspergillus diseases guttural pouch mycosis

Answer 44

In horses Inhalation of spores can result in mycelia germ and cover large muc areas Infection can involve arteries and nerves and can cause horse abortion

Question 45

Aspergillus diseases | Brooder pneumonia

Answer 45

Avian Diffuse airway infection Hyphae often visualised by microscopy of assoc lesions Most prod granulomatous react around nasal area or at wound site

Question 46

Inhalation sensitivity and best doc eg

Answer 46

Many airborne can be involved in hypersensitivity react Best documented is actinomycete - micropolyspora faeni cause of farmers lung in hum, extrinsic allergic alveolitis if cattle and maybe COPD of horses

Question 47

Mycotoxosis and cause

Answer 47

Acute or chronic intoxication by ingest tox released by fungi on crops or in feed stores Toxins are metabolic by products prod under spec circumstances Outbreaks often seasonal and sporadic assoc with batches or certain pastures

Question 48

Mycotoxosis diagnosis and severity dep

Answer 48

On quantity and type of toxin and re exposure prev | Diagnosis difficult as req demo of tox in food, tissue or excretion

Question 49

Ergotism

Answer 49

``` Ingestion of infected grasses and cereals Usually caused by claviceps purpurea Release ergot alkaloids Gangrenous (chronic) Convulsive (acute) Caused by ergotamine and ergometrine ```

Question 50

Aflatoxosis

Answer 50

Aflatoxins prod by aspergillus flavis and parasticus growing on stored crops Effects pigs cattle poultry and trout Can have long term carcinogenic effects