fungal physiology, infections and therapeutics

Question 1

What are the features of fungi?

Answer 1

-cytoplasm enclosed in cell wall
-cell wall composed of complex carb polymers including chitin

Question 2

How do fungi reproduce?

Answer 2

sexual meiosis or asexual mitosis spores

Question 3

What are the two main morphological forms of fungi?

Answer 3

moulds and yeast

Question 4

What are hyphae?

Answer 4

-the basic cell unit of the moulds
-an apically elongating cylinder capable of branching

Question 5

what are the features of hyphae?

Answer 5

-at intervals, cross walls or septa strengthen the tubular wall but as these have a central pore, the cytoplasm can stream through
-the hypha is therefore acellular often with several nuceli per segment

Question 6

what are mycelium?

Answer 6

Network of hyphae forming the body of the mould

Question 7

what are the types of mycelium?

Answer 7

-conidia
-sporangiospores

Question 8

what are yeasts?

Answer 8

-an alternative growth form to the hypha

Question 9

how do yeasts reproduce?

Answer 9

budding

Question 10

how can some spores produce both yeasts and hyphae?

Answer 10

-depends on environmental conditions
=dimorphic

Question 11

what is pseudo-mycelium?

Answer 11

Intermediate form of growth between hyphae and yeasts, in which elongated budding cells form pseudohyphae.

Question 12

what is phylum deuteromycota?

Answer 12

-fungi imperfecti
-if dont fit into a group

Question 13

what are the features of deuteromycota?

Answer 13

-an artificial assemblage of fungi which only produce conidia, there being no sexual reproductive state
-most of the pathogenic species fit here

Question 14

what is an example of a deuteromycota?

Answer 14

-aspergillus fumigatus
-causes airway disease
-conidiophore- bears a conidia
-conidia are fruiting bodies
-vesticles and phialides too

Question 15

what are arthrospores?

Answer 15

-Conidia formed by simple fragmentation of hyphae in dermatophytes

Question 16

how do fungi act as pathogens?

Answer 16

-mycosis (infection)
-allergy (inhaled spores)
-toxicosis

Question 17

what are the ways fungi are involved in toxicosis?

Answer 17

-mycotoxicosis (spoiled feed)
-mycetism (ingesting poisonous fungi)

Question 18

what is fungal allergy?

Answer 18

spores have chitin so animal allergic as doesnt recognise

Question 19

what are endogenous sources of infection?

Answer 19

-commensal flora
-e.g. canidia in GI tract
-oral thrush

Question 20

what are exogenous sources of infection?

Answer 20

-free living saphrophytes e.g. aspergillus in hay
-parasitic on other animal host e.g. microsporum causing ringworm

Question 21

what are the three types of mycoses infections?

Answer 21

-superficial mycoses
-subcutaneous mycoses
-deep mycoses

Question 22

what is superficial mycoses?

Answer 22

-epidermis
-nail/hair/claws/spines/feathers
-fungi have evolved to grow outside in colder environment which will be on outside
-land on skin and burrow roots deep down

Question 23

what is an example of superficial mycoses?

Answer 23

-microsporum canis
-fungi glow in dark so with UV light can see ringworm lesions

Question 24

what are subcutaneous mycoses?

Answer 24

-traumatic inoculation through skin

Question 25

what are deep mycoses?

Answer 25

-inhaled -deep wound -endogenous

Question 26

what are the effects of cattle ringworm?

Answer 26

-loss in growth rate -lower milk yield -scarring affects high value and stock sales -contamination persists for years

Question 27

what are the topical treatments of ringworm?

Answer 27

-miconaxole- shampoo -enilconazole- wash or spray

Question 28

what are the systemic treatments of ringworm?

Answer 28

-griseofulvin -terbinafine and itraconazole- not licensed

Question 29

what are the methods of environmental deconamination?

Answer 29

-restrict movements of animals -burn bedding, collars, grooming tools -fog spray or wash other surfaces with enilconazole, bleach or persulphate

Question 30

what type of growth do deep mycoses have?

Answer 30

opportunistic predisposition

Question 31

what influences predisposition to fungal infection?

Answer 31

-immune suppression (natural or induced) -age (young and old) -trauma -exposure to heavy spore loads

Question 32

what are deep mycoses mould infection examples?

Answer 32

-aspergillosis -mucoromycosis -mycotic abortion

Question 33

what are deep mycoses yeast infection examples?

Answer 33

-candidosis -cryptococcosis -malassezia

Question 34

What Aspergillosis features?

Answer 34

-main sources: hay, straw -spores 2-3um, impact on alveloar wall -separate hyphae in tissues

Question 35

aspergillosis in dogs

Answer 35

-bony sinuses which is difficult yo get topical agent into -squirt it until it comes out of dogs nostrils -difficult to diagnose and treat -usually have the euthanise

Question 36

what is bovine mycotic abortion?

Answer 36

-infection of placenta and foetus -not contagious

Question 37

what is the gross pathology of bovine mycotic abortion?

Answer 37

-thickened cotyledons, amnion and foetal skin

Question 38

what is seen in cells trying to get rid of mycotic abrotion?

Answer 38

growth of cells thickened skin, necrosis and lesions in amnion

Question 39

what is candidosis?

Answer 39

-yeasts of normal gut flora -opportunistic infections -mucosal lesions- thrush, gut ulcers, mastitis, deep systemic -can be deadly

Question 40

how are mould infections diagnosed e.g. mycotic abortion?

Answer 40

-gross pathology- thickened cotyledons amnion and foetal skin -direct microscopy- fungal hyphae in tissues and foetal stomach contents -culture identification- only trust foetal stomach contents

Question 41

what is cryptococcosis

Answer 41

-yeasts with capsule outside -saprophytic in bird guano -opportunistic (immunosuppression) -big outbreak in mexico, live in bat poo, bird poo or caves -can live for years and then activate and then kill

Question 42

what is an important control of cryptococcosis?

Answer 42

dont let it dry out

Question 43

what are the methods of diagnosis of fungi infections

Answer 43

-direct microscopy -culture and ID -serology -molecular ID

Question 44

what is serology?

Answer 44

-detect antibodies and antigens -detect what cannot see -like chitin -circulating around system