Intro to fungi

Question 1

classification of fungi

Answer 1

Kingdom: fungi
3 main groups within kingdom: Ascomycetes
Basidiomycetes
Zygomycetes

Question 2

What is a fungus?

Answer 2

a chemo-organotrophic eukaryote that lacks chlorphyll and forms spores (like to get nutrients from environment)

Question 3

informally what are the major types of fungi referred to as

Answer 3

moulds
mushrooms
yeast

Question 4

What are fungi a significant cause of? examples

Answer 4

non-fatal diseases such as athlete’s foot, thrush

Question 5

Fungi and fatal diseases

Answer 5

Candida species infect deep organs of patients with various types of immune dysfunction e.g after abdominal surgery, burns etc
aspergillus- infect deep organs of patients undergoing e.g chemotherapy and stem cell transplantation

Question 6

What contribute to pathogenicity of fungal infections?

Answer 6

Host factors

favourable micro-environments (warm, moist areas) encourage growth of fungi on skin and mucus membranes

broad-spectrum antibacterial agents (antibiotics) can reduce competition for epithelial colonisation sites in the gut- they kill off some bacteria but others can be resistant- stay around.

immuno-suppresion of all types may create a window of opportunity for fungal invasion

Question 7

What can cause immunosuppression of host defences?

Answer 7

Iatrogenic: steorids, anti-cancer chemo, solid- organ transplantation
disease processes: aids, leukaemia

or combo of both

Question 8

diagnostic methods for detecting fungi

Answer 8

direct detection:- histophatology (the study of changes in tissues caused by disease), high-res CT scans

direct smear:- microscopy, staining etc

culture of fungus from normally sterile site- growth on selective medium

detection of circulating fungal antigens detection of circulating antibodies to fungi
PCR for fungal DNA

Question 9

Problems with anti-fungal treatment

Answer 9

spectrum of activity
static or cidal
IV vs oral
Toxicity
costly
resistance

Question 10

What are antifungal medicines available as

Answer 10

topical- directly onto infection, gel, cream, ointment or spray
oral- capsule, tablet, liquid
IV
intravaginal anti-fungal pessaries- small soft tablets you can insert up the vagina

Question 11

Common antifungal medicine names

Answer 11

clotrimazole
econazole
miconazole

Question 12

Structure of a fungal cell

Answer 12

Nucleus
Cell wall
plasma membrane
mitochondrion
endoplasmic reticulum
ribosome
lipid inclusion- stored lipid droplets

Question 13

Common types of fungal infection

Answer 13

ringworm- a skin infection
athlete's foot- contagious 
fungal nail infection
vaginal thrush
some kinds of severe dandruff

Question 14

Common types of local fungal infections

Answer 14

ringworm- a skin infection
athlete's foot- contagious 
fungal nail infection
vaginal thrush
some kinds of severe dandruff

Question 15

structure of fungi- a stylized mould mycelium

Answer 15

hypha
septa
clamp connection

Question 16

What is mycelium?

Answer 16

mycelium is the vegetative part of a fungus- consisting of a mass of branching, thread-like hyphae

Question 17

What is clamp connection on fungi?

Answer 17

a hook-like structure formed by growing hyphal cells of certain fungi

Question 18

What is septa?

Answer 18

Septa divide hyphae. They have openings called pores between the cells, to allow the flow of cytoplasm and nutrients throughout the mycelium

Question 19

What are hypha?

Answer 19

branching filaments making up mycelium of fungus

Question 20

What are chains of conidia?

Answer 20

the asexual, non-motile spores that grow externally off a fungus. Borne from conidiophore- specialised hyphal branch.

Question 21

Systemic fungal infections

Answer 21

Systemic mycoses are fungal infections affecting internal organs

Question 22

What 2 main varieties of systemic fungal infection are there

Answer 22

endemic respiratory infections and opportunistic infections

Question 23

Endemic infection

Answer 23

can cause systemic infection in people with normal immune function as well as those who are immune compromised
Histoplasma capsulatum (causing histoplasmosis) a fungus found in the droppings of birds and bats in humid areas- fatal if spread throughout the body

Question 24

Opportunistic infection

Answer 24

Fungi that only result in systemic infection in immuno-compromised or sick people
i.e those going through chemo, stem cell transplant, HIV patients

Question 25

Dermatophytic fungal infection

Answer 25

most common fungal infections of the skin, hair, and nails

Question 26

general properties of fungi

Answer 26

all fungi are eukaryotic

they have polysaccharides in their cell wall and ergosterol in cell membrane

non- motile due to rigid cell wall

they take up
dissolved organic compounds by osmosis for nutrition

Question 27

Fungi are good at…

Answer 27

utilising any nutrients available to them

Question 28

superficial diseases

Answer 28

skin, nails

Question 29

biofilms can be formed on equipment such as

Answer 29

catheters

Question 30

cryptococcal meningitis

Answer 30

1 million deaths/ year in Africa and Asia

Question 31

fungi cell wall

Answer 31

cell wall of fungi is unique- have polysaccharides - (good targets for antifungal drugs)

Question 32

How do fungi get obtain nutrients?

Answer 32

decompose dead organic matter

Question 33

fungal cell reproduction

Answer 33

Fungi reproduce by budding:-
Mother cell produces a bud
when the bud becomes the same size as the mother size then a wall is formed between them and they then separate
- doubling time approx 2 hours (slower than bacteria)

Question 34

dermatophytes cause what type of infection

Answer 34

• tinea
  -they attack the skin
  result in ringworm like infections
• Like to digest keratin as nutrient source

Question 35

Favourable conditions for fungal growth

Answer 35

warm temperatures (human body perfect)
skin and mucus membranes

Question 36

Candida allbicans

Answer 36

cause 40% of candida infections
oral infections
different cell shapes under microscope

Question 37

important virulence factor:- fungal dimorphism?

Answer 37

ability to switch between hyphae (multicellular) and yeast (unicellular) cell

Question 38

Ascomycetes

Answer 38

moulds and yeasts, some mushrooms

Question 39

zygomycetes

Answer 39

moulds

Question 40

basidiomycetes

Answer 40

mainly moulds and mushrooms, a few yeast

Question 41

Systemic fungi:- candida

Answer 41

A species of fungi commensal to the GI tract, but one which can cause a lot of problems. They are yeasts and responsible for oral, vaginal, skin, nail, esophageal and many other forms of infections