Su1D2 - Dentistry 646 Mircro/immuno - E3 - Fungi

Front 1

There are at least 100,000 species of fungi, what percentage of these are known to cause disease?

Back 1

1%

Front 2

T/F Fungi are known to degrade organic waste and derive nutrients from decaying matter.

Back 2

True

Front 3

Is Fungi a eukaryote or prokaryote? What are it's defining features?

Back 3

Eukaryote:
Has a definied nucleus enclosed by nuclear membrane
Has a CELL WALL - unlike most eukaryotes

Front 4

Fungi have a cell membrane that differs from mammalian cell membranes; how?

Back 4

fungal cell mem. consists of ERGOSTEROL
mammalian has cholesterol

ergosterol...is a great target for antifungal drugs.

Front 5

What is found within the cell wall of fungi? (is it similar to plant cell walls?)

Back 5

chitin, mannan, and glucan
UNLIKE plant cell walls

Front 6

Which is bigger - fungi or bacteria?

Back 6

Fungi are 10-fold bigger than bacteria

Front 7

Are fungi anaerobic or aerobic?

Back 7

STRICT AEROBES
one minor exception: baker's yeast

Front 8

Fungi are free-living in nature
They grow at ___ pH
And their optimal temp is:
With some pathogenic fungi growing well at:

Back 8

LOW pH
25-30 degree
pathogenic: 37 degrees

Front 9

Fungi that cause disease have what two forms?

Back 9

UNIcellular - YEAST
MULTIcellular filamentous - MOLD

Front 10

The unicellular (yeast) form are single cells (spherical/ovoid) that divide by?

Back 10

budding (blastoconidia) or binary fission

Front 11

What is a Pseudomycelium in reference to yeast?

Back 11

if incorrect budding (modified budding) occurs = new cells remain attached to parental cells = long chains. Which are more difficult to attack with anti-fungals

Front 12

The filamentous (mold) form have branching filaments, called?

Back 12

Hyphae (that lay on top of substrate, ex: mold on bread)

Front 13

What is a mycelium?

Back 13

Hyphal Mass

Front 14

If hyphae have cross walls what is this called? What if it doesn't have cross walls; then what is it called?

Back 14

With cross walls: septate
without cross walls: coenocytic (multinuclueate)

Front 15

The mold fungal form is vegetative (growing on substrate), if the food in that area runs out, what happens?

Back 15

can form spores and spread out in search of food, when ALL food runs out AERIAL Spores are produces and sent to colonize other places.

Front 16

What does it mean when a fungus exhibits dimorphism?

Back 16

Can convert from Mold -> yeast or vice versa
The conversion of free living organism (mold) to parasite (yeast)

Front 17

Many pathogenic fungi exist as molds and yeast, although almost ALL existing in the free environment are?

Back 17

MOLDS
exception: cryptoccocus is YEAST
Candida glabrata - always a yeast
Most candida are the dimorphism exception: mycelial form, not yeast form , many times found in tissue

Front 18

How can the dimorphism be induced?

Back 18

temperature changes
ex: Mold -> (heat) -> Yeast
Thus, yeast is more typical at human body temperatures.
exception: coccidoides dimorphism is not temp dependen.

Front 19

What is the exception to yeast being the typical form at human body temp?

Back 19

Candida exception: mold (mycelial) form found in tissue

Front 20

Fungi are encountered via 2 mechanisms, which are?

Back 20

Incidental environmental contact
Normal Human Flora

Front 21

When encounter fungal via incidentally via environment (they're everywhere!) What is usually the result?

Back 21

Most healthy pple develop no symptoms
High inoculum exposures and/or immunosuppression can result in infection

Front 22

What fungal form is usually found in the normal human flora?

Back 22

yeast
If existing in an immunocompromised individual there can be disseminated infections

Front 23

What is the main cell responsible for keeping fungi "in check" in the human?

Back 23

NEUTROPHILS - they phagocytose and kill (primary mechanisms) to contain fungal infections

Front 24

If fungi are too large to be ingested by the neutrophils what happens? Does this kill the infection? (give an example of a type of fungi)

Back 24

Phagocytic cells line up along surface of fungi and secrete lysosomal enzymes (b/c can't engulf hyphae)
- doesn't kill just keeps it dec. numbers so antibodies (minor responsibility) and T-cells (major responsibiliy) can help come and kill it.
(ex: Aspergillius - opportunistic fungus)

Front 25

What type of immunity is REQUIRED to eliminate fungal infections?

Back 25

T cell-mediated immunity

Front 26

What is the level of innate immunity with fungal entry? give examples

Back 26

the level of innate immunity is HIGH (most fungal infections are mild and self-limiting)
ex: intact skin and mucosal surfaces are primary barriers

Front 27

Why is the primary barrier (skin and mucosal surfaces) good to protect against fungi?

Back 27

Dessication, epithelial cell turnover, fatty acids and/or low pH (which they actually like) limits fungi
normal baceterial flora compete with fungi and inhibit growth

Front 28

When a patients is put on antibiotics is it a good thing or bad thing in relation to a fungal entry?

Back 28

The antibacterials can alter normal flora or compromise skin/mucosal surfaces (trauma, etc) and allow entry and infection - but usually they are a good thing - in this case they "set it up " for infection (opportunisitc infections)

Front 29

What is the disease and damage determined by?

Back 29

Virulence of infecting fungus
Size of inolculum (more = worse)
Adequacy of host defenses (immunocompromised and older pt = more prone to get it )

Front 30

Most invasive fungi ________ (do/don't) secrete toxins that harm the host.

Back 30

almost all secrete toxins but they ARE NOT harmful to host

Front 31

Tissue damage varies with fungus and organs involved; it is usually due to what?

Back 31

direct invasion and GROWTH (mainly)
Some effects due to inflammatory response

Front 32

Mycoses (infections caused by fungi). There are two different types, which are?

Back 32

Endemic
Opportunistic

Front 33

What is the difference between endemic and opportunistic mycoses?

Back 33

Endemic: fungal pathogens restricted geographically
TRUE pathogens that typically result in systemic infections in healthy pple.
Opportunistic:
NOT TRUE pathogens
cause systemic infectsions in immunocompromised pt's only.

Front 34

T/F ALL endemica pathogenic fungi are dimporhic.

Back 34

True:
Enviornment = mold
Host = yeasts (Histo and Blasto), spehrules (Coccidioides)

Front 35

What Endemic Fungal Pathogens are we responsible for?

Back 35

HIstoplasma Capsulatum
Blastomyces dermatitidis
Coccicioides immitis

Front 36

Where is the "histo belt"?

Back 36

mid-southeastern U.S. - in endemic areas, as much as 90% has been infected

Front 37

The Entry of HIstoplasma is not well understood, but once it does enter it transforms to yeast phase...why is this impt?

Back 37

Transformation is required for pathogenicity

Front 38

What is the virulence of histoplasma directly related to?

Back 38

tolerance of warmer temperatures (hotter =more virulent)

Front 39

What type of infection is H. Capsulatum?

Back 39

RETICULOENDOTHELIAL SYSTEM INFECTIONS - LYMPH INFECTION!

Front 40

How does the H. capsulatum organism prevent it's death?

Back 40

modulating pH of phagolysosome
Removing growth factors form the phagocytic cell