Lecture 7 - Fungus (Candida)

Question 1

T or F, The fungi Candida are commonly a part of the normal flora of the mouth, GI tract and genitourinary tract

Answer 1

True

Question 2

Candidiasis usually results from what:

Answer 2

Defects in normal host defenses and/or lack of competitive normal flora:

1. Periods of modified host flora - like during antibiotic treatment
2. During periods of decreased host defense such as immunosuppressive therapies

Question 3

Saprobe:

Answer 3

Organisms that live on dead or decaying organic matter

Question 4

Parasites:

Answer 4

Organisms that live on or within a host from which they derive benefits without making any useful contributions in return

Question 5

Fungal cell membrane is different from humans how?

Answer 5

It is similar to ours except for the addition of ergostal in contrast to cholesterol
- Many antifungal strategies are based on the presence of ergosterol in fungal membranes

Question 6

What do Azoles do?

Answer 6

Inhibit ergosterol synthesis

Question 7

What do polyenes do?

Answer 7

Bind and form pores in ergosterol-containing membranes rather than cholesterol containing membranes

Question 8

Do fungi have cell wall?

Answer 8

Yes, fungi are surrounded by a multi-layered, rigid cell wall made up mainly of cross-linked glucans (another antifungal target)

Question 9

Is there a large amount of effective anti fungals available to treat fungal infections? Why or Why not?

Answer 9

No, relatively few effective anti-fungals
- Because fungal cells, like mammalian cells, are eukaryotic and to develop something specific to fungal cells but nontoxic for human cells is difficult

Question 10

Fungi can be divided into what two basic morphologies:

Answer 10

1. Yeasts (single cells)

2. Hyphae or filamentous (multinucleated branched, mold-like)

Question 11

What is mycelium

Answer 11

The collective term for a mass of hyphae (mycelium is also synonymous with mold)

Question 12

Why is the morphology of some fungi not fixed?

Answer 12

Becasue some are dimorphic, that is, they can exist in both a filamentous or yeast morphology depending on conditions of growth

Question 13

the morphology of Candida albicans is further complicated and fairly unique why?

Answer 13

They can be dimorphic - yeast-like or filamentous (true hyphae) - but can also assume a pseudohyphae morphology where cells are elongated and linked like sausages. thus they could be called POLYMORPHIC

Question 14

What types of immunity are used to fight fungi?

Answer 14

Good innate defenses

Cellular immunity

Question 15

Explain Fungal cell wall

Answer 15

B-1,4 N-AGM (Chitin wall)

Question 16

What are the two major targets for anti-fungals

Answer 16

Cell wall

Sterols (ergosterol)

Question 17

What serves as the primary barrier to fungal pathology?

Answer 17

Functioning epithelium. Healthy people have a very high level of innate immunity to fungal diseases

Question 18

What things contribute to host resistance to fungus

Answer 18

1. Fatty acids
2. pH
3. epithelial cell turnover
4. normal bacterial flora

Question 19

7 fungal pathologies

Answer 19

1. Mycotoxicoses
2. Hypersensitivities
3. Superficial Mycoses
4. Cutaneous Mycoses
5. Subcutaneous Mycoses
6. Systemic Mycoses
7. Opportunistic Mycoses

Question 20

Is mycotoxicoses rare or common?

Answer 20

Rare

Question 21

Type I hypersensitivities like hay fever and asthma have what reaction to the pathology?

Answer 21

IgE mediated

Question 22

Type IV hypersensitivities like contact dermatitis to fungal products:

Answer 22

Cellular immunity, Th, Tc, CK

Question 23

What fungal pathology deals with outermost skin layers and hair and has no immune response?

Answer 23

Superficial mycoses

Question 24

Cutaneous Mycoses is caused by what?

Answer 24

Dermatophytes

• Tricophyton species
• Micosporum species
• Epidermophyton species

Question 25

What are the 3 major types of dermatophytes that causes cutaneous mycoses

Answer 25

- Tricophyton species - Micosporum species - Epidermophyton species

Question 26

How are subcutaneous mycoses transfered?

Answer 26

Fungi/spores introduced via wounds

Question 27

Systemic mycoses is passed how?

Answer 27

``` Lung infections (Inhaled spores) Inhaled ```

Question 28

4 different groups found to cause opportunistic mycoses

Answer 28

1. Candidiasis (Fairly common (oral and vagina)) 2. Cryptococcus (bird droppings) 3. Aspergillosis (soil, spores infect lungs) 4. Pneumocystis (yeast-like fungus, lung infections in in AIDS)

Question 29

Why are oppportunistic mycoses a growing concern?

Answer 29

Because of AIDS, the growing use of immunosuppressive therapies and broad use of antibiotics

Question 30

What hosts are commonly found with Candidiasis?

Answer 30

Candidiasis is a major disease problem of immunocompromised hosts

Question 31

What is the #1 species of Candida?

Answer 31

C. albicans causing Oral, esophageal, and vaginal diseases

Question 32

T or F, Candidiasis is a disease almost exclusively of immunocompromised individuals?

Answer 32

True

Question 33

In acidic pH, what morphologic state will Candida be in?

Answer 33

The more acidic goes yeast --> Pseudohyphae | Less acidic would be true hyphae

Question 34

Does a body's adaptive or specific immunity help fight fungi?

Answer 34

No, yeast proteases degrade Ab and C3b so there is no effective humal immunity

Question 35

What are the primary defenses against fungal infections

Answer 35

Innate and T cell-mediated (cellular)

Question 36

What cells respond to fungal antigens by producing cytokines that galvanize anti-fungal immunte (innate and adaptive)

Answer 36

Th1 cells

Question 37

Candida can act oppportunistically if ...?

Answer 37

Either the innate defenses or adaptive immunity becomes compromised.

Question 38

Primary oral candidiasis clinical presentations:

Answer 38

1. Acute pseudomembranous (White) 2. Erythematous (Red) - No pseudomembrane) 3. Chronic Hyperplastic (Grey) 4. Chronic mucocutaneous

Question 39

Primary oral candiasis is presanet whre?

Answer 39

Only on oral and surrounding tissues

Question 40

Secondary oral candidiasis is present where?

Answer 40

Oral tissues that are associated with other candidial infections at other mucosal and cutaneous sites.

Question 41

A typical case of thrush =

Answer 41

Oral candidiasis