12.7: Mycology I Flashcards Preview

MHD VI: Pulm > 12.7: Mycology I > Flashcards

Flashcards in 12.7: Mycology I Deck (55)
1

Structure of fungi?

- Eukaryotes
- Nucleus / nuclear membrane / chromosomes
- Rigid chitin cell wall
- Cytoplasmic organelles
- Ergosterol is main sterol

2

Only microorganisms with chitin in cell wall?

Fungi

3

How can fungi produce a sexually?

1. Single celled yeast bud
2. Hyphae break off and grow on own
3. Hyphae can also produce fruiting bodies: spores

4

What is mycelium?

Collection of multiple hyphae

5

What forms of fungi produce hyphae?

Mould

6

What forms of fungi produce Blastoconidia / germ tubes?

Yeast

7

What is dimorphism?

Fungi can take on mould or yeast form
1. Yeast at 35 degrees in body fluid
2. Mold at 25 degrees in lab temp

8

2 main types of spores?

1. Sporangiospores: Zygomycete species
- Sack full of spores that will burst
2. Conidia: Aspergillus species
- Strings of spores

9

Structure of Sporangiospores?

- Column known as sporangiophore comes off hyphae
- Sack on end known as sporangium
- Sporangiospores contained inside
- Sack will burst to release spores
***Seen in Zygomycete species

10

Structure of Conidia?

- Column known as conidiophore comes off hyphae
- Vesicle swells off conidiophore with tubular phialides on end
- Conidia come off this like string of spores
***Seen in aspergillus species

11

What are arthroconidia?

- Pieces of hyphae that break off to form sporing structure

12

Why do humans need to eat so much?

Takes a lot of energy to keep body temp up

13

Why are humans immune to some fungi?

- Our body temp is to warm for them to grow
- May have protected us from fungi in time of dinosaurs

14

How can fungal infection be spread?

1. Human to human: athletes food
2. From environment
3. Contact with animals

15

What is found in bird droppings?

Cryptococcus

16

Pathogenesis of fungi?

- Use adhesions to stick to mucus membrane
- Invade via trauma, inhalation, catheters

17

Histoplasm interaction with macs?

- Are phagocytosed but multiply in macs

18

What type of immunity is needed to prevent fungal infection?

- Cellular immunity needed to eradicate infection
- Humoral immunity not protective

19

What is most common fungal pathogen?

- Candida
- Normal flora of GI/GU

20

When is germ tube found?

- Only in candida albicans

21

Only candida not producing hyphae?

- Glabrata
- Associated with UTIs
- Resistant to fluconazole

22

Candid associated with HIV?

C. Dubliniensis

23

Go to drug for candida infections?

- Fluconazole
***Glabrata is resistant

24

Pathogenesis of candida?

1. Mucosal adherance
2. Lytic enzymes for keratin for invasion of epithelium
3 Bind to fibrin/collagen using adhesin
4. Bind to C3b making unavailable for opsonization

25

Host defenses for candida?

1. Intact skin
2. Normal GI flora: bost antibiotic infection
3. Candid cell wall manin activating complement path, IgG, and hypersensitivity

26

What cells are key in defending from candida?

Neuts and macs

27

What is mucocutaneous forms of candida associated with?

Defect in cell mediated immunity

28

What is systemic forms of candida associated with?

Neutropenia

29

Risk factors of candida?

1. Antibiotics
2. Corticosteroids
3, Diabetes
4. Low T cell function
5. Stress
6. Pregnancy

30

Where can candida effect?

1. Skin
2. Nails
3. Thrush
4. Vagina
5. Eyes
6. Esophagus
7. Systemic: heart, lungs etc

31

What is thrush?

Fungal (yeast) infection of mouth and tongue causing white patches

32

What is chronic mucocutaneous candidiasis?

- Hereditary T cell deficiency
- Consistent fungal infections from infancy
- Thrush and diaper rash first signs
- Disfiguring rashes

33

What is candida endophthalmitis?

- Candida infection of eye that can lead to blindness

34

Lab diagnosis of candida albicans?

- Production of germ tube
- Calcofluor stain from chitin in cell wall
- Poor gram stain with pseudohyphae
- White smooth colony on sabouraud dextrose agar

35

What is yeast with pseudohyphae indicative of?

Invasive yeast infection in contrast to normal flora of body

36

Most common mold?

- Aspergillus
- Mold that is in air we note in summer air counts
- Count inside should be lower than outside

37

Aspergillus characteristics?

- Rapidly growing mold w/ septate hyphae and dichotomous branching
- Found in soil, air, construction dust and inhaled

38

Clinical manifestations of aspergillus?

1. Allergy from high spore count inair
2. Fungus ball in preexisting cavity
3. Systemic infection

39

Common specie for aspergillus? ID?

"Fumigatus"
- Blue green fuzzy mold on agar
- Conidiophores on microscopy

40

What are mucormycosis?

"Angiotropic"
- Blood vessel invading fungi that are very deadly

41

What is the most common mucormycosis?

- Rhizopus
- Causes acute, often fatal infection
- Invade vessels leading to ischemia, necrosis, and infarc
- Lead to black puss formation

42

Who is at risk for Rhizopus?

1. HSC transplan/ solid organ
2. Granulocytopenia
3. Acidosis in diabetics

43

What should not be administered in mucormycosis?

- Fe or blood products

44

How is mucormycosis treated?

- Surgery to debride tissues
- Often very disfiguring

45

Mucormycosis Diagnosis?

- Ribbon like structure with no septum
- Branch at 90 angle
- Wooly white and gray growth
- Express sporangia containing sporangiospores

46

Another term for Dermatophytosis?

"Ringworm"
- Fungal infection of keratinized structure: skin, hair, nails
- Invasive growth is rare
- Transmitted by close personal contact

47

Another name for ringworm?

Dermatophytosis

48

3 genre of Dermatophytes?

1. Epidermophyton
2. Microsporum
3. Trichophyton

49

Appearance of Dermatophytosis?

- Circular rash with inflammation greatest at periphery

50

How to collect sample of Dermatophytosis?

- Scrape skin at edge where there is most inflammation / fungus

51

What does "Tinea" before a body part mean?

- Dermatophytosis of that body part

52

Most common form of Dermatophytosis?

"Tinea Pedis" / "Athlete's foot"
- Weeping peeling lesion between toes
- Itching and burning of feet

53

What is tinea capitis?

- Dermatophytosis of hair / scalp

54

What is tinea cruris?

Infection of groin area: Jock itch

55

Diagnosis of Dermatophytosis?

- White wooly on one side of plate, red on other
- Candida seen on microscopy