Exam 2: 15-16

Question 1

DIMORPHISM

Between Yeast and Mold which is found in the heat and which is found in the cold?

Purpose is to help escape phagocytosis

Answer 1

YEAST = HEAT
MOLD = COLD

Question 2

Dimorphism

During what phase would you find the hyphae in soil and decaying vegetation, making spores

25 C

Answer 2

SAPROBIC Phase

Question 3

During what phase would you find yeast adapted to grow in 37 C, reproduce asexually in mucosa and escape host immunity

More rapid than hyphae and less immunogenic

Answer 3

PARASITIC Phase

Question 4

Spores are easily phagocytosed

1. Macrophages/Neutrophils recognize these spoers –> phagosome
2. NADPH oxidase and iNOS activation releases what to prevent DNA replication/expression and inactivate enzymes ?

Answer 4

NADPH Oxidase and iNOS activation release ROS and RNS

Question 5

What does the phagosome do to the pH to be fuse with the lysosome and digest microbes using acid hydrolases

Answer 5

LOWERS pH by pumping H+

Question 6

Yeasts are resistant to phagocytosis

What do yeasts do to allow them to be resistant from phagocytosis?

Answer 6

Shed immunodominant antigen from the cell surface and modify the cell wall components to block phagocytosis

WI-1 is shed permitting blastomyces escape from phagocytosis

Question 7

CD4+ T Cells Release ____ – recruit other cells
CD8+ T Cells Release ____ – kill pathogens and infected host

Answer 7

CD4+ T Cells Release CYTOKINES
CD8+ T Cells Release CYTOXINS

Question 8

Which T cell respnose involves macrophage function, pro-inflammatory

Answer 8

Th1

Question 9

Which T cell response recruits and activates neutrophils

Answer 9

Th17

Question 10

Which T cell responses are MOST effective for fungal response?

Answer 10

Th1 and Th17

Question 11

Which T cell response would allow fingus to evade immunity?

Answer 11

Th2 cells promote B cell, mast cell and eosinophil activation – allergy and anti inflammatory which sustains viability of the fungus

Question 12

this saprobe is small in size and easily aerosolized so when inhaled it can access the lower respiratory tract

Answer 12

ARTHOCONIDIA

Question 13

these have a protein covering allowing it to be antiphagocytic, therefore if taken up the conidia are not digested

Answer 13

HYDROPHOBINS

Question 14

this coats spherule and modulates for Th2 response

Answer 14

SOWgp (SOW glycoprtein)
– favors fungal persistence

Question 15

HISTOPLASMA CAPSULATUM

inhaled conidia spores transform into yeast –> alveolar macrophages (ingestion by phagocytes)
* pH of phagolysosome INC preventing what??

Answer 15

preventing the activation of acid hydrolases and interefering with antigen processing

Question 16

Histoplasma Capsulatum

Alpha (1,3) glucan in the cell walls allow for what?

Answer 16

Allows for replication in phagolysosome and phagocyte lysis

Question 17

Cryptococcus Neoformans

Encapsulated Yeast protects the fungus from phagocytosis how?

Answer 17

Negative charge of capsule repells immune cells
Blocks NO access to the fungus
Interferes with antigen processing

Question 18

Cryptococcus Neoformans

What in the cell wall contributes to the NEG charge in the cell wall/capsule and contributes to protection form phagocytosis, NO, temp. extremes, and iron loss

Answer 18

MELANIN

Question 19

Urease catalyzes hydrolysis of urea to yield ammonia therefore doing what to pH

Saprobe urease release – alkaline soil for optimal growth

Answer 19

INC pH – INC ALKALINITY

Question 20

Both saprobe and parasitic forms produce proteinases during cell growth, which are responsible for the breakdown and degradation of?

Answer 20

breakdown of ECM proteins and degrade hemoglobin and IgA and IgG

allows fungus to breach respiratory mucosal barrier/ enter blood stream

Question 21

this type of fungi produces the disease by going on/in host
Ex: Athletes Foot

Answer 21

MYCOSES

Question 22

exposure to toxins/metabolites of toxin produces the disease

Answer 22

Mycotoxicoses

Question 23

= toxigenic fungi
- dont produce significant amount during disease
- synthesis requires a temp lower than body temp

Answer 23

MYCOTOXINS

Question 24

this toxin is found in PEANUTS, MAIZE and CORN
made when aspergillus replicates, invades crops in tropical areas

Answer 24

AFLATOXINS

Question 25

# **mechanism** of toxin this toxin metabolizes in the liver to an EPOXIDE whivh interfers with DNA replication and cell division

Answer 25

AFLATOXIN

Question 26

# mycotoxins seen on moldy corn inhibits ceramide generation, INC TNF-alpha production and induces cell apoptosis

Answer 26

FUMONISMS

Question 27

# mycotoxin **dark** in grain kernels that can be milled into flour Can cause **VASOSPASMS** -- constriction (lack of O2 can cause **gangrene**)

Answer 27

ERGOT

Question 28

# Microscopic Exam specimen can be immediately stained with reagents Add Stain: KOH, lactophenol cotton blue, india ink

Answer 28

WET MOUNT

Question 29

# Lactophenol Cotton Blue has three components: **Phenol** -- kills fungi **Lactic Acid** -- preserves **Cotton Blue** stains the ___ in the cell wall

Answer 29

stains the chitin in the cell wall

Question 30

# Microscopic Exam This stain stains the **polysaccharide** in fungal walls to **stain bright red**

Answer 30

Periodic Acid Schiff (PAS) Stain

Question 31

# Microscopic Exam This stain causes **fungi to turn black with a green background** Used for **Pneumocystis** **Jirovecii** using bronchoalveolar lavage

Answer 31

Grocott Gomoris Methenamine Silver GMS Stain

Question 32

# Microscopic Exam used for detection of fungal spores and hyphae **Calcofluor White binds to CHITIN** in cell wall -- fluoresces in UV **Wood Lamp** detects **dermatophytes**

Answer 32

Immunofluorescence

Question 33

# Culture of Fungi This has **DEXTROSE** which promotes fungal growth (pH 5-6) Inhibits growth of bacteria (**Antibiotics -- chloramphenicol**) Incubate between 25-37 C

Answer 33

Sabouraud Dextrose Agar SDA

Question 34

This test is used for **specific antibodies**, to screen for disease, establish specifi diganoses and montior disease Performed with puriofied or recombinant Ags to detect disease-specific anitbodies | Postive indirect test for Antibodies and Antigens

Answer 34

AGGLUTINATION

Question 35

# Aggulination Method Ags attached to a carrier (RBC or beads) --> add sample --> if Ig is present in the sample what will happen?

Answer 35

Ag-coated RBC or beads will clump

Question 36

# Fungal Pathogen Characterstics of this fungi: Yeast Cells bud with a **unique"lip" -- colarette** **Liphophilic** fungi -- growth stimulated by oil

Answer 36

Malassezia Furfur

Question 37

# **transmission** of this fungi is through **direct/indirect transfer of keratinous material from person-to-person** Prevalence in the **tropics**

Answer 37

Malassezia Furfur

Question 38

# PITYRIASIS this fungi presents as small, **hypopigmented/hyperpigmented spots** on chest, back, arms, shoulders

Answer 38

Malassezia Furfur

Question 39

# Microscopy spaghetti and meatball appearance = mix of hyphae and yeast

Answer 39

Malassezia Furfur

Question 40

# Characterstics **Dematiaceous** = soil fungi dark in color due to melanin expression branched septate hyphae **Melanin = antiphagocytic virulence factor**

Answer 40

Hortaea Weneckii

Question 41

# Presentation -- Tinea Nigra **solitary, irregular pigmented macules on palms** and soles Biopsy to r/o melanoma

Answer 41

Hortaea Weneckii

Question 42

**Trichophyton, Epidermophyton and Microsporum** are reffered as? **Produce keratinases** to utilize keratin as a nutrient

Answer 42

Dermatophytes

Question 43

# Presentation -- **RINGWORM** -- Tineas classic pattern = **ring of inflammatory scaling** with diminution of inflammation toward center of lesion if nails are infected they will thicken, discolor, raise and be deformed | Jock Itch -- groin, feet -- athletes foot

Answer 43

**Trichophyton, Epidermophyton and Microsporum**

Question 44

# Characterstics -- dimorphic fungi Mold = **daisy petal** conidia in soil Yeast = **cigar shaped** blastoconidia in humans outbreaks from gardencing -- **rose growers disease**

Answer 44

Sporothrix Schenckii

Question 45

# Presentation -- **sporothrichosis** **painless nodular lesions** (cellulitis) along lymphatics draining from inoculation site May ulcerate with pus formation | Entry = spores introduced into skin but damage (thorn)

Answer 45

Sporothrix Schenckii

Question 46

# Virulence Factor -- Sporothrix Schenckii **blocks the action of ROS** to evade phagosome-mediated damage in phagocytes

Answer 46

**Ergosterol Peroxide**

Question 47

# Characterstics **Gray to wooly colony** growth on SDA cycloheximide

Answer 47

Mucorales

Question 48

# Presentation -- zygromucosis -- rhinocerebral meningitis also involving facial structures, nasal sinuses and orbits necrotic eschars on nasal cavity, hard palate, or face

Answer 48

Mucorales

Question 49

# Presentation -- zygromucosis -- pulmonary focal pulmonary lesions with necrosis -- fungus ball fever, labored breathing, cough

Answer 49

Mucorales

Question 50

# Presentation -- zygromucosis -- cutaneous cellulitis that progresses to dermal necrosis and black eschar formation associated with IV drug use

Answer 50

Mucorales

Question 51

# Virulence Factor -- Mucorales **proliferate in the walls** of blood vessels and cause **tissue infarcation**

Answer 51

Invasive Hyphae

Question 52

# Characterstics Dematiaceous **Muriform Bodies** founds in animals and humans = brown septated cells with vertical/horizontal lines in same planes

Answer 52

Chromoblastomycosis

Question 53

# Presentation -- fonsecaea pedrosoi **Chronic, pruritic, progressive** warty papules Develop - **cauliflower like lesions** clustering in the same region

Answer 53

Chromoblastomycosis