Mycology (Bbd Exam Ii)

Front 1

Candida
General Facts

Back 1

1. It colonizes most healthy individuals
2. Part of the normal flora
3. Candida albicans causes most Candida sp. infections

Front 2

C. albicans
Morphology

Back 2

Dimorphic (yeast cells or hyphae)

Front 3

C. albicans
What is the confirmatory test?

Back 3

1. Germ Tube Test
2. Incubate yeast cells at body temp for 90 min and you should see hyphal growth.
3. Germ tube has different antigens that allow C. albicans to adhere to tube.

Front 4

C. albicans
Adherence Characteristics

Back 4

1. Readily adheres to plastic (catheters can be problematic)
2. Adheres to mucosal cells
3. Mech of attachment is the presence of integrin-like molecules that bind to extracellular matrix

Front 5

C. albicans
Problems for Infants

Back 5

1. Problematic if bacterial normal flora is not yet established
2. May develop oral thrush or severe diaper rash.

Front 6

C. albicans
Sites of common infection for adults

Back 6

Areas of excessive moisture and warmth
1. Opposing skin folds
2. Nail beds

Front 7

C. albicans
Factors that influence vaginal thrush

Back 7

1. Doubled risk with pregnancy
2. Antibiotic use increases risk
3. Oral contraceptive
Anything disruptive of "balance"

Front 8

C. albicans
Factors that influence muscutaneous candidiasis

Back 8

1. Impaired cell-mediated immunity
2. Corticosteroid treatment
3. Any chronic illness or immunosuppressed state

Front 9

What is the most common systemic mycosis?

Back 9

C. albicans (indwelling catheters)

Front 10

What is the taxology of Pneumocystis jirovecii?

Back 10

Heavily debated between a fungus and a protozoan

Front 11

What are the reasons for classifying P. jirovecii as a fungus?

Back 11

1. Morphological features
2. Ribosomal RNA sequences
3. Mitochondrial DNA
4. Chitin cell wall

Front 12

What are the resons for classifying P. jirovecii as a protozoan?

Back 12

1. DNA content
2. Absence of highly conserved fungal EF-3
3. Susceptibility to anti-protozoan and not anti-fungal chemotherapeutics

Front 13

P. jirovecii
Replication

Back 13

8 sporozoites in each cyst

Front 14

P. jirovecii
Epidemiology

Back 14

1. Highly lethal in immunocompromised patients and premature infants
2. Latent infection
3. Opportunistic pathogen

Front 15

P. jirovecii
Clinical Manifestations

Back 15

"Pneumocystis"
1. Alveoli fill with cells, organisms, and fluid
2. Death is by progressive asphyxia

Front 16

Systemic Mycoses
General Characteristics

Back 16

1. Initial site of infection is the lung
2. These fungi are opportunistic pathogens
3. Given the opportunity infection will become systemic
4. In systemic infections, each fungus has a specific area it attacks
5. Restricted to geographical regions
6. Not normal flora

Front 17

Systemic Mycoses
What are the organisms responsible?

Back 17

1. Cryptococcus neoformans
2. Histoplasma capsulatum
3. Coccidiodes immitis
4. Blastomyces dermatitidis

Front 18

Histoplasma capsulatum
General Characteristics

Back 18

1. No capsule
2. Molds grow in high nitrogen soil (bird and bat droppings)
3. Birds not naturally infected; bats may be infected

Front 19

Histoplasma capsulatum
Growth

Back 19

1. Intracellular growth in phagocytic macrophages
2. Starts in lung; if becomes systemic, it can involve the reticuloendothelial system

Front 20

Histoplasma capsulatum
Geographic Endemic Areas

Back 20

Areas drained by the Ohio and Mississippi Rivers

Front 21

Coccidioides immitis
General Characteristics

Back 21

1. Dimorphic fungus
2. Instead of yeast phaste, large distinct spherules appear in the lung which contain endospores
3. Most virulent of all human mycotic pathogens
4. Fungus grows best in arid soil enhanced by bat droppings

Front 22

Coccidioides immitis
Clinical Manifestation

Back 22

"Vally Fever" or "Desert Rheumatism"
1. Malaise
2. Cough
3. Chest pain
4. Fever (lasts 2-6 weeks)
5. Skin lesions from dissemination of primary infection in lungs
Most cases resolve

Front 23

Coccidioides immitis
Geographic Endemic Areas

Back 23

1. Most geographically restricted
2. Fungus routinely isolated from soil.
3. Arizona, Nevada, New Mexico, western Texas, and southern California

Front 24

Cryptococcus neoformans
Epidemiology

Back 24

1. Found worldwide in pigeon droppings and in soil contaminated with them
2. Birds are not infected.

Front 25

Cryptococcus neoformans
Diagnostic test

Back 25

Encapsulated yeast from India ink preparation is an approach used to diagnose an infection

Front 26

Cryptococcus neoformans
Clinical Manifestations

Back 26

1. Most common cause of fungal meningitis
2. Cryptococcal meningitis
3. Detection of antigens in cerebrospinal fluid
4. Gives severe headache
5. Skin lesions may result from dissemination of yeast

Front 27

Blastomyces dermatitidis
Epidemiology and Characteristics

Back 27

1. Limited to North America and parts of Africa
2. May cause skin lesions if systemic infection develops
3. Dogs are susceptible to infection

Front 28

Aspergillus species
Characteristics

Back 28

1. Source of nosocomial infections
2. Often found in ventilation ducts
3. Colonization in lung can lead to extensive growth and invasion of other tissues
4. Forms fungus ball that requires surgical removal

Front 29

Zygomycosis
Characteristics

Back 29

1. Abundant in environment
2. Blood vessels, eye, CNS, nose, sinuses, and lungs are most commonly involved
3. Predisposing factors: immunosuppression
4. Represents a serious nosocomial infection

Front 30

What are the 2 basic morphologic forms of Fungi?

Briefly Describe them...

Back 30

1. Yeast - UNICELLULAR growth form of fungi (reproduce by budding and fission)
2. Molds - MULTI-CELLULAR hyphal growth by apical elongation (involves production of multicellular, filamentous colonies)
3. Fungi can grow in both forms (Dimorphism)

Front 31

What composes the CELL WALL of Fungi?

Back 31

1. Chitin - a target of anti-fungal drugs (ECHINOCANDINS, NIKKOMYCIN)

*analogous to PG layer of bacteria*

Front 32

Name 4 reasons CHITIN is medically important in fungal infections...

Back 32

1. Mediates attachment
2. Promotes colonization and invasion
3. Promotes antigens
4. Mammalian tissues lack enzymes to degrade chitin

Front 33

Name the UNIQUE plasma membrane lipid in fungi...

Back 33

1. ERGOSTEROL - we use this to target and kill fungi (target of AZOLES, ALLYLAMINES)

*cell membranes are in lipid-bilayer format*

Front 34

How do fungi acquire nutrients?

Back 34

1. they DO NOT engulf their nutrients
2. bacteria SECRETE DIGESTIVE ENZYMES and ABSORB their nutrients

Front 35

Name the MAIN components of POLARIZED GROWTH of hypha...

Back 35

1. Enzymes arrive in vacuoles
2. Rigid cell wall is degraded
3. Other vacuoles arrive with "rebuilding" enzymes
4. Growth in ONE direction

**budding in yeast cells use similar concept**

Front 36

Name the MAIN TYPES of FUNGAL DISEASES...

Back 36

1. Allergies - simply an allergic reaction to fungal spores **NO GROWTH OF FUNGUS NEEDED**
2. Mycotoxicoses - Toxins like AFLATOXIN (A. flavus) and AMATOXINS from mushrooms
3. Superficial Mycoses - (details covered on separate flashcard)

Front 37

Name 4 characteristics of SUPERFICIAL MYCOSES...

Back 37

1. noninvasive
2. outermost layer of the skin
3. colonize NONLINING tissue
4. NO IMMUNE RESPONSE

Front 38

Name 4 SUPERFICIAL MYCOSIS clinical manifestations...

Back 38

1. Pityriasis versicolor - found in areas with sweat glands; results in hyper/hypopigmented macular lesions.
2. Tinea nigra - CAN BE CONFUSED WITH MELANOMA; black macular lesions on palms/soles
3. Black piedra - DARK fungus on SHAFT of hair follicle
4. White piedra - WHITE fungus on hair SHAFT

Front 39

Name 5 characteristics of CUTANEOUS MYCOSES...

Back 39

1. **Caused by DERMATOPHYTES** TQ
2. Restricted to KERATINIZED LAYERS (skin and nails)
3. IMMUNE RESPONSE INVOLVED (this determines the severity)
4. Can be of geophilic, zoophilic, or anthrophilic origin
5. Referred to as "ringworm"

Front 40

What are the 3 main genera of DERMATOPOHYTES relating to cutaneous mycoses and what are their targets?

Back 40

1. Trichophyton
2. Microsporum
3. Epidermophyton

**they can infect MORE THAN ONE site (scalp, hair, skin, or nails)

Front 41

What clinical manifestation is associated with Tinea pedis?

Back 41

1. Athlete's foot

Front 42

What clinical manifestation is associated with Tinea cruris?

Back 42

1. Jock itch

Front 43

What clinical manifestation is associated with Tinea corporis?

Back 43

1. Simply a Tinea infection on the body

Front 44

What clinical manifestation is associated with Tinea barbae?

Back 44

1. Tinea infection of the BEARD

Front 45

What clinical manifestation is associated with Tinea capitus?

Back 45

1. Tinea infection of the head (site of hair loss)

Front 46

Tinea capitus caused by Microsporum canis causes hair loss. Why is this so and what is the site of hair loss called?

Back 46

1. Severe inflammation of the hair follicles causes the hair loss
2. Kerion - site of hair loss

Front 47

How would you diagnose a fungal disease?

Back 47

1. Scrape and KOH preparation

Front 48

Name 3 characteristics of SUBCUTANEOUS MYCOSES...

Back 48

1. Infection usually from soil/vegetation
2. A lesion usually develops at site of trauma
3. infection is DEEPER than the layer of the DERMIS (can go into muscle or bone)

Front 49

What is one of the most clinically relevant SUBCUTANEOUS MYCOSES (Lymphocutaneous sporotrichosis) ?

Back 49

1. Sporothrix schenkii - causes Lymphocutaneous sporotrichosis

Front 50

What are the typical clinical presentations of in infection with Sporothrix schenkii?

Back 50

1. You should observe lesions along the lymphatics draining the primary lesion

Front 51

Where would one be more likely to be infected with Chromoblastomycosis? How do you treat it? Outcome?

Back 51

1. Tropics
2. Surgery
3. You have it for life