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Flashcards in Tasos Fungi Deck (31)
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1
Q

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A

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2
Q

What is medical mycology?

A

The study of fungi as animal and human pathogens

3
Q

What are the 2 types of fungi classified by growth form?

A

1) Filamentous
- growing as multinucleate, branching hyphae, forming a mycelium
2) Yeasts
- growing as ovoid or spherical cells, multiply by budding and division

4
Q

What are the 3 types of fungi classified by type of infection?

A

1) Superficial mycoses - mild - surface or skin or hair
2) Cutaneous and subcutaneous mycoses - mild - deeper in nail and skin
3) Deep mycoses - can be life threatening
(include opportunistic fungi)

5
Q

What are the 3 types of fungi classified by type of infection?

A

1) Superficial mycoses - mild
2) Cutaneous and subcutaneous mycoses - mild
3) Deep mycoses - can be life threatening
(include opportunistic fungi)

6
Q

What are the 3 artificial groups of fungi that are human pathogens?

A

1) Obligate parasite
- Usually dermatophytes
- Attack external structures i.e skin, nail
2) Soil Fungi
- Found in soil, can invade humans
3) Opportunistic Saprobes
- Can only usually attack when immune system is suppressed

7
Q

Why do dermatophytes infect the skin, nails and hair?

A

The are keratin-loving organisms and invade keratinized body structures
- Their arthrospores adhere to keratinocytes, germinate and invade

8
Q

What is the most common disease caused by dermatophytes?

A

Tinea (ringworm)

9
Q

What is the structure of the skin in relation to fungal infection?

A

2 main layers of skin:
- Epidermis (outermost layer)
- Dermis (inner layer)
Epidermis is dead and is the only area where superficial fungi called dermatophytes can grow

10
Q

What is the structure of the skin in relation to fungal infection?

A

2 main layers of skin:
- Dermis
- Epidermidis
Epidermidis is dead and is the only area where superficial fungi called dermatophytes can grow

11
Q

What is the immunological defense of the skin against infection?

A

1) The epidermis, particularly the stratum corneum (outermost keratinized skin layer) provides passive defense against organism entry and also performs active role in immunity through immunological surveillance by epidermal Langerhan’s cells (Ag presenter cells)
2) Antigen presents to Langerhans cells
3) Ag then presented to lymph node
4) Ag specific T cells enter blood and spread to site of invasion and activate cytokines

12
Q

What are the 8 types of tinea and where does each have effect? (remember a couple)

A
Tinea barbae - beard
Tinea capitis - head
Tinea corporis - body
Tinea manuum - hands
Tinea pedis - foot
Tinea ungium - nail
Tinea cruris - groin
Tinea axillae - arm pit
(word e.g barbae, is latin for the part of body)
13
Q

What is Tinea capitis and how is it tested for?

A
  • Most common world wide dermatophyte infection
  • Infected hairs will floresce under UV light and then extracted with forceps
  • Hairs then treated with 40% KOH
    > This clarifies hair and allows spores to be seen
  • Chopped up hair added to petri dish containing Sabourauds agar (rich in glucose)
  • Incubated for up to 14 days at 30oC
  • Colonies transferred to slide using sticky tape and Lactophenol cotton blue stain added
14
Q

What is Tinea corporis and how is it diagnosed?

A
  • Infection of body
  • Appears as a round ring on skin with slightly raised edge often with small blisters
  • Skin should be scraped with scalpel blade from edge of ring
  • Scrape onto black cardboard for visibility
  • Treated in the same way as hair
  • Hyphae appear as little threads - their presence is diagnostic
15
Q

What is Tinea ungium and how is it diagnosed?

A
  • Common in damaged nails
  • Nail clippings taken by bone forceps or by dental drill and collect nail powder
  • Processed as before but may need longer on KOH
16
Q

What is Tinea pedis?

A
  • Athletes food
  • V common minor fungal infection usually between 4th and 5th toe
  • Result of microbial cascade
  • normal flora of feet is around 10^5 organisms per square cm
17
Q

What is Candida, what does it cause and what is the most common type?

A

Candida is a genus of yeast

  • Causes candidasis
  • most common cause of fungal infections (yeast infections)
  • Candida albicans is most common species
18
Q

What is Candida, what does it cause and what is the most common type?

A

Candida is a genus of yeast

  • most common cause of fungal infections
  • Candida albicans is most common species
19
Q

What are the different types of candidiosis?

A
Oral candidiasis (oral thrush)
- common in children and immunocompromised adults
Mucocutaneous candidiasis
- non-invasive infection of mucous membranes
Gentital candidiasos
- Yeast infection, common in women
Gastrointestinal candidiasis
Invasive candidiasis
- Infection in bloodstream
20
Q

What is Tinea versicolor?

A
  • Chronic skin condition caused by yeast called pityrosporon orbiculare
  • Most people no disease
  • Some people the yeast is more active and causes itchy rash
21
Q

What is Mycetoma?

A
  • Fungal infection of feet most prevalent in tropics, but does occur in south US
  • Early lesions are granulomatous (inflammed) but becomes surrounded by dense fibrous capsule
  • Advanced cases: Mass of cyst with mescle, tendon and bone eventually destroyed
22
Q

What is chromoblastomycosis?

A
  • Chronic fungal infection in which there are raised crusted lesions affecting the skin and subcutaneous tissue
  • Usually affects limbs and may be due to several fungi found in soil, wood and decaying plant material
  • Organism is inoculated into the skin by minor injury e.g cut with splinter
  • Relatively common in warmer areas such as Pacific Islands
23
Q

Describe the life cycle of C.immitis

A
2 phases:
1) Saprophytic phase in soil
2) Parasitic phase in infected tissue
Saprophytic phase:
- When soil becomes dry, brancing hyphae develop into arthrospores, which produce free arthrospores into the air
Parasitic phase:
- Developing endospore in tissue
- Becomes mature spherule with endospores
- Endospores released
24
Q

What does C.immitis cause?

A

Coccidioidomycosis

  • pyogenic infection (involving pus)
  • eventually, a granulomatous respiratory infection
25
Q

What system is the key factor in coccidioidomycosis recovery?

A

Cell mediated immunity, particulary T cells

Majority of patients recover from respiratory infection

26
Q

How are fungal respiratory problems commonly identified?

A

Respiratory infection usually results in endobronchiolitis

  • A spectrum of signs may be observed using a chest X-ray
  • these include pulmonary markings, patchy bronchopneumonia and others
27
Q

What is disseminated coccidioidomycosis and when does it usually occur?

A

When the C.immitis spreads from the lungs to other tissue

- occurs within weeks to months of the primary pneumonia

28
Q

What groups of people are susceptible to dissemination and what are common dissemination sites?

A

Males and certain ethnic groups such as African Americans and Filipinos
- Common sites are skin, bones and meninges

29
Q

What are Microsporidia?

A
  • Group of spore forming unicellular parasites
  • Important pathogens of humans infected with HIV
  • Phylogenetic analyses, biochemical and physiological characteristics are related to fungi
30
Q

What is the basic life cycle of Microsporidia? (All I could find)

A
  • Polar filament of microsporidia injects the infectious content into cytoplasm (spores)
  • Sporoplasm develops, producing new spores
  • cell ruptures releasing spores
31
Q

What are the 4 main areas that microsporidia can infect (microsporidiosis) and what are the symptoms of each?

A

1) Intestines
- chronic diarrhea, wasting, malabsorption
2) Lungs
- cough, difficulty breathing
3) Infection of urinary tract + kidney, bladder, bowel
4) Eye
- inflammation of cornea and conjunctiva
- Eye pain, redness, blurred vision