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BM211: Introduction to Microbiology > Block C Lecture 2: Fungal Pathogens > Flashcards

Block C Lecture 2: Fungal Pathogens Flashcards

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1
Q

What are the 3 categories of medical importance when dealing with diseases caused by fungi?

A

Mycotoxicases
Hypersensitivity Diseases
Host colonisation and resulting disease state
(Slide 4)

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2
Q

What are 3 examples of specialised metabolites that fungi produce?

A

Alkaloids
Toxins
Psychotropic Agents
(Slide 5)

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3
Q

What do mycotoxicoses result from?

A

Due to accidental or recreational ingestion of fungal toxins
(Slide 5)

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4
Q

How are mycotoxicoses treated?

A

Firstly by induced emesis (vomiting) followed by supportive therapy (assisted breathing / fluid)
(Slide 5)

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5
Q

What do ergot alkaloids result in?

A

Convulsions and gangrene (due to vasoconstriction)
(Slide 5)

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6
Q

What do aflatoxins cause?

A

Gross hemorrhage and necrosis of tissue in birds
(Slide 6)

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7
Q

How can aflatoxins affect humans?

A

As it can also affect the human food chain
(Slide 6)

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8
Q

What chemical property do aflatoxins have?

A

They are carcinogenic
(Slide 6)

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9
Q

What is fungal hypersensitivity caused by?

A

Host inhaling fungal antigen, then hypersensitivity arises as a result of immunoglobulin production + lymphocyte stimulation
(Slide 7)

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10
Q

What do fungal hypersensitivity diseases not require?

A

Fungal growth
(Slide 7)

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11
Q

What can be used to identify fungal hypersensitivity?

A

Skin tests
(Slide 7)

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12
Q

What are the 3 different types of mycoses?

A

Superficial
Subcutaneous
Systemic
(Slide 9)

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13
Q

What cell trait do many pathogenic fungi exhibit?

A

They are dimorphic (exist either as yeasts or in filamentous form)
(Slide 10)

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14
Q

Why is the morphology of spores important?

A

In identification and diagnosis of fungal diseases
(Slide 10)

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15
Q

What is superficial mycosis?

A

When the fungus only infects the surface layer of the skin, hair or nails
(Slide 11)

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16
Q

What can be used to treat superficial mycosis?

A

It is mostly treatable with topical antifungal creams or liquid aerosols
(Slide 11)

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17
Q

What are fungi capable of producing superficial mycoses collectively called?

A

Dermatophytes
(Slide 11)

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18
Q

What do Trichophyton Spp. cause?

A

Fungal infections of the feet and other moist skin surfaces
(Slide 11)

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19
Q

How are Trichophyton species transmitted?

A

By spores (via flaking and itching skin)
(Slide 11)

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20
Q

What is subcutaneous mycosis?

A

A fungal disease which infects the deeper layers of the skin
(Slide 12)

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21
Q

What 2 ways can subcutaneous mycosis be treated?

A

Mostly treatable with topical drugs and azole antifungal agents are also often used to treat it
(Slide 12)

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22
Q

What fungi causes sporotrichosis?

A

Sporothrix schenckii
(Slide 12)

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23
Q

What is sporotrichosis?

A

An occupational hazard of anyone who works in close contact with soil agriculture, as spores can enter through cut skin
(Slide 12)

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24
Q

What is chromoblastomycosis?

A

Causes formation of crusty, wart-like lesions on the hands / legs and can be caused by fungal infection via puncture wound
(Slide 12)

25
Q

What is systemic mycosis?

A

When fungal growth infects the internal organs
(Slide 13)

26
Q

Where do systemic fungal pathogens normally live?

A

In soil
(Slide 13)

27
Q

How do systemic fungal pathogens infect humans?

A

Due to inhalation of airborne spores, with the infection then travelling from the lungs to the other organs and the skin
(Slide 13)

28
Q

Why is chemotherapy of systemic mycosis difficult?

A

Because of issues with toxicity
(Slide 13)

29
Q

What 2 groups do systemic fungal pathogens generally infect?

A

The elderly or otherwise immunocomprimised individuals (such as AIDS patients)
(Slide 13)

30
Q

What is the difference between primary and secondary mycosis?

A

Primary mycosis is when an healthy individual is infected whereas secondary mycosis is when an individual with a predisposing condition is infected
(Slide 13)

31
Q

What is histoplasmosis?

A

When inhaled spores from histoplasma capsulatum germinate and grow in the lung
(Slide 14)

32
Q

What does Coccidioides immitis cause?

A

Coccidioidomycosis
(Slide 15)

33
Q

What symptoms does coccidioidomycosis exhibit?

A

Respiratory symptoms
(Slide 15)

34
Q

What can coccidioidomycosis eventually lead to?

A

Pneumonia
(Slide 15)

35
Q

What fungi causes blastomycosis?

A

Blastomyces dermatitidis
(Slide 16)

36
Q

Where does blastomyces dermatitidis live?

A

In rotten wood and soil near bodies of water
(Slide 16)

37
Q

What is blastomycosis?

A

A lung infections that can lead to skin lesions if untreated
(Slide 16)

38
Q

What does paracoccidioides brasiliensis cause?

A

Paracoccidioidomycosis
(Slide 17)

39
Q

What is paracoccidioidomycosis?

A

A initially pulmonary fungal infection that can lead to lesions forming on the face or other extremities (such as the limbs)
(Slide 17)

40
Q

How can paracoccidioidomycosis be treated?

A

With azole antifungal agents
(Slide 17)

41
Q

What does Cryptococcus neoformans cause?

A

Cryptococcosis
(Slide 18)

42
Q

Where can cryptococcosis occur?

A

In almost any organ in the body
(Slide 18)

43
Q

Where does cryptococcosis first infect?

A

Either the lungs or a wound
(Slide 18)

44
Q

What kind of people does cryptococcosis infect?

A

HIV/AIDS patients (immunocompromised individuals)
(Slide 18)

45
Q

What can candida albicans be a minor component of?

A

Normal human flora
(Slide 20)

46
Q

What severity are infections caused by candida albicans?

A

Can be mild (such as thrush) to severe in individuals who are immunocompromised
(Slide 20)

47
Q

What method does candida albicans use to generate genetic diveristy?

A

Chromosomal rearrangements
(Slide 20)

48
Q

Why are biofilms a problem in medical settings?

A

As they are difficult to treat with antifungal agents
(Slide 20)

49
Q

What fungi is pneomocytosis pneumonia often caused by?

A

Pnemocytosis jirovecil
(Slide 21)

50
Q

What are 3 examples of people which pneomocytosis can infect?

A

People undergoing chemotherapy
People with AIDS
Premature / severely malnourished children
Elderly people
Infants with hyper IgM syndrome or an X-linked or autosomal recessive trait
(Slide 21)

51
Q

Why are fungal infections difficult to treat in eukaryotes?

A

As fungi share alot of cellular machinery with animals and humans and few drugs target metabolic processes that are unique to fungi
(Slide 22)

52
Q

What is ergosterol?

A

An analogue of cholesterol found in fungal plasma membranes
(Slide 23)

53
Q

What are the 2 main classes of ergosterol inhibitors?

A

Polyenes and Azoles
(Slide 23)

54
Q

What is the mechanism of action of azoles and polyenes?

A

They bind to ergosterol, deplete it in the membrane and then toxic intermediates accumulate resulting in the destabilisation of fungal cell membranes, leading to cell death
(Slide 23)

55
Q

What is the mechanism of action of echinocandins?

A

The inhibit the synthesis of glucan in the cell wall via the inhibition of the enzyme 1,3-ß glucan synthase.
(Slide 24)

56
Q

What are ß glucans?

A

Carbohydrate polymers that are cross-linked with other fungal cell wall components
(Slide 24)

57
Q

What does the inhibition of ß-glucans prevent?

A

Fungal cell wall synthesis
(Slide 24)

58
Q

What are DNA synthesis inhibitors?

A

They are nucleic acid analogues which inhibit enzymes required for DNA synthesis
(Slide 25)

59
Q

What infections are DNA synthesis inhibitors used to treat?

A

Candida infections and Cryptococcus neoformans
(Slide 25)

BM211: Introduction to Microbiology (21 decks)

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