Week 228 - Fungal Disease Flashcards

1
Q

Week 228 - Fungal Disease: What is pneumocystis jirovecii?

A

Opportunistic fungal parasite which can cause pneumonia in patients with impaired immune systems, such as those with AIDS or are receiving immunosuppressive drugs.

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2
Q

Week 228 - Fungal Disease: What is often the cause of candida of the oesophagus?

A

• Often follows a treatment of broad spectrum antibiotics, steroids or other immunosuppression.

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3
Q

Week 228 - Fungal Disease: What is the macroscopic appearance of oesophageal candida?

A

Soft white plaques.

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4
Q

Week 228 - Fungal Disease: How is oesophageal candida diagnosed? How is it confirmed?

A
  • Endoscopic appearance.

* Confirmed by biopsy or brushings.

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5
Q

Week 228 - Fungal Disease: How might non-invasive aspergillus affect the following individuals, 1) Heavy exposure but normal, 2) Asthma or cystic fibrosis, 3) Pre-existing cavitating lung disease.

A

1) Hypersensitivity pneumonitis
2) Allergic bronchopulmonary Aspergillosis (ABPA)
3) Colonisation of cavities - mycetoma

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6
Q

Week 228 - Fungal Disease: How would invasive aspergillus affect the immunocompromised?

A

Invasion of blood vessels and tissues within and outside the lungs.

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7
Q

Week 228 - Fungal Disease: What is the pathological mechanism behind hypersensitivity pneumonitis?

A

• Combination of a type 3 and type 4 immune hypersensitivity response to a large dose of a number of antigens.

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8
Q

Week 228 - Fungal Disease: What is a type 3 hypersensitivity reaction?

A

• Antigen and antibody complexes precipitate in tissues which trigger the complement system leading to inflammatory damage.

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9
Q

Week 228 - Fungal Disease: What is a type 4 hypersensitivity reaction?

A
  • T Lymphocytes drive macrophages to cause tissue damage.

* Cell mediated.

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10
Q

Week 228 - Fungal Disease: Give some examples of those at risk to hypersensitivity pneumonitis.

A
  • Pigeon fanciers - Serum, feather, faecal proteins.
  • Farmers - Fungi in mouldy hay
  • Humidifier fever - Organisms in air conditioning
  • Brewers - Aspergillus
  • Cheese workers - Aspergillus, Penicillium
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11
Q

Week 228 - Fungal Disease: What are the symptoms of hypersensitivity pneumonitis?

A
• Dyspnoea
• Cough
• Fever
• Flu like symptoms
(Develop 4-6hours after exposure)
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12
Q

Week 228 - Fungal Disease: What would you find on examination and investigation in someone with hypersensitivity pneumonitis?

A
  • Examination - Fine crackles at the end of expiration.
  • Chest X-ray - Diffuse reticulo-nodular shadowing.
  • CT thorax - Bilateral areas of consolidation and air trapping.
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13
Q

Week 228 - Fungal Disease: What is the treatment for hypersensitivity pneumonitis?

A
  • Prevent further exposure.

* Immunosupression - Reduce bodies excessive T-cell response to antigen.

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14
Q

Week 228 - Fungal Disease: What is ABPA?

A
  • Allergic bronchopulmonary aspergillosis.

* In patients with asthma or cystic fibrosis, that have been exposed to a low dose of airborne aspergillosis.

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15
Q

Week 228 - Fungal Disease: What are the symptoms of allergic bronchopulmonary Aspergillosis (ABPA)?

A

• Cough, Dyspnoea, (Worsening of asthma), coughing up casts.

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16
Q

Week 228 - Fungal Disease: What is a type 1 hypersensitivity reaction?

A

• IgE mediated.

  • An antigen is presented to CD4+ (Th2) cells, these stimulate B-cells to produce IgE antibodies. These coat mast cells and basophils.
  • A secondary exposure to the antigen, causes these sensitised cells to release inflammatory mediators such as histamine and prostaglandins.
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17
Q

Week 228 - Fungal Disease: Asthma is due to which type of hypersensitivity reaction?

A

• Type I

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18
Q

Week 228 - Fungal Disease: What is the type 3 hypersensitivity reaction to aspergillus?

A
  • Immune complexes form as antibodies bind to proteins from the fungus.
  • These activate the complement system leading to inflammation and damage to local tissues.
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19
Q

Week 228 - Fungal Disease: What is the type 4 hypersensitivity reaction to aspergillus?

A
  • Activation of lymphocytes which recruit and activate macrophages.
  • The macrophages form granulomas - which cause cell damage.
  • This eventually leads to bronchiectasis and fibrosis.
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20
Q

Week 228 - Fungal Disease: What is a granuloma?

A

Ball of highly active macrophages that cause damage to surrounding tissues.

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21
Q

Week 228 - Fungal Disease: How is ABPA diagnosed?

A
  • Hyphae in sputum
  • Blood -eosinophilia, raised IgE, positive antibodies.
  • Positive skin test to aspergillus proteins.
  • Broncho-alveolar lavage
  • Bronchiectasis develops with time - tram line, ring and gloved finger signs.
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22
Q

Week 228 - Fungal Disease: What is the treatment for ABPA?

A
  • Oral steroid to suppress immune mediated damage.
  • Management of asthma
  • Physiotherapy
  • Bronchoscopy to remover plugs if CXR shows collapse lasting more than 7 days.
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23
Q

Week 228 - Fungal Disease: What are some of the cavities that can be colonised by aspergillus?

A
  • Old TB
  • Abscess
  • Bronchiectasis
  • Chronic interstitial lung disease
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24
Q

Week 228 - Fungal Disease: Why does haemoptysis occur in cavitating aspergillus?

A

Oxalic acid released from the hyphae causes erosion of the blood vessels.

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25
Q

Week 228 - Fungal Disease: What are symptoms of a mycetoma?

A

(Mycetoma is a fungal ball, that colonises a pre-existing cavity in the lungs)
• May be an asymptomatic incidental finding.
• Recurrent haemoptysis.
• Non-specific weight loss, lethargy.

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26
Q

Week 228 - Fungal Disease: What is the histology of a mycetoma?

A
  • Pink necrotic centre.
  • Rim of active hyphae.
  • Presence of fruiting bodies.
27
Q

Week 228 - Fungal Disease: How is mycetoma diagnosed?

A
  • Radiological appearance.
  • Hyphae on sputum cytology.
  • Culture of sputum.
  • Skin sensitivity test.
  • Serum antibodies (precipitins)
  • Fine needle / core biopsy.
28
Q

Week 228 - Fungal Disease: What is the treatment of mycetoma?

A
  • Depends on severity of symptoms.
  • Can be monitored.
  • Anti-fungals no good.
  • Surgical resection if troublesome.
  • Bronchial artery embolisation.
29
Q

Week 228 - Fungal Disease: What are the symptoms of invasive aspergillosis?

A
  • Gravely ill.
  • Rapidly spreading consolidation, necrosis and cavitation of lungs.
  • Copious blood stained sputum.
30
Q

Week 228 - Fungal Disease: What is histology of invasive aspergillosis?

A
  • Acute necrotising inflammation with plugging of vessels by fibrin.
  • Heavy infiltration by fungus.
  • Plugged vessels cause infarction of organs.
31
Q

Week 228 - Fungal Disease: What is the treatment for invasive aspergillosis?

A

• IV anti-fungals by slow infusion.

- Amphotericin and flucytosine.

32
Q

Week 228 - Fungal Disease: How can mouldy peanuts cause cancer?

A

• High incidence in Asia of hepatocellular carcinoma caused by Aspergillus growth on mouldy peanuts.
- The aspergillus causes aflatoxin which causes the cancer.

33
Q

Week 228 - Fungal Disease: Give three dermatophytes that are commonly responsible for causing ‘ring worm’.

A
  • Trichophyton
  • Epidermophyton
  • Microsporum
34
Q

Week 228 - Fungal Disease: What are the types of anti fungal therapy?

A
  • Azoles
  • Echinocandins
  • Allyamines
  • Terbinafine
  • Polyenes
  • Other antifungals
35
Q

Week 228 - Fungal Disease: What is dermatophytosis?

A
  • A superficial localised infection of keratinized tissue such as skin, hair and nails.
  • Digest keratin by their keratinases.
36
Q

Week 228 - Fungal Disease: Give examples of dermatophytes and the area they may affect?

A
  • Microsporum - Hair + Skin
  • Epidermophyton - Skin and Nails
  • Trichophyton - Hair, Skin and Nails
37
Q

Week 228 - Fungal Disease: How does dermatophytosis manifest when in the skin?

A

Circular, dry, erythematous, scaly, itchy lesions.

38
Q

Week 228 - Fungal Disease: How does dermatophytosis manifest when in the nail?

A

Thickened, deformed, friable, discoloured nails, subungual debris accumulation.

39
Q

Week 228 - Fungal Disease: How does dermatophytosis manifest when in the hair?

A

Typical scaly lesions, hair loss.

40
Q

Week 228 - Fungal Disease: What is pityriasis versicolor?

A
  • Superficial infection of stratum corneum (outer layers of the skin).
  • Caused by the skin commensal Malassezia furfur
41
Q

Week 228 - Fungal Disease: What infection does Malassezia furfur commonly cause?

A

• Pityriasis versicolor

42
Q

Week 228 - Fungal Disease: How does pityriasis present?

A

Hyperpigmented or depigmented macules on the trunk or proximal parts of the limbs.

43
Q

Week 228 - Fungal Disease: What do skin scrapings of pityriasis versicolor reveal?

A

Yeast cells in clusters and short hyphae (KOH,PAS)

44
Q

Week 228 - Fungal Disease: What is the treatment for pityriasis versicolor?

A
  • Topical - Ketonazole shampoo or other topical agent.

* Oral - Itraconazole or fluconazole

45
Q

Week 228 - Fungal Disease: Which species of candida is most commonly the cause of candidiasis?

A

Candida albicans

46
Q

Week 228 - Fungal Disease: What is cryptococcosis?

A
  • Fungal infection caused by cryptococcus neoformans.
  • Usually presents as CNS infection but can sometimes present as a pulmonary infection, particularly in AIDS patients.
  • Pigeon droppings.
47
Q

Week 228 - Fungal Disease: Give examples of endemic or true pathogens (Fungi)?

A
  • Histoplasmosis
  • Coccidioidomycosis
  • Blastomycosis
  • Paracoccidiodomycosis
48
Q

Week 228 - Fungal Disease: Which anti-fungal groups work by inhibiting membrane synthesis?

A
  • Azoles
  • Echinocandins
  • Allylamines
49
Q

Week 228 - Fungal Disease: Which anti-fungal group work by inhibiting membrane function?

A

• Polyenes

50
Q

Week 228 - Fungal Disease: How do Flucytosine and Griseofulvin work as anti-fungals?

A

• Inhibit nucleic acid synthesis and mitosis.

51
Q

Week 228 - Fungal Disease: Azoles are split into two subgroups, what are they give examples of each.

A
  • Imidazoles - Ketoconazole, Topical imidazoles

* Triazoles - Fluconazole, Voriconazole, Itraconazole

52
Q

Week 228 - Fungal Disease: Give an example of Echinocandins.

A

Capsofungin.

53
Q

Week 228 - Fungal Disease: Give an example of an allylamine.

A

Terbinafine.

54
Q

Week 228 - Fungal Disease: Give examples of some polyenes.

A
  • Amphotericin B

* Nystatin

55
Q

Week 228 - Fungal Disease: Give the mechanism of action of Azole anti-fungals.

A
  • Inhibit fungal cytochrome p450 which depletes ergosterol in the cell membrane.
  • This causes the accumulation of toxic intermediates resulting in the inhibition of growth of the membrane.
56
Q

Week 228 - Fungal Disease: What is Clotrimazole used for?

A

The topical treatment of candida, tinea pedis and tinea cruris. (Skin only)

57
Q

Week 228 - Fungal Disease: What anti-fungal is used for the treatment of SKIN candida, tinea pedis and tinea cruris?

A

Clotrimazole (Topical)

58
Q

Week 228 - Fungal Disease: What is Fluconazole used for?

A

Treatment of Candida, Cryptococcus and dermatophytes.

59
Q

Week 228 - Fungal Disease: What are the side effects of fluconazole?

A

GI disturbances, liver damage.

60
Q

Week 228 - Fungal Disease: What is Voriconazole used for?

A
  • Fungicidal against Aspergillus and Candida.

* Available orally and IV.

61
Q

Week 228 - Fungal Disease: What are the side-effects of voriconazole?

A

GI disturbances, visual disturbances.

62
Q

Week 228 - Fungal Disease: What is Itraconazole used for?

A

Candida, Aspergillus, Cryptococcus, Dermatophytes.

63
Q

Week 228 - Fungal Disease: What are the side effects of itraconazole?

A

Negative inotropic effect, liver damage.

64
Q

Week 228 - Fungal Disease: What is the mechanism of action of Echinocandins?

A
  • Inhibits 1,3 beta-glucan synthase.
  • Reduces glucan in cell wall.
  • Weakens the cell wall.