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Infection > Fungal Infections > Flashcards

Fungal Infections Flashcards

1
Q

What are the main fungal pathogens?

A
  • Aspergillus species
    • Aspergillus fumigatus
  • Candida species
    • Candida albicans
  • Cryptococcus species
    • Cryptococcus neoformans
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2
Q

What are fungal pathogens in nature?

A

Fungal pathogens are opportunistic in nature:

  • Affects patients with impaired immune systems
    • Primary immunodeficiency’s
    • Patients with HIV/AIDS
    • Patients with malignancies
    • Premature neonates
    • Patients with transplants
  • Affects patients with chronic lung diseases
    • Asthma
    • Cystic fibrosis
    • Chronic obstructive lung disorders
  • Patients in ICU
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3
Q

What are some specific fungal diseases?

A
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4
Q

What is candidiasis?

A

Infection due to any type of candida (type of yeast)

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5
Q

What kind of fungus is candida?

A

Yeast

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6
Q

What is mucocutaneous candidiasis also known as?

A

Thrush

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7
Q

What is thrush caused by?

A

Candida spp

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8
Q

What is thrush?

A

An immune disorder of T cells characterised by chronic infections with candida that are limited to mucosal surfaces, skin and nails

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9
Q

What is the presentation of thrush?

A
  • Characterised by neutropenia, low CD4 T cells and impared IL-17 immunity
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10
Q

What is the treatment for thrush?

A

Inhaled steroids

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11
Q

What is invasive candidiasis?

A
  • Gut commensal (candida), infection mostly endogenous in origin
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12
Q

What are risk factors for invasive candidiasis?

A
  • Broad spectrum antibiotics
  • IV catheters
  • Total parenteral nutrition
  • Abdominal surgery
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13
Q

How is invasive candidiasis diagnosed?

A
  • Blood culture or culture from normal sterile site
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14
Q

How is aspergillus transmitted?

A
  • Sporulation
  • Airborne/inhalation
  • Diameter 2-3um
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15
Q

What is a common disease caused by aspergillus?

A

Invasive pulmonary aspergillosis

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16
Q

Describe the pathogenesis of invasive pulmonary aspergillosis?

A

1) Sporulation
2) Inhalation
3) Germination occurs in absence of pulmonary defences
4) Causes neutropenia due to excessive hyphal growth and dessemination

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17
Q

What are the different classifications of pulmonary aspergillus?

A
  • Acute invasive pulmonary aspergillosis
    • Usually occurs in neutropenic patients, post-transplant and patients with defects in phagocytes
    • Neutropenic host:
      • Rapid and extensive hyphal growth
      • Thrombosis and haemorrhage
      • Angio-invasive and dissemination
      • Non-specific clinical signs and symptoms
    • Non-neutropenic host
      • Non-angiovasive
      • Limited fungal growth
      • Tissue necrosis and excessive inflammation
      • Non-specific clinical signs and symptoms
  • Chronic pulmonary aspergillosis (>3 months)
    • Occurs in patients with underlying chronic lung conditions
    • Pulmonary exacerbations that do not respond to antibiotics
    • Lung function decline
    • Increased respiratory symptoms such as cough, decreased exercise tolerance and dyspnoea
    • Positive sputum culture for aspergillus
  • Allergic aspergillosis
    • Allergic bronchopulmonary aspergillosis occurs in CF and asthma patients
    • Immunological response to variety of A. Fumigatus antigens causing
      • Acute/subacute deterioration of lung function and respiratory symptoms
      • Elevated immunoglobulin E (IgE) levels
      • Positive aspergillus specific IgG
  • Pulmonary aspergilloma
    • Fungal mass that usually grows in lung cavities
    • Occurs in patients with
      • TB
      • Sarcoidosis
      • Bronchiectasis
      • Bronchial cysts and bullae
      • After pulmonary infections
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18
Q

What are the different classifications of host for acute invasive pulmonary aspergillosis?

A
  • Neutropenic host:
    • Rapid and extensive hyphal growth
    • Thrombosis and haemorrhage
    • Angio-invasive and dissemination
    • Non-specific clinical signs and symptoms
  • Non-neutropenic host
    • Non-angiovasive
    • Limited fungal growth
    • Tissue necrosis and excessive inflammation
    • Non-specific clinical signs and symptoms
19
Q

Compare and contrast neutropenic and non-neutropenic hosts for acute invasive pulmonary aspergillosis?

A
  • Neutropenic host:
    • Rapid and extensive hyphal growth
    • Thrombosis and haemorrhage
    • Angio-invasive and dissemination
    • Non-specific clinical signs and symptoms
  • Non-neutropenic host
    • Non-angiovasive
    • Limited fungal growth
    • Tissue necrosis and excessive inflammation
    • Non-specific clinical signs and symptoms
20
Q

Who does acute invasive pulmonary aspergillosis usually occur in?

A
  • Usually occurs in neutropenic patients, post-transplant and patients with defects in phagocytes
21
Q

Who does chronic pulmonary aspergillosis usually occur in?

A
  • Occurs in patients with underlying chronic lung conditions
22
Q

What is the clinical presentation for chronic pulmonary aspergillosis?

A
  • Pulmonary exacerbations that do not respond to antibiotics
  • Lung function decline
  • Increased respiratory symptoms such as cough, decreased exercise tolerance and dyspnoea
23
Q

Who does allergic aspergillosis usually occur in?

A
  • Allergic bronchopulmonary aspergillosis occurs in CF and asthma patients
24
Q

What is pulmonary aspergilloma?

A
  • Fungal mass that usually grows in lung cavities
25
Q

Who does pulmonary aspergilloma normally occur in?

A
  • Occurs in patients with
    • TB
    • Sarcoidosis
    • Bronchiectasis
    • Bronchial cysts and bullae
    • After pulmonary infections
26
Q

Invasive aspergillosis is often a presenting symptom of what?

A

Invasive aspergillosis is often presenting symptoms of primary immunodeficiency, such as:

  • Congenital neutropenis
  • Chronic granulomatous disease
    • Phagocytic disorder
  • Hyper IgE syndrome
    • Phagocytic disorder and impaired IL-17 pathway
  • CARD-9 deficiency
    • Innate immune pathways
27
Q

Describe the diagnosis of pulmonary aspergillosis?

A
  • In non-neutropenic patients
    • Cultures of sputum and/or bronchoalveolar lavage and/or biopsy
    • Aspergillus specific IgG and IgE in chronic and allergic pulmonary aspergillosis
  • In neutropenic patients
    • High resolution CT chest
    • Molecular markers in blood
      • Galactomannan and PCR-aspergillus
    • BAL and biopsies if clinical conditions allow
28
Q

What is cryptococcosis caused by?

A

Cryptococcus spp

29
Q

How is cryptococcosis transmitted?

A

Transmission by inhalation:

  • Found on the bark of trees, bird faeces and organic matter
30
Q

What does cryptococcosis cause?

A

Causes pulmonary infection from asymptomatic to pneumonia:

  • Dissemination to brain causing meningoencephalitis in HIV/AIDs patients
    • Clinical presentation
      • Headache
      • Confusion
      • Altered behaviour
      • Visual disturbances
      • Coma (due to increased ICP
31
Q

What is the clinical presentation of meningoencephalitis due to cryptococcosis?

A
  • Headache
  • Confusion
  • Altered behaviour
  • Visual disturbances
  • Coma (due to increased ICP
32
Q

Describe the diagnosis of cryptococcosis?

A
  • CSF fluid
    • Culture, high protein, low glucose, Cryptococcus antigen
  • Blood
    • Culture, Cryptococcus antigen
33
Q

What are factors associated with mortality with cryptococcosis?

A
  • Delay in presentation and diagnosis
  • Lack of access to antifungals
  • Delays to starting therapy
34
Q

What is used to treat invasive fungal infections?

A

Antifungal agents

35
Q

What are different classes of antifungal agents?

A
  • Amphotericin B formulation (IV)
    • Acting on ergosterol causing lysis
    • Broadest antifungal activity
  • Azoles (IV, oral)
    • Inhibiting ergosterol synthesis
  • Echinocandins (IV)
    • Inhibits glucan synthesis
  • Flucytosine (IV, oral)
    • Inhibiting fungal DNA synthesis
36
Q

What is the mechanism of action of amphotercin B formulation?

A
  • Acting on ergosterol causing lysis
  • Broadest antifungal activity
37
Q

What is the mechanism of action of azoles?

A
  • Inhibiting ergosterol synthesis
38
Q

What is the mechanism of action of echinocandins?

A
  • Inhibits glucan synthesis
39
Q

What is the mechanism of action of flucytosine?

A
  • Inhibiting fungal DNA synthesis
40
Q

What is the treatment for invasive candidiasis?

A
  • Echinocandins and fluconazole
41
Q

What is the treatment for invasive aspergillosis?

A
  • Voricanazole and isavucanazole
42
Q

What is the treatment for cryptococal meningitis?

A
  • AmB and flucytosine followed by fluconazole maintainence
43
Q

What drugs are given for antifungal prophylaxis?

A
  • Itraconazole and posazonazole
44
Q

Why are emerging new species of fungus creating a problem?

A

Emerging new species are creating an antifungal resistance problem

Infection (16 decks)

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