introduction to fungi mw% + Flashcards Preview

ME2308 Principles of Disease > introduction to fungi mw% + > Flashcards

Flashcards in introduction to fungi mw% + Deck (14)
Loading flashcards...
1

What is a fungus?

  • A chemo-organotrophic eukaryote that lacks chlorophyll and forms spores. 
  • Its cell wall contains polysaccharides, often chitin or glucan, and it absorbs nutrients. 
  • Its membrane contains ergosterol as the major sterol. 
  • Classification is principally based on morphology.
  • Informally we refer to the major types as moulds, yeasts or mushrooms

2

Yeasts

  • Fungi that favour a unicellular habit

3

The fungal kingdom

  • Fungi from all 3 groups can cause disease in humans
  • Mycytes

4

Dermatophytosis

Moulds with a tendancy to degrade keratin (protein that protects epithelial cells from damage or stress) as a nutrient source.

Causative agents ►:Epidermophyton, Microsporum and Trichophyton spp.

5

Fungi are a significant cause of non-fatal diseases

Athlete’s foot: caused by Epidermophyton, Microsporum and Trichophyton spp.

Thrush: caused by Candida spp.

Pityriasis versicolor: caused by Malassezia spp.

6

Fungal infections 

 

 Acting as opportunistic pathogens of immunocompromised patients such as:

  • Candida species 
  • Aspergillus spp

7

Candida species

  • Infect deep organs of patients with various types of immune dysfunction, e.g. after abdominal surgery, burns, etc

8

Aspergillus spp

Infect deep organs of patients undergoing chemotherapy, stem cell transplantation

9

Describe the host factors that contribute to the pathogenicity of fungal infections?

  • Favourable micro-environments encourage growth of fungi on skin and mucous membranes
  • Broad-spectrum antibacterial agents reduce competition for epithelial colonization sites in the gut
  • Immunosuppression of all types may create a window of opportunity for fungal invasion

 

10

Candida and candidiasis

  • Worldwide distribution.  Candida species commensal to GI tract, some are environmental. Most infections are endogenous.
  • Candida spp. are yeasts

 

11

Candida infection

Superficial: mouth, vagina, penis, skin, nails

Deep-seated:disseminated infections in immunocompromised hosts(abdominal surgery, major burns, etc.)

 

12

Aspergillosis

  • Aspergillus spp. are moulds
  • They are ubiquitous in the environment: infection occurs by inhalation of conidia
  • These fungi are strongly angioinvasive (penetrate the walls of blood vessels)

13

Cryptococcosis

14

  Describe the diagnostic methods for detecting fungi?►

  • Direct detection such as histopatholgy  (tissue examination) and high resolution CT-scan.
  • Direct smear
  • Detection of circulating fungal antigens
  • Detection of circulating antibodies to  fungi
  • PCR for fungal DNA
  • Culture of fungus from normally sterile site