Fungal Infection Flashcards
What are characteristics of fungi?
- Fungi has sevral chromosomes and massive complex genome
- Anythings that works on yeast is likely to have similair effect on us becuae metabolism similair
What are the 2 phyla?
- Basidiomycota
- Cryptococcus neoformans
- Cryptococcus gattii
- Ascomycota
- 90% of infection
- Aspergillus fumigatus
- Candida albicnas (bloodstream infection)
How do basidiocytes cause infection?
Can be inhaled into lungs and alvelolar macorphages usualyl good at mopping up but may get into brain (sugar rich environment) and cause mengintis
How do fungi digest food?
extracellularly by secreting hydrolytic enzymes which can break down biopolymers to be absorbed for nutrition.
How are spores dispersed?
- Produce large numebr of spores
- Dispersed over large distances
- Humans constantly exposed to spores
3 types of diseases that fungus causes?
Allergy – allergic reactions to fungal products e.g. allergic bronchopulmonary aspergillosis (ABPA).
Mycotoxicoses – ingestion of fungi and their toxic products e. g. aflatoxin.
Mycoses – superficial, subcutaneous or systemic colonisation, invasion and destruction of human tissue.
How can mycoses be classified?
- by level of tissue affectes as:
- Superifical
- Subcutaenous
What causes fungal allergies?
- Inhalation of spores
- Reaction differs by individual and psecies
What are the consequences?
- Rhinitis
- Dermatitis
- Asthma
- Allergic broncho pulmonary aspergillosis (ABPA)
What is mycotoxicoses?
- toxic reaction due to ingestion/inhalation of toxins produced by fungi
- Secondary metabolite of moulds that exert toxic effect on animals and humans
What are the symptoms?
- Breathing problems
- Dizziness
- Severe vomiting
- Diarrhoe
- Dehydration
- Hepatic and renal failure
What is the treatment?
- Gastric tavage
- Liver transplant
What is aspergillus flavus?
- Aflatoxin produced is most carcinogenic natural compound known
- Contaminates grain
- If get poisoned have liver damage from Hep B and high risk for cancer
- High rates of liver cancer possibly due to larger exposure
Define mycoses:
- Disease caused by fungus classigied by level of tissue affected
What are the classifications and examples?
- Superficial
- Skin/hair
- No living tissue invaded
- No cellular host repsonse
Malessezia globosa: produces oleic acid causing inflammation of stratum corneum and dnandruff
- Cutaneous
- Produces kertaniases capable of hydorlyising
keratin - Inflammation cuased by host repsonse to metabolic
by products
- Produces kertaniases capable of hydorlyising
Dermatophytes or keratinophilic fungi
E.g tinea (ringworm)
- Subcutaenous
- Chronic localised infections of skin and subcutaenous tissue following traumatic implantation fo aetilogic agent
E.g sporotrichosis, chromoblastomycosis, mycetoma
- Deep/systemic
What type of pathogen is candida albicans?
Opportunitstic commensal
Where does candida normal lie?
- GIT
- Genito-urinary tract
- Skin
What causes systemic fungal infections?
- Usually due to impaured epithelial barrier function
- Most common in elderl and young
- not in healthy people
Where is systemic candida found?
- Superificial
- Mucosal
- systemic
What are the risk factors?
- Chemotherapy
- Catheters
- Gut related issues
Why are they difficult to diagnose?
Few signs and symptoms specific to fungal infections
How do you diagnose a fungal infection?
- Sample acquisistion
- Skin
- Sputum
- Blood
- Spinal fluid
- biopsy
- etc - Microscopy
- infection needs to be well established to see under mucorpscope - Culture
- Difficult because takes long time and suceptible to contamination
- once identified needs to be cultured to allow sucseptibiltiy testing
What are some non culturing methods?
Anitbody and antigen based assays to detect fungal polysaccharides
What are some antifungal treatments?
- Membrane function
- Polyenes
- Nucleic acid synthesis
- 5-flucytosine
- Cell wall synthesis
- Echinocandins
- Membrane ergosterol biosynthesis
- Azoles
- Terbinafine
- fenpropimorph
