Fungal infection Flashcards
What are the 3 types of disease caused by fungi?
- Allergies
- Mycotoxicoses
- Mycoses
Inhalation of/contact with fungal spores may induce a wide range of allergic diseases. Name some of these diseases
- Rhinitis
- Dermatitis
- Asthma
- Allergic broncho-pulmonary aspergillosis (ABPA) caused by Aspergillus fumigatus
What are mycotoxins? What is mycotoxicosis?
MYCOTOXINS = secondary metabolites of moulds that exert toxic effects on animals and humans
MYCOTOXICOSIS = a toxic reaction caused by ingestion or inhalation of a mycotoxin
What are the symptoms of mycotoxicosis?
- Breathing problems
- Dizziness
- Severe vomiting
- Diarrhoea
- Dehydration
Aflatoxin is amongst the most carcinogenic natural compound known. What produces aflatoxin?
Aspergillus flavus
What is mycoses?
Disease caused by fungi that is classified based on the level of tissue affected
What are the four types of mycosis?
- Superficial
- Cutaneous
- Subcutaneous
- Systemic (deep)
What are superficial mycoses?
Fungal infections of the skin or hair shaft
TRUE OR FALSE:
Superficial mycoses invades living tissue
FALSE
No living tissue is invaded and there is no cellular response from the host
Give 3 examples of superficial mycoses
- Black piedra
- White piedra
- Dandruff
- Tinea nigra
What are cutaneous mycoses?
Dermatophytes, or keratinophilic fungi.
Produce extracellular enzymes (keratinases) which are capable of hydrolysing keratin.
Inflammation is caused by host response to metabolic by-products
Give 3 examples of dermatomycoses
- Epidermophyton
- Trychophyton
- Microsporum
- Candida albicans
-
Tinea (aka “ringworm”)
- Tinea capitis (head/neck)
- Tinea pedis (athletes foot)
- Tinea corporis (body)
How are cutaneous mycoses treated?
Antifungal creams or orally
What are subcutaneous mycoses?
Chronic, localised infections of the skin and subcutaneous tissue following traumatic implantation of the aetiologic agent
Give 3 examples of subcutaneous mycoses
- Sporotrichosis (Sporothrix)
- Chromoblastomycosis
- Mycetoma
What is the difference between primary and opportunistic deep/systemic mycoses?
PRIMARY = able to establish infection in a normaly healthy host
OPPORTUNISTIC = require a compromised host in order to establish infection
Give 3 examples of primary systemic mycoses
- Coccioides immitis
- Histoplasma capsulatum
- Blastomyces dermatidis
- Paracoccidioides brasiliensis
Give 3 examples of opportunistic systemic mycoses
- Cryptococcus neoformans
- Candida
- Aspergillus
- Penicillium marneffei
What are the three types of candida infection that can occur in the immunocompromised?
Superficial
Mucosal
Systemic
TRUE OR FALSE:
Healthy people are all colonised by candida
TRUE
In the gastrointestinal and genito-urinary tract
TRUE OR FALSE:
Systemic candida are found in normal healthy individuals
FALSE
What are the risk factors for systemic candida infections?
- Chemotherapy
- Gut-related surgery
- Catheters
What type of patients are susceptible to invasive pulmonary aspergillosis (IPA)?
- Neutropenic/transplant
- HIV/AIDS
- Diabetic
- Congenital susceptibility
- Influenza
- Leukaemia
What are the three types of mucosal candida infections that occurs in people with HIV?
- Oropharyngeal
- Esophagal
- Vulvovaginal
How are fungal infections diagnosed?
- Sample aquisition
- Skin
- Sputum
- Bronchoalveolar lavage
- Blood
- Vaginal swab/smear
- Spinal fluid
- Tissue biopsy
- Microscopy
- Culture
What are the 4 targets of front-line clinical antifungal drugs?
- Membrane function
- Nucleic acid synthesis
- Cell wall synthesis
- Membrane ergosterol biosynthesis
How do antifungals that target the cell membrane work?
- Fungal cell membranes contain ergosterol instead of cholesterol
- Some antifungals inhibits ergosterol synthesis
How do antifungals that target DNA synthesis work?
Pyrimidine analogues are used to interfere with DNA synthesis
How do antifungals that target the cell wall work?
They inhibit the assembly of fungal cell wall components such as glucans and chitin (which are not found in mammalian cell walls)
Name 4 major antifungal classes
- Azoles
- Pyrimidine analogue
- Echinocandins
- Polyenes
