Fungal pathogens Flashcards
1
Q
Fungi
A
- Eukaryotic
- Equal in rank to plants and animals
- Fewer antifungals because the essential functions targeted by them are the same as in host cells
- Specificity to kill a fungus is difficult
- Produce secreted hydrolytic enzymes which they secrete into the environment that breaks down complex organic materials into simple molecules which they can then take up
2
Q
Types of fungi
A
- Filamentous fungi Mould Eg. Aspergillus sp. - Yeasts Unicellular Eg. Saccharomyces cerevisiae - A subgroup of yeasts are dimorphic/ polymorphic Eg. Candida albicans
3
Q
Human disease
A
- Superficial mycoses
- Subcutaneous mycoses
- Systemic mycoses
4
Q
Superficial mycoses
A
- Dermatophytes Eg. tinea pedis
- Candida sp. Eg. thrush
- Malassezia sp. Eg. dandruff
5
Q
Subcutaneous mycoses
A
- Rare infections
- Black moulds
- Madurella mycetomatis
6
Q
Invasive mycoses
A
- Primary pathogens
- Oppurtunistic pathogens
7
Q
Superficial mycoses
Dermaptophytes
A
- Superficial infection of the skin, hair and nails
Eg. tinea pedis + tinea corporis
Caused by 3 genera, all filamentous fungi:
- Microsporum sp.
- Epidermophyton sp.
- Trichophyton sp.
- It is from soil, animals and people
- It produces keratinase, digests keratin as a growth substrate. Infects keratin rich tissues
Non mycophogical classification, divided into 3 groups on habitat: - Anthrophilic Host is man Eg. Trichophyton rubrum - Zoophilic In animals They give the most severe inflammatory response Eg. Microsporum canis - Geophilic Found in soil
8
Q
Superficial mycoses
Candida albicans
A
- Commensal organism
- Present in the mouth, GI tract and in women in genital tract
9
Q
Superficial mycoses
Candida infections
A
Sites:
- Mouth
- Vagina
- Skin
Predisposing factors:
- Antibitotics, pregnancy
- Occurance
75% have 1+ vaginal infection - Causes thrush
10
Q
Candidiasis
A
- A fungal infection due to any type of Candida
- When it affects the mouth it is commonly called thrush
- When it affects the vagina, it is called a yeast infection
11
Q
Subcutaneous mycoses
A
- Geographically limited
- Wide range of causative species
- Affects subcutaneous tissue
Introduced by puncture wounds - Disease develops slowly
- Challenge to treat
Limited facilities (locally)
Poor response to treatment (chronic)
Eg.
- Chromoblastomycosis
12
Q
Invasive mycoses
A
Primary pathogens: - Histoplasma capsulatum - Blastomyces dermatidis - Parracoccoidiodes brasiliensis Infect healthy individuals Route of infection; inhalation of spores
Oppurtunistic pathogens:
- Candida sp.
- Aspergillus sp.
- Cryptococcus sp.
- 90% of all reported fungal- related deaths are from:
Cryptococcus, Candida, Aspergillus + Pneunmocystis
13
Q
Invasive mycoses
Primary fungal pathogens
A
- All thermally dimorphic
Saphrophytic filamentous form at 25
Parisitic yeast form at 37 - Types of disease
Asymptomatic
Mild respiratory infection
Can progress to serious pulmonary infection
14
Q
Oppurtunistic pathogen
Candida auris
A
- An emerging pathogen
Key concerns:
- multidrug resistance (azoles, polyenes + echinocandins)
- misdiagnosis
- hospital outbreaks
15
Q
Oppurtunistic pathogen
Aspergillosis
A
Causative organisms:
- Most Aspergillosis species do not cause disease
- Causative organisms limited to, A. fumigatus + A. flavus
Route of infection:
- Inhalation of spores
Type of disease:
- Allergy
- Toxins
- Invasive bronchopulmonary Aspergillosis
- Disseminated Aspergillosis
