14-15. Fungal Pathogens Flashcards
what are the two types of fungi
Chromistan - pseudo fungi with cellulosic hyphen walls
Eumycotan - true fungi with chitinous hyphen walls
3 ways in which fungi cause disease
- cause immune response that results in allergic reaction
- produce toxins
- infection
3 types of fungal infection
cutaneous
sub cutaneous
systemic
Two examples of cutaneous mycoses and the causal organisms
Candidiasis - Candida albicans
Athlete’s foot - Trichtophyton
Two examples of sub-cutaneous mycoses and the causal organisms
Sporotrichosis - Sporothrix schenckii
Chromoblastomycosis - several
Two examples of systemic mycoses and the causal organisms
Cryptococcosis - Cryptococcus neoformans
Histoplasmosis- Histoplasma capsulatum
Why is the disease process of ringworm unique? 2
- No living tissue invaded, stratum corner is colonised
2. The dermatophytes - only fungi that have evolved a dependency on human or animal infection for survival
Which oral anti fungal can be used for treatment of skin infections?
Flucanazole
What does flucanazole do?
Inhibits cytochrome P450 14a-demethylase - enzyme in the sterol biosynthesis pathway
What can Candida albicans do in addition to its usual oval budding form and what does this do?
produce pseudohyphae which help the yeast to invade deeper tissues
What is used to treat cutaneous candida infections?
topical imidazole
What is used to treat oral candida infections?
nystatin
amphotericin B
miconazole
What are the causative organisms of chromoblastomycosis?
Fonsecaea, Phialophora spp
Drugs used to treat chromoblastomycosis
Fluorocytosine
Azoles - thiabendazole and itraconazole
Drugs used to treat sporotrichosis
Saturated potassium iodide
Itraconazole
How does terbinafine work?
Inhibits action of squalene epoxidase which is part of the fungi sterol synthesis pathway
What can cryptococcus neoformans cause?
cryptococcal meningoencephalitis
What can Pneumocystis carinii cause in the immunocompromised?
a lethal pneumonia (PCP)
3 common diseases caused by Aspergillus species
allergic bronchopulmonary aspergillosis
pulmonary aspergilloma
invasive aspergillosis
