Microbiology - Yeasts And Moulds (w21) Flashcards
What is mycology ?
The study of fungi
What are macroscopic fungi ?
Mushrooms and truffles
What are chemoheterotrophs ?
Microorganisms that use organic chemical substances as sources of energy
What are saprophytes ?
Microorganisms that obtain nutrients from dead organic material
Most fungi are _______ aerobes …..
Obligate
What classification of cells does fungi (yeasts/moulds) come under ?
Eukaryotic cells
Are yeasts monocellular or pluricellular ?
Monocellular
Are moulds pluricellular or monocellular ?
Pluricellular
What are the differences between fungal and mammalian cells ?
- presence of cells wall
- plasma membrane possesses different sterols (containing ergosterol and not cholesterol)
- presence of vacuoles (large compartments for storage of molecules, proteins, degradation)
What is the cell wall in fungi a target for ?
For selective antifungal drugs
What are the 2 classes of antifungal drugs ?
1) Polyenes (e.g. nystatin, natamycin, and amphotericin B), targets ergosterol and causes pores in the cell membrane
2) Azoles (e.g. fluconazole, itraconazole, voriconazole) and allylamines prevent the synthesis of ergosterol (2 distinct steps)
What are beneficial roles/ activities of fungal microorganisms ?
- Degrading organic materials
- Making alcoholic beverages (wine, beer)
- Food preparation (bread, some cheeses, soy sauce)
- Commercial production of some organic acids (gallic, citric)
- Manufacturing of drugs (ciclosporins) and antibiotics (penicillin)
- Commensal microbes of normal microbiota (just some of them)
What are some harmful effects f fungal microorganisms ?
- Food spoilage
- Contamination of pharmaceutical preparations
- Causing diseases —> MYCOSES
What is a superficial fungal infection ?
- one on the outer skin layer or on hair shafts
caused mostly by yeasts - examples = Black Piedra, Dandruff
What is a cutaneous fungal infection ?
- one that affects keratin-containing tissues (hair, nails, skin)
- examples = ringworm, athletes foot
What is a subcutaneous fungal infection ?
- a chronic infection of subdermal tissues may require surgical intervention
- example = sporotrichosis
What is a systemic fungal infection ?
- an infection deep within body, affects many tissues and organs
- example = blastomycosis
What is an opportunistic fungal infection ?
- one that is caused by normal microbiota or fungi that are not usually pathogenic (immune compromised patients)
- examples = candidiasis, aspergillosis
What are the risk factors for patients in relation to developing mycosis ?
- impaired immune system
- surgery and long-term use of corticosteroids
- indwelling catheters
- chemotherapy for malignant cancers
- solid organ transplant
What are yeasts ?
Unicellular and non-filamentous organisms with oval/spherical shape
What is the most common cause of fungal opportunistic infections ?
immunocompromised patients or when the microbiota is altered (overgrowth)
What is candidiasis ?
Any infections caused by any species of candida
What are the three main types of candidiasis (thrush) ?
1) Oral candidiasis/thrush
Candida accumulates on the lining of your mouth (creamy white deposit on tongue or inner cheeks)
2) Vaginal candidiasis/thrush
Symptomatic inflammation of the vagina
3) Invasive candidiasis/thrush
Serious infection that could affect many tissues and organs. The severity usually depends on the state of the host’s immune system
What are moulds ?
Multicellular organisms consisting of threadlike tubular structures called hyphae
What is a mycelium ?
A structure made up of hyphae that have formed together producing a mat-like structure with a fuzzy appearance.
What are the two different areas of a mould colony ?
1) Vegetative mycelium = elongates to obtain nutrients and anchor the mould on the Agar
2) Aerial mycelium = grow on top and have reproduction function (producing spores)
What are the genus: aspergillus ?
Genus Aspergillus are ubiquitous moulds found in soil, on plants
2 species that can cause aspergillosis (A. fumigatus and A. flavus)
