Microbiology - Yeasts And Moulds (w21)

Question 1

What is mycology ?

Answer 1

The study of fungi

Question 2

What are macroscopic fungi ?

Answer 2

Mushrooms and truffles

Question 3

What are chemoheterotrophs ?

Answer 3

Microorganisms that use organic chemical substances as sources of energy

Question 4

What are saprophytes ?

Answer 4

Microorganisms that obtain nutrients from dead organic material

Question 5

Most fungi are _______ aerobes …..

Answer 5

Obligate

Question 6

What classification of cells does fungi (yeasts/moulds) come under ?

Answer 6

Eukaryotic cells

Question 7

Are yeasts monocellular or pluricellular ?

Answer 7

Monocellular

Question 8

Are moulds pluricellular or monocellular ?

Answer 8

Pluricellular

Question 9

What are the differences between fungal and mammalian cells ?

Answer 9

• 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)

Question 10

What is the cell wall in fungi a target for ?

Answer 10

For selective antifungal drugs

Question 11

What are the 2 classes of antifungal drugs ?

Answer 11

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)

Question 12

What are beneficial roles/ activities of fungal microorganisms ?

Answer 12

• 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)

Question 13

What are some harmful effects f fungal microorganisms ?

Answer 13

• Food spoilage
• Contamination of pharmaceutical preparations
• Causing diseases —> MYCOSES

Question 14

What is a superficial fungal infection ?

Answer 14

• one on the outer skin layer or on hair shafts
  caused mostly by yeasts
• examples = Black Piedra, Dandruff

Question 15

What is a cutaneous fungal infection ?

Answer 15

• one that affects keratin-containing tissues (hair, nails, skin)
• examples = ringworm, athletes foot

Question 16

What is a subcutaneous fungal infection ?

Answer 16

• a chronic infection of subdermal tissues may require surgical intervention
• example = sporotrichosis

Question 17

What is a systemic fungal infection ?

Answer 17

• an infection deep within body, affects many tissues and organs
• example = blastomycosis

Question 18

What is an opportunistic fungal infection ?

Answer 18

• one that is caused by normal microbiota or fungi that are not usually pathogenic (immune compromised patients)
• examples = candidiasis, aspergillosis

Question 19

What are the risk factors for patients in relation to developing mycosis ?

Answer 19

• impaired immune system
• surgery and long-term use of corticosteroids
• indwelling catheters
• chemotherapy for malignant cancers
• solid organ transplant

Question 20

What are yeasts ?

Answer 20

Unicellular and non-filamentous organisms with oval/spherical shape

Question 21

What is the most common cause of fungal opportunistic infections ?

Answer 21

immunocompromised patients or when the microbiota is altered (overgrowth)

Question 22

What is candidiasis ?

Answer 22

Any infections caused by any species of candida

Question 23

What are the three main types of candidiasis (thrush) ?

Answer 23

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

Question 24

What are moulds ?

Answer 24

Multicellular organisms consisting of threadlike tubular structures called hyphae

Question 25

What is a mycelium ?

Answer 25

A structure made up of hyphae that have formed together producing a mat-like structure with a fuzzy appearance.

Question 26

What are the two different areas of a mould colony ?

Answer 26

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)

Question 27

What are the genus: aspergillus ?

Answer 27

Genus Aspergillus are ubiquitous moulds found in soil, on plants
2 species that can cause aspergillosis (A. fumigatus and A. flavus)