Medical Mycology

Question 1

what are negative effects of fungus?

Answer 1

• crops economogy
• asthma irritation of fungal spores
• infect many tissues

Question 2

what are mycoses?

Answer 2

infection caused by fungus

Question 3

what are mycotoxins?

Answer 3

apart from invasive mycoses, fungi release toxins in food and airborne

Question 4

jobs that disrupt environment…

Answer 4

increase chances of fungal infection

Question 5

the burden of fungal disease compared to malaria?

Answer 5

much less

Question 6

what is transient exposure?

Answer 6

fungal colonization on skin (occurs without host knowledge)

Question 7

most fungi have…

Answer 7

low virulence

Question 8

why is it difficult to diagnose fungal infection?

Answer 8

similar symptoms to bacteria and viruses = misdiagnosis

Question 9

what are the ways of classifications of mycoses?

Answer 9

1. site of infection
2. route of acquision (exogenous:environement/endogenous: commensal)
3. type of virulence

Question 10

what are potential sites of infection for mycoses?

Answer 10

1. superficial (skin surface)
2. cutaneous (epidermis layer)
3. subcutaneous (wound in dermal layer)
4. systemic (bloodstream)

all besides systemic can clear on its own

Question 11

what are Types of fungal virulence

Answer 11

1. primary mycoses (uncommon, healthy)
2. opportunistic mycoses (immunocompromised, common)

Question 12

superficial and cutaneous mycoses are caused by

Answer 12

dermatophytes

Question 13

dermatophytes infections are caused by – in the genera

Answer 13

molds

trichophyton, microsporum, and epidermophyton

Question 14

dermatophytes infections are usually—

Answer 14

self-liming with no ceppular immune response bc superficial and not much redness

Question 15

what is the dermatophytes fungi treatment?

Answer 15

topical antifungal drug or in sever cases, oral drugs

Question 16

examples of dermatophytes infections?

Answer 16

athletes foot and ringworm

Question 17

what are common types of opportunistic fungal pathogens?

Answer 17

• Candida budding yeasts with haephal projections
• Aspergillus mold spores

Question 18

risk factors for fungal infection?

Answer 18

1. HIV/AIDS infection
2. solid organ transplants (suppress immunity meds)
3. cancer chemo
4. granulocytopenia: deficient in neutrophils
5. premature birth
6. old age (defective immunity)
7. corticosteroid use (suppress immunity)
8. broad spec antibiotics (kills good and bad bacteria)
9. certral vascular catheters
10. gasterointerestinal surgery (contaminated tools)
11. colonization with fungus (recurrent)

CCCGGPOOHA

Question 19

Where can Candidiasis species be found?

Answer 19

innocuous carrying on skin/epithelial surfaces

Question 20

What is the most infectious Candidasis species?

Answer 20

Candidiasis albicans

Question 21

Types of Superficial candidiasis infections? characteristics of each?

Answer 21

oropharyngeal candidiasis
- oral, breastfed infants, ORAL thresh

denture stomatitis
- ulcers in mouth - elderly detures

vulvovaginal candidiasis
- antibiotic use

chronic mucocutaneous cadidiasis
- recurrent

Question 22

virulence factors of candida?

Answer 22

1. adhesins (attach to epithelial cells)
2. dimorphism
3. phenotypic switching (discrete change colour and protein)
4. extracellular hydrolases (proteins that host cells have to prevent attack)

Question 23

how does candidiasis become invasive?

Answer 23

1. budding yeast form
2. adhere to epithelial cells and dimorphism
3. hyphael projections invade epidermis
4. enter blood stream

Question 24

Candida diagnosis?

Answer 24

1. culture medium inoculum (swab skin and blood)
2. detect anti-candida antibodies and antigens in blood
3. DNA fingerprinting, micoarrays, PCR to see if endemic region

Question 25

what type of fungus is Aspergillus? where is it found

Answer 25

filamentus, saprophytic fungus always present in environment found in decaying vegetation and soil

Question 26

common infectious ASPERGILLOSIS in humans?

Answer 26

Aspergillus fumigatus

Question 27

CONIDIA OF ASPERGILLUS? immune response?

Answer 27

A. fumigatus conidia (spores) in air and inhaled and penetrate lower Respiratory tract - Immunocompetent individuals: conidia are detected and destroyed by alveolar macrophages - Immunocompromised individuals: spores settle, germinate, and invade, (invasive aspergillosis)

Question 28

virulence factors of aspergillus?

Answer 28

1. thermal tolerance (cold and fever) 2. proteinase production (degrades extracellular matrix) 3. gliotoxin production: causes apoptosis due to toxins 4. environmental stress resistant (pH, salt, temp)

Question 29

steps for aspergillosis invasion in blood stream?

Answer 29

1. spores inhaled to lungs 2. spore on surface of cell 3. hyphael projections allow entry past alveolar cells from dimorphism 4. dissemenation in blood

Question 30

asperogilliosis symptoms?

Answer 30

1. high mortality rate ( >50%) 2. recurrent, hard to get rid of 3. nonspecific fever, chest discomfort, cough with blood

Question 31

asperogilliosis diagnosis?

Answer 31

- histopathological analysis - culure of biopsy bronchoalveolar lavage fluid taken from the infected area of the lung post mortem cloudy lung xray

Question 32

what are **endemic systemic mycoses**?

Answer 32

targets immunocompetent primary pathogens covers a lot of the globe have dimorphic switch (yeast or filamentous)

Question 33

why are antifungal agents difficult to make?

Answer 33

fungus similar to humans

Question 34

3 types of antifungal agent targets?

Answer 34

1. plasma membrane 2. cell wall 3. nucleic acid/protein synthesis

Question 35

How is Plasma Membrane targeted by antifungal agents?

Answer 35

1. **polyenes**: binds to ergosterol and removes from plasma membrane 2. **azoles**: targets ergosterol producing enzyme

Question 36

How is Cell Wall targeted by antifungal agents?

Answer 36

1. **echinocandins**: targets B-glucans - chitin binders 2. **nikkomycin**: targets chitin production

Question 37

How is Nucleic Acid and Protein Synthesis targeted by antifungal agents?

Answer 37

1. **5-flurocytosine**: uptake and cell turns it to 5'UTP used in RNA/DNA synthesis and disrupts 2. sordarin: protein synthesis by targeting tRNA

Question 38

what is combination therapy for antifungal agents?

Answer 38

combination of fungicidal and static (slow growth) drugs (helps for resistance)

Question 39

what are the challenges of getting rid of fungal infection?

Answer 39

1. early diagnosis 2. limited antifungal drugs 3. cytotoxicity (harmful off target effects to host) 4. antifungal resistance 5. emerging pathogens