Fungi

Question 1

What are characteristics of fungi ?

Answer 1

• Eukaryotes
• Heterotrophs
• cell wall made of chitin
• multinucleated cells
• lacking chloroplasts and chlorophyll
• devoid of leaves, stems or roots

Question 2

What are some characteristics of yeasts ?

Answer 2

single celled fundal forms

Question 3

What are some characteristics of molds ?

Answer 3

multiple cells forming a filamentous mycelium

Question 4

What are some characteristics of spores ?

Answer 4

• fungi reproduce by spores (sexually or asexually)
  -morphology, arrangement, and mode of derivation of spores serve as criteria for genus and species identification

Question 5

What are the habitats of fungi ?

Answer 5

• found in nearly every habitat on Earth where organic materials exist

Question 6

What are the 4 ways fungi can harm humans ?

Answer 6

1. allergic reaction
2. reaction to toxin
3. fungi that destroy the human food supply
4. colonization of the human body by fungi (mycoses)

Question 7

What are some examples of allergic reactions caused by fungi ?

Answer 7

mold allergy causes your immune system to overreact when you breathe in the spores
- exposure causes person to become sensitized
- can cause coughing, itchy eyes, etc
- can be linked to asthma and cause restricted breathing and other airway symptoms

Question 8

How does a reaction to a toxin cause harm to humans ?

Answer 8

• hallucinogenic properties of some mushrooms
• poisonous effects of ergot fungus (rye smut)
• carcinogenic toxins of Aspergillus (aflatoxins)

Question 9

What is an example of a reaction to a toxin caused by fungi ?

Answer 9

ergot fungi causes Ergotism
- causes severe vasoconstriction leading to gangrene due to loss of blood circulation
- ergot alkaloids may cause hallucinations and attendant irrational behavior, convulsions, and even death
- Ergometrine (from Ergot) is also used to induce uterine contractions and to control bleeding after childbirth

Question 10

What is an example of a way that fungi destroy the human food supply ?

Answer 10

• Wheat Rust: Puccinia graminis
• Potato Blight: phytophthora infestans

Question 11

What are the 3 ways the fungi colonize the human body through mycoses ?

Answer 11

1. superficial
2. intermediate
3. systemic

Question 12

What are some infections caused by superficial mycoses ?

Answer 12

• candidiasis (thrush, vaginal (yeast infection) )
• dermatophytes (athletes food, jock itch, nails)
• sporotrichosis (gardener’s hazard)
• blastomycosis (skin)

Question 13

What is athlete’s foot (tinea pedis) ?

Answer 13

common skin infection of the webs of the toes and soles of the feet
- may spread to the palms, groin
- S&S: itching, scaling, and redness
- in severe cases it can cause skin blistering

Question 14

What is candidiasis ?

Answer 14

develops in the mouth or throat (thrush), or oropharyngeal candidiasis. or in the vagina (yeast infection)

Question 15

What are some infections caused by intermediate mycoses ?

Answer 15

• Aspergillus (lungs, gut-ingested spores, fungal ball)
• Candidiasis (children and immunocompromised)
• Cryptococcus (pulmonary, cerebral)
• All dimorphic (any organ)
• Mucormycosis: rhino cerebral (nasal passages and brain), pulmonary, GI, fungal ball

Question 16

What is Aspergillosis ?

Answer 16

wide array of diseases caused by infection by fungi of the genus Aspergillus
- majority of cases happen in pt’s with underlying illnesses like TB, COPD
- pt’s that are immunocompromised are at higher risk for disseminated disease

Question 17

What is a fungus ball ?

Answer 17

another name for Aspergillosis

Question 18

What are the S&S of a fungal ball ?

Answer 18

may cause no symptoms
- may be discovered only with a chest X-ray
- or can cough up blood, chest pain, occasionally severe even fatal bleeding

Question 19

What happens is Aspergillosis isn’t treated ?

Answer 19

can disseminate through the blood stream to cause widespread organ damage

Question 20

What are some infections caused by systemic mycoses ?

Answer 20

• Mucormycosis (necrotizing, rapid, fulminating)
• Aspergillosis
• Candidiasis
• Cryptococcus
• All dimorphics

Question 21

What are dimorphic ?

Answer 21

mycotic organisms that possess different morphological forms under different temp conditions
- histoplasmosis
- blastomycosis
- coccidiomycosis

Question 22

What is Mucormycosis ?

Answer 22

serious but rare fungal infection caused by a group of molds called mucoromycetes
- affects people that are immunocompromised
- these molds live throughout the environment
- affects the sinuses or lungs after inhalation of spores from air or skin

Question 23

What is Cryptococcus Neoformans ?

Answer 23

fungus that lives in the environment throughout the world
- infection occurs after breathing in microscopic fungus
- extremely rare in otherwise healthy adults
- most cases occur in immunocompromised pt’s (especially advanced AIDS/HIV)

Question 24

What are some positive effects of fungi ?

Answer 24

for genetic and biochemical studies
- yeasts (produce human insulin, growth hormone, somatostatin, vaccine against viral hepatitis)
- fungi as food (mushrooms and yeast in breads and alcohol)
- in symbiosis (lichens)

Question 25

What are 3 ways to identity fungal infections ?

Answer 25

• direct observation
• culture
• preliminary isolate observations