Parasitology/Mycology

Question 1

Fungal membranes contain ____________ rather than cholesterol.

Answer 1

Ergosterol

Question 2

Fungal cells are surrounded by a rigid ___________ composed of carbohydrate polymers and ___________.

Answer 2

Cell wall; protein

*chitin, α-glucan, β-glucan, α-mannan

Question 3

Most fungi are ___________, require only an organic carbon source, nitrogen source and are _____________.

Answer 3

Free-living

Nonmotile

Question 4

Yeast reproduce by ___________ or __________.

Answer 4

Budding

Fission

Question 5

Some yeast elongate and adhere to one another forming _______________.

Answer 5

Pseudohyphae

Question 6

Hypahe/mycelium are also referred to as _______.

Answer 6

Mold

Question 7

What are 3 types of hyphae?

Answer 7

Nonseptate
Septate uninucleate
Septate multinucleate

Question 8

Blastoconidia, chlamydoconidia, arthroconidia are three types of __________________.

Answer 8

asexual reproductive elements

Question 9

What are two types of conidiospores?

Answer 9

Macroconidia - large, multicelled

Microconidia - small, unicellular

Question 10

Sporangiospores are ___________ spores formed within sacs (sporangia)

Answer 10

Single celled, asexual

Question 11

Fungal infections can cause superficial, ____________, _____________, _____________ and opportunistic infections.

Answer 11

1. cutaneous
2. subcutaneous
3. systemic

Question 12

Hypersensitivity to airborne conidia/spores can lead to ___________________.

Answer 12

Strong allergic reactions

Question 13

Fungal infections can cause superficial, ____________, _____________, _____________ and opportunistic infections.

Answer 13

1. cutaneous
2. subcutaneous
3. systemic

Question 14

Hypersensitivity to airborne conidia/spores can lead to ___________________.

Answer 14

Strong allergic reactions

Question 15

What is a mycotoxin?

Answer 15

Poisonous secondary metabolite produced by fungi.

Question 16

What 4 systems to anti-fungal drugs target?

Answer 16

1. Ergosterol
2. Cell wall synthesis
3. Nucleic acid synthesis
4. Disruption of microtubules

Question 17

What are a few broad classes of anti-fungals?

Answer 17

1. Azoles - imidazole
2. Polyenes - amphotericin
3. Echinocandins
4. Antimetabolites

Question 18

What are possible drawbacks to combination therapy for fungal infections?

Answer 18

1. Action of one reduces the concentration of the target for the second
2. Action of one modifies the target of the second
3. Action of one blocks the accessibility of the second

Question 19

Resistance to antifungal drugs can occur thru which 3 mechanisms?

Answer 19

1. Efflux pumps
2. Target alterations
3. Reduced access to drug targets

Question 20

What are 4 mechanisms of resistance to azoles?

Answer 20

1. Increased expression of efflux pumps
2. Decreased affinity of target
3. Increased expression of target
4. Alternative metabolic pathways leading to the synthesis of ergosterol
5. Use of azoles in agriculture?

Question 21

Are fungi displaying the eagle effect?

Answer 21

Yes

Question 22

What are 4 mechanisms of resistance to azoles?

Answer 22

1. Increased expression of efflux pumps
2. Decreased affinity of target
3. Increased expression of target
4. Alternative metabolic pathways leading to the synthesis of ergosterol
5. Use of azoles in agriculture?

Question 23

Innate immunity is the __________ source to overcome a fungal infection.

Answer 23

Primary. Phagocytes, complement system and PRRs

Question 24

A persistant fungal infection causes T cells to differentiate to ______ CD4+ cells. These T cells activate _____________ which ultimately control the infection.

Answer 24

1. Th1

2. Macrophages

Question 25

What kind of organisms are parasites?

Answer 25

eukaryotic pathogens

Question 26

Endoparasites are divided into _____, unicellular, and ______, multicellular.

Answer 26

protozoan | helminths

Question 27

A ____ host is the host in which the sexual stage of a parasite life cycle (when mating occurs) whereas a _____ host is the host in which asexual reproduction/development occurs.

Answer 27

- definitive | - intermediate

Question 28

For Schistomosoma, ____ are the definitive host and ___ are the intermediate host.

Answer 28

- humans | - snails

Question 29

For malaria, ____ are the definitive host and ____ are the intermediate host.

Answer 29

- mosquitos | - humans

Question 30

The _____ host is not an obligate part of the parasite life cycle. Give an example and explain why most people get really sick if they are this type of host.

Answer 30

incidental/accidental - ex: toxoplasma - get sick because parasite not adapted to living in humans, so immune system is active

Question 31

A ____ transmits an infectious form of the parasite to another host species. Give two examples:

Answer 31

- vector 1. snail = schistomosoma 2. mosquito = malaria

Question 32

When do physicians need to think about possible parasites?

Answer 32

1. when patients going to travel abroad 2. returning from overseas 3. patients in endemic areas (rural south) 4. immunocompromised patients (AIDS, steroids, transplant, pregnancy, obesity)

Question 33

Which parasites belong in the protista kingdom? Animalia?

Answer 33

- protists | - helminths

Question 34

Give the common names for these helminths and which type they are: (a) cestoda (b) trematoda (c) nematoda

Answer 34

(a) tapeworms; platyhelminthes (b) flukes; platyhelminthes (c) roundworms; nemathelminthes

Question 35

Define an egg vs. a larva vs. a cyst vs a hydatid

Answer 35

``` egg = product of sexual reproduction; prelarval larva = immature post-ovum cyst = dormant stage encysted in host hyadatid = specialized larvae form of Echinococcus granulosus ```

Question 36

Tapeworms give off _____ that come off in your stool. They are transmitted via _____. Give an example.

Answer 36

- proglottids - eggs/larval cysticerci ex) taenia saginata/solium, diphyllobothrium latum (fish), echinococcus granulosis

Question 37

Flukes of the lungs/liver/blood have ____ intermediate host. They are transmitted by _____. Give an example

Answer 37

- one or more - invasive/ingestive ex) schistosoma

Question 38

Taenia solium/saginata: Definitive host: ____; sheds _____ Int host: _____ Transmission/pathology (2): ________

Answer 38

Definitive host: HUMANS; sheds EGGS/PROGLOTTIDS Int host: PIGS/HUMANS Transmission/pathology (2): (a) ingestion of proglottids causes vomiting/diarrhea/ weight loss (b) ingestion of eggs causes cysticercosis, which can go to any tissue (lumps in muscle DEADLY in brain) [T. solium is more common]

Question 39

Diphyllobothrium latum Definitive host: ____; sheds _____ Int host: _____ Transmission/pathology: ________

Answer 39

- Definitive host: HUMANS; sheds EGGS - Int host: COPEPOD and FISH - Transmission/pathology: ingestion when swimming in contaminated water/raw fish; causes B12 deficiency, anemia, neuro symptoms

Question 40

Echinococcosis granulosus (Hydatid Disease) Definitive host: ____; sheds _____ Int host: _____ Transmission/pathology: ________

Answer 40

- Definitive host: DOGS; sheds EGGS in feces - Int host: HOOFED ANIMALS/HUMANS - Transmission/pathology: in rural areas/hunters due to ingestion of eggs from dogs' feces having eaten animal organs; causes lung (alveolar), Hydatid disease (pastoral cycle) = when cysts cause pain/rupture/ANAPHYLAXIS * NOTES: latent up to 20 years; can be mistaken for tumor; hydatid cysts are usually in liver

Question 41

What are the major differences between Schistosoma mansoni, S. japonicum and S. haematobium.

Answer 41

Infection: RIVERS SM = colon; Africa, Caribbean, Brazil; lateral spike; in feces SJ = small intestine; SE Asia; no spike; in feces SH = bladder; Africa; terminal spike; in bladder *NOTES: larva invades skin-->Swimmer's Itch; may have rash; may get Katayama syndrome (cytokine storm), diarrhea/liver disease/colon cancer (SJ/SM) or GU problems/blood in urine/bladder cancer (SH)

Question 42

Describe how to tell pinworm, whipworm and Ascarias apart (lumenal nematodes) and how can you tell them apart?

Answer 42

1. Enterobius vermicularis (pinworm) = intestinal; direct person-person egg FO contact; no IM host; NOTES: children, perianal scratching (puritis)/psychological trauma 2. Trichuris trichiuria (whipworm) = only humans; intestine; soil egg FO; rural south; malnutrition, bloody stool 3. Ascaris lumbricoides = intestinal; only human; soil; eggs in stool and egg ingestion; rural south; cough; enters venous circulation then migrates to lungs where coughed up and pooped out eventually; malnutrition, poor mental/physical development; inflammation

Question 43

Describe Hookworms.

Answer 43

Necator americanus; in soil; burrows into skin (NO SHOES!!!; coughed up and goes to intestine; fecal transmission; pruritis between toes, bronchitis, anemia, eggs in stool

Question 44

Describe Strogyloides stercoralis.

Answer 44

larvae penetrates skin; rural south; LARVAE in stool/SPUTUM; have 3 different life cycles and can autoinfect host; greater in immunocompromised patients; cough for autoinfection; rash on buttocks; malabsorption/dysentery;