Fungi & Antifungals

Question 1

Fungi live in colonies called _

Answer 1

Fungi live in colonies called mycelia

Question 2

Fungi are connected to each other via _ which are like the arms of the fungus

Answer 2

Fungi are connected to each other via hyphae which are like the arms of the fungus
* Secrete enzymes that help to absorb nutrients from the environment
* Play a role in reproduction

Question 3

Fungi most commonly reproduce (asexually/ sexually) via mitosis to form _

Answer 3

Fungi most commonly reproduce asexually via mitosis to form spores
* The spores are specialized haploid cells that are optimized for transportation

Question 4

Fungal spores can also be called _ ; if the hyphae (arms of the fungi) break apart into propagating spores, they are called _

Answer 4

Fungal spores can also be called conidia ; if the hyphae (arms of the fungi) break apart into propagating spores, they are called arthroconidia

Question 5

We can also have budding off the mature hyphae which is called _

Answer 5

We can also have budding off the mature hyphae which is called blastoconidia

Question 6

Multicellular spores are called _ and unicellular spores are called _

Answer 6

Multicellular spores are called macroconidia and unicellular spores are called microconidia

Question 7

Conidia that are enclosed in a sac (sporangium) are called _

Answer 7

Conidia that are enclosed in a sac (sporangium) are called endospores

Question 8

Spores congregate to form a mass called _

Answer 8

Spores congregate to form a mass called mycelium

Question 9

Mycelium either form spores and then undergo germination through asexual reproduction, or they can undergo plasmogamy in which nuclei fuse to form a (haploid/ diploid) zygote –> meiosis can then occur

Answer 9

Mycelium either form spores and then undergo germination through asexual reproduction, or they can undergo plasmogamy in which nuclei fuse to form a diploid zygote –> meiosis can then occur (sexual reproduction)

Question 10

Some fungi are dimorphic, which means _

Answer 10

Some fungi are dimorphic, which means they can exist as unicellular yeast or multicellular molds
* They exist as “mold in the cold” and “yeast in the heat”

Question 11

In the human body (37 degrees celcius), dimorphic fungi will exist as (mold/ yeast)

Answer 11

In the human body (37 degrees celcius), dimorphic fungi will exist as yeast
* The exception is C albicans

Question 12

Antifungals that are fungistatic target _ while fungicidal drugs target _

Answer 12

Antifungals that are fungistatic target synthesis of enzymes while fungicidal drugs target cell wall

Question 13

One of the most important polysaccharides in the thick cell wall of fungi is _

Answer 13

One of the most important polysaccharides in the thick cell wall of fungi is Beta-glucans

Question 14

The enzyme _ is involved in the production of the beta-glucans and _ is a group of antifungal medications that target this enzyme

Answer 14

The enzyme Beta-1-3- glucan synthase is involved in the production of the beta-glucans and echinocandins is a group of antifungal medications that target this enzyme

Question 15

Caspofungin, micafungin, anidulafungin

Answer 15

Caspofungin, micafungin, anidulafungin = echinocandins

Question 16

Certain antibiotics can also be used as (antiprotozoal/ antifungal) medications

Answer 16

Certain antibiotics can also be used as antiprotozoal medications
* We can’t use antibiotics against fungi because fungi are eukaryotes

Question 17

Humans have cholesterol in the cell membrane phospholipid bilayer; fungi have _

Answer 17

Humans have cholesterol in the cell membrane phospholipid bilayer; fungi have ergosterol

Question 18

Amphotericin B and nystatin are drugs that bind to _

Answer 18

Amphotericin B and Nystatin are drugs that bind to ergosterol –> pokes holes in the membrane –> causes ions to leak out of the cell

Question 19

_ is a drug that is known to cause the “shake-and-bake” fever and chills associated with infusion; it also can lead to hypokalemia

Answer 19

Amphotericin B is a drug that is known to cause the “shake-and-bake” fever and chills associated with infusion; it also can lead to hypokalemia
* Sterols in the fungal and human cell membranes look similar; amphotericin can perforate our renal tubual collecting duct –> drops K+

Question 20

Name the substrates in ergosterol production

Answer 20

Squalene –>
Squalene epoxide –>
Lanosterol –>
Ergosterol

Question 21

Squalene –> squalene epoxide is catalyzed by _

Answer 21

Squalene –> squalene epoxide is catalyzed by squalene epoxidase

Question 22

Lanosterol –> ergosterol is catalyzed by _

Answer 22

Lanosterol –> ergosterol is catalyzed by 14-alpha-demethylase
* This is a P450 enzyme

Question 23

_ is a group of an antifungals that blocks squalene epoxidase

Answer 23

Allylamine is a group of an antifungals that blocks squalene epoxidase
* Includes terbinafine

Question 24

_ is a group of antifungals that blocks 14-alpha-demethylase

Answer 24

Azoles is a group of antifungals that blocks 14-alpha-demethylase

Question 25

Ketoconazole can be used for cutaneous dermatophyte infections; however, newer drugs like _ and _ are more commonly used

Answer 25

**Ketoconazole** can be used for cutaneous dermatophyte infections; however, newer drugs like **itraconazole** and **voriconazole** are more commonly used

Question 26

Oral Ketoconazole is used sparingly because of its side effect profile; it has a hard time differentiating between human _ and fungal _

Answer 26

Oral Ketoconazole is used sparingly because of its side effect profile; it has a hard time differentiating between human **liver CYP450** and fungal **CYP450** * Leads to a decrease in our cholesterol levels

Question 27

The antifungal medication flucytosine interupts the synthesis of _

Answer 27

The antifungal medication **flucytosine** interupts the synthesis of **nucleic acids** * Deoxyuridine monophosphate (dUMP) --> deoxythymidine monophosphate (dTMP) via thymidylate synthase * Fungal cells convert flucytosine --> 5-fluorouracil which inhibits thymidylate synthase

Question 28

Fungal cells convert flucytosine (antifungal drug) into _ which effectively inhibits _ to halt replication

Answer 28

Fungal cells convert **flucytosine** (antifungal drug) into **5-FU** which effectively inhibits **thymidylate synthase** to halt replication * Flucytosine- amphotericin B combo can be used against *cryptococcal meningitis* but it is otherwise avoided due to toxicity

Question 29

(Local/ Opportunistic/ Systemic) Fungi are those that are dimorphic fungi found in soil that normally act to decompose organic matter; ingestion of spores can cause illness

Answer 29

**Systemic** Fungi are those that are dimorphic fungi found in soil that normally act to decompose organic matter; ingestion of spores can cause illness * *Local* are usually dermatophytes that attack nails, skin, hair * *Opportunistic* are already in our own bodies

Question 30

_ is native to the southwest region of the US and causes Valley fever

Answer 30

***Coccidioides immitis*** is native to the southwest region of the US and causes Valley fever

Question 31

_ is transmitted through inhalation of the mold in soil contaminated with bird or bat droppings; it causes pneumonia symptoms and is native to Mississippi and Ohio river valleys (in caves especially)

Answer 31

***Histoplasma capsulatum*** is transmitted through inhalation of the mold in soil contaminated with bird or bat droppings; it causes pneumonia symptoms and is native to Mississippi and Ohio river valleys (in caves especially)

Question 32

_ causes a systemic granulomatous infection, primarily involving the lungs, following inhalation of the conidia of the dimorphic fungus; it is native to the Mississippi River valley

Answer 32

***Blastomyces dermatitidis*** causes a systemic granulomatous infection, primarily involving the lungs, following inhalation of the conidia of the dimorphic fungus; it is native to the Mississippi River valley

Question 33

_ is a delayed hypersensitivity reaction to fungal antigens circulating in the bloodstream; occurs from systemic mycoses; painful rash on the shins

Answer 33

**Erythema nodosum** is a delayed hypersensitivity reaction to fungal antigens circulating in the bloodstream; occurs from systemic mycoses; painful rash on the shins

Question 34

Granulomas are formed from fibrosis around the fungal infection site due to the signaling of _

Answer 34

Granulomas are formed from fibrosis around the fungal infection site due to the signaling of **TNF-alpha**

Question 35

Patients who are taking corticosteroids for asthma are prone to oral thrush; which is the overgrowth of _

Answer 35

Patients who are taking corticosteroids for asthma are prone to oral thrush; which is the overgrowth of *Candida*

Question 36

We can use a _ test of scrapings of infected skin, hair, or nail is used to determine the presence of dermatophytes or C albicans

Answer 36

We can use a **potassium hydroxide** test of scrapings of infected skin, hair, or nail is used to determine the presence of **dermatophytes** or **C albicans**

Question 37

What do we use Sabouraud dextrose agar for?

Answer 37

**Sabouraud dextrose agar** is a broad use fungal agar that can grow most fungi

Question 38

A Wood lamp examination uses ultraviolet light to cause _ infection to fluoresce on the skin (an exception to the rule that bacterial but not fungal infections will fluoresce)

Answer 38

A **Wood lamp examination** uses ultraviolet light to cause **microsporum** infection to fluoresce on the skin (an exception to the rule that bacterial but not fungal infections will fluoresce) * Microsporum is the class of dermophytes with tinea capitis, tinia corporis, ringworm