Infectious Disease - Fungal Basics

Question 1

What is mycology?

What are mycoses?

Answer 1

Study of fungi;

fungal diseases

Question 2

Answer 2

4. Fungi have one or more nuclei and chromosomes

Question 3

Fungi are _____karyotes that ____ (do/do not) have membrane-bound organelles (e.g. nuclei).

Answer 3

Fungi are eukaryotes that do have membrane-bound organelles (e.g. nuclei).

Question 4

Are fungi single or multicellular?

Answer 4

Can be either

Question 5

Most fungi are ____robic.

Answer 5

Most fungi are aerobic.

Question 6

What type of medication is used to treat fungal infections?

Answer 6

Antimycotics

Question 7

Fungi are _______ (smaller/larger) and _______-growing (slower/faster) than most bacteria.

Answer 7

Fungi are larger and slower-growing than most bacteria.

Question 8

A mass of fungal filaments (also known as ________) is called a ________.

Answer 8

A mass of fungal filaments (also known as hypha) is called a mycelium.

Question 9

True/False.

Pathogenic fungi are always either yeasts and/or molds.

Answer 9

True.

Pathogenic fungi are always either yeasts and/or molds.

Question 10

Describe yeast morphology.

Answer 10

Singular round-to-oval cells

Question 11

Describe mold morphology.

Answer 11

Long multicellular filamentous structures

Question 12

What does it mean that some fungi are dimorphic?

Answer 12

They can exist in two forms

Question 13

Dimorphic fungi are capable of growing as either ________ or ________. What determines the difference?

Answer 13

Dimorphic fungi are capable of growing as either yeasts or molds.

Temperature

Question 14

Dimorphic fungi are capable of growing as either yeasts or molds.

When are they yeasts?

When are they molds?

Answer 14

Yeasts at 37°C;

molds at 25°C

Question 15

What is oral thrush?

Answer 15

Candidiasis of the buccal mucosa

Question 16

What fungus can often result in otomycoses?

Answer 16

Aspergillus

Question 17

Yeast undergo a _________ process in order to replicate.

The most common example yeast is _________.

_________ is a unique form in that it has a capsule.

Answer 17

Yeast undergo a budding process in order to replicate.

The most common example yeast is Candida.

Cryptococcus is a unique form in that it has a capsule.

Question 18

True/False.

Yeast can be multicellular or single-celled.

Answer 18

False.

Yeast are single-celled.

Question 19

Molds are composed of ________ (filamentous structures) and are ________ (_____-colored).

A common example is ________.

Answer 19

Molds are composed of hypha (filamentous structures) and are

dematiaceous (dark-colored).

A common example is Aspergillus.

Question 20

_______ undergo a budding process in order to replicate.

The most common example _______ is Candida.

Cryptococcus is a unique form in that it has a capsule.

Answer 20

Yeast undergo a budding process in order to replicate.

The most common example yeast is Candida.

Cryptococcus is a unique form in that it has a capsule.

Question 21

_______ are composed of hypha (filamentous structures) and are dematiaceous (dark-colored).

A common example is Aspergillus.

Answer 21

Mold are composed of hypha (filamentous structures) and are dematiaceous (dark-colored).

A common example is Aspergillus.

Question 22

Answer 22

2. Molds produce hyphae that may or may not be partitioned with cross-walls or septa

Question 23

Fungi can reproduce asexually or sexually, but only the ________ are associated with human disease.

Answer 23

Fungi can reproduce asexually or sexually, but only the asexual are associated with human disease.

Question 24

What is the name for the fungal spores found at the ends of specialized hypha?

Is this sexual or asexual reproduction?

Answer 24

Conidia;

asexual

Question 25

Describe the process of fungal germination / sporulation.

Answer 25

Question 26

Answer 26

1. Ergosterol

Question 27

Describe fungal dimorphism. ## Footnote \_\_\_\_\_\_\_\_ in natural habitats: 25°C; ____ oxygen and ____ nutrients \_\_\_\_\_\_\_\_ in animal hosts: 37°C; ____ oxygen and ____ nutrients

Answer 27

Describe fungal dimorphism. ## Footnote **_Molds_** in natural habitats: 25°C; **_more_** oxygen and **_more_** nutrients **_Yeasts_** in animal hosts: 37°C; **_less_** oxygen and **_less_** nutrients

Question 28

Describe the composition of the fungal membrane/wall from in to out.

Answer 28

**Membrane** **Wall** Chitin Glucans Mannoproteins (peptidomannan)

Question 29

Which portion of the fungal wall is thickest? Which portion is immunogenic? Chitin --- glucans --- mannoproteins

Answer 29

Glucans; mannoproteins (peptidomannan)

Question 30

There are approximately ____ fungi that cause disease in humans.

Answer 30

There are approximately **_200_** fungi that cause disease in humans.

Question 31

**True/False**. Fungi have multiple strong virulence factors.

Answer 31

**False**. Fungi have multiple ***weak*** virulence factors. E.g. * Adherence to cells* * Resistance to phagocytosis* * Capsule production* * Destructive enzymes* * Immunomodulating factors*

Question 32

Most fungal diseases are either: \_\_\_\_\_\_\_\_\_\_ (hypersensitivities), \_\_\_\_\_\_\_\_\_\_ (toxin ingestion), or __________ (systemic disease).

Answer 32

Most fungal diseases are either: **_allergies_**, **_mycotoxicoses_**, or **_mycoses_**.

Question 33

Mold allergies are usually a result of inhaled ______ or \_\_\_\_\_\_.

Answer 33

Mold allergies are usually a result of inhaled **_conidia_** or **_hypha_**.

Question 34

What mold is typically involved in fungal allergies? Is any fungal replication necessary?

Answer 34

*Aspergillus*; no

Question 35

**True/False**. Most mycoses are either superficial, cutaneous, subcutaneous, or systemic.

Answer 35

True.

Question 36

Answer 36

C. Aflatoxin B1

Question 37

Mycotoxicoses result due to ingestion of fungal toxins. What are the two most prominent categories?

Answer 37

Ergot alkaloids (e.g. psilocybin); aflatoxins (B1 especially)

Question 38

Aflatoxin B1 comes from what fungus? It is known to cause what cancer?

Answer 38

*Aspergillus*; hepatocellular carcinoma

Question 39

What does it mean that fungal mycoses can be either true or opportunistic?

Answer 39

**True**: dimorphic fungi that cause disease in virtually all hosts **Opportunistic**: fungi that cause disease in compromised hosts

Question 40

Which 'true' pathogens cause mycoses?

Answer 40

* Histoplasma*; * Blastomyces*; * Coccidiodes*; * Paracoccidiodes*

Question 41

Which 'opportunistic' pathogens cause mycoses?

Answer 41

* Candida*; * Cryptococcus*; * Aspergillus*; * Pneumocystis*

Question 42

\_\_\_% of all nosocomial infections are fungal in nature.

Answer 42

**_10_**% of all nosocomial infections are fungal in nature.

Question 43

In what geographic regions are *Histoplasma* infections most common?

Answer 43

Eastern U.S.; southern U.S.; northern South America; mid-Africa

Question 44

In what geographic regions are *Blastomyces* infections most common?

Answer 44

The eastern U.S.

Question 45

In what geographic regions are *Coccidiodes* infections most common?

Answer 45

The western U.S.

Question 46

In what geographic regions are *Paracoccidiodes* infections most common?

Answer 46

Central America; South America

Question 47

Broad-spectrum antibiotic use commonly leads to what fungal infection?

Answer 47

Vaginal candidiasis

Question 48

What pulmonary mycoses is considered a hallmark of infection in AIDS patients?

Answer 48

*Pneumocystis carinii* pneumonia

Question 49

What mycoses sometimes results in cerebromeningeal involvement?

Answer 49

*Cryptococcus*

Question 50

Does *Candida* cause superficial or systemic mycoses?

Answer 50

Either

Question 51

**True/False**. *Aspergillus* can cause a variety of infectious patterns, including allergic reactions, mycotoxicoses, non-invasive mycoses, and invasive mycoses.

Answer 51

True.

Question 52

Name a few stains/preparations used for direct examination of fungal samples.

Answer 52

**KOH**; India ink; Giemsa; Calcofluor

Question 53

A _______ lamp is a ______ lamp used to detect fluorescence in fungal samples.

Answer 53

A **_Wood's_** lamp is a **_UV_** lamp used to detect fluorescence in fungal samples.

Question 54

What stains can be used in fungal histology?

Answer 54

**PAS**; **GMS** (Gomori's methenamine silver nitrate)

Question 55

**True/False**. Fungi often require special medias for culturing and may need to be cultured at both 25°C and 37°C.

Answer 55

True.

Question 56

What process allows for amplification of fungal DNA for analysis?

Answer 56

PCR

Question 57

What medication interferes with microtubule activity in fungi?

Answer 57

Griseofulvin

Question 58

Answer 58

3. (also 1. to a lesser extent)

Question 59

Types of mycoses: ## Footnote \_\_\_\_\_\_\_\_\_ -infections deeper in the epidermis and its integuments (skin, hair) with host response component \_\_\_\_\_\_\_\_\_ -infections in the dermis, subcutaneous tissues, muscle & fascia. Host response can be severe. \_\_\_\_\_\_\_\_\_ -limited to the outermost layers of the skin and hair with no/minimal host response.

Answer 59

Types of mycoses: ## Footnote **Cutaneous** -infections deeper in the epidermis and its integuments (skin, hair) with host response component **Subcutaneous** -infections in the dermis, subcutaneous tissues, muscle & fascia. Host response can be severe. **Superficial** -limited to the outermost layers of the skin and hair with no/minimal host response.

Question 60

Types of mycoses: ## Footnote **Superficial** -limited to the outermost layers of the skin and hair. Host response: \_\_\_\_\_\_\_\_\_\_\_. **Cutaneous** -infections deeper in the epidermis and its integuments (skin, hair). Host response: \_\_\_\_\_\_\_\_\_\_\_. **Subcutaneous** -infections in the dermis, subcutaneous tissues, muscle & fascia. Host response: \_\_\_\_\_\_\_\_\_\_\_.

Answer 60

Types of mycoses: ## Footnote **Superficial** -limited to the outermost layers of the skin and hair. Host response: **_minimal or none_**. **Cutaneous** -infections deeper in the epidermis and its integuments (skin, hair). Host response: **_present_**. **Subcutaneous** -infections in the dermis, subcutaneous tissues, muscle & fascia. Host response: **_can be severe_**.

Question 61

What type(s) of mycoses is(are) limited to the epidermis?

Answer 61

Superfcial and cutaneous mycoses

Question 62

Name a few infectious agents that are causes of superficial mycoses.

Answer 62

***Malassezia furfur**,* * Hortae werneckii,* * Piedraia hortae,* * Trichosporon beigelii*

Question 63

Name a few infectious agents that are causes of cutaneous mycoses.

Answer 63

***Trichophyton spp.,*** ***Epidermophyton spp.,*** ***Microsporum spp.***

Question 64

Name a few infectious agents that are causes of subcutaneous mycoses.

Answer 64

***Sporothrix schenckii,*** * Fonsecaea spp.,* * Exophiala,* * Fusarium*

Question 65

Name the presentations illustrated (these are examples of superficial mycoses).

Answer 65

A. Pityriasis versicolor B. Tinea nigra C. Black piedra D. White piedra

Question 66

**Pityriasis (tinea) versicolor** is a superficial infection of the _______ layer of epidermis. Characterized by fawn to brown, or at times, achromatic, _______ patches.

Answer 66

**Pityriasis (tinea) versicolor** is a superficial infection of the **_horny_** layer of epidermis. Characterized by fawn to brown, or at times, achromatic, **_scaly_** patches.

Question 67

What is the etiological agent of pityriasis (tinea) versicolor?

Answer 67

*Malassezia furfur*

Question 68

Pytyriasis (tinea) versicolor results in what? ## Footnote Multiple \_\_\_\_\_\_pigmented or \_\_\_\_\_\_pigmented macules surrounded by normal skin. * Can appear in ________ of the body. * Skin can be dry and scaly. _____ (is / is not) contagious * Pain\_\_\_\_, skin may _____ where the spots appear. * Spots become more noticeable as the skin tans. The yeast prevents the skin from tanning. * In warm climates some people are continuously symptomatic

Answer 68

Pytyriasis (tinea) versicolor results in what? ## Footnote Multiple **hyper**pigmented or **hypo**pigmented macules surrounded by normal skin. * Can appear in **any part** of the body. * Skin can be dry and scaly. **is not** contagious * Pain**less**, skin may **itch** where the spots appear. * Spots become more noticeable as the skin tans. The yeast prevents the skin from tanning. * In warm climates some people are continuously symptomatic

Question 69

What infectious agent causes tinea nigra?

Answer 69

*Hortae werneckii*

Question 70

How does tinea nigra appear grossly?

Answer 70

Asymptomatic dark lesions on palms and hands

Question 71

Where are black piedra found? What is the etiological agent?

Answer 71

Hard, black, gritty nodules along hair shaft; *Piedraia hortae*

Question 72

How are the black piedra caused by *Piedraia hortae* and/or the white piedra caused by*Trichosporon beigelii* treated?

Answer 72

Shaving affected hairs

Question 73

What is the etiological agent of white piedra?

Answer 73

*Trichosporon beigelii*

Question 74

Where are white piedra found? What is the etiological agent?

Answer 74

White nodules along the hair shaft; *Trichosporon beigelii*

Question 75

Which of the following describes ringworm? ## Footnote **Superficial mycoses** **Cutaneous mycoses** **Subcutaneous mycoses**

Answer 75

**Cutaneous mycoses**

Question 76

\_\_\_\_\_\_\_\_\_\_\_, the causative agent in cases of ringworm, can penetrate and parasitize all layers of skin, hair, and nails and produce significant lesions. What layers of skin does it affect?

Answer 76

**_Dermatophytes_**, the causative agent in cases of ringworm, can penetrate and parasitize all layers of skin, hair, and nails and produce significant lesions. ## Footnote **Keratinized epidermdal layers**

Question 77

What are the three main dermatophytes that cause ringworm?

Answer 77

* Trichophyton*, * Microsporum*, * Epidermophyton floccosum*

Question 78

Describe the difference between fungal macroconidia and microconidia.

Answer 78

**Macroconidia**: - Large, complex, can be multinucleated **Microconidia**: - Smaller single, single nucleus

Question 79

**True/False**. There are many different types / causative agents of ringworm.

Answer 79

True.

Question 80

Another term for athlete's foot is? Another term for scalp ringworm is? Another term for jockitch is? Another term for body ringworm is?

Answer 80

Tinea pedis; tinea capitis; tinea cruris; tinea corporis

Question 81

How do chronic cutaneous mycoses (dermatocyte) present?

Answer 81

Chronic infections are associated with: ## Footnote **- A minimal tissue response** **- High antibody titers (typically with allergic responses)** **- Failure to clear the infection**

Question 82

What are dermatophytid reactions?

Answer 82

Hypersensitive state, probably resulting from circulating fungal antigens (lesion does NOT have fungi) ## Footnote *(_multiple forms_: vesicles, papules, erysipelas-like plaques, erythema nodosum, or urticaria)*

Question 83

What infectious agent is a cause of Tinea that is sometimes passed from kittens to humans?

Answer 83

*Microsporum canis*

Question 84

Name the four major causes of subcutaneous mycoses.

Answer 84

**Sporotrichosis** (follows trauma --- rose handlers' disease) **Eumycotic** **mycetoma** (draining sinuses in tissues, fascia, and bone) **Chromoblastomycosis** ('cauliflower lesions') **Phaeohyphomycosis**

Question 85

What is the main thing to know regarding sporotrichosis?

Answer 85

It typically follows trauma --- rose handlers' disease

Question 86

What is the main thing to know regarding eumycotic mycetomas?

Answer 86

They present as swelling and draining sinuses in tissues, fascia, and bone

Question 87

What is the main thing to know regarding chromoblastomycosis?

Answer 87

It causes cauliflower-like lesions