Infectious Disease - Fungal Basics Flashcards
What is mycology?
What are mycoses?
Study of fungi;
fungal diseases
- Fungi have one or more nuclei and chromosomes
Fungi are _____karyotes that ____ (do/do not) have membrane-bound organelles (e.g. nuclei).
Fungi are eukaryotes that do have membrane-bound organelles (e.g. nuclei).
Are fungi single or multicellular?
Can be either
Most fungi are ____robic.
Most fungi are aerobic.
What type of medication is used to treat fungal infections?
Antimycotics
Fungi are _______ (smaller/larger) and _______-growing (slower/faster) than most bacteria.
Fungi are larger and slower-growing than most bacteria.
A mass of fungal filaments (also known as ________) is called a ________.
A mass of fungal filaments (also known as hypha) is called a mycelium.
True/False.
Pathogenic fungi are always either yeasts and/or molds.
True.
Pathogenic fungi are always either yeasts and/or molds.
Describe yeast morphology.
Singular round-to-oval cells
Describe mold morphology.
Long multicellular filamentous structures
What does it mean that some fungi are dimorphic?
They can exist in two forms
Dimorphic fungi are capable of growing as either ________ or ________. What determines the difference?
Dimorphic fungi are capable of growing as either yeasts or molds.
Temperature
Dimorphic fungi are capable of growing as either yeasts or molds.
When are they yeasts?
When are they molds?
Yeasts at 37°C;
molds at 25°C
What is oral thrush?
Candidiasis of the buccal mucosa
What fungus can often result in otomycoses?
Aspergillus
Yeast undergo a _________ process in order to replicate.
The most common example yeast is _________.
_________ is a unique form in that it has a capsule.
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.
True/False.
Yeast can be multicellular or single-celled.
False.
Yeast are single-celled.
Molds are composed of ________ (filamentous structures) and are ________ (_____-colored).
A common example is ________.
Molds are composed of hypha (filamentous structures) and are
dematiaceous (dark-colored).
A common example is Aspergillus.
_______ 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.
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.
_______ are composed of hypha (filamentous structures) and are dematiaceous (dark-colored).
A common example is Aspergillus.
Mold are composed of hypha (filamentous structures) and are dematiaceous (dark-colored).
A common example is Aspergillus.
- Molds produce hyphae that may or may not be partitioned with cross-walls or septa
Fungi can reproduce asexually or sexually, but only the ________ are associated with human disease.
Fungi can reproduce asexually or sexually, but only the asexual are associated with human disease.
What is the name for the fungal spores found at the ends of specialized hypha?
Is this sexual or asexual reproduction?
Conidia;
asexual
Describe the process of fungal germination / sporulation.
- Ergosterol
Describe fungal dimorphism.
________ in natural habitats: 25°C; ____ oxygen and ____ nutrients
________ in animal hosts: 37°C; ____ oxygen and ____ nutrients
Describe fungal dimorphism.
Molds in natural habitats: 25°C; more oxygen and more nutrients
Yeasts in animal hosts: 37°C; less oxygen and less nutrients
Describe the composition of the fungal membrane/wall from in to out.
Membrane
Wall
Chitin
Glucans
Mannoproteins (peptidomannan)
Which portion of the fungal wall is thickest?
Which portion is immunogenic?
Chitin — glucans — mannoproteins
Glucans;
mannoproteins (peptidomannan)
There are approximately ____ fungi that cause disease in humans.
There are approximately 200 fungi that cause disease in humans.
True/False.
Fungi have multiple strong virulence factors.
False.
Fungi have multiple weak virulence factors.
E.g.
- Adherence to cells*
- Resistance to phagocytosis*
- Capsule production*
- Destructive enzymes*
- Immunomodulating factors*
Most fungal diseases are either:
__________ (hypersensitivities),
__________ (toxin ingestion),
or __________ (systemic disease).
Most fungal diseases are either:
allergies,
mycotoxicoses,
or mycoses.
Mold allergies are usually a result of inhaled ______ or ______.
Mold allergies are usually a result of inhaled conidia or hypha.
What mold is typically involved in fungal allergies?
Is any fungal replication necessary?
Aspergillus;
no
True/False.
Most mycoses are either superficial, cutaneous, subcutaneous, or systemic.
True.
C. Aflatoxin B1
Mycotoxicoses result due to ingestion of fungal toxins. What are the two most prominent categories?
Ergot alkaloids (e.g. psilocybin);
aflatoxins (B1 especially)
Aflatoxin B1 comes from what fungus?
It is known to cause what cancer?
Aspergillus;
hepatocellular carcinoma
What does it mean that fungal mycoses can be either true or opportunistic?
True: dimorphic fungi that cause disease in virtually all hosts
Opportunistic: fungi that cause disease in compromised hosts
Which ‘true’ pathogens cause mycoses?
- Histoplasma*;
- Blastomyces*;
- Coccidiodes*;
- Paracoccidiodes*
Which ‘opportunistic’ pathogens cause mycoses?
- Candida*;
- Cryptococcus*;
- Aspergillus*;
- Pneumocystis*
___% of all nosocomial infections are fungal in nature.
10% of all nosocomial infections are fungal in nature.
In what geographic regions are Histoplasma infections most common?
Eastern U.S.;
southern U.S.;
northern South America;
mid-Africa
In what geographic regions are Blastomyces infections most common?
The eastern U.S.
In what geographic regions are Coccidiodes infections most common?
The western U.S.
In what geographic regions are Paracoccidiodes infections most common?
Central America;
South America
Broad-spectrum antibiotic use commonly leads to what fungal infection?
Vaginal candidiasis
What pulmonary mycoses is considered a hallmark of infection in AIDS patients?
Pneumocystis carinii pneumonia
What mycoses sometimes results in cerebromeningeal involvement?
Cryptococcus
Does Candida cause superficial or systemic mycoses?
Either
True/False.
Aspergillus can cause a variety of infectious patterns, including allergic reactions, mycotoxicoses, non-invasive mycoses, and invasive mycoses.
True.
Name a few stains/preparations used for direct examination of fungal samples.
KOH;
India ink;
Giemsa;
Calcofluor
A _______ lamp is a ______ lamp used to detect fluorescence in fungal samples.
A Wood’s lamp is a UV lamp used to detect fluorescence in fungal samples.
What stains can be used in fungal histology?
PAS;
GMS (Gomori’s methenamine silver nitrate)
True/False.
Fungi often require special medias for culturing and may need to be cultured at both 25°C and 37°C.
True.
What process allows for amplification of fungal DNA for analysis?
PCR
What medication interferes with microtubule activity in fungi?
Griseofulvin
- (also 1. to a lesser extent)
Types of mycoses:
_________ -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.
Types of mycoses:
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.
Types of mycoses:
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: ___________.
Types of mycoses:
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.
What type(s) of mycoses is(are) limited to the epidermis?
Superfcial and cutaneous mycoses
Name a few infectious agents that are causes of superficial mycoses.
Malassezia furfur,
- Hortae werneckii,*
- Piedraia hortae,*
- Trichosporon beigelii*
Name a few infectious agents that are causes of cutaneous mycoses.
Trichophyton spp.,
Epidermophyton spp.,
Microsporum spp.
Name a few infectious agents that are causes of subcutaneous mycoses.
Sporothrix schenckii,
- Fonsecaea spp.,*
- Exophiala,*
- Fusarium*
Name the presentations illustrated (these are examples of superficial mycoses).
A. Pityriasis versicolor
B. Tinea nigra
C. Black piedra
D. White piedra
Pityriasis (tinea) versicolor is a superficial infection of the _______ layer of epidermis. Characterized by fawn to brown, or at times, achromatic, _______ patches.
Pityriasis (tinea) versicolor is a superficial infection of the horny layer of epidermis. Characterized by fawn to brown, or at times, achromatic, scaly patches.
What is the etiological agent of pityriasis (tinea) versicolor?
Malassezia furfur
Pytyriasis (tinea) versicolor results in what?
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
Pytyriasis (tinea) versicolor results in what?
Multiple hyperpigmented or hypopigmented macules surrounded by normal skin.
- Can appear in any part of the body.
- Skin can be dry and scaly. is not contagious
- Painless, 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
What infectious agent causes tinea nigra?
Hortae werneckii
How does tinea nigra appear grossly?
Asymptomatic dark lesions on palms and hands
Where are black piedra found?
What is the etiological agent?
Hard, black, gritty nodules along hair shaft;
Piedraia hortae
How are the black piedra caused by Piedraia hortae and/or the white piedra caused byTrichosporon beigelii treated?
Shaving affected hairs
What is the etiological agent of white piedra?
Trichosporon beigelii
Where are white piedra found?
What is the etiological agent?
White nodules along the hair shaft;
Trichosporon beigelii
Which of the following describes ringworm?
Superficial mycoses
Cutaneous mycoses
Subcutaneous mycoses
Cutaneous mycoses
___________, 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?
Dermatophytes, the causative agent in cases of ringworm, can penetrate and parasitize all layers of skin, hair, and nails and produce significant lesions.
Keratinized epidermdal layers
What are the three main dermatophytes that cause ringworm?
- Trichophyton*,
- Microsporum*,
- Epidermophyton floccosum*
Describe the difference between fungal macroconidia and microconidia.
Macroconidia:
- Large, complex, can be multinucleated
Microconidia:
- Smaller single, single nucleus
True/False.
There are many different types / causative agents of ringworm.
True.
Another term for athlete’s foot is?
Another term for scalp ringworm is?
Another term for jockitch is?
Another term for body ringworm is?
Tinea pedis;
tinea capitis;
tinea cruris;
tinea corporis
How do chronic cutaneous mycoses (dermatocyte) present?
Chronic infections are associated with:
- A minimal tissue response
- High antibody titers (typically with allergic responses)
- Failure to clear the infection
What are dermatophytid reactions?
Hypersensitive state, probably resulting from circulating fungal antigens (lesion does NOT have fungi)
(multiple forms: vesicles, papules, erysipelas-like plaques, erythema nodosum, or urticaria)
What infectious agent is a cause of Tinea that is sometimes passed from kittens to humans?
Microsporum canis
Name the four major causes of subcutaneous mycoses.
Sporotrichosis (follows trauma — rose handlers’ disease)
Eumycotic mycetoma (draining sinuses in tissues, fascia, and bone)
Chromoblastomycosis (‘cauliflower lesions’)
Phaeohyphomycosis
What is the main thing to know regarding sporotrichosis?
It typically follows trauma — rose handlers’ disease
What is the main thing to know regarding eumycotic mycetomas?
They present as swelling and draining sinuses in tissues, fascia, and bone
What is the main thing to know regarding chromoblastomycosis?
It causes cauliflower-like lesions
