Final; Fungi Flashcards by Courtney Kast

What does the cell membrane and the cell wall of fungi contains

cell membrane; ergosterol

cell wall; chitin, manna, and glucan

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Fungi that cause disease in humans have what two forms

unicellular; yeast

multicellular filamentous; mold

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What percentage of fungi cause disease in humans

less than 1%

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What do yeasts use to divide

budding or binary fission

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This is modified budding, where the new cells remain attached to parental cells

pseudomycellum

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Filamentous multicellular fungi have what type of branching filaments

hyphae

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True or False

Many pathogenic fungi exist as molds and yeasts

True; dimorphism

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*What induces phase changes of fungi in and which is most likely to be found in the human body and what is the exception

temperature
yeasts
Candida is the exception, it is a mold found in tissues

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What is important about fungi as pathogens invading the human body

they invade as opportunistic infections, in those who are immunosupressed

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What are the mechanisms of which fungi are encountered

incidental environment contact

normal human flora

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What is the primary human mechanism to get rid of fungal infections

neutrophagocytosis and killing, in those that are too large to be phagocytosed, they secrete lysosomal enzymes onto the fungi
minor antibody response
T cell-mediated needed to eliminate infection

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What allows entry and infection of the fungi

alteration in normal flora or compromised skin/mucosal surfaces

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*This type of mycoses infection is caused by fungal pathogens that are restricted geographically

endemic mycoses

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*This type of mycoses infection is caused by fungi that are not true pathogens

opportunistic mycoses

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*This type of mycoses are true pathogens that typically result in systemic infections in healthy individuals

endemic mycoses

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*This type of mycoses cause systemic infections only in immunocompromised patients

opportunistic mycoses

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Where is histoplasma most likely to be found

In the soil enhanced by high nitrogen content

“histo-belt” mid southeastern US; Mississippi river area

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How does histoplasma gain entry into the host

not well understood

conidia (spores and filaments) are inhaled and invade mucosal barriers and transform to yeast phase

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What is required for histoplasma pathogenicity

transforation to yeast phase

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What is the virulence of histoplasma directly related to

tolerance of warmer temperatures

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What system infection does H. capsulatum cause

reticuloendothelial system infection

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How does H. capsulatum spread and multiply

phagocytosis does not always kill
spreads via lymph
cell mediated immunity required to resolve infection; can be reactivated

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How does H. capsulatum induce damage

damage due to inoculum size and immune response

extensive or prolongues exposure can result in pneumonia

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What may develop in pre-disposed patients (COPD) due to H. capsulatum

chronic cavitary pulmonary histoplasmosis; fatal

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What types disseminated histoplasmosis are there

acute; cell mediated immune deficiencies such as T cell function chronic; older adults, may die without treatment

Where is blastomycosis found

soil and decaying wood | found in mississippi river valley and southeastern states, but extends into canada; Wisconsin

How does B. dermatitidis spread and multiply

multiplies in lungs and causes pneumonia skin lesions develop cell medited immunity needed to eradicate and granulomas develop

Where is coccidioidomycosis found

burrows in desert animals exists only in lower sonoran; SW US and upper mexico blooms form

How does coccidioides enter the host

highly infectious, inhaled into alveoli transform to large sperules (not temp. dependent), filled with hundreds of endospores spherule is resistant to phagocytosis

How does C. immitis spread and multiply in the host

targets lungs and causes acute pulmonary infection arthralgias and skin nodules can develop desert rheumatism or valley fever usually self limiting

C. immitis causes this in dark-skinned individuals, pregnant women, and the immunocompromised

disseminated coccididodiomycosis | chronic meningitis complication is fatal if not treated

This treatment for coccididodiomycosis involves binding to cell wall ergosterol and forming channels

polyenes | amphoericin B in diseminated infections

This treatment for coccididodiomycosis involves the interference with ergosterol synthesis; it is fungistatic

Azoles | intraconazole

This type of mycoses involved the skin, subcutaneous tissue, and lymphatics

subcutaneous mycoses

This type of mycoses is limited to skin and skin structures

superficial and cutaneous mycoses

This has round or oval yeasts, reproduces by forming buds or blastoconidia and some for hyphae in vivo

Candida albicans

*This is the most frequent opportunistic fungal pathogen

Candida albicans

*Most Candida albicans infections are what

endogenous; derived from the host normal flora

*Where is Candida albicans present in the human

pharynx, bowels, vagina, skin of healthy individuals | troposim for kidney

*When does Candida albicans cause infection

When normal flora is disrupted | due to broad spectrum antibiotics, decreasing T cell function resulting in mucosal infection

*What is the dimorphism exception for Candida albicans

mycelial form, not the yeast for, many times found in tissue

Where in the body would you find candidasis

muscoal surfaces (invasion not known) cutaneous systemic

True or False | All systemic candida infection are potentially life threatening

True

What are the symptoms of candidasis

trush; white lesions intertriginous candidasis; moist warm areas disseminated infection

Where is cryptococcus found

yeast found in soil contaminated with bird excreta; pigeons/rotted fruits/veggies grows well at 37º

What does cryptococcus produce in tissues, but not in the environment

a large polysaccharide capsule

*This is prominent in AIDS, transplant, and other immunosupressed patients; 20% of patients infected are immunocompetent

cryptococcosis

*A pulmonary cryptococcus infection can cause what if inhaled

pneumonia | can be asymptomatic with damage

*A disseminated cryptococcus infection can cause what

neurotropism; meningitis brain abcesses have little or no inflammatory responses damage due to displacement and pressure on brain tissue

What does the body do to contain the spread of cryptococcus

neutrophils and macrophages protect against initial infection but phagocytosis is inhibited by capsule, it also down regulated Th1

What does C. neoformans produce that enhances virulence by increases the strength of its cell wall, resisting enzyme degradation and free radicals

melanin

Where is aspergillus found

its ubiquitous; found in air, soil, water, and vegetation filamentous in environemnt septated hyphae

What are the major pathogenic species of aspergillus

A. fumigatus and A. flavus do not grow in normal tissues, only causes disease in profoundly immunocompromised patients can be nonscomial

*How is aspergillus spread

inhalation into upper and lower respiratory tract

*What does aspergillus germinate into

conidia into hyphae

*What is different about the immune respond to conidia of aspergillus compared to the hyphae

pulmonary macrophages phagocytose conidia but not hyphae | neutrophils line up along the hyphae to kill it using oxygen radicals

*How does the hyphae of aspergillus invade

angioinvasive; invade through blood vessel walks causing tissue infarction, hemorrhage, and necrosis

What is the initial site of invasion involving aspergillus

lung or paranasal sinus

What may invasive pulmonary aspergillosis cause

intracerebral and other organ abcesses | necrotic skin lesions

What noninfectious disease can aspergillus cause

allergy and asthma pneunomia toxic metabolic products

Murcormycosis is similar to aspergillus how

it is similar in the invasion of its hyphae (angioinvasiveness) opportunistic fungal infections

What are the two principal clinical manifestations of Murcormycosis

rhinocerebral form; unique to diabetics | disseminated murcormycosis; pulmonary lesions

This have never been grown in vitro, is extracellular, does not readily invade tissues, and is confined to pulmonary spaces

pneumocystis

A pneumocystis infection is common, but disease is rare, why is this

it may qualify as normal flora | it is presumably inhaled from the environment but the niche is unknown

What disease does pneumocystis cause

pneunomia | sentinel infection in AIDS - highly virulent

What infections can superficial mycoses

colonization of stratum corneum by yeast seborrheic dermatitis tinea versicolor

*This is the most common fungal infections in humans

dermatophyte skin infections; examples are athletes foot, ringworm, jock itch, etc.

*What are the clinical disease of dermatophyte skin infections called

tineas | may be acute or chronic

*How can adults encounter dermatophytes

coming into close contact with lots of children

*What are the clinical manifestations of dermatophytes

it may vary scaly, itchy, lesions of scalp patchy hair loss

*This type of dermatophyte is isolated from soil

geophilic

*This type of dermatophyte is from domestic and wild animals

zoophilic

*This type of dermatophyte is exclusively in humans and their habitat

anthropophilic

*Which type of dermatophyte often causes chronic infections and may be difficult to treat

anthropophilic

*This type of immunity to pathogenic fungi is high for most people

innate

*Why is innate immunity high for most people involved with fungal infection

skin and mucosa are excellent barrier to fungi; dry, cell sloughing, fatty acids, and low pH bacterial flora hostile to fungi

*What is required for entry of dermatophytes

skin trauma; continuous moist conditions are important

*Infections are more common when when is what

occluded with nonporous materials; increases hydration and temp of skin interferes with stratum corneum function

How do dermatophytes cause damage

it grows outward in centrifugal pattern; viable fungal elements at inflamed margin, central area has few/no viable fungi

What type of infection is rare with dermatophytes

systemic infections; due to the inability of them to grow at human body temperature and the presence of non-specidic serum factors

Subcutaneous mycoses disease cause caused only under what conditions

conditions of trauma; enter the skin via thorns, splinters; and evolve over several weeks

What is the characteristic of a subcutaneous mycoses infection

generally localized with few systemic symptoms; lesions heal after antifungals can cause more damage in the immunocompromised

This type of subcutaneous mycoses is found in the soil, moss, decaying wood, and vegetation; can cause sporotrichosis

sporothric schenckii

How does subcutaneous mycoses spread

skin lesion leads to lymph and vessels

What are some further diseases following a subcutaneous mycoses infection

pulmonary sporotrichosis | disseminated sporotrichosis

Where in the world do you find subcutaneous mycoses

tropical areas | soil

These are scaly wart like lesions on the feet requiring surgery or amputation

chromoblastomycosis

This anti fungal inhibits squalene epoxidase blocking ergosterol synthesis

allylamines

This anti fungal inhibits the synthesis of β-(1-3)-D-glucan in fungal cell walls

echinocandins