Final; Fungi Flashcards
What does the cell membrane and the cell wall of fungi contains
cell membrane; ergosterol
cell wall; chitin, manna, and glucan
Fungi that cause disease in humans have what two forms
unicellular; yeast
multicellular filamentous; mold
What percentage of fungi cause disease in humans
less than 1%
What do yeasts use to divide
budding or binary fission
This is modified budding, where the new cells remain attached to parental cells
pseudomycellum
Filamentous multicellular fungi have what type of branching filaments
hyphae
True or False
Many pathogenic fungi exist as molds and yeasts
True; dimorphism
*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
What is important about fungi as pathogens invading the human body
they invade as opportunistic infections, in those who are immunosupressed
What are the mechanisms of which fungi are encountered
incidental environment contact
normal human flora
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
What allows entry and infection of the fungi
alteration in normal flora or compromised skin/mucosal surfaces
*This type of mycoses infection is caused by fungal pathogens that are restricted geographically
endemic mycoses
*This type of mycoses infection is caused by fungi that are not true pathogens
opportunistic mycoses
*This type of mycoses are true pathogens that typically result in systemic infections in healthy individuals
endemic mycoses
*This type of mycoses cause systemic infections only in immunocompromised patients
opportunistic mycoses
Where is histoplasma most likely to be found
In the soil enhanced by high nitrogen content
“histo-belt” mid southeastern US; Mississippi river area
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
What is required for histoplasma pathogenicity
transforation to yeast phase
What is the virulence of histoplasma directly related to
tolerance of warmer temperatures
What system infection does H. capsulatum cause
reticuloendothelial system infection
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
How does H. capsulatum induce damage
damage due to inoculum size and immune response
extensive or prolongues exposure can result in pneumonia
What may develop in pre-disposed patients (COPD) due to H. capsulatum
chronic cavitary pulmonary histoplasmosis; fatal
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
