Fungi Flashcards
fungi are prokaryotic or eukaryotic?
eukaryotic
fungi cell wall is comprised of:
ergosterol
oxygen requirement of fungi
strict aerobe (one exception is facultative anaerobe)
fungi are free living in nature, what does this mean?
grow at lower pH optimal temperatures (25-30*C)
what are the two forms of fungi that are capable of causing disease in humans?
unicellular
multicellular filamentous
unicellular fungi are responsible for causing
yeast
multicellular filamentous fungi are responsible for
mold
what are the 2 ways fungi are encountered
incidental environmental contact
normal human flora
primary mechanism for containing fungal infections
neutrophil phagocytosis
killing
what type of immunity is required to eliminate fungal infections?
t-cell mediated
innate methods of limiting fungi
dessication
epithelial cell turnover
fatty acids
low pH of skin
infections caused by fungi that are not true pathogens, cause systemic infections in immunocompromised patients
opportunistic
infections caused by fungal pathogens that are restricted geographically
typically result in systemic infections in healthy individuals
endemic
what are the endemic fungal pathogens
histoplasmosis
blastomycosis
coccidiomycosis
this endemic fungal pathogen is found mainly in soil in certain parts of the country
histoplasmosis
why does histoplasmosis grow well in soil?
growth enhanced by high nitrogen content of soil fertilized by bird or bat guano
describe histoplasmosis method of entry
conidia (spores and filaments) inhaled and evade mucosal barriers and transform to yeast phase
T/F? Histoplasmosis virulence directly related to tolerance of warmer temperatures
true
what are the two types of mycoses?
endemic
opportunistic
found primarily in Mississippi river valley, southeastern states, extends to Canada
Blastomycosis
found in mid-southeastern belt in US, particularly Indiana
Histoplasmosis
which type of disseminated histoplasmosis is more likely to affect an AIDS patient?
acute disseminated histoplasmosis
What typically causes death in untreated patients with Chronic disseminated histoplasmosis?
organ infection
what symptom is a hallmark of blastomycosis?
skin lesions as result of hematogenous dissemination
what type of immunity needed to eradicate blastomycosis?
cell mediated
blastomycosis multiplication
multiplies in lungs and causes pneumonia
causes “Valley Fever”
coccidiomycosis
extreme joint pain, difficulty breathing, possible migration of infection to brain
however, majority of healthy people are asymptomatic
coccidiomycosis
found only in lower Sonoran life zone - AZ, NM, SoCal, TX
coccidiomycosis
T/F? Dimorphism in cocciodiodes is temperature dependent
false
arthralgias and skin nodules (host neutrophil and T lymphocyte response) is characteristic of
Valley Fever
targets lungs and causes acute pulmonary infection but hematogenously spreads to other organs
Coccidiomycosis
chronic meningitis is a complication of
disseminated cocciodiomycosis
what populations are at risk for disseminated cocciodiomycosis?
dark skinned people
pregnant women
immunocompromised
coccidiomycosis treatment
polyenes
azoles
antifungal interferes with ergosterol synthesis ; fungistatic
azoles
antifungal is lipophilic and binds to cell wall ergosterol and forms channels
polyenes (amphotericin B)
amphotericin B is an example of a
polyene
T/F? Opportunistic mycoses usually cause systemic infections
false; only cause systemic infections in immunocompromised
why are opportunistic infections often seen in immunocompromised?
hematological malignancies organ or hematopoietic transplants neutropenia HIV immunosuppressants
most frequent opportunistic fungal pathogen
candida albicans
list the opportunistic fungal pathogens
candidiasis cryptococcus aspergillosis mucomycosis pneumocystosis
candida albicans shape
round or oval
how do candida reproduce?
forming buds or blastoconidia
T/F? most candida albicans infections are endogenous (derived from host’s normal flora)
true
list the variosu forms of candidiasis infections
mucosal cutaneous systemic thrush intertriginous disseminated
candida infection that can follow superficial infections and central IV catheters
systemic candidiasis
proliferation of candida in warm, moist areas of skin and in babies (diaper rash)
intertriginous candidiasis
T/F? Cryptococcus produces large polysaccharide capsule in tissues and in environment
false; only in tissues
yeast found in soil contaminated with bird poop (particularly pigeons) and rotten fruits/veggies
crytococcus
T/F? Cryptococcus grows well in cool temperatures
false; 37 degrees
how does polysaccharide capsule in cryptococcus add to its virulence?
capsule formation inhibits phagocytosis
stalls intracellular killing after phagocytosis by downregulating Th1 mediators
what does cryptococcus neoformans produce that increases its virulence?
polysaccharide capsule
melanin
what does melanin do for virulence?
increases strength of cell wall - resist enzyme degradation and resist free radicals
fungal pathogen that is ubiquitous in air, soil, water, vegetation and is filamentous in environment
aspergilus
major pathogenic aspergilus species
A.fumigatus
A.flavus
how does aspergilus spread?
inhalation into URT and LRT
germination of conidia (spores and filaments) into hyphae
aspergilus phagocytosis
pulmonary macrophages phagocytose conidia but not hyphae
neutrophils line up on hyphae to kill with O2 radicals
how does host act against hyphae of aspergilus?
neutrophils line up on hyphae to kill with O2 radicals
angioinvasive
hyphae invade thru blood vessel walls causing tissue infarction, hemorrhage, necrosis
Which fungal pathogen is angioinvasive?
aspergilus and mucormycosis
what is initial site of invasion for aspergillosis?
lung or paranasal sinuses
invasive pulmonary aspergillosis may lead to:
intracerebral and other organ abscesses
necrotic skin lesions
T/F? Pulmonary macrophages phagocytose conidia and hyphae
false; do not phagocytose hyphae
nosocomial outbreaks in hospitals near construction sites
aspergillosis
aspergilus is capable of producing
toxic metabolic products
what toxic metabolic products can be made by aspergilus?
aflatoxins
phospholipase
T/F? Aspergilus can cause noninfectious disease like allergy, asthma, pneumonia
true
causes necrotizing fungal soft tissue wound infections
mucromycosis
which has septated hyphae? mucormycosis or aspergilus?
aspergilus - septated
mucormycosis - nonseptated
two clinical manifestations of mucormycosis
rhinocerebral form
disseminated mucormycosis
which mucormycosis form is unique to diabetics?
rhinocerebral
why is rhinocerebral mucormycosis unique to diabetics?
growth stimulated by acidotic state
type of mucormycosis that forms pulmonary lesions
disseminated mucormycosis
T/F? Pneumocystis has never been grown in vitro
true; not part of NSF
T/F? Pneumocystis is an intracellular pathogen confined to pulmonary spaces
false; EXTRAcellular pathogen only confined to pulmonary spaces
T/F? pneumocystis commonly causes disease
false; infection common but disease rare
commonly causes sentinel infection in AIDS
pneumocystis
pneumocystis only causes one disease which is:
pneumonia
2 common superficial mycoses
seborrheic dermatitis
tinea versicolor
hypo or hyperpigmented patches on chest or neck with scaling
tinea versicolor
most common type of fungal infections in humans
dermatophyte skin infections
“tinea” - name of clinical disease
three etiological genera of dermatophyte skin infections (tinea)
microsporum
trichophyton
epidermophyton
T/F? Dermatophytes are part of normal skin flora
false
dermatophyte infections are more common when:
skin occluded with nonporous materials which increases hydration and temperature of skin
interferes with str. corneum function
T/F? Systemic dermatophyte infections are very rare
true
direction of dermatophyte organism growth
outward in centrifugal pattern
AKA mycoses of implantation
subQ mycoses
mycoses of implantation
diseases caused only under conditions of trauma
via thorns or splinters
rose grower’s disease
lymphocutaneous sporotrichosis - a subQ mycoses
found in soil, moss, decaying wood, vegetation
subQ mycoses - sporothrix schenckii??
how do subQ mycoses spread?
skin lesions form at point of entry and along lymph nodes and vessels
T/F? In subQ mycoses, more lesions appear until a chronic ulcer develops
true
associated with inhalation of spores, nodules / cavitations of lungs, fibrosis, swollen hilar lymph nodes
pulmonary sporotrichosis
disseminated sporotrichosis is characterized spread of initial infection to
joints and CNS (meningitis)
chronic subQ mycoses infection with sinus tract nodules
mycetoma
where do most subQ mycoses occur?
tropical regions in soil fungi
antigungal that inhibits squalene epoxidase activity and blocks ergosterol synthesis
works against dermatophytes & C. albicans
allyamines
antifungal that is IV only; inhibits glucan synthesis in fungal cell wall
works against candida and aspergillus
echinocandins
