Chapter 46-50 Fungi 1 Flashcards
describe fungi
- eukaryotes
- spore forming
- no chlorophyll
- most are aerobic - some facultative and strict anaerobes
what do fungi cell walls contain
chitin and polysaccharide containing NAG
what are the two growth forms
- filamentous
- unicellular
describe the filamentous growth form
- threadlike filaments = hyphae
- mycelium = mass of hyphae
- septate vs coenocytic hyphae
- grow by extension of tip and branching
describe unicellular growth
-single cells ( ovoid or spherical)
- reproduce asexually by cell division
- sexually by cell fusion and spore formation
some yeast form fungi perform_______
asexual cell division by budding, other by transverse division
describe asexual reproduction
- cell division budding
- transverse division
- spore formation
- involves production of sexual spores by meiosis of a diploid cell
what is an anamorph
form producing asexual spores
- often mold like growth form
what is a teleomorph
form producing sexual spores
- typically a fruiting body
what is dimorphism
ability to grow as yeast form or mold form
many pathogenic fungi are _____
dimorphic
yeast form is more typical at ____; except
human body temperature; candida
both candida forms exist ____and ____
inside and outside the body
candida actually forms _____ and ____
psuedohyphae and pseudomycelia
what is pseudohyphae
hyphal growth is a modified budding where newly budded cells remain attached to mother cell
what pathogenic fungi are not dimorphic
aspergillus - mold form only
cryptococcus neoformans- yeast form only
what are mycoses
fungal infections
what are the primary mechanisms for fighting fungi
-neutrophil phagocytosis and killing
- T cell mediated immunity
what are the types of mycoses
- superficial
- cutaneous
- subcutaneous
- systemic
describe superficial mycoses
- keratinized outer layers of skin, hair, and nails
- mild infections/minimal inflammatory response
- easy to treat or clears without treatment
what are piedras and what microbe is responsible
infections of hair shaft
- trichosporon beigelii
what are tineas and what microbe is responsible
- infections involving outer layers of skin, nails and hair
- malassezia furfur
where do superficial mycoses occur mostly
in tropics
how is M furfur transmitted
human to human
what do superficial mycoses look like
pigmented macules- not elevated but altered color
what are cutaneous mycoses
- keratinized outer layers of skin, hair, and nails
- skin infection: no invasion beyond stratum corneum
what are dermaphytes
- microsporum
- trichophyton
- epidermophyton
- keratinophilic and keratinolytic
what do cutaneous mycoses cause
tineas - ringworm
- tinea pedis: athletes foot
- tinea cruris: jock itch
what is tineas caused by
inflammation ring of inflammatory scaling
how are cutaneous mycoses transmitted
person to person
- some are soil organisms
- others are zoonoses
what are subcutaneous mycoses
- dermis and subcutaneous tissue
- do not respond well to antifungal chemotherapy
- need to excise
what do subcutaneous mycoses cause and what microbe is responsible
sporotrichosis
- sporothrix schenkii
- thorns and splinters
- responds to oral potassium iodine
what do systemic mycoses do
invade internal organs
what are systemic mycoses caused by
endemic dimorphic fungal pathogens
what is a saprobe
organism living on dead or decaying matter
what is a spherule
100s of endospores
what is a histoplasmosis caused by
histoplasma capsulatum
what is a blastomycosis caused by
blastomyces dermatitidis
what is a coccidiodes immitis caused by
coccidioidomycosis
what are histoplasma capsulatum transmitted by
- bird or bat droppings
- acquire fungus by inhalation of conidia
what do histoplasma capsulatum do in the body
remains viable within macrophages
- modulate pH of phagolysosome
- antibody plays no role in resolution
- cell mediated immune system of CD4 T lymphocytes and activated macrophages are important for immunity
- granulomas develop in lung with caseous necrosis
primary infections of histoplasma capsulatum are often _____
asymptomatic
what is the treatment for histopalsma capsulatum
3-12 months of antifungal agent
where are blastomyces dermatiditis found and how are they transferred
- found in decaying matter
- acquire fungus by inhalation of conidia
describe blastomyces dermatitis in the body
- cell mediated immune system of CD4 T lymphocytes and activated macrophages are important for immunity
- granulomas develop with caseous necrosis
- cutaneous lesions are a hallmark of disease heaped up borders and small, central microabscesses
how are blastomyces dermatiditis diagnosed
histopathological examination- thick walled yeasts with single broad based bud
what is the treatment for blastomyces dermatiditis
6-12 months of antifungal agent
where are coccidioides immitis found
southwestern USA- lower sonoran life zone
what is the primary target of coccidioides immitis
lung but the fungus spreads through the circulatory system and infects many organs
what symptoms go with coccidioides immitis
- acute pulmonary infection
- arthralgias and skin lesions
- “desert rheumatism” or “fvalley fever”
- disseminated coccidioidomycosis
- chronic meningitis
how long is the treatment for coccidiodes immitis
12-24 months
