L37- Fungi Flashcards
unicellular fungi are known as (1)
multicellular fungi are known as (2)
1- yeast
2- molds (+ mushrooms)
describe mushrooms in relation to fungal infections
- mushrooms are the ‘fruiting bodies’ of Molds
- mushrooms are not found in fungal infections
(1) are fungi that decompose dead things
(2) are fungi that invade and decompose living material
1- saprophytes
2- parasitic fungi
(note- some parasitic fungi will do both)
fungal cell walls are very different than bacterial cell walls and act as (1) and (2) while being simultaneously (3)
1- pressure barrier
2- defensive structure
3- highly antigenic
list the components of fungal cell wall
-chitin
-β (1,3) & β (1,6) glucans
-mannose modified proteins
-GPI (glycosylphosphatidylinositol) anchored proteins
-ergosterol (instead of cholesterol)
NOTE- host cell receptors and complement interact with these external proteins
multicellular fungi connect together via (1)- tangled masses of (1) are called (2)
1- hyphae
2- mycelia
describe the difference between sepate and aseptate
Septate: cell walls between neighboring cells, perforated for mitochondria and nuclei to migrate along hyphal strand
Aseptate: aka coenocytic, no cell wall, only single plasma membrane surrounding multi-nucleated cells
fungal nuclei are (haploid/diploid)
haploid
define dikaryon
fungal cell with two haploid nuclei (NOT diploid) during generation of zygote
describe conditions and status of dimorphic fungi in animal habitat
- inc Temp (35-40), reduced O2, suboptimal nutrients
- parasitic, yeast phase
- reproduction thru budding or endospores
describe conditions and status of dimorphic fungi in natural habitat
- dec Temp (<30), optimal O2, inc nutrients
- saprobic (free-living), mycefial phase
- reproduction thru sporulation
Asexual reproduction of fungi can be occur equally through (1) or unequally through (2). Asexual spores are known as (3) and are formed directly from (4).
1- mitosis
2- budding
3- conidia
4- hyphae or specialized hyphal structures
Sexual reproduction of fungi occurs when (1) fuses to produce (2) which then produces (3)
1- haploid gametes
2- transient diploid zygote
3- haploid spores
what are the portals of entry for fungi
- respiratory: inhaled spores)
- gastrointestinal
- blood stream
- skin, hair, nails: contamination on skin surface or inoculated skin / trauma (subcutaneous)
- urinary tract
list some virulence factors of fungi
- thermal dimorphism
- toxin production
- capsules + adhesion factors
- hydrolytic enzymes
- inflammatory stimulants
the main antifungal defenses humans have is (1) and (2) and if those fail (3), (4), (5) are critical
1- barrier integrity
2- respiratory cilia integrity
3/4/5- cell-mediated immunity, phagocytosis, inflammation
(T/F) long-term immunity can develop for all fungi
F- only for some fungi
list the conditions that are ideal for opportunistic fungal infections
Weakened Immune System:
- inheirited immunodeficiency disease
- immunosuppressant drug therapy
- radiation therapy
- infection (HIV)
- cancer, DM, advanced age, malnutrition
list the 4 types of fungal diseases
1) hypersensitivity: allergic rxn to molds/spores
2) mycotoxicoses: poisoning via contaminated food with toxin producing fungi (lethal to poultry/livestock)
3) mycetismus: ingestion of pre-formed toxins (mushroom poisoning)
4) infections: mycoses
fungal infection = …
mycoses
list the 4 fungal classifications (morphological)
1) ascomycota
2) basidiomycota
3) zygomycota
4) mitosporic fungi
Ascomycota reproduce (a-/sexually) within (2) to produce (3)
1- sexually
2- sacs called ascus
3- ascopspores
Basidiomycota reproduce (a-/sexually) within (2) to produce (3)
1- sexually
2- sacs called basidium
3- basidiospores
Zygomycota reproduce (a-/sexually) within (2) via formation of (3) and (4)
1- both
2- sacs called zygosporagium
3- gametes sexually
4- zygospores asexually
Mitosporic Fungi (fungi imperfecti) reproduce (a-/sexually) and make up most of (2) fungi
1- no recognizable form of sexual reproduction
2- pathogenic fungi
(1) is the largest fungal phylum in nature and includes (2), (3), and most all human fungal pathogens
1- ascomycetes (ascomycota)
2- Candida albicans
3- Pneumocytosis jirovecii
the most important Basidiomycete as a human pathogen is (1), although most are commonly (2)
1- Cryptococcus neoformans
2- mushrooms
Malassezia furfur is a dimorphic fungi that causes (superficial / cutaneous / subcutaneous) mycoses called (2) with (3) as symptoms
1- superficial
2- Pityriasis (Tinea) versicolor
3- alters skin color
Note- floresces under UV light
Hortaea werneckii causes (superficial / cutaneous / subcutaneous) mycoses called (2) with (3) as symptoms
1- superficial
2- Tinea Nigra
3- skin darkening
Piedra hortae causes (superficial / cutaneous / subcutaneous) mycoses called (2)
1- superficial infection of hair shaft
2- black piedra (white piedra)
Trichophyton rubrum and T. mentagrophytes cause (superficial / cutaneous / subcutaneous) mycoses called (2) with (3) as symptoms
1- superficial infection of fingernails and toenails
2- Onychomycosis
3- discolored, brittle nails
(1) type of fungi are cause superficial mycoses and don’t typically penetrate deeper as they acquire their nutrition because they are (2)
1- dermatophytes
2- keratinolytic
Cutaneous mycoses can form (1) lesions and are spread via (2). Most causative agents are (3) introduced through (4). (5) is the biggest danger to these infections. With treatment (6) can result, but (7) usually occurs.
1- macular, papular, pustular (herpetiform) lesions (itchy) 2- itching/scratching 3- soil organisms 4- to extremities after trauma 5- secondary bacterial infections 6- permanent patchy baldness 7- resolution w/o scarring
Sporothrix schenckii is a soil fungus that causes (superficial / cutaneous / subcutaneous) mycoses called (2) with (3) as symptoms
1- subcutaneous
2- Sporotrichosis
3- subacute / chronic granulomatous infection
(1) is a granulomatous inflammation that can extend from subcutaneous region to bone. (2) drain through sinuses producing (3) to help with this diseases identification.
1- mycetoma (eumycetoma)
2- pigmented nodules
3- colored grains
______ is a subcutaneous infection forming warty pigmented lesion which grows outward from site of introduction
Chromoblastomycosis
Candida albicans causes (1) described as (2)
(opportunistic infection)
1- candidiasis
2- superficial skin infection (cutaneous candidiasis), oral cavity (thrush), genitalia (vulvovaginal yeast infection), large intestine –> off-white pasty colony with yeasty odor
(1) is a very common airborne soil fungus that infects (2)- a major threat to (3) patients
1- Aspergillosis
2- lungs
3- AIDS, leukemia, transplant Pts
(if invasive it can involve many organs)
Cryptococcus neoformans causes (1), is usually found in (2), and infects (3); commonly in (4) patients
(opportunistic infection) 1- Cryptococcosis 2- soil around pigeon roosts 3- lungs + others/brain 4- AIDS, cancer, DM Pts
(1) is caused by saprobic fungi found in soil/water/organic debris/food and is usually harmless but can invade (2) areas and have bad consequences particularly in (3) patients
(opportunistic infection)
1- zygomycosis/mucormycosis
2- nose, eyes, heart, brain
3- DM, malnutrition Pts
Pneumocystis jiroveci is a small unicellular fungus that causes (1) and is the most prominent opportunistic infection in (2) patients
1- pneumocystis pneumonia (PCP)
2- AIDS
(fatal if not controlled with medication)
describe transport of fungal specimens
- hardy organism –> no special transport media required for culture submission
- sterile containers used to prevent bacterial contamination
describe the common fungal culture medium
- solid media, SDA (Sabouraud Dextrose Agar): pH- 5.4
- Antibiotics: gentamicin, chloramphenicol (inhibit bacterial contamination)
- Cycloheximide to inhibit saprophytic fungi
- Other Agars: potato dextrose agar, brain heart infusion agar, Czapek Dox agar
- Special Media used if particular fungus is suspected
septate fungi lesion are nearly always (1)
aseptate fungi lesions are (2)
1- ascomycetes
2- zygomycetes
pseudohyphae is a characteristic of ___ infections
Candida spp.
low-angle hyphal branching is characteristic of (1)
right angle branching is characteristic of (2)
1- Aspergillus spp.
2- zygomycetes
hyphae coloration is describe as (1) or (2)
1- dematiaceous (dark)
2- hyaline (transparent)
enclosed spores = (1)
open spores = (2)
1- sporangia
2- conidiophores
what are Phialides
flask shaped cells from which conidia bud (a spore produced asexually by various fungi at the tip of a specialized hypha)
(1) are cells that become conidia as they break off from hypha, (2) are produced by budding from the ends of phialides or sides of hypha
1- arthrospores
2- chlamydospores
big spores = (1)
small spores = (2)
1- macroconidia
2- microconidia
define tuberculate
refers to ‘knobby’ appearance of a spore
describe typical microscopic features of yeast
oval/spherical, budding, or encapsulated
describe typical microscopic features of molds
hyphae, spores + spore forming structures
fungal samples may be prepared for stain by treatment with (1) where only the (2) feature survives and is visible in LM as (3)
1- 10% KOH
2- chitinous hyphae
3- hyaline shadows
Calcofluor white stain binds to (1) and is critical because it (2)
1- chitin
2- fluoresces under UV light
____ is a key Gram+ fungi
Candida albicans
_____ is stain used to demonstrate hyphae, spores, and conidiophores
gomori methenamine silver staining
list ways to control fungal infections
- anti-fungal compounds that target specific pathways
- surgical removal of damaged tissue (some cases)
- prevention of infection via masks and protective clothing to reduce contact w/ spores
Note- immunization is usually not effective
list two key pathways targeted by anti-fungals
- inhibition of ergosterol, β-glucan, chitin biosynthesis
- inhibition of DNA synthesis by depleting thymine pools
