Fungi Flashcards
Fungi are
Eukar and heterotrophic
Nomenclature
Mycota- mycetes- ales-acea
GENERAL CHARACTERISTICS
● Unlike animals, most fungi are nonmotile and
possess a rigid cell wall.
● Unlike plants, fungi are non photosynthetic
● Approximately 80,000 species of fungi but fewer
than 400 are medically important and less than
50 species of fungi cause more than 90% of
fungal infections of humans and other animals.
● Has at least one nucleus with nuclear membrane,
ER, mitochondria & secretory apparatus.
● Most are obligate or facultative aerobes
● They are chemotropic; secreting enzymes that
degrade organic substrates into soluble nutrients
passively taken into the cell by active transport.
Fungal infections are
mycoses
yeast
● Baking
● Brewing
antibiotics
● Penicillin
● Cephalosporin
Cyclosporin
foods
● Cheeses
● Blue
● Roquefort
steroids
● Hormones (reproductive)
experimental
● Metabolic studies
● Pathway studies
BIOREMEDIATION
● The use of some microorganisms to correct
mistakes in the environment
● Furthermore, in comparison with eight other
genera, aspergillus and penicillium species were
the most efficient metaboliser of hydrocarbons.
● Cyanide in mining operations
Oil spills:
Mucorales and Monilales, as well as in
the genera aspergillus and penicillin (order
eurotiales).
BAD EFFECTS OF THE FUNGI
● Destruction/Damages ● Food spoilage ● Crop destruction (photo pathogens) e.g strawberry roasts. ● Diseases - Harmful effects ● Destruction of wood and other part of the body
HYPERSENSITIVITY
An allergic reaction to molds and spores
Farmer’s lung-
moldy hay
Malt worker’s disease-
moldy barley
Cheese washer’s lung-
moldy cheese
Wood trimmer’s disease-
moldy wood
MYCOTOXICOSES
Poisoning of man and animals by food products
contaminated by fungi which produce toxins from
the grain substance
● Copra may also be devastated by the myecitus
group
MYCETISMUS
● The ingestion of toxins (amanita mushroom
poisoning)
● Not all mushrooms (biggest fungus) are edible
INFECTION
● Tissue invasion with a host response
● Diseases caused by fungi are referred to as the
mycoses
Tinea Nigra (Superficial)
○ Tinea nigra (or tinea nigra palmaris) is a superficial chronic and asymptomatic infection of the stratum corneum caused by the dematiaceous fungus Hortaea (Exophiala) werneckii. ○ The lesions appear as a dark (brown to black) discoloration, often on the palm. ○ Microscopic examination of skin scrapings from the periphery of the lesion will reveal branched, septate hyphae and budding yeast cells with melanized cell walls.
Pityriasis versicolor (Superficial)
○ Pityriasis versicolor is a highly prevalent, chronic superficial infection of the stratum corneum caused by species of the lipophilic yeast, Malassezia. ○ Mainly caused by the organism Malassezia furfur; the reaction of the melanocytes from the sun will be protected producing a whitish color if the person has brown skin; if the person has white skin, the area will be darker than the normal skin ○ The infection is characterized by discrete, serpentine, hyper- or hypo pigmented maculae that develop on the skin, usually on the chest, upper back, arms, or abdomen. These patches of discolored skin may enlarge and coalesce, but scaling, inflammation, and irrita- tion are minimal.
Black Piedra (Superficial)
a nodular infection of the hair shaft
caused by Piedraia hortae
White Piedra (Superficial)
due to infection with Trichosporon
species, presents as larger, softer,
yellowish nodules on the hairs
Athlete’s foot (Cut)
(TineaPedis
Ringworm (Cuta)
Tinea corporis
Dermatophytosis (Cuta)
Organism/s involved: Microsporum spp,
Trichophyton spp & Epidermophyton
floccosu
Candidias (cuta)
○ Organism involved: Candida albicans &
other speci
SPOROTRICHOS (SubQ)
○ Sporothrix schenckii is a thermally
dimorphic fungus that lives on vegetation
○ S. schenckii are introduced into the skin
by trauma and cause sporotrichosis, a
chronic granulomatous infectio
● Mycetomas (SubQ)
○ chronic subcutaneous infection induced by traumatic inoculation with any of several saprophytic species of fungi or actinomycetous bacteria that are normally found in soil. ○ The clinical features defining mycetoma are local swelling of the infected tissue and interconnecting, often draining, sinuses or fistulae that contain granules, which are microcolonies of the agent embedded in tissue material. ○ An actinomycetoma is a mycetoma caused by an actinomycete; a eumycetoma (maduromycosis, Madura foot) is a mycetoma caused by a fung
Chromoblastomycosis and
Phaeohyphomycosisv(SubQ)
similar diseases resulting from infection with dark-pigmented fungi. ○ Both are acquired by traumatic introduction of fungi into the skin. ○ Lesions may be extensive and can spread internally. ○ The two diseases are distinguished by differences in fungal morphology in tissue sections.
Histoplasmosis (Systemic)
○ Histoplasma capsulatum, which causes histoplasmosis, is associated primarily with bat and bird droppings in soil in the Ohio River valley. ○ Generally, histoplasmosis is an occupationally acquired disease, but recreational exposure does occur. H. capsulatum can be carried from the lungs inside macrophages
Blastomycosis (Systemic)
○ caused by Blastomyces dermatitidis, which normally lives in soil rich in organic material. ○ B. dermatitidis almost always spreads beyond the lungs to produce cutaneous lesions.
Coccidioidomycosis (Systemic)
Coccidioides immitis, which is limited to deserts, causes coccidioidomycosis, which is common in AIDS patients. ○ Contaminated dust is a major source of transmission.
Paracoccidioidomycosis (Systemic)
○ Paracoccidioides brasiliensis causes paracoccidioidomycosis. ○ Following a pulmonary phase, the fungus spreads and creates permanently disfiguring lesions on the face and neck
Oral candidiasis or thrush (opportunistic)
○ Commonly seen on patients with acute immunodeficiency ○ Classified by: ○ Lungs = caused by true pathogenic fungi ○ Other organ systems = caused by saprophytes
PATHOGENIC FUNGI
- NORMAL HOST
● Systemic pathogens = 25 species
● Cutaneous pathogens = 33 species
● Subcutaneous pathogens = 10 species - IMMUNOCOMPROMISED HOST
● Opportunistic fungi = 300 species
SEVERITY
● In general, the severity of mycotic infections
depends more on the host immune system than
on the virulence of the fungus.
● Fungi, in general, do not have very specific
virulence factors,except for some.
SPECIES
100,000 – 200,000 species
● About 300 are known to be pathogenic to man
● Earth is a moldy earth
● Most of them are soil saprophytes
CHARACTERISTICS
● Chemoheterotrophs (requires organic compounds for energy and a carbon source) ● Mainly terrestrial ● Lack Chlorophyll ○ Dark habitats ● Spore bearing ○ Reproduce sexually or asexually ● Thallus body ○ Collection or mass of the organism ○ Mass of hyphae
Cell wall =
chitin, glucan
Cell membrane
ergosterol
Nucleus
○ Membrane bound
○ Diploid chromosome
Cytoplasm
○ Similar to plants
○ Differential ribosomal synthesis
○ Different microtubule protein
Reproduction
○ Sexually (meiotic)
○ Asexually (mitotic)
Mode of nutrition
Heterotrophs ■ saprotrophs - dead organisms or their wastes (dung) ■ parasites - living cells of other fungi, plants or animals
Molds
● Made of long filaments called hyphae
● Hyphal or mycelial colony or form of growth
● You see in culture “cotton-like” and “leathery-like”
Yeast
Are non-filamentous unicellular fungi that are oval
or spherical in shape
● Unicellular, spherical to ellipsoid (3-15um) fungal
cells that usually reproduce by budding
● In some fungi, the two forms exist. Fungi, which
remain as molds, are monomorphic molds
while yeasts, which remain as yeasts are
monomorphic yeasts.
● Most molds grow at room temperature (30 to 35).
Generally, in the mold phase,if the organism
enters the body, they will change into the yeast
