DD- MEDICAL MYCOLOGY Flashcards
Fungi are _______ to bacteria, and thus, are largely insensitive to antibacterial antibiotics.
unrelated
_____ are eukaryotic, aerobic, unicellular or filamentous, heterotrophic organisms encased in a rigid cell wall
Fungi
Fungi may reproduce by _________means, and the nature reproduction is used in classification
sexual and/or asexual
As eukaryotes, fungal cells contain membrane bound organelles including
nuclei, mitochondria, Golgi apparatus, endoplasmic reticulum, and _____
lysosomes.
Fungi lack ______and are not photosynthetic (autotrophic) like plants and algae, but instead obtain necessary organic substrates from their surroundings.
chlorophyll
Fungi have _____walls
rigid cell
Fungi have cell walls contain chitin (a material also found in the exoskeleton of insects) and also _______ (a material found in plant matter).
cellulose
Fungi also have a cell membrane inside of the cell wall which contains ______.
ergosterol
As eukaryotes, fungal cells contain membrane bound organelles including
______, mitochondria, Golgi apparatus, endoplasmic reticulum, and lysosomes.
nuclei
Fungal species may be subclassified as (4)
saprobes
symbionts
commensals
parasites
________live upon dead and decaying organic matter.
Saprobes
Fungi have cell walls contain ______ (a material also found in the exoskeleton of insects) and also cellulose (a material found in plant matter).
chitin
As eukaryotes, fungal cells contain _____
membrane bound organelles
_______live upon another organism to the mutual advantage of both.
Symbionts
______live upon another organism with no detriment to the host.
Commensals
_______live upon another organism with clear detriment to the host.
Parasites
YEAST - a ______ growth form
unicellular
MOLDS - a ______growth form
filamentous
the fungus reproduces via budding
to form blastoconidia, or by dividing in half through fission
YEAST- unicellular
the fungus reproduces via formation of spores or conidia. These filamentous elements are called hyphae.
MOLDS- filamentous
A mass of hyphae is referred to collectively as:.
mycelium
Septa divide hyphae into ______, but do not strictly divide the fungus into “cells,”
compartments
_______ are simply elongated yeast linked together like sausages
Pseudohyphae
- DO NOT have cytoplasmic connections
specialized from of hyphal elements that grow like roots from larger hyphae
rhizoids
demonstrate complete cell walls that
subdivide the hyphae into compartments
SEPTA – septate hyphae
*subdivisions are NOT equivalent to “cells,”
asexual spores usually borne off of specialized aerial hyphae
CONIDIA
large and multinucleated (macroconidia) or small and unicellular (microconidia)
similar to macroconidia, except that the asexual spores are enclosed in a membranous sac that breaks and the
entire structure is borne by a sporangiphore
SPORANGIA
thick-walled, round spores that
are highly resistant to adverse environmental conditions.
CHLAMYDOSPORES
like chlamydospores, arthrospores develop along the hyphae, but in general they are more numerous and elongated, often with a
shape likened to a “barrel.”
ARTHROSPORES
large, asexual spores that develop during the yeast phase of some organisms growth. The yeast form of the dimorphic fungus
spherules in tissue that are filled with endospores
SPHERULES
yeasts that bud asymmetrically are said to form:
BLASTOCONIDIA
thick-walled, environmentally
protective forms of yeast that are produced by some medically-relevant fungi
that reproduce by fission
SCLEROTIC BODIES
250,000 known forms of fungus, but only about ______ which are implicated in disease of humans
100-150
medically-relevant fungi are divided simply into:
- Superficial fungal infections
2. Deep fungal infections/Systemic mycoses
The three most common superficial fungal infections include:
dermatophytes, Candida and Pityrosporum species.
defined as a group of hyphal fungi that utilizes keratin as a substrate for growth.
DERMATOPHYTES
a non-dermatophyte yeast that prefers the glucose of interstitial fluids for growth.
CANDIDA
yeast that prefers breakdown products of sebum (“skin oil”)
PITYROSPORUM
dermatophytes, Candida and Pityrosporum species are
The three most common superficial fungal infections
The presence of ______ in fungal cell membranes, and its absence in animal cell membranes, makes it a useful target for antifungal drugs
ergosterol
bind with ergosterol in the fungal cell membrane, and react with animal sterols to much lesser extent
POLYENES
fungicidal
binds to ergosterol, creating a pore in the fungal membrane, which causes ions and other molecules to leak out of the cell
common medication for life-threatening fungal infections.
Amphotericin B
inhibit the enzyme, 14α-demethylase. This enzyme converts lanosterol to ergosterol, and it is required in fungal cell membrane synthesis.
imidazole and triazole antifungals
interfere with cytochrome P450 enzymes,
leading to potentially fatal drug interactions with certain medications
imidazole and triazole antifungals
inhibit the enzyme squalene epoxidase, another enzyme required for ergosterol synthesis. The inhibition of this enzyme leads to accumulation of squalene within the fungal cell and this is directly toxic, making these agents fungicidal, rather than fungistatic.
ALLYLAMINES/BENZYLAMINES
inhibit the synthesis of glucan in the cell walls of some fungi, probably via inhibition of the enzyme 1,3-β glucan synthase.
ECHINOCANDINS
inhibits fungal cell mitosis by disrupting mitotic spindle formation, a critical step in cellular division.
Griseofulvin
interrupts DNA synthesis, inhibiting fungal
growth.
Flucytosine
chelate polyvalent metal cations, such as Fe3+ and Al3+ leading to inhibition of many different fungal enzymes,
Ciclopirox olamine
