Intro to Mycology Flashcards
What composes the cell wall of bacteria?
peptidoglycan
What composes the cell wall of fungi?
Glucan and chitin (glucosamine), and ergosterol
What makes treatment difficult for fungi?
they resemble human cells, eukaryotes
What is a single cell yeast?
conidium (conidia)
What is a bud from asexual reproduction?
blastoconidia
What are products of sexual reproduction (less common)?
ascospores
These form from elongation of blastoconidia (constrictions).
pseudohyphae
These are the beginning of true hyphae (no constrictions) .
germ tubes
If molds look fuzzy or wooly macroscopically and have entertwined hyphae this is also known as what?
Mass of mycelia
These are crosswalls that are present in hyphae.
septate
This means crosswalls are absent (or sparse), aka coenocytic
aseptate
This means hyphae growth within the surface of the medium (agar).
vegetative
These hyphae filaments extend above the agar surface (on top).
aerial
These hyphae are nonpigmented or slightly pigmented.
hyaline
These hyphae are dark or black (melanin) on the reverse side of the colony.
dematiaceous
These hyphae break or fragment; look like floating logs in a river
Arthroconidia
These are round and thick-walled conidia that form directly within or at the ends of hyphae; example includes Candida albicans
chlamydoconidia
This is a specialized part of the hyphal filament that gives rise to conidia.
conidiophore
What stains hair, skin, and nails and also breaks down keratin leaving an outline of the hyphae?
KOH
What stains patient specimens, chitin, using a fluorescent dye?
Calcofluor White
What stains the capsule of Cryptococcus in patient specimens?
India Ink
In this patient specimen stain, yeast stains blue.
Giemsa stain
All yeasts and hyphae turn brown-black with this patient specimen stain.
GMS (Gomori’s Methenamine Silver)
What is the best way to culture blood and bone marrow?
Isolator (lysis centrifugation)
What is the best way to culture hair, skin, and nails (dermatophyte infections)?
scrape outer edge of skin lesion and use 10-20% KOH
What two types of fungal isolation media do we use most commonly?
sabouraud dextrose agar (SDA or SAB) and potato dextrose (PDA) or Potato Flake (PFA)
What are the incubation requirements for molds and yeast?
mold: 22-25’C
yeast: 37’C
Describe what molds look like macroscopically?
fluffy and fuzzy (aerial mycelia)
Describe what yeast looks like macroscopically?
usually creamy (sometimes dry)
What is the best method to view molds?
slide cultures with LPCB (lactophenol cotton blue)
why do we see more recent cases of mycoses?
the host has changed, not the fungi
How do people get mycoses?
inhalation of mold condida most common way of mold infections
Describe fungal treatment, including common azole.
many agents are toxic to patients because cell wall structure so similar; common cause of renal toxicity= Amphotericin B
What is the most common antimicrobial susceptibility test of fungi?
broth dilution (standard method)
Most yeast like fungi stain gram ______.
Positive
Why do we use a class II safety hood when handling these organisms?
airborne conidia can cause infections with inhalation
What is CSAB (SAB with antimicrobials) used in lab?
Cyclohexamide inhibits bacteria and environmental fungi
What agar is used to examine yeast phase of dimorphics?
BHI with blood
What two other methods, besides slide culture, can you use to observe molds microscopically?
Tease mount in LPCB and cellophane tape preparation with LPCB
