Intro to Mycology

fungi does not contain chlorophyll

true

fungi contains chlorophyll

false

fungal cell wall has

chitin and glucan

fungal cell membrane has

ergosterol

found in cell wall of zygomycota, B (1,4)-linked polymer of glucosamine

chitosan

previously phylum zygomycota or mucormycota, lower group of fungi, 4 subphyla, 2 zoopathogenic orders Mucorales and Entomophthorales

phylum glomeromycota

includes >60% of known fungi and about 85% of human pathogens

phylum ascomycota

cause Pneumocystis pneumonia

phylum ascomycota

cause cryptococcosis

phylum basidiomycota

infection limited to very superficial surface of skin and hair, nondestructive, cosmetic importance only

superficial

infection of keratinized layer of skin, hair, nails, elicit host responses, symptomatic

cutaneous

involve deeper skin layers, localized, rarely systematic, by trauma

subcutaneous

true pathogens, infection in healthy individuals, by dimorphic fungal pathogens

systemic

by fungi normally found as human commensals, low or limited virulence, cause infection in debilitated, immunosuppressed, implanted devices

opportunistic

unicellular organism, reproduce by budding or fission

yeast

chain of elongated yeast cells when buds fail to detach

pseudohyphae

multicellular, with thread-like tubular structures called hyphae that elongate at their tips

mold

occur as 2 forms

dimorphic fungi

yeast can be gram-positive

true

yeast can be gram-negative

false

hyphae elongate at tips known as apical extension

true

hyphae elongate at ends known as terminal extension

false

mass of hyphae

mycelia

formed as process of hyphal extension, have septal pore for cytoplasmic and organelle movement

primary septa

imperforate, formed to wall off ageing parts of mycelium or adventitious

secondary septa

filaments lack crosswalls

coenocytic

growth within surface of medium (agar)

vegetative

filaments extend above surface, stick up into air

aerial

in dimorphic fungi, pathogenic form, seen in human tissue, cultured at 37C

yeast

in dimorphic fungi, saprophytic form, observed in nature, cultured at 25C

mold

reproduction via meiosis, forms ascospores

se xual reproduction

formed by mitosis in or on conidiophores or sporangiophores, conidia → conidiospores → sporangiospores

ase xual reproduction

form of fungi that produce sexual spores

teleomorph

form of fungi that reproduce asexually

anamorph

borne naked on specialized structures

conidia

produced in sporangia, seen in Order Mucorales

sporangiospores

seen in Aspergillus, Penicillium, dermatophytes

conidia

type of conidia, cell reproduce by budding, daughte cell pinch off from mother cell

blastoconidia

type of conidia, hyphae break or fragment at separation points and form small pieces that give rise to new hyphae

arthroconidia

type of conidia, has terminal and intercalary chlamydospores, round and thick-walled conidia that form within or at ends of hyphae

chlamydoconidia

interfere with serologic test, cause false positive

skin testing

most tests for antibodies lack sensitivity and specificity for diagnosis of invasive infections

true

most tests for antibodies lack specificity only for diagnosis of invasive infections

false

detected in serum of patients with Candida and Aspergillus through limulus lysate assay

1,3 B-glucan

immunoassay detects Aspergillus

galactomannan

immunoassay detect Candida

mannan and anti-mannan

blue nucleus, clear or pink cytoplasm

giema stain

brown-black yeast and hyphae, green counterstain, stain cell wall only

GMS or silver stain

pink cell wall, counterstain is blue or green

periodic acid schiff

detect intracellular H. capsulatum and both intracystic and trophic form of P. jirovecii, DO NOT stain cyst wall of Pneumocystis

giemsa stain

best stain for detecting all fungi

GMS or silver stain

rapidly detects fungal cell wall chitin by bright fluorescence

calcofluor white stain

demonstrate host reaction in infected tissue

H&E

for demonstrating capsular materual of C. neoformans, stain cell walls of B. dermatitidis

mucicarmine stain

SDA culture not considered negative for growth until after 4 weeks of incubation

true

SDA culture not considered negative for growth until after 2 weeks of incubation

false

has largely replaced SDA to grow fungi, promote faster growth of fungi

brain heart infusion agar

coupled with rapid trehalose test for Candida isolation

CHROMagar

bind ergosterol in fungal cell membrane that results in leakage of intracellular contents

amphotericin B

disrupts ergosterol synthesis by inhibiting lanosterol 14-a-demethylase cytochrome

azoles

modest broad spectrum and toxicity, endocrine side effects

ketoconazole

excellent bioavailability, primary therapy for candidemia, cryptococcosis, coccidioidomycosis, agent of choice in meningitis by C. immitis

fluconazole

treatment of choice for lymphocutaneous sporotrichosis

itraconazole

primary indication for invasive aspergillosis

voriconazole

slow acting drug for skin and nail infections, accumulate in stratum corneum

griseofulvin

interferes with RNA/DNA synthesis, used in combination with amphotericin B and fluconazole

5-fluorocytosine

inhibits squalene epoxidase

allylamines

inhibit glucan synthesis in fungal cell wall

echinocandins