Mycology 1 Flashcards
what is structure of fungi capsule? what is the function of this?
polysaccharide; antiphagocytic and virulence factor
aka encapsulated yeast
Cryptococcus neoformans
what makes up cell wall of fungi
polysaccharides (hexose and hexosamine polymer), proteins and glycoproteins
energy source for fungi
heterotrophs or chemotrophs
fungi grow best at pH less than this
5
are yeast or molds aerobes?
molds
this protects most fungi from osmotic shock
cell wall
formed by fragmentation of septate hyphae into single, slightly thickened cells
arthrospore
formed by rounding and enlargement within a hyphae segment
chlamydospore
this if formed within a sac (sporangium) at the end of an aerial hyphae (sporangiophore)
sporangiospore
what are asexual spores?
arthrospore, chlamydospore, sporangiospore, conidiospore, blastospore
unicellular or multicellular spore that is not enclosed in a sac…produced at chain at end of conidiophore
conidiospore
formed by a bud coming off the parent cell
blastospore
what does lactophenol cotton blue stain? what structures will stain as a result?
chitin and cellulose; yeast cells, mycelia, fruiting structures
what is mounting fluid for lactophenol cotton blue?
phenol
three antimicrobial agents used in Dermatophytes test medium (DTM)
cycloheximide, chlortetracycline, gentamicin
this is produced by dermatophytes…changes phenol red indicator from yellow, to pink, to red (in DTM test)
alkaline metabolites
used for isolation/cultivation of path and non-pathogenic yeasts and molds; what enriches this growth? what inhibits?
Sabouraud Dextrose Agar; carbohydrate, low pH
metabolism for fungi
aerobic or facultative anaerobic
Blue-gree mold that makes Raquefort cheese
Penicillium roqueforti
how yeast can divide
binary fission, budding, sexual
extend below the surface of the medium for food collection (root structure)
vegetative mycelium
part of mycelium above the surface, fleshy fungi (like mushrooms)
reproductive/aerial mycelium
the vegetative body of a fungus
mycelium
polymers found in polysaccharides of fungal cell wall
chitin, chitosan, cellulose, a-Glucan, B-Glucan, mannan
sterols in cell membrane of fungi (instead of cholesterol)
ergosterol and zymosterol
enzyme necessary for ergosterol synthesis (lanosterol to 1 4-demethyl lanosterol)
cyto p450 1 4a demethylase
typical reproductive unit of fungi
spore
sexual spores
ascospore, basidiospore, zygospore
asexual spores
arthrospore, chlamydospore, sporangiospore, conidiospore, blastospore
formed within saclike cells (after cellular and nuclear union); sexual spore
acospore
formed at end of club shaped structures, sexual spore)
basidiospore
sexual spore…formed after cellular and nuclear fusion, large thick walled single structure
zygospore
this is used to detect fungi by dissolving human cells in a culture (denatures proteins in human cell but not fungus wall)
KOH
what is added in KOH test procedure to make structures more clear
lactophenol cotton blue
this relies on oxidation of carbohydrates w/in fungus to form aldehyde groups…fungus stains black
methenamine silver stain
carbs and glycogen oxidized to aldehydes…Reagent colors them a bright magenta color (*polysaccharides are strongly stained*)
PAS stain
india ink is used to detect these kinds of fungi (specificity is limited)
encapsulated fungi
makes brown colonies on growth medium containing extract of seeds of Indian thistle plant (caffeic acid in seed, oxidized by phenol oxidase)
Cyptococcus neoformans
what do polyenes bind to in fungi to increase membrane permeability?
ergosterol (increase membrane permeability)
used as oral or topical treatment for vaginal candidiasis
Nystatin
polyene used for disseminated fungal infections (given IV)…have severe side effects
amphotericin B
what makes polyenes nystatin and amphotericin B?
Streptomyces bacteria
azoles applied topically for superficial infections
miconazole, ketoconzaole, clotrimazole
azoles that treat systematic infections (such as cadidiasis, cryptococcus, histoplasmosis, blastomycosis)
itraconzaole, fluconazole, voriconazole
what do azoles inhibit?
cytochrome P450 (block ergosterol synthesis)
first step in synthesis of ergosterol (catalyzed by cytochrome P450…inhibited by azoles)
demethylation of lanosterol
what does flucytosine inhibit?
DNA synthesis
used for dermatophytes infection…binds to tubulins involved in MT formation…prevenst separation chromosomes at mitosis
Griseofulvin
used for dermatophyte infection…inhibits squalene eposixdase (in ergosterol synthesis)…as tables or cream
Terbinafine
used to treat aspergillosis, candida spp….inhibits glucan synthesis (block cell way synthesis)
Caspofungin
what does Caspofungin inhibit?
glucan synthesis (block cell wall synthesis)
what does Terbinafine inhibit?
squalene epoxidase (ergosterol synthesis)
infection caused by fungi
mycose
how is superficial dermatophytes transmitted?
direct contact with spores
infect most superficial area of skin…adhere to keratinized tissue…secrete keratinase…invade and grow (*little or no host immune response*)
superficial dermatophytes
two superficial dermatophytes that involved hair of scalp
black and white piedra
two superficial dermatophytes that involve hairless skin
Tinea versicolor and Tinea nigra
superficial dermatophyte that has mild to chronic colonization of stratum corneum…Tinea infection of hairless skin
Pityriasis versicolor
causes Pityriasis versicolor…yeast is lipophilic (needs oil)
Malassezia furfur
what is infected by Tinea nigra/Pityriasis nigra (*Exophiala werneckii*)
stratum corneum
presents with brown/black nonscaly macules with well defined borders; what part of body is most affected?
Tinea nigra; palms
treatment for Tinea nigra
oral azoles
diagnosis for Tinea nigra
scraping mounted in 10% KOH
where is Tinea nigra commonly found?
tropical climates (contact with decaying vegetation, wood, soil)
transmission of cutaneous dermatophytes (dermatophytosis) by these routes are easily treated
soil and animales
will see this on skin for diagnosis of dermatophytosis (cutaneous dermatophytes)
septate, branching hyphae or chain of arthroconidia
cutaneous dermatophyte genera…form dense sheath of spores around the hair (*ectothrix*)
microsporum
cutaneous dermatophyte genera…produce arthrocondidia inside hair shaft (*endothrix*)
trichophyton
cutaneous dermatophyte genera…produce thin-walled macroconidia, banana bunches
Epiermophyton
dermatophyte infection that infects nails
Tinea Ungulum
dermatophyte infection that infects fingers and palms
Tinea manus
these cause Tinea capitis (ringworm of scalp, hair of head, eyebrows, eyelashes)
Trichophyton tonsurans, Microsporum audouinii, M. canis, T. verrucosum
age group affected by Tinea capitis (scaly scalp presentation)
4/14/2015
responsible for more than 90% of Tinea capitis in North America and UK
Trichophyton tonsurans
treatments for Tinea capitis
Griseofulvin and Ketoconazole
what causes Tinea Cruris (aka Jock Itch)…ringworm of groing, perineum, perianal region
E. floccuosum and T. rubrum
sharp demarcated lesions w/ raised erthematous margin, thin dry epidermal scaling (in groin, perineum, perianal region)
Tinea cruris
what areas of body are typically affected by Tenia superficial dermatomycoses (brown/red de-pigmented lesions, scaly patches of skin)
back, chest, abdomen, neck, upper limb
diagnosis of Tinea (Pityriasis versicolor)
yellow-green fluorescence under Wood’s lamp
what are systemic therapy options for Tinea (Pityriasis versicolor)
ketoconazole, fluconazole, itraconazole
shampoos that can treat Tinea (Pityriasis versicolor)
selenium sulfide, zinc pyrithione
what are other topicals that can treat Tinea (Pityriasis versicolor)
ciclopirox olamine, propylene glycol lotions, topical terbinafine (LAMISIL), benzoyl peroxide
only contagious fungal infections
cutaneous dermatomycoses/Ringworm
Trichophyton that cause cutaneous dermatomycoses
Rubrum, tonsurans, mentagrophytes, schoenleinii
Epidermophyton that causes cutaneous dermatomycoses
E. floccuosum
Microsporum that causes cutaneous dermatomycoses
M. audouinii
ringworm of the beard (bearded region of face and neck)
Tinea barbae
fungi that cause Tinea barbae
T. mentagrophytes and T. verrucosum
characterized by diffuse erythema, perifollicular papules and pustules (*endothrix*)…nodular lesions convered with crusts, hairs become loose and brittle
Tinea barbae
treatment for Tinea barbae
systemic antifungal agents
causes for Tinea corporis and Tinea faciei (ringworm of body, infection hairless region of skin and face)
Trichophyton rubrum, Microsporum canis, T. verrucosum, M. audouinii
characterstic lesions of Tinea corporis and Tinea faciei
active erythematous and spreading borders (central clearing…usually noninflammatory)
systemic therapy for inflammatory lesions of Tinea corporis and Tinea faciei
griseofulvin, terbinafine, ketoconazole, itraconazole
aka athlete’s foot…infection of feet, especially the toe web soles
Tinea pedis
what causes athlete’s foot (aka Tinea pedis)
E. floccosum, T. rubrum, T. mentagrophytes
what causes Tinea manus (dry scaly lesions of hand)
T. rubrum
what causes Tinea unguium (infection of nail plate…disfigured and distorted)
T. rubrum, T. mentagrophytes, E. floccosum
Tinea unguium epidemiology…more likely to happen if have these factors
older population, poor hygiene, immunodeficient, chronic water exposure
treatment for Tinea unguium
systemic antifungal
