dermatophytes Flashcards
the cause of tinea or ringworm infections
dermatophytes
common characteristics of dermatophytes
all have septate hyphae- slow growers
often seen in KOH prep
ID by type of conidia they have
found on supporting structures known as conidiophores
microsporum
infect hair and skin
IF macroconidia- thick walled
macro and micro
trichophyton
infect hair, skin, and nails
if there are macro conidia they are thin walled
epidermopyton
infect skin and nails
macroconidia- club shaped; rare
dermatophytes can cause the hair to have
endothrix or ecothrix
ecothrix
usually doesn’t invade into the hair shaft
endothrix
means that is normally will invade into the hair shaft itself
what are dermatophytes best plated on
cornmeal or potato dextrose
gold standard for viewing conidial structure
slide cultures
microsporum audouinii
more common in kids
infect scalp, sometimes skin
microscop- juse see sterile hyphae (no spores); a few chlamydospores
comb like pectinate hyphae
wood lamps+
microsporum audouinii color
greyish white in color
Microsporum canis
transmitted puppies or kittens
scalp or skin infections
fluffy, yellow pigmented
reverse yellow
Microsporum canis ID
by macroconidia- have 6 septations and pointed ends
remember all dermatophytes have septate hyphae
microsporum gypseum
adults
geophilic organism and transmitted by infected dirt
skin infections
how is gypsum differentiated from canis
gypseum is more rounded at the end
-6 or less septations and described as cigar shaped
Trichophyton mentagrophytes
very common in lab
transmitted: animals, dirt of humans
common cause of athletes foot and infection of nails
Trichophyton mentagrophytes
hair infection type
endothrix- infect shaft
can see in hair penetration test
urea + in 4 days
characteristics of Trichophyton mentagrophytes
microconidia looks like cross
characteristics coiling!!
how is Trichophyton mentagrophytes
different from canis
mentagrophytes
-top is tan or buff colored and reverse is salmon
most common infecting human
T.Rubrum
-mainly affecting skin and nails
T.Rubrum
another common cause of athletes foot
elliptical or tear drop shape
micro- resemble “birds on a wire”
T.Rubrum color
whitish and reverse is red
-enhance on corn meal
major cause of tinea capitis
T.tonsurans
disease that T.tonsurans causes
black dot ringworm
-hair will break off at shaft of scalp leaving black dot
T.tonsurans microscopically
bizarre shaped microcon
may see club shaped or balloon
may see chlamydospores
most severe form of tinea capitis
T.schoenleneii
T.schoenleneii infection
may result in permanent hair loss and scarring of scalp
called favus
T.schoenleneii microscopically
produce irregular hyphae said to look like favic chandeliars
-moose antlers
no macro or micro conidia
common cause of jock itch
Epidermophyton floccosum
Epidermophyton floccosum
ID
club shaped macro conidia in clusters of 2 or 3 at the end of hypael element
looks different for each cultures
