Cutaneous and Subcutaneous Mycoses PART2 Flashcards
are immediately recognized by the
presence of large (8 to 15 μm × 35 to
150 μm) spindle-shaped, echinulate
(covered with small spines), rough-walled macroconidia with thick walls (up to 4 μm) containing four or more septa
Microsporum spp.
The exception Microsporum
which characteristically produces
macroconidia with two cells instead of 4 or more cells
Microsporum nanum,
Microconidia, when present, are
small (3 to 7 μm) and club-shaped
and are borne on the hyphae, either
laterally or on short conidiophores.
Microsporum spp.
develop either rapidly or slowly (5 to 14 days) and produce aerial hyphae that may be velvety, powdery, glabrous, or cottony, varying in color from whitish, to buff, to a
CINNAMON BROWN with varying shades
on the reverse side of the colony.
Microsporum spp.
is anthropophilic and is spread directly by
means of infected hairs on hats, caps, upholstery, combs, or barber clippers
.Most infections are chronic; some heal spontaneously, whereas others may persist for several years
M. audouinii
Infected hair shafts fluoresce yellow-green under a Woods lamp. Grow more slowly than other members of the genus Microsporum (10 to 21 days)
M. audouinii
- produce a velvety aerial mycelium that is colorless to light gray to tan
- reverse side often appears salmon-pink to
reddish-brown
M. audouinii
Most commonly, atypical vegetative forms, such as terminal chlamydoconidia and antler and racquet hyphae, are the only clues to the identification of this organism
M. audouinii
often is identified as a cause of infection by
exclusion of all the other dermatophytes.
M. audouinii
primarily a pathogen of animals (zoophilic) .Hairs infected with ___fluoresce a bright
yellow-green under a Woods lamp
M. canis
Direct examination of a calcofluor white or potassium hydroxide preparation of infected hairs reveals small spores (2 to 3 μm) outside the hair
M. canis
grow rapidly, are granular or fluffy with a feathery border, white to buff, and characteristically have a lemon-yellow or yellow-orange fringe at the periphery
M. canis
On aging, the colony becomes dense and cottony and a deeper brownish-yellow or -orange and frequently shows an area of heavy growth in the center
M. canis
reverse side of the colony is bright yellow, becoming orange- or reddish-brown with age
M. canis
shows an abundance of large
(15 to 20 μm × 60 to 125 μm), spindle shaped,
multisegmented (four to eight) macroconidia with curved ends; thick-walled with spiny (echinulate) projections on their surfaces
M. canis
free-living fungi of the soil (geophilic) that
only rarely causes human or animal infection and occasionally m .Infected hairs generally do not fluoresce under a Woods lamp
M. gypseum
microscopic examination of the infected hairs shows them to be irregularly covered with clusters of spores (5 to 8 μm), some in chains
M. gypseum
grow rapidly as flat, irregularly fringed colonies with a coarse, powdery surface that appear to be buff or cinnamon colored
M. gypseum
underside of the colony is orange to brownish
M. gypseum
macroconidia are seen in large numbers and are characteristically large, are ellipsoidal, have rounded ends, and are multisegmented (three to nine) with echinulated surfaces
M. gypseum
the only member of the genus Epidermophyton, is a common
cause of tinea cruris and tinea pedis
E. floccosum
susceptible to cold, specimens
submitted for dermatophyte culture
should not be refrigerated before
culture, and cultures should not be
stored at 4°C
E. floccosum
Direct examination of skin scrapings
using the calcofluor white or potassium hydroxide preparation, the fungus is seen as fine branching hyphae
E. floccosum
grows slowly; the growth appears olive-green to khaki, with the periphery surrounded by a dull orange-brown
E. floccosum
After several weeks, colonies develop
a cottony white aerial mycelium
that completely overgrows the colony the mycelium is sterile and remains so
even after subculture
E. floccosum
Microscopically, numerous smooth, thin-walled, club-shaped, multiseptate (2 to 4 μm)
macroconidia are seen
Epidermophyton sp
They are rounded at the tip and are
borne singly on a conidiophore or in
groups of two or three
Epidermophyton sp.
Microconidia are absent, spiral
hyphae are rare, and chlamydoconidia
are usually numerous
Epidermophyton sp.
