CUTANEOUS MYCOSES Flashcards
- Most common fungal infections of humans
Cutaneous mycoses
Usually referred to as tinea
Cutaneous mycoses
Tinea latin
Worm or ringworm
Ringworm of the body
Tinea corporis
Ringworm of the groin or “jock itch”
Tinea cruris
Ringworm of the scalp and hair
Tinea capitis
Ringworm of the beard
Tinea barbae
Ringworm of the nail
Tinea unguium
Scalp (crusty hair)
Tinea favosa
Tinea manuum
Palmar region of hand
Back, arms and abdomen
Tinea imbricate
Region of face without beard
Tinea faciei
Arms, neck and hands
Tinea gladiatorum
Cutaneous mycoses
a. Trichophyton
b. Epidermophyton
c. Microsporum
Cutaneous mycoses
Trichophyton spp.
Trichophyton rubrum
Trichophyton mentagrophytes
Trichophyton tonsurans
Trichophyton verrucosum
Trichophyton shoenleinii
Trichophyton violaceum
most important and common causes of infections of the feet and nails
Trichophyton spp.
Cutaneous mycoses
Commonly seen in adult infections
Trichophyton spp.
Cutaneous Mycoses
- Most cosmopolitan species are anthropophilic or “human loving”
Trichophyton spp.
Cutaneous Mycoses
Trichophyton spp most of them are
Anthropophilic or human loving
Hairs infected with Trichophyton
organisms do not fluorescence under the UV light of a ________________
Woods lamp
Hairs infected with _______ organisms do not fluorescence under the UV light of a Woods lamp
Trichophyton
reveal the presence of hyaline septate hyphae or arthroconidia
Calcofluor white/KOH preparations
Infected hairs that show external masses of spores that ensheaths the hair shaft
Ectothrix infection
infected hairs reveal hyphae and air spaces within the shaft
Trichophyton schoenleinii
Final identification of of dermatophytes are typically made by ____
Cultivation
Initial growth must be subcultured onto _______________ or ______________ to induce sporulation
cornmeal agar or potato dextrose agar
birds on a fence
Trichophyton spp.
Macroconidia of trichophyton
Smooth, club-shaped, thin-walled
macroconidia are borne singly at the terminal ends of hyphae or on short conidiophores
Microconidia trichophyton
Microconidia described as “birds on a fence” predominate and are usually spherical, pyriform (teardrop-shaped) or clavate (club-shaped)
complex are the most common species recovered in the clinical laboratory
T. rubrum and T. mentagrophytes
slow-growing, produces a flat/heaped-up colony, generally white to reddish, with a cottony or velvety surface
T. Rubrum
Reverse side of T.rubrum
Cherry red color
T. Rubrum Two types of colonies may be produced:
Fluffy and granular
microconidia are uncommon in most of the fluffy strains and more common in the granular strains
T. Rubrum
Microconidia occur as small, teardrop-shaped conidia often borne laterally along the sides of the hyphae
T. Rubrum
Macroconidia are less common; they appear in granular strains as thin-walled, smooth-walled, multi celled, cigar-shaped conidia with three to eight septa
T. Rubrum
has no specific nutritional requirements
T. rubrum
Does not perforate hair in vitro or produce
urease
T. Rubrum
T. mentagrophytes produce two distinct colonial forms:
downy variety recovered from patients with tinea pedis
the granular variety recovered from lesions acquired by contact with animals
Rapidly growing colonies
T. Mentagrophytes
Appear white to cream-colored or yellow
T. Mentagrophytes
T. Mentagrophytes
Reverse side of colony is usually
Rose-brown occasionally orange to deep red (may be confused for T. rubrum)
T.mentagrophytes macro and microconidia
microconidia in grapelike clusters and thin-walled,
smooth walled, cigar-shaped
Macroconidia characteristically exhibit a definite narrow attachment to their base.
_________________ produce urease within
2 to 3 days after inoculation onto____________
T.mentagrophytes
Christensen urea agar
Perforate hair
T.mentagrophytes
responsible for an epidemic form of tinea capitis that commonly occurs in children
T.tonsurans
causes a low-grade superficial lesion of varying
severity and produces circular, scaly patches of
alopecia (loss of hair)
T.tonsurans
The stubs of hair remain in the epidermis of the scalp after the brittle hairs have broken off, which may give the typical “_________________” appearance
Black dot ringworm
The stubs of hair remain in the epidermis of the scalp after the brittle hairs have broken off, which may give the typical “black dot” ringworm appearance
T.tonsurans
buff to brown, wrinkled, and suedelike in appearance.
T.tonsurans
colony surface shows radial folds and often develops a craterlike depression in the center with deep fissures
T.tonsurans
T.tonsurans Reverse side of the colony
yellowish- to reddish-brown
T.tonsurans
With age, the microconidia tend to become pleomorphic, are swollen to elongated, and are referred to as
Balloon forms
T.tonsurans growth is greatly enhanced by the presence of
Thiamine and inositol
most often seen in farmers, who acquire the infection from cattle
T.verrucosum
lesions are found chiefly on the beard, neck, wrist, and back of the hands and are deep, pustular, and inflammatory
T.verrucosum
T.verrucosum Direct examination of the hair shaft reveals
sheaths of isolated chains of large spores
T.verrucosum
surrounding the hair shaft
Ectothrix
T.verrucosum
hyphae within the hair
Endothrix
T.verrucosum growth is enhanced at 35°C to 37°C and on media enriched with
Thiamine and inositol
T.verrucosum Early detection medium by
Kane and Smitka
T.verrucosum
Early detection medium (Kane and Smitka)
4% casein and 0.5% yeast extract
organism is recognized by its early hydrolysis of
casein and very slow growth rate
Kane and Smitka= 4% casein and 0.5% yeast extract
Colonies are small, heaped, and folded; occasionally they are flat and disk-shaped.
T.verrucosum
T.verrucosum
At first, they are _________________________________. Colonies range from _______________________________.
glabrous and waxy, with a short aerial mycelium
gray and waxlike to bright yellow.
causes a severe type of infection called favus; characterized by the formation of yellowish cup-shaped crusts, or scutulae on the scalp
T. schoenleinii
Trichophyton schoenlii
A distinctive invasion of the infected hair, the _____________, is demonstrated by the presence of large, _________________ of hyphae and arthroconidia at the base of the hair follicle and branching hyphae throughout the length of the hair shaft
Favic type
Inverted cones
T.schoenleinii
produces a ______________colony with a _________
White to light gray
Waxy surface
Colonies have an irregular border consisting mostly of submerged hyphae, which tend to crack the agar.
T.schoenleinii
The surface of the colony is usually nonpigmented or tan, furrowed, and irregularly folded
T.schoenleinii
T.schoenleinii The reverse side of the colony is usually
Tan or nonpigment
The hyphae tend to become knobby and club-shaped at the terminal ends, with the production of many short lateral and terminal branches
T.schoenleinii
All strains may be grown in a vitamin-free medium and grow equally well at room temperature or at 35°C to 37°C.
T.schoenleinii
Beginning as cone-shaped, cream-colored, glabrous colonies
T.violaceum
Later these become heaped up, verrucous (warty), violet to purple, and waxy in consistency
T.violaceum
T.violaceum
Colonies may often be described as
Port wine
T.violaceum
The reverse side of the colony is
Purple or nonpigment
microconidia and macroconidia generally are not present; only sterile, distorted hyphae and chlamydoconidia are found
T.violaceum
Growth of T. violaceum is enhanced on media
containing
Thiamine
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 is ____________________, which characteristically produces macroconidia with two 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
Cultures of Microsporum spp. develop either __________________________ and produce aerial hyphae that may be velvety, powdery, glabrous, or cottony, varying in color from ______________, to __________, to a _______________, with varying shades on the reverse side of the colony.
rapidly or slowly (5 to 14 days)
whitish, to buff, to a cinnamon-brown
is anthropophilic and is spread directly by means of infected hairs on hats, caps, upholstery, combs, or barber clippers
Microsporum audouinii
Most infections are chronic; some heal spontaneously, whereas others may persist for several years
M.audouinii
M. audouinii
- Infected hair shafts fluoresce _________ under a Woods lamp.
Yellow-green
M.audouinii produce a velvety aerial mycelium that is ______________
colorless to light gray to tan
M.audouinii reverse side often appears
salmon-pink to reddish-brown
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)
Microsporum canis
Hairs infected with M. canis fluoresce a_____________ under a woods lamp
Bright yellow green
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
Microsporum canis
M.canis
On aging, the colony becomes dense and cottony and a ________________________ and frequently shows an area of heavy growth in the center.
deeper brownish-yellow or -orange
M.canis reverse side of the colony is ___________ , becoming ___________________ with age
Bright yellow
orange- or reddish-brown
Microscopically, _______ 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 surface
M.canis
free-living fungi of the soil (geophilic) that only rarely causes human or animal infection and occasionally may be seen in the clinical laboratory
M.gypseum
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 __________
M.gypseum
Buff or cinnamon colored
M.gypseum underside of the colony is
Orange to brownish
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
Epidermophyton floccosum
____________ , specimens submitted for dermatophyte culture should__________________ before culture, and cultures should not be stored at _______
Susceptible to cold
Should not be refrigerated
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Epidermophyton direct examination of ________________ using______________ or _____________ is seen as ________________
Skin scrapings
Calcoflour white or pottasium hydroxide
Fine branching hyphae
E. floccosum grows slowly; the growth appears______________, with the periphery sorrounded by ____________________
Olive-green to khaki
Dull orange-brown
After several weeks, colonies develop a cottony white aerial mycelium that completely overgrows the colony
Epidermophyton
Epidermophyton the mycelium is _____________ and remains so even after subculture
Sterile
Microscopically, numerous smooth, thin-walled, club-shaped, multiseptate (2 to 4 μm) macroconidia are seen
E.floccosum
They are rounded at the tip and are borne singly on a conidiophore or in groups of two or three
E.floccosum
Microconidia are absent, spiral hyphae are rare, and chlamydoconidia are usually numerous
E.floccosum
