DERMATOPHYTOSISElmer W. Koneman, M. D.University of Colorado School of MedicineRomanian Society of Laboratory Medicine 2008 Congress -- Bucharest, Oct. 20 22

COMMON DERMATOPHYTES

Genus MicrosporumMicrosporum canisMicrosporum gypseumGenus TrichophytonTrichophyton mentagrophytesTrichophyton rubrumTrichophyton tonsuransTrichophyton verrucosumGenus EpidermophytonEpidermophyton floccosum

THE DERMATOPHYTOSESCUTANEOUS MANIFESTATIONS: TINEA CORPORISThe lesions illustrated here are still annular and demarcated, but distinctly spreading.Illustrated are multiple, annular, sharply marginated lesions with a raised borderthus the name ringworm. Skin scrapings for examination and culture should be taken from the active outer margin of growth.

THE DERMATOPHYTOSESCUTANEOUS MANIFESTATIONS: TINEA CORPORISIllustrated in the photograph is an inflammatory type of dermatophytosis with erythema prominently displayed.The lesions here are distinctly vesicular with several bullae clearly visible.

THE DERMATOPHYTOSESTINEA CAPITIS CLINICAL VARIATIONSIllustrated is a well-demarcated area of hair loss (alopecia) with mild inflammation of the exposed skin.A more chronic manifestation of a circular area of alopecia that seen upper left, with surface crusting.

THE DERMATOPHYTOSESCUTANEOUS MANIFESTATIONS: TINEA CORPORIS.Progressive alopecia (favus) and mild inflammation involving the major portion of the scalp.Illustrated is the so-called black dot type of tinea capitus in which endothrix-infected hair shafts break off just above the surface leaving tiny black crusts.

THE DERMATOPHYTIC FUNGITinea capitis/corporis and Microsporum canisClose-in view of scalp illustrating a circumscribed area of alopecia, a picture consistent with tinea capitis. M. canis was recovered in culture.Close-in view of scalp illustrating a circumscribed area of alopecia, a picture consistent with tinea capitis. M. canis was recovered in culture.

THE DERMATOPHYTIC FUNGITinea manuumDirect presumptive diagnosisChronic tinea manuum infection illustrating extensive involvement of the palm of the hand with scaling and mild erythrma. Itching is often intense.10% potassium hydroxide mount of exfoliated skin scales from a suspected dermatophyte infection (left frame). Note the distinct hyphal strands, that segment into arthroconidia.

THE DERMATOPHYTIC FUNGIMicrosporum canis

THE DERMATOPHYTIC FUNGIMicrosporum canis: Culture characteristicsThe colony illustrated here is cottony. Characteristic of M. canis is an outer apron with a lemon-yellow pigmentation, that can be observed also on the reverse of the colony.Illustrated are multi-celled, spindle-shaped macroconidia, each with a tapered outer cell, and a break-away hilar cell (arrow). The conidia wall is thickened and rough.

THE DERMATOPHYTIC FUNGIMicrosporum canis: Laboratory IdentificationIllustrated are two views of the cottony colonies with the outer lemon-pigmented apron characteristic of M. canis.

THE DERMATOPHYTIC FUNGIMicrosporum canis: Laboratory IdentificationIllustrated are several spindle-shaped macroconidia of M. canis. Note that the terminal cell is tapered and slightly diplaced to one side (arrows).

THE DERMATOPHYTIC FUNGIMicrosporum canis: Clinical Correlation Microsporum canis is world-wide in distribution The major natural reservoir for M. canis is cats and dogs M. canis most commonly produces tinea capitis and tinea corporis ringworm type infections in humans Hair invasion is ectothrix in type The lesions tend to be inflammatory and generally resolve without progressing to chronic infections Other animals may be infected with different species: M. canis var. distortum is found in rural areas of New Zealand and Australia, with monkeys serving as host M. canis, var. obesum is also native to monkeys an apes M. canis, var. equinum has been recovered primarily from horses

THE DERMATOPHYTIC FUNGIMicrosporum gypseum

THE DERMATOPHYTIC FUNGITinea corporis and Microsporum gypseumImmature colony of M. gypseum after 3 days at 30oC. The granular surface indicates sporu-lation. The cinammon- yellow pigment is typical.Mature colony of M. gypseum illustrating a powdery (sportulating) surface and cinammon-buff pigmentation.Macroconidia of M. gypseum. Note the oval outline and the rounded terminal cell, in contrast to the tapered structure of the macroconidia of M. canis.THE DERMATOPHYTIC FUNGIMicrosporum canis: Laboratory Identification

THE DERMATOPHYTIC FUNGIMicrosporum gypseum: Clinical Correlation Microsporum gypseum is commonly recovered from soil throughout the world M. gypseum, similar to M. canis, produces tinea capitis and tinea corporis ringworm type infections in humans Hair invasion is ectothrix in type with the arthroconidia arranged in chains The lesions tend to be inflammatory and may become vesicular or pustular, with rapid development and resolution Other animals that may be infected and serve as sources of infections for humans include cats, dogs, rodents, horses, and monkeys

THE DERMATOPHYTIC FUNGITrichophyton mentagrophytes

THE DERMATOPHYTIC FUNGITrichophyton mentagrophytes: Laboratory DiagnosisInflammatory type of dermatophytosis, commonly observed in infections caused by Trichophyton mentagrophytes.Young colony of Trichophyton mentagrophytes illustrating a smooth to floccose white surface.

THE DERMATOPHYTIC FUNGITrichophyton mentagrophytes: Laboratory DiagnosisMature colony of T. mentagrophytes after 5 days incubation at 30oC. This colony becomes more floccose to granular indicating sporulation.Trichophyton mentagrophytes produces many microconidia that are spherical, uniform in size, and aggregate in loose clusters. Macro-conidia are few or absent.

THE DERMATOPHYTIC FUNGIT. mentagrophytes: Laboratory Features in ReviewA. A fluffy colony of T. mentagrophytes, with a slight tinge of reddish pigmentation at the periphery. The micro-scopic morphology (B) supports this identifi-cation. The diagnosis is confirmed by evidence of invasion of a hair shaft in the hair penetra-tion test shown by the arrow (C) and the strong positive urease test (diffuse red pigmenta-tion) in Frame D.

THE DERMATOPHYTIC FUNGITrichophyton mentagrophytes: Clinical Correlation Trichophyton mentagrophytes is comopolitan and among the most commonly recovered dermatophyte from humans and animals. T. mentagrophytes produces inflammatory lesions of tinea capitis, tinea corporis, tinea unguium, and tinea barbae infections in humans T. mentagrophytes is the usual etiologic agent of ringworm infections in labodratory animals and humans in the US. Hair invasion is small spore ectothrix type In tinea unguium infections, invades the nail plate, causing white-spot nail diseaseT. mentagrophytes

THE DERMATOPHYTIC FUNGITrichophyton rubrum

THE DERMATOPHYTIC FUNGIPhotograph of mild chronic tinea pedis infection with scaling and mild erythrma. Itching is often intense.Tinea unguium begins with the accumulation of subungual debris under the leading edge of the nail, or along the sides. The nail becomes thickened, chalky or yellow, often showing signs of cracking.Tinea unguium may continue until the entire nail is involved. Loosening of the distal nail may occur, potentially with detach-ment. Infection of the adjacent skin (paronychia) is evident in this photograph.Tinea rubrum: Clinical Infections

THE DERMATOPHYTIC FUNGITrichophyton rubrum: Laboratory FeaturesPhotomicrographs of colonies of T. ruburm after 5 days incubation at 30oC on Sabourauds dextrose agar. The surface of the colony (left frame) is flat and yellow-buff. Note the intense red water-soluble pigment produced by the isolate shown in the center frame. This characteristic pigment production (rubrum) may be best observed on the reverse side (right frame).

THE DERMATOPHYTIC FUNGITrichophyton rubrum: Laboratory FeaturesThe hyphae are hyaline, septate, and delicate. Diagnostic is the production of uniform, tiny, spherical microconidia that line up in a birds- on-a-fence arrange-ment along the hyphal strand. Macroconidia may be observed. They are multi-celled, long and pencil shaped with a thin, smooth wall, in contrast to the thick-walled, rough conidia seen with Microsporum sp.

THE DERMATOPHYTIC FUNGITrichophyton rubrum: Clinical Correlation Trichophyton rubrum is a common anthropophilic species and has become the most frequent etiologic agent of tinea cruris, tinea corporis, tinea pedis, and tinea manuum infections in humans throughout the world Hair invasion is uncommon but may be endothrix in type, serving as a reservoir for repeated exacerbations of disease The infection with T. rubrum is often chronic, and some individuals become lifetime carriers. In tinea unguium infections, T. rubrum does not invade the nail plate

THE DERMATOPHYTIC FUNGITrichophyton tonsurans

THE DERMATOPHYTIC FUNGITinea capitis/corporis and Trichophyton tonsuransT. tonsurans may cause both tinea capitis and tinea corporis. Tinea capitis is of the black-dot type, with black points of crusting where the endothrix-invaded hair shaft has fractured above the skin surface (left frame). Tinea corporis (right frame) is usually erythematous and spreads with a distinct outer border. Such infections are contagious and can be spread through human to human contact.

THE DERMATOPHYTIC FUNGITrichophyton tonsurans: Laboratory IdentificationThe colony of T. tonsurans is relatively slow growing ( 5 7 days). It is thiamine dependent and will not grow on Trichophyton #1 agar. It has a distinctive buff-brown, granular surface, often with radial rugae. The identification can be made by observing delicate hyphae that produce birds on a fence conidia along the sides (similar to T. rubrum); however, those of T. tonsurans are larger, irregular in size, with balloon and club forms.

THE DERMATOPHYTIC FUNGITrichophyton tonsurans: Clinical Correlation Trichophyton tonsurans is an anthropophilic species causing tinea capitis and tinea corporis, the latter being spreading in type and contagious via direct human contact T. tonsurans is worldwide in distribution and is particularly prevalent in Mexico and other Latin American countries T. tonsurans less commonly causes tinea pedis and tinea unguium infections In cases of tinea capitis, hair invasion is common, and endothrix in type, with the invaded hairs tending to break near the surface of the scalp, resulting in a black dot appearance

THE DERMATOPHYTIC FUNGITrichophyton verrucosum

THE DERMATOPHYTIC FUNGITrichophyton verrucosum: Laboratory FeaturesT. verrucosum is slow-growing, requiring 10 20 days for colonies to reach maturity. The colonies appear white with a smooth surface. Growth is enhanced in Trichophyton agars #3 and #4, which contain inositol and thiamine, serving as growth supplements respectively.Sporulation is poor and both macroconidia and microconidia are usually absent in microscopic preparations. Observed instead are most commonly only branching antler-like hyphae (upper left) and/or chains of chlamydospores (right frame).

THE DERMATOPHYTIC FUNGIMicrosporum verrucosum: Clinical Correlation Microsporum verrucosum is a cosmopolitan zoophilic species serving as a principal cause of ringworm in cattle Humans most commonly contract M. verrucosum infections directly from cattle. Tinea barbae in the past has been a common manifestation as a result of hand-milking of infected cows The lesions are inflammatory, usually on the scalp or face, often appearing as sycosis (inflammation of hair follicles) of the lips and chin Invasion of hair is large-spored ectothrix type and arthroconidia are produced in chains on the hair shaft.

THE DERMATOPHYTIC FUNGIEpidermophyton floccosum

THE DERMATOPHYTIC FUNGIEpidermophyton floccosum: Clinical/Colony Presentations Common cause of tinea cruris. Infections more common in men involving the groin, perineum, scotum, and perianal area. Lesions are erythematous, spreading, and hyperpigmented. The margin is usually well delineated.Colony growth is observed in 5 14 days at 30oC on Sabourauds dextrose agar. The surface is typically granular, with a khaki pigment when mature. The reverse of the colony is devoid of pigmentation.

THE DERMATOPHYTIC FUNGIEpidermophyton floccosum: Microscopic FeaturesThe macroconidia of E. floccosum are large, smooth-walled, multiseptate and clavate, often borne in clusters of two or three. Microconidia are not produced. In contrast, the macroconidia of Microsporum gypseum (frame to the right) have a thick, roughened cell wall and microconidia are observed.

THE DERMATOPHYTIC FUNGIMicrosporum nanum

THE DERMATOPHYTIC FUNGIMICROSPORUM NANUM/TRICHOPHYTON AJELLOI Trichophyton ajelloiM nanum is a geophilic species causing ringworm in pigs. Human infections are uncommon, but cases of tinea capitis have been reported.The colonies are rapidly growing, initially white, and later turning a buff color as conidia are formed (left frame).The conidia are small, oval to elliptical, usually with two cells, covered by a thick, rough outer wall (frame to right).T. ajelloi is a soil fungus that has been recovered as a commensal from human skin. Colonies grow rapidly and are buff colored with production of purple pigment.Microscopically, long, fusiform-to-cylindrical, thick-walled macroconidia are produced, possessing from 5-12 cells. Microconidia may be observed.

Miscellaneous: TINEA VERSICOLORMalassizia furfurMalasseizia furfur is a fungus that causes superficial skin infections that present as macular or scaly spots ranging in color from yellow-brown to dark brown, interspersed with areas of discoloration (left upper frame). Diagnostic is the microscopic observation in KOH mounts of skin scrapings (left lower frame) of short, 3um in diameter abortive hyphae, and clusters of spherical, 4 8um in diameter conidia , simulating sphagetti and meat balls. M. furfur is lipophilic and grows on the agar surface as yellow-white yeast-like colonies only in the drip areas where olive oil is present (photograph to the right).

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