Dematophytes (name based on the Greek for 'skin plants') are a common label for a group of three types of that commonly causes skin disease in animals and humans. — These anamorphic (asexual or imperfect fungi) genera are: , Epidermophyton and . There are about 40 species in these three genera. — Species capable of reproducing sexually belong in the teleomorphic genus Arthroderma, of the — The organisms are transmitted by either direct contact with infected host (human or animal) or by direct or indirect contact with infected exfoliated skin or hair in combs, hair brushes, clothing, furniture, theatre seats, caps, bed linens, towels, hotel rugs, and locker room floors. — Depending on the species the organism may be viable in the environment for up to 15 months. — There is an increased susceptibility to infection when there is a preexisting injury to the skin such as scares, burns, marching, excessive temperature and humidity. — Dermatophytes are classified as anthropophilic, zoophilic or geophilic according to their normal habitat. Geophilic species species are usually recovered from the soil but occasionally infect humans and animals. — They cause a marked inflammatory reaction, which limits the spread of the infection and may lead to a spontaneous cure but may also leave scars. Anthropophilic dermatophytes are restricted to human hosts and produce a mild, chronic inflammation. Zoophilic organisms are found primarily in animals and cause marked inflammatory reactions in humans who have contact with infected cats, dogs, cattle, horses, birds, or other animals. — This is followed by a rapid termination of the infection. — Dermatophytes cause infections of the skin, hair and nails due to their ability to obtain nutrients from keratinized material. — The organisms colonize the keratin tissues and inflammation is caused by host response to metabolic by-products. — are usually restricted to the nonliving cornified layer of the epidermis because of their inability to penetrate viable tissue of an immunocompetent host. — Invasion does elicit a host response ranging from mild to severe. — The development of cell-mediated immunity correlated with delayed hypersensitivity and an inflammatory response is associated with clinical cure. — Whereas the lack of or a defective cell-mediated immunity predisposes the host to chronic or recurrent infection. — Some of these infections are known as ringworm or tinea. — Toe- and fingernail infection are referred to as . — Dermatophytes usually do not invade living tissues, but colonize the outer layer of the skin. — Occasionally the organisms do invade subcutaneous tissues, resulting in kerion development.

Types of Dermatophyte Infections

— Athlete's foot or tinea pedis. — Jock itch or . — Ringworm of the body or tinea corpora. — Facial ringworm or . — Blackdot ringworm or . — Ringworm of the hands or tinea manuum. — Ringworm of the nail, Onychomycosis, or tinea unguium.

Anthropophilic

— — — Trichophyton mentagrophytes (cottony and velvety) — — Trichophyton schoenleinii — Trichophyton soudanense — — Trichophyton violaceum Zoophilic

— (cats, dogs, etc.) — Microsporum equinum (horses) — Microsporum nanum — Trichophyton mentagrophytes(granular) (rodents, rabbits, hedgehogs, etc.) — Trichophyton verrucosum (cattle) Geophilic

— Clinical Significance

Dermatophyte Skin Hair Nails

Microsporum X X

Trichophyton X X X

Epidermophyton X X — Conidia, sometimes termed asexual chlamydospores, or chlamydoconidia are asexual, non-motile spores of a fungus, from the Greek word for dust, konis. — They are also called mitospores due to the way they are generated through the cellular process of mitosis. The two new haploid cells are genetically identical to the haploid parent, and can develop into new organisms if conditions are favorable, and serve in biological dispersal. — The asexual spores may be large (macroconidia, chlamydospores) or small (microconidia, blastospores, arthroconidia) The dermatophytes consist of three genera: — Epidermophyton produces only macroconidia, no microconidia and consists of 2 species, one of which is a pathogen. — Microsporum Both microconidia and rough-walled macroconidia characterize Microsporum species. There are 19 described species but only 9 are involved in human or animal infections. — Trichophyton When produced the macroconidia of Trichophyton species are smooth-walled. There are 22 species, most causing infections in humans or animals. — Microscopic morphology of the micro and/or macroconidia is the most reliable identification character, but you need a good slide preparation and you may need to stimulate sporulation in some strains. — Culture characteristics such as surface texture, topography and pigmentation are variable and are therefore the least reliable criteria for identification. — Clinical information such as the site, appearance of the lesion, geographic location, travel history, animal contacts and race is also important, especially in identifying rare non-sporulation species like M. audouini, T. concentricum and T schoenleinii etc. Tinea capitis — Tinea capitis refers to of the scalp. Three types of in vivo hair invasion are recognised: 1. Ectothrix invasion is characterised by the development of arthroconidia on the outside of the hair shaft. The cuticle of the hair is destroyed and infected hairs usually fluoresce a bright greenish yellow colour under Wood's ultraviolet light. Common agents include M. canis, M. gypseum, T. equinum and T. verrucosum. Laboratory DiagnosisDirect Examination

— Examine hair for fluorescence ¡ Wood’s lamp

¡ Yellow green fluorescence = positive 2. hair invasion is characterised by the development of arthroconidia within the hair shaft only. The cuticle of the hair remains intact and infected hairs do not fluoresce under Wood's ultraviolet light. All endothrix producing agents are anthropophilic eg T. tonsurans and T. violaceum. 3. Favus usually caused by T. schoenleinii, produces favus-like crusts or scutula and corresponding hair loss.

Endothrix Ectothrix Blackdot ringworm or tinea capitis — Infected hair shafts are broken off just at the base, leaving a black dot just under the surface of the skin. — Scraping these residual black dot will yield the best diagnostic scrapings for microscopic exam. — Numerous green arthrospores will be seen under the microscope inside the stubbles of broken hair shafts at 400x. — Tinea capitis can not be treated topically, and must be treated systemically with antifungals Laboratory Identification of Dermatophytes

Specimen Collection: — Skin should be scraped from the margin of the lesion. — Hair should be plucked, not cut, from the edge of the lesion. — Choose hairs that fluoresce under a Wood's lamp or, if none fluoresce, choose broken or scaly ones. — Nails scrapings are obtained from the nail bed or from infected areas after the outer layers are discarded. — A Wood's lamp is a diagnostic tool used in dermatology by which ultraviolet light is shone (at a wavelength of approximately 365 nanometers) onto the skin of the patient; a technician then observes any subsequent fluorescence. For example, porphyrins — associated with some skin diseases — will fluoresce pink. Direct Examination: — A small sample of the specimen is selected for direct microscopic examination and investigated for the presence of fungal elements. — The specimen is mounted in a small amount of potassium hydroxide or calcofluor white. — The KOH slides are gently heated and allowed to clear for 30 to 60 minutes before examining on a light or phase contrast microscope. — Calcofluor white slides are examined on a fluorescent microscope.

— When present in the direct examination dermatophytes appear as hyaline (non-pigmented), septated elements. — Hyphae rounding up into arthroconidia are diagnostic of dermatophyte involvement. Without the presence of arthroconidia the elements could also be due to a non-dermatophyte agent of onycho- or a small segment of a contaminating organism. — When hair is involved the arthroconidia may be found on the periphery of the hair shaft (ectothrix) or within the shaft (endothrix). Culture — Nails are scraped or minced into small pieces — Hair is cut into short segments — Each specimen is divided between at least two types of culture media — The use of antibiotics will inhibit the overgrowth of bacteria and incorporation of cycloheximide will prevent the overgrowth of the rapidly growing saprophytic fungi — The cultures are incubated at 30°C and examined frequently for 4 weeks. — Potato dextrose agar is a media useful for the production of pigment. — Sabouraud dextrose agar (Emmon's modification) is a non-selective media which supports the growth of most fungi. — A special media called Dermatophyte Test Medium (DTM) has been formulated to grow and identify dermatophytes. — Without having to look at the colony, the hyphae, or macroconidia - one can identify the dermatophyte by a simple color test. — The specimen (scraping from skin, nail, or hair) is embedded in the DTM culture medium — It is incubated at room temperature for 10 to 14 days. If the fungus is a dermatophyte, the medium will turn bright red. — If the fungus is not a dermatophyte, no color change will be noted. — If kept beyond 14 days, false positive can result even with non-dermatophytes. — Specimen from the DTM can be sent for species identification if desired.

Hair perforation — Many dermatophytes have the ability to degrade hair. The hair perforation test determines whether the organism simply erodes the hair shaft or produces an enzyme that will penetrate and invade the shaft resulting in perforating bodies or cones. — To distinguish between isolates of dermatophytes, particularly Trichophyton mentagrophytes and its variants. Ingredients: — Autoclaved blonde pre-pubital hair cut into short pieces (1cm) — Sterile distilled water 5 ml in a suitable vial. Method: 1. Place hair in water in vial. 2. Inoculate with small fragments of the test fungus. 3. Incubate at room temperature. 4. Individual hairs are removed at intervals up to 4 weeks and examined microscopically in lactophenol cotton blue. Isolates of T. mentagrophytes produce marked localised areas of pitting and marked erosion whereas those of T. rubrum do not.

Slide culture — The slide culture is a method of examining the microscopic structures of a fungus. — The organism is grown on a glass coverslip placed on a block of agar. — When sufficient growth has occurred the coverslip is placed on a drop of mounting media on a microscope slide and examined by phase contrast microscopy. Urea — Christensen's urea broth indicates the presence of the enzyme urease, which splits urea into ammonia, resulting in an alkaline environment. The phenol red indicator turns the media from a straw yellow to fuschia at pH 8.4. Vitamin requirements — Certain species of dermatophytes have distinctive nutritional requirements that may be beneficial to differentiate from similar species. — The agar base is vitamin free and various vitamins are added to the basal media. — The growth on the vitamin-enriched media is compared to the vitamin free media to determine enhancement of aerial mycelium. Trichophyton sp.

Description and Natural Habitats — Trichophyton is a dermatophyte which inhabits the soil, humans or animals. Related to its natural habitats, the genus includes anthropophilic, zoophilic, and geophilic species. — Some species are cosmopolitan. Others have a restricted geographic distribution. — The genus Trichophyton has several species. Most common are Trichophyton mentagrophytes, Trichophyton rubrum, Trichophyton schoenleinii, Trichophyton tonsurans, Trichophyton verrucosum, and Trichophyton violaceum. — Trichophyton rubrum is the commonest causative agent of dermatophytoses worldwide — . Trichophyton species may cause invasive infections in immunocompromised hosts . — Several morphological and physiological characteristics are used in differentiation and identification of Trichophyton species. — Trichophyton differs from Microsporum and Epidermophyton by having cylindrical, clavate to cigar-shaped, thin-walled or thick-walled, smooth macroconidia. Macroscopic Features

The growth rate of Trichophyton colonies is slow to moderately rapid. The texture is waxy, glabrous to cottony. From the front, the color is white to bright yellowish beige or red violet. Reverse is pale, yellowish, brown, or reddish-brown T. rubrum — Colonies flat, woolly, or granular to cottony, white to cream with a blood red or olivaceous reverse; — The red pigment production is best seen on potato dextrose agar or cornmeal dextrose agar.

Microscopic morphology — The downy type is characterized by the production of scanty to moderate numbers of slender clavate microconidia and no macroconidia. — The granular type is characterized by the production of moderate to abundant numbers of clavate to pyriform microconidia and moderate to abundant numbers of thinwalled, cigar-shaped macroconidia. — Microconidia are characteristically tear-shaped and form singly all along the sides of the hyphae. — Some species may be sterile and the use of specific media is required to induce sporulation T.rubrum

— Lab identification — ++++++ pigment production on specific media (PDA, cornmeal agar). — - ve in-vitro hair perforation test. T. violaceum

— Trichophyton violaceum is an anthropophilic fungus causing inflammatory or chronic non-inflammatory finely scaling lesions of skin, nails, beard and scalp, producing the so-called "black dot" tinea capitis. — Distribution is world-wide, particularly in the Near East, Eastern Europe, USSR and North Africa. — Invaded hairs show an endothrix infection and do not fluoresce under Wood's ultra-violet light. — On Sabouraud's dextrose agar, colonies are very slow growing, glabrous or waxy, heaped and folded and a deep violet in colour. — Cultures often become pleomorphic, forming white sectors and occasional non-pigmented strains may occur.

— Hyphae are relatively broad, tortuous, much branched and distorted. — Young hyphae usually stain well in lactophenol cotton blue, whereas older hyphae stain poorly and show small central fat globules and granules. — No conidia are usually seen, although occasional pyriform microconidia have been observed on enriched media. Numerous chlamydoconidia are usually present, especially in older cultures.

Nutritional requirements: — T. violaceum has a partial nutrient requirement for thiamine. There is minimal growth on casein vitamin-free agar. — The partial requirement for thiamine separates this organism from T. gourvillii, T. rubrum, and other species that may produce purple pigmented colonies. Trichophyton tonsurans

— Trichophyton tonsurans is a fungus in the family that causes ringworm infection of the scalp. — Adult infections more often manifest as . — This species is a major cause of family and institutional outbreaks because of its persistent nature in indoor environments, and its ability to be transmitted through asymptomatic carriers. — Trichophyton tonsurans may be identified through analysis of its fast-growing colonies. — Colonies tend to be flat, powdery, and yellow with a reddish undercolour. — It develops into a folded colony, and may vary in colour from off-white to grey, with dark pigments that may diffuse into the medium. — The younger colonies fluoresce green on Sabouraud's agar, and are also flat, but are mahogany red or lemon- yellow coloured — On this agar the fungus grows peripherally and develops into a flatter, creamy disk with raised edges. — Trichophyton tonsurans also produces many inflated, pear-shaped microconidia, borne on matchstick-like stalks. It also forms fewer macroconidia that are 4-6 cells long, with thick cell walls. — Microconidia are longer and larger than in T. rubrum. — Intercalary and terminal chlamydoconidia common in older cultures. — Macroconidia not common, irregular in form. Trichophyton tonsurans Trichophyton verrucosum

— Associated with cattle ("barn itch"). — On Sabouraud's dextrose agar, colonies are slow growing, small, button-or-disk-shaped, white to cream coloured, with a suede-like to velvety surface, a raised centre, and flat periphery with some submerged growth. — Reverse pigment may vary from non-pigmented to yellow. Broad, irregular hyphae with many terminal and intercalary chlamydospores. — — Chlamydospores are often in chains. — The tips of some hyphae are broad and club-shaped, and occasionally divided, giving the so-called "antler" effect. — All strains require thiamine and approximately 80% require thiamine and inositol. There is no growth on casein vitamin free agar. — Occasional strains produce clavate to pyriform microconidia borne singly along the hyphae. Macroconidia are only rarely produced, but when present have a characteristic tail or string bean shape. Trichophyton verrucosum

http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Dermatophytes/Trichophyton/verrucosum.html Trichophyton verrucosum DERMATOPHYTES

— Trichophyton schoenleinii — Endothrix infection of hair. — Causes tinea favosa (cup-shaped crusts on scalp called favus). — tinea favosa may lead to alopecia or permanent baldness. — Colonies waxy to suede-like; off white in color. — Colony may become convoluted from folds that develop — No conidia (micro- or macro-) even on enriched media . — Grows well at 37 C. — Trichophyton schoenleinii is the causative agent of favus (tinea favosa) of the scalp, a scalp infection which is characterized by the presence of scutula. Scatula is described as crusts which are composed of an accumulation of fungal hyphae and skin debris — Hyphae are displayed in the form of “favic chandeliers”, or with “nail head” tips which are often present in the submerged mycelium; and — Both microconidia and macroconidia are typically absent Trichophyton schoenleinii

http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Dermatophytes/Trichophyton/schoenlenii.html Trichophyton schoenleinii

T. mentagrophytes

— T. mentagrophytes is the zoophilic form of T. mentagrophytes with a world-wide distribution and a wide range of animal hosts including mice, guinea- pigs, kangaroos, cats, horses, sheep and rabbits. Produces inflammatory skin or scalp lesions in humans, particularly in rural workers. — Kerion of the scalp and beard may occur. — Invaded hairs show an ectothrix infection but do not fluoresce under Wood's ultra-violet light — On Sabouraud's dextrose agar, colonies are generally flat, white to cream in colour, with a powdery to granular surface. — Some cultures show central folding or develop raised central tufts or pleomorphic suede-like to downy areas. — Reverse pigmentation is usually a yellow-brown to reddish-brown colour. — Numerous single-celled microconidia are formed, often in dense clusters.

— Microconidia are hyaline, smooth-walled, and are predominantly spherical to subspherical in shape, however occasional clavate to pyriform forms may occur. — Varying numbers of spherical chlamydoconidia, spiral hyphae and smooth, thin-walled, clavate shaped, multicelled macroconidia may also be present.

— Hydrolysis of Urea: Positive within 7 days (usually 3 to 5 days). — Hair Perforation Test ("in vitro"): Positive within 14 days. Positive hair perforation test Microsporum sp.

— Microsporum species form both macro- and microconidia on short conidiophores. — Macroconidia are hyaline, multiseptate, variable in form, fusiform, spindle-shaped to obovate, with thin- or thick- echinulate to verrucose cell walls. Their shape, size and cell wall features are important characteristics for species identification. — Microconidia are hyaline, single-celled, pyriform to clavate, smooth-walledand are not diagnostic for any one species. — The separation of this genus from Trichophyton is essentially based on the roughness of the macroconidial cell wall, although in practice this may sometimes be difficult to observe. Microsporum canis — Microsporum canis is a zoophilic dermatophyte of world-wide distribution which is a frequent cause of ringworm in humans, especially children. Invades hair, skin and rarely nails. — Cats and dogs are the main sources of infection. Invaded hairs show an ectothrix infection and fluoresce a bright greenish-yellow under Wood's ultra-violet light. — Colonies (SDA) are flat, spreading, white to cream- coloured, with a dense cottony surface which may show some radial grooves. — Colonies usually have a bright golden yellow to brownish yellow reverse pigment, but non- pigmented strains may also occur.

— Macroconidia and/or microconidia are often not produced on primary isolation media and it is recommended that sub-cultures be made onto boiled polished rice grains to stimulate sporulation.

— Macroconidia are typically spindle-shaped with 5-15 cells, verrucose, thick-walled and often have a terminal knob, 35-110 x 12-25 µm — A few pyriform to clavate microconidia are also present. — Macroconidia and/or microconidia are often not produced on primary isolation media and it is recommended that sub-cultures be made onto boiled polished rice grains to stimulate sporulation.

— Macroconidia are typically spindle-shaped with 5-15 cells, verrucose, thick-walled and often have a terminal knob. A few pyriform to clavate microconidia are also present.

Identification

— Growth on Rice Grains: good growth of white aerial mycelium with production of yellow pigment. Microscopy reveals numerous characteristic macroconidia and microconidia. — Reverse Pigment on Potato Dextrose Agar: Bright yellow (both M. audouinii and M. canis var. equinum are salmon to pinkish-brown). — Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special nutritional requirements. — Hair Perforation Test: Positive at 14 days. Key Features: — distinctive macroconidia and culture characteristics. — Abundant growth and sporulation on polished rice grains and in vitro perforation of hair. — Dysgonic strains of M. canis are rare but may also occur. — Cultures are typically heaped and folded and yellow- brown in colour. Macroconidia are usually absent in these strains. — However, typical colonies and macroconidia of M. canis are usually produced by this variant when subcultured onto polished rice grains.

Microsporum audouinii

— No teleomorph state (sexual reproduction has yet to be observed in this species). — Usually devoid of conidia (macro- or microconidia). — Septate hyphae with terminal chlamydoconidia, often pointed at the end. — Macroconidia are often irregular or non-uniform in shape. — Colonies on culture media are flat, silky in appearance. — Growth of colonies on culture media is tight. — On reverse of colony - pigment is reddish-brown in color. — This fungus is often found in soil that is rich in keratinous material. — Microsporum audouinii is effective in utilizing its carbon sources, but growth is strongest in the hexoses (glucose, mannose and fructose) and weakest in maltose, sucrose, lactose and galactose. — It is unable to synthesize the vitamins thiamine, niacin and riboflavin and requires an exogenous supply of these materials to support its growth. — The fungus is only able to utilize organic nitrogen sources, particularly nitrogen from arginine and urea.[5] M.audouinii

— - Terminal chlamydospore (T) shown, often exhibits a little apical point or peak. Also an intercalary chlamydospore (IC) (in the middle of a hyphae or perhaps a hyphae running through it) — The fungus is characterized by its spindle shaped macroconidia (7-30 × 35-160 µm), clavate microconidia (2.5-3.5 × 4-7 µm) as well as its pitted or spiny external walls Microsporum audouinii

http://www.doctorfungus.org/thefungi/microsporum_audouinii.htm http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Dermatophytes/Microsporum/Microsporum_audouinii.html Microsporum gypseum

— Teleomorphs are Arthroderma gypseum and A. incurvatum. — Produces abundant macroconidia brownish-yellow due to large numbers macroconidia. Surface of culture colony often is powdery in appearance. — Reverse of colony often appears ragged around edges. — Macroconidia usually have 4-6 septa or crosswalls. — Microconidia are smaller than in M. canis. — Macroconidia up to 40 µm long — In lactophenol, water is extracted and can cause the macroconidia walls to collapse. This is an artifact due to mounting media. Macroconidia do not form on infected hair! — The colonies of M. gypseum are described as cottony or powdery, they grow rapidly with a colour range of white to buff, with a reserve that can range from pink, to red, to yellow (cinnamon); they may occasionally have overtones of violet. The powdery appearance of the colony is due to the abundant production of macroconidia on the older mycelium, while the edges of the colony are described as scalloped to ragged and can exhibit pleomorphism — Macroconidia of M. gypseum have a substantial range that can occur as short pedicels, terminal, solitary, spindle shaped, large, thick walled, that are smooth or roughened, borne directly on hyphae or on short branches. They are often very large, ellipsoid to fusiform, moderately thick, have verrucose and are 4–6 septate — The macroconidia also possess a rat-like tail at the edges of the conidia.

— The hyphae are hyaline, pale buff, septate, and are branched with thinly but have densely verrucose walls. — Microconidia are drop shaped, clavate, unicellular, smooth- walled or can be slightly roughened and are created laterally on the hyphae.The abundance of microconidia is characteristic of the fungus. Microsporum gypseum

http://www.doctorfungus.org/thefungi/microsporum_gypseum.htm http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Dermatophytes/Microsporum/Microsporum_gypseum.htm Epidermophyton floccosum

— Epidermophyton floccosum is an anthropophilic dermatophyte with a world-wide distribution which often causes tinea pedis, tinea cruris, tinea corporis and onychomycosis. — It is not known to invade hair in vivo and no specific growth requirements have been reported. — On Sabouraud's dextrose agar colonies are usually slow growing, greenish-brown or khaki coloured with a suede-like surface, raised and folded in the centre, with a flat periphery and submerged fringe of growth. — Older cultures may develop white pleomorphic tufts of mycelium. — A deep yellowish-brown reverse pigment is usually present.

— Microscopic morphology shows characteristic smooth, thin-walled macroconidia which are often produced in clusters growing directly from the hyphae. — Numerous chlamydoconidia are formed in older cultures. — No microconidia are formed. Macroconidia of E. floccosum Chlamydoconidia of E. floccosum. Dermatophyt e Hair Urease Growth Macro-conidia Micro-conidia Distinguishing Differentiatio Perforation Test at 37°C Characteristics n Table: Test Trichophyton Negative Negative Positive Pencil shaped/cigar Club shaped to Red reverse pigment rubrum shaped pyriform, along the Hair perf. test neg. sides of the hyphae Club shaped microconidia Trichophyton Positive Positive Positive Club shaped when Numerous Round microconidia in mentagrophytes present Unicellular to round grape like clusters in grape like clusters Spiral hyphae Trichophyton Usually (-) Positive Positive Cylindrical to cigar Numerous, varying Microconidia varying in tonsurans Occasionally + shaped and in shape and size, shape and size sinuous, if present club shaped to Growth enhanced by balloon shaped thiamine Trichophyton Negative Negative Positive “Rat-tailed” if Rare or Absent Chlamydospores in chains verrucosum present Chlamydospores in Growth better on media chains typically seen with thiamine and inositol Trichophyton Positive Positive Negative 2-8 celled borne at Club shaped with Microconidia with terrestre right angles to squared-off base on squared-off base on short hyphae pedicels pedicels Epidermophyton Negative Positive Positive Club shaped, often Absent Khaki colored colony with floccosum in clusters brown reverse Microconidia absent Microsporum Positive Positive NA Fusoid, thick, Typically absent Fusoid, rough walled rough walled with Club shaped if macroconidia with canis recurved apex present recurved apex Microsporum Positive Positive NA Ellipsoidal to Moderately abundant Thin walled macroconidia gypseum fusiform, thin, Club shaped Tawny-buff granular Rough walled colony Microsporum Positive Positive NA Typically 2 celled Clavate when 2 celled pear shaped nanum Pear or egg shaped present macroconidia Rough walled Treatment of dermatophytosis

— Dermatophytes are located in the stratum corneum within the keratinocytes. The signs and symptoms that appear in infected individuals are due to acute and chronic inflammatory changes that appear in the dermis. — For these reasons, antifungal agents should have the ability to penetrate the stratum corneum cells to be efficient when applied topically. — The vast majority of antifungals are fungistatic with the concentrations achieved in the skin when applied topically; the growth of dermatophytes is delayed and these are shed with the skin renewal and healing is achieved. — The antifungal agents and the components incorporated on the vehicle should be non-irritant and well tolerated. — Skin lesions located on face, trunk and limbs usually require two or three weeks of treatment. — Inflammatory dermatophyte infections of the feet should be treated for four or six weeks and hyperkeratotic lesions of palms and soles are best treated with oral antifungals since they are usually unresponsive to topical antifungals. — Oral treatment is indicated in widespread skin lesions, tinea capitis, tinea barbae, tinea unguium, in skin lesions with folliculitis, and when either there is no response to topical treatment or tolerance is not adequate. — Griseofulvin is still currently the gold standard for treatment of dermatophytosis (excluding tinea unguium). — No new oral antifungal agents appeared until ketoconazole was introduced in 1980. This drug was an advance in the treatment of mycoses, but nowadays there are many concerns about its use, basically due to a significant incidence of idiosyncratic hepatic toxicity — Itraconazole is a triazole agent, poorly water-soluble and whose bioavailability improves when the drug is taken with a fatty meal. — Accumulation in skin is slow and antifungal therapeutically active high concentrations persist up to a month after the end of treatment. — Fluconazole is a triazole that is water-soluble and extremely well absorbed. — Most of the drug is excreted unchanged in the urine since it undergoes no hepatic metabolism. It is eliminated more slowly from skin, and therefore clinical cures may be achieved after the withdrawal of treatment. — Voriconazole is a third generation triazole. — From a dermatological point of view it is interesting to note that voriconazole is active in vitro against dermatophytes and Malassezia spp — Terbinafine is a fungicidal allylamine that is absorbed from the gastrointestinal tract. — When treatment with terbinafine ceases the concentration in stratum corneum remains high (0,1 µg/ml) for 8 weeks and enables the use of short courses of treatment. — The incidence of adverse effects with terbinafine therapy is approximately 10%. Malassezia

— Malassezia (formerly known as Pityrosporum) is a genus of related fungi, classified as yeasts, naturally found on the skin surfaces of many animals including humans. It can cause hypopigmentation on the trunk and other locations in humans if it becomes an opportunistic infection — Malassezia were originally identified by the French scientist Louis-Charles Malassez in the late 19th century. — In the mid 20th century, it was reclassified into two species: — Pityrosporum (Malassezia) ovale which is lipid dependent and found only on humans. P. ovale was later divided into two species, P. ovale and P. orbiculare, but current sources consider these terms to refer to a single species of fungus, with M. furfur the preferred name. — Pityrosporum (Malassezia) pachydermatis, which is lipophilic but not lipid dependent and found on the skin of most animals. — In the mid 1990s, scientists at the Pasteur Institute in Paris, France discovered additional species, Currently there are 10 recognized species: — M. furfur, M. pachydermatis , M. globosa , — M. restricta , M. slooffiae , M. sympodialis[8] — M. nana[ ,M. yamatoensis ,M. dermatis — M. obtusa — As the fungus requires fat to grow, it is most common in areas with many sebaceous glands: on the scalp, face, and upper part of the body. When the fungus grows too rapidly, the natural renewal of cells is disturbed and dandruff appears with itching (a similar process may also occur with other fungi or bacteria). Pityriasis versicolor: — This is a chronic, superficial fungal disease of the skin characterised by well-demarcated white, pink, fawn, or brownish lesions, often coalescing, and covered with thin furfuraceous scales. — The colour varies according to the normal pigmentation of the patient, exposure of the area to sunlight, and the severity of the disease. — Lesions occur on the trunk, shoulders and arms, rarely on the neck and face, and fluoresce a pale greenish colour under Wood's ultra-violet light. Young adults are affected most often, but the disease may occur in childhood and old age.

Laboratory diagnosis:

— Clinical material: Skin scrapings from patients with superficial lesions, blood and indwelling catheter tips from patients with suspected fungaemia. — Direct Microscopy: — Skin scrapings taken from patients with Pityriasis versicolor stain rapidly when mounted in 10% KOH, glycerol and Parker ink solution and show characteristic clusters of thick-walled round, budding yeast-like cells and short angular hyphal forms up to 8um in diameter. — These microscopic features are diagnostic for Malassezia furfur and culture preparations are usually not necessary.

Culture: — Culture is only necessary in cases of suspected fumgaemia. — M. furfur is a lipophilic yeast, therefore in vitro growth must be stimulated by natural oils or other fatty substances. — The most common method used is to overlay Sabouraud's dextrose agar containing cycloheximide (actidione) with olive oil or alternatively to use a more specialized media like Dixon's agar.

— Symptomatic scalp infections are often treated with selenium disulfide or ketoconazole containing shampoos. Other treatments include coal tar, zinc pyrithione (ZPT), miconazole, or tea tree oil medicated shampoos. — Hydrogen peroxide is also used to manage symptoms of itching.