Superficial And Cutaneous Mycoses

Microbiology /Parasitology Superficial and Cutaneous Mycoses 11 January 08

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SUPERFICIAL MYCOSES Pityriasis versicolor Keratomycosis Tinea nigra Black piedra White piedra PITYRIASIS VERSICOLOR Superficial chronic infection of Stratum corneum Etio: Malassezia furfur (Pityrosporum orbiculare) (Lipophilic yeast: Commensal of N skin) (+) accumulation of sebum and skin oils –proliferates during times of poor hygiene Clinical findings: Manifest early on: o Irregular patches of hypo/ hyperpigmentation: noticeable on exposure to sunlight o Intermittent areas of scaling with variegated hues o Light yelloew and dark brown maybe observed as infection progresses o Folliculitis (+) in severe cases – infection extends into hair shafts and sebaceous glands o Most commonly involved: skin of chest, back, arms o Condition: chronic; irritation and inflammation absent; mild pruritus Diagnosis: o Direct observation of skin o Wood’s lamp – yellow fluorescence o Microscope:  tight clusters of spherical yeast cells admixed with hyphal fragments (spaghetti and meatballs) o Culture:  Sabouraud’s dextrose agar  Yeast-like colonies  Creamy consistency after 2 – 4 days  Incubation at 35 C o Microscopically:  1x2 to 2x4 um broadly budding yeast cells observed  Bottle-shaped with a colarette-like thickening seen at the junction of the mother and daughter cells o Systemic infection (parenteral lipid solution) o Micr.: Short hyphae, yeast cells o Culture: Yeast (suppl.: olive oil) Treatm. o Topical selenium sulfide o Oral ketaconazole o Oral itraconazole KERATOMYCOSIS (Mycotic keratitis) Posttraumatic / postsurgical corneal inf. Etio: Saprophytic fungi (Aspergillus, Fusarium, Alternaria, Candida), Histoplasma capsulatum Clinical findings: Corneal ulcer Micr.: Hyphae in corneal scrapings Treatm.: o Surgery (keratoplasty) o Topical pimaricin o Nystatin o Amphotericin B

Elyu, Brim & Virns

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TINEA NIGRA Etio: Exophiala werneckii (pigmented) – produce melanin (impart brown to black color) Frequent in tropical areas Clinical findings: Brownish maculae on palms, fingers, face Micr. o Septate hyphae and yeast cells (brown in color) Culture: o Black colonies Treatm.: o Topical salicylic acid, tincture of iodine BLACK PIEDRA Fungal infection of the scalp hair Etio: Piedraia hortae Frequent in tropical areas Clinical findings: Discrete, hard, dark brown to black nodules on the hair Micr. o Septate pigmented hyphae, and asci; unicellular and fusiform ascospores with polar filament(s) Culture: o Brown to black colonies Treatm.: o Topical salicylic acid, azole creams WHITE PIEDRA Fungal infection of scalp, facial, axillary or genital hair Trichosporon beigelii Frequent in tropical and temperate zones Clinical findings: o Soft, white to yellowish nodules loosely attached to the hair o Occur as a sleeve or collarette around the hair shaft o Micr.: Intertwined septate hyphae, blasto- and arthroconidia o Culture: Soft, creamy colonies o Treatm.: Shaving, azoles CUTANEOUS MYCOSES DERMATOPHYTOSIS (=Tinea = Ringworm) Infection of the skin, hair or nails caused by a group of keratinophilic fungi, called dermatophytes o Microsporum Hair, skin o Epidermophyton Skin, nail o Trichophyton Hair, skin, nail

GENUS Epidermophyton Microsporum Trichophyton

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SPECIES E. floccosum M. canis M. gypseum T. mentagrophytes T. rubrum T. tonsurans

Digest keratin by their keratinases Resistant to cycloheximide

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Microbiology/Parasitology – Superficial and Cutaneous Mycoses by Dra Bunyi ●

Classified into three groups depending on their usual habitat o ANTROPOPHILIC  Trichophyton rubrum... o GEOPHILIC  Microsporum gypseum... o ZOOPHILIC

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Microsporum canis: cats and dogs Microsporum nanum: swine

Trichophyton verrucosum: horse and swine… Pathogenesis and Immunity o Contact and trauma o Moisture o Crowded living conditions o Cellular immunodeficiency à(chronic inf.) o Re-infection is possible (but, larger inoculum is needed, the course is shorter ) Clinical Classification o Infection is named according to the anatomic location involved: a. Tinea barbae b. Tinea corporis c. Tinea capitis d. Tinea cruris (Jock itch) e. Tinea pedis (Athlete’s foot) f. Tinea manuum g. Tinea unguium Clinical manifestations o Skin: Circular, dry, erythematous, scaly, itchy lesions o Hair: Typical lesions,”kerion”, scarring, “alopecia” o Nail: Thickened, deformed, friable, discolored nails, subungual debris accumulation o Favus (Tinea favosa) TINEA CAPITIS Ringworm of the scalp Peak in the early school years (M.canis) Direct contact: infected child; variety of families Asymptomatic carrier state; persistence This is most likely caused by trichophyton tonsurans in the US Microsporum audinii has been prominent cause of children’s fungal disease Gray-patch ringworm o communicable ectothrix infection o M. audorum/canis Inflammatory ectothrix infection o T. mentagrophytes o animal origin Black-dot ringworm o endothrix infection o infected degenerate hair breaks off at the skin surface producing black dot o T. tonsurans Fungating exophytic masses o Kerions o T. tonsurans o Favus infections  T. schoenleini  T. violaceum TINEA CORPORIS

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Typical annular lesions on the skin of the SMOOTH parts of the skin Acquired from cats and dogs Spreading, hemorrhagic border caused by: o T. rubrum o T. mentagrophytes o T. tonsurans T. rubrum o Well suited to survive on the surface of the skin à chronic infection (lifetime) o Mannnans better able to suppress CMI reactions à evade host response à survival o Survive off human body as spores in desquamated skin scales

TINEA BARBAE Ringworm of the bearded area ● Common among farm workers ● T. mentagrophytes ● Lesions tend to be inflammatory ● Can spread during shaving ● Fungal folliculitis

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TINEA CRURIS (jock itch) Ringworm of the groin, perineum, and perianal areas E. floccosum Circinate and serpiginous with inflammatory, vesicular, enlarging margins May reach epidemic proportions in athletes, soldiers, ship crews Shared towels, linen, clothing Perspire freely or obese TINEA PEDIS Athlete’s Foot – most common fungal infection among adolescents – T. rubrum T. mentagrophytes, T. rubrum, E. flocossum Occurs in 3 main forms: o Moccasin

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Mild to severe scaling à soles Interdigital

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Peeling and cracking in the toe webs (4th web)  Itchy, burning or painful o Vesicular  Sudden appearance of itchy or painful blisters (instep, heel, or ball of the foot) Keratin : soles of feet, palms of hands – vulnerable Capability of T. rubrum to survive as spores in desquamated skin scales – vulnerable bath towels, locker room floors, etc. TINEA UNGUIUM Involvement of nails by dermatophyte fungi T. mentagrophytes, T. rubrum, E. flocossum Onychomycosis o Nail infections caused by nondermatophytic fungi o Aspergillus spp., C. albicans, Geotricum spp., etc. Begin at the lateral or distal edge of the nail plate à paronychial inflammation Progresses à nail becomes thickened and brittle with accumulation of subungal keratinized debris Nail plate separates from the nail bed à split and crumble Nail may thicken, become elevated and distorted May occur in a single nail (great toe nail) Usually lasts a lifetime, rarely healing spontaneously

Microbiology/Parasitology – Superficial and Cutaneous Mycoses by Dra Bunyi      

DERMATOPHYTOSIS (in general) ● Transmission o Close human contact o Sharing clothes, combs, brushes, towels, bedsheets... (Indirect) o Animal-to-human contact (Zoophilic) ●

Diagnosis o Clinical  Appearance  Wood lamp (UV, 365 nm) o Lab  Direct microscopic examination − (10-25% KOH) − Ectothrix/endothrix/favic hair  Culture − Mycobiotic agar − Sabouraud dextrose agar

Microscopic features Genus Microsporum  Macroconidia − (+) multicelled with thick rough walls  Microconidia − (+) in small numbers − Unevenly dispersed − Generally oval or elliptical − NO distinguishing morphologic features o M. canis ●

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In vitro hair perforation test Special amino acid and vitamin requirements Urea hydrolysis Growth on BCP-milk solids-glucose medium Growth on polished grains Temperature tolerance and enhancement

If microscopic morphology is not distinct, perform: Urease, Hair baiting test Urease Hair baiting test T. mentagrophytes Convert urease to red Invade shaft within 7-10 color within 1-2 days days à conical shaped holes T. rubrum (hindi ko n mabasa.. Non-invasive sorry) ●

Laboratory Presentation Colony Cotton or wooly

M. canis

M. gypseum T. mentagrophytes

Sugary, granular surface granular Microconidia

T. rubrum Microconidia

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Barrel or spindle shaped Macroconidia − Multicelled − Pointed and slightly turned to one side at the tip o M. gypseum  Macroconidia − More numerous than M. canis − Less barrel shaped with rounded tips − Features not always clear-cut Genus Trichophyton  Macroconidia − Typically absent or present only in small numbers − Elongated and pencil-shaped − Muticelled − Thin, smooth walls  Microconidia − Small, regular sized − abundant  ● Identification o Colony characteristics o Microscopic morphology Macroconidium___Microconidium Microsporum fusiform (+) Epidermophyton clavate (-) Trichophyton (few)cylindrical/ (+) clavate/fusiform single, in clusters 

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Physiological tests

Macroconidia T. tonsurans

Genus Epidermophyton

Flat, granular, rugose with folds radiating outward from center Microconidia

Macroconidia Microconidia Macroconidia

E. flocossum

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Suede appearance, gentle folds

Pigment Lemon-yellow around growing periphery or underside of the colony Cinnamon brown to buff Less intense than T. rubrum Cluster in grapelike masses (en grappe); spiral hyphae may also be seen Burgundy-red Tear shaped; irregular size; distributed on either side of the hyphal strands (bird on the fence appearance) Uncommon, if (+) pencil shaped; thin smooth walls Buff to tan brown Elongated, club shaped or large balloon shaped forms; admixed with the smaller oval or tear shaped microconidia NEVER seen ABSENT Club shaped; (+) 3 – 5 cells; thin smooth walls; cluster in groups of 3 or 4; chlamydochonidia typically present in older cultures Khaki or green yellow

Treatment o Azole derivatives

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Interfere with the cyP450 dependent enzyme systems at the demethylation step from lanosterol to ergosterol à defective cell membrane with altered permeability characteristics Hair infection

Microbiology/Parasitology – Superficial and Cutaneous Mycoses by Dra Bunyi Griseofulvin − Interferes with the mitotic spindle and cytoplasmic microtubules Foot infections  Acute phase − Soak in KMnO4 1:5000 until acute inflammation subsides then apply antifungal  Chronic phase − A.M. : powder − P.M. : cream Topical  Miconazole  Clotrimazole  Econazole  Terbinafine Oral  Griseofulvin  Ketaconazole  Itraconazole  Terbinafine 

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