Superficial and Cutaneous Mycoses PDF

MYCV311 PRELIM LECTURE TOPIC #2 − Colonies: straw to cream colored and yeast like MS. HAULA GUIAMALODDIN − Greenish to black w/ raised center...

MYCV311 PRELIM LECTURE TOPIC #2 − Colonies: straw to cream colored and yeast like MS. HAULA GUIAMALODDIN − Greenish to black w/ raised center − 10-20% KOH SUPERFICIAL AND CUTANEOUS MYCOSES D. Biochemical reactions: − Absence of carbohydrate fermentation SUPERFICIAL MYCOSES − (+) Potassium Nitrate − Infections confined to the outermost layer of the skin or hair (non- − (+) Urease invasive infx) E. Treatment: − (P) Mycoses; (S) Mycosis = disease caused by fungi − 1:200 solution of bichloride mercury − Tinea = latin word for “worm” (ring-shaped pattern in the skin) − 3% sulfur ointment MALASSEZIA INFECTIONS − Benzoic acid and Salicylic acid − Causative agent of Pityriasis versicolor / Tinea versicolor TINEA NIGRA ✓ Discoloration or depigmentation of skin − Tinea nigra or Tinea nigra palmaris ✓ Chronic superficial infection of stratum corneum − Brown or black macular patches and non-scaly macules ✓ Caused by species of lipophilic yeast (Malassezia) − Primarily on the palms and soles of the feet − Majority of cases of pityriasis versicolor are caused by: ✓ Malassezia furfur complex Hortaea werneckii ✓ Malassezia globosa ✓ Obsolete names: ✓ Malassezia sympodialis Phaeoannellomyces wernecki (Cladosporium ✓ Malassezia restricta werneckii) Exophiala werneckii − Causes seborrheic dermatitis or dandruff A. Lab Dx − Treatment: Ketoconazole Microscopic: − Hypo/hyperpigmentation: usually on the − Skin scrapings: 10-20% KOH chest, trunk, abdomen, and face. − Septate hyphal elements and budding cells Malassezia furfur − Strongly dematiaceous hyphae A. Microscopic Examination: − Branched melanized cell walls − short unbranched hyphae B. Medium: SDA − spherical cells Macroscopic: − “Spaghetti and meatballs fungus” − Shiny, moist, yeast-like colonies B. Macroscopic Examination: − Begins with a brownish coloration → olive to − Cream-colored, moist and smooth greenish black C. Treatments: − Branched, septate hyphae and budding yeast cells − Anti-dandruff shampoos with melanized cell walls − Selenium sulfide (daily application) C. Treatment: − Topical or oral azoles − Keratolytic solutions − Ketoconazole − Salicylic acid D. Medium used: − Azole antifungal drugs − Requires lipid for growth (M. furfur) − Overlaid with olive oil (yeast-like colonies) E. Diagnosis to confirm: CUTANEOUS MYCOSES − Direct KOH (10-20%) – digesting agent DERMATOPHYTES − Stained with calcofluor white − Dermatomycoses are fungal disease of the keratinized tissues of − LPCB – used for fungal identification − humans and other animals (Dermatophyte: ringworm) − Woods Lamp – Malassezia fluorescence = YELLOW − Ringworm: inflammation at advancing margin of lesion − Dermatophytes belong to three genera: PIEDRA 1. Trichophyton – skin, hair, nails − Latin word of Piedra: hair shaft 2. Microsporum – skin, hair − Nodules are composed of hyphae and cement-like substance 3. Epidermophyton – skin, nails − May infect hair of the axilla, genitalia, beard and scalp hair − Restricted to the nonviable skin − most are unable to grow at 37 or in the presence of serum o BLACK PIEDRA diagnosed by the presence of hyaline, septate, branching hyphae, − Caused by Piedraia hortae or chains or arthroconidia − Hard, dark brown to black gritty nodules − Keratinophilic: hair, nails, and cutaneous layers of the skin that − Nodules: consist of asci (sac like structures) with 8 ascospores contain the scleroprotein keratin A. To confirm: − The species are classified as: − 10% KOH: skin, hair or 20% KOH: nail ✓ Geophilic: soil – Microsporum gypseum − Nodules may be crushed open to reveal the asci ✓ Zoophilic: animals – Microsporum canis B. Medium: SDA ✓ Anthropophilic: human host – Microsporum audouinii − Brown, restricted colonies that remain sterile − Dark brown with metallic green tinge − Compact, raised center, slightly fuzzy WHITE PIEDRA − Caused by Trichosporon spp. − Soft mycelial mat surrounding scalp hair, A. Medium: face and public region − SDA: 2 weeks at 25 C − Mycosel medium or Mycobiotic medium: 3 weeks A. Immunocompromised hosts: − Hematologic disorders or malignancies MACROSCOPIC EXAMINATION − Underegoing chemotherapy ASEXUAL CONIDIA Reproductive cells: macroconidium or microconidium Commonly observed B. Most common Trichosporon: SEXUAL CONIDIA Reproductive cells: ascospores Trichosporon asteroids Rarely observed Trichosporon asahii – severe and fatal disease in immunocompromised host VARIOUS FORMS OF DERMATOPHYTESES AND THE RESPECTIVE AFFECTIVE SITES Trichosporon mucoides – recovered from CSF as a TYPE OF RINGWORM SITE AFFECTED cause of meningitis Tinea capitis Head Tinea favosa Head (distinctive pathology) Trichosporon beigelii – facial and genital hair Tinea barbae Beard C. Lab Dx: Tinea corporis Body (glabrous skin) − Trichosporon spp: arthroconidia, hyphae, blastoconidia Tinea manuum Hand Tinea unguium Nails VALENZUELA, ATASHA NICOLE DE JESUS  Tinea cruris Groin ✓ formed along undifferentiated hyphae Tinea pedis Feet a. macroconidia – pencil shaped (mostly elongated) Tinea imbricate Body (distinctive lesion) b. microconidia – tear drop/pear shaped (small and piriform) − Most strains developed a rede to deep burgundy wine-colored HAIR / HEAD INFECTED pigment on the reverse. Tinea favosa / Favus − (-) HPT, (+) UT − infection of hair follicle Tinea unguium − Causative agent: Trichophyton schoenleinii − aka Onychomycosis ✓ Crusty, cup-shaped flakes (scutula) − most often caused by dermatophytes ✓ Hair loss, crusty lesion and scar tissue − nail and nail bed infection may be among the most difficult ✓ Ringworm on scalp dermatomycoses to treat. (Terbinafine and Itraconazole) − Subungual – most common form of onchomycosis Tinea capitis − Causative agent: − Nails become thick, discolored and flaky Microsporum audouinii − Some common agents: Microsporum ferrugineum Trichophyton rubrum − 2 distinct forms: Trichophyton mentagrophytes a. Gray patch ringworm Trichophyton tonsurans ✓ common childhood disease which Epidermophyton floccosum easily spread among children. Tinea pedis b. Black dot ringworm − aka Athlete’s foot ✓ Ectothrix hair (outer portion of hair − Common disease for shoe-wearing human population shafts) − Affects soles of the feet and toe webs ✓ Site of infection: hair follicle − Arises from infected skin scales coming into contact with carpet, ✓ Brittle, infected hair shafts break off at shower. the scalp which leaves black dot stubs − Genetic predisposition ✓ Causative agent: − Severe cases: extensive scaling with fissuring and erythema Trichophyton tonsurans Trichophyton violaceum Moccasin foot Trichophyton tonsurans − Disease may progress around the sides of the foot from sole − Endothrix hair Trichophyton metagrophytes − Round peg shape miniature balloon app. − Athlete’s foot (most common) − Grows well with thiamine supplement agar − Microconidia – primarily globose but may appear tear-shaped in − Medium: SDA – rust colored pigment on colony’s reverse. cluster = grapelike clusters/cigar shaped − Leading cause of T. capitis in children in US. − Macroconidia – thin-walled, smooth and clear-shaped with 4-5 cells septated by parallel cross walls. Microsporum gypseum ✓ Spiral hyphae − Rapidly growing geophilic species found in soils worldwide ✓ Granular colonies noted with abundant microconidia − Ectothrix hair are formed (zoophilic) − Causative agent: Tinea barbae − (+) HPT, (-) UT − Fusiform, moderate thick-walled conidia DOWNY – conidia are less abundant; white and fluffy (anthrophilic) − 8-15 um x 25-60 um with 6 cells − Distal end of the macroconidium might bear a thin, filamentous SYSTEMIC DERMATOPHYTE INFECTIONS tail. − Immunocompromised patients − Spindle-shaped spore with 4-6 septa − Manifests as granulomas or nodules; pea-walnut sized − Cinnamon color, powdery, granular app. on colony surfaces − Seen in kidney transplant patient; spread from athlete’s foot. FRESH ISOLATED COLONIES: Epidermophyton floccosum − Tan to buff conidial masses − Smooth, thin-walled macroconidia are produced (cloud shaped) − Tends to develop pleomorphic tufts of − The distal end of the conidium is broad or spatulate and white sterile hyphae reminiscent of a beaver’s tail. (microconidia = 2-4 club-shaped) − Brown to red pigment can form beneath − Conidia may be single celled, but usually they are separated into some strains but other remains colorless. 2-5 cells by perpendicular cross-walls. − Yellow to yellow-tan colonies, flat with feathered edges, and Microsporum audouinii remain small in dm. − Slow-growing anthropomorphic dermatophyte − Causes T. cruris / T. pedis and does not produce microconidia − responsible for most of the gray patch tinea capitis of children − Cottony-white app. colonies, generally form little or no pigment on Epidermophyton reverse. − Its isolated are notorious for developing pleomorphic tufts of sterile hyphae in older cultures. Microsporum canis − Distributed worldwide − Macroconidia – spindle shaped with echinulate, thick walls and tapered ends. TESTS TO PERFORM − 12-25 um x 35-110 um; 3-15 cells HAIR PERFORATION TEST (modified hair baiting test) − Fluffy and white app. colonies − Sterile 5-10 mm hair fragments are floated on sterile water − Reverse side colony shows developing supplemented with a few drops of sterile 10% yeast extract. lemon yellow pigment on PDA. − Conidia or hyphae from the dermatophyte in question are − Worldwide distribution fungus inoculated onto the water surface. − Hair shafts are removed and microscopically examined in LPCB at weekly intervals for up to 1 month. FOOT / NAIL INFECTED − Some laboratories also use this test to distinguish penetration- Trichophyton rubrum capable Microsporum canis from M. equinum, which does not − Foot and toenail infection penetrate hair Urease Test. − Known to produce 3-8 cells cylindric macroconidia T. rubrum − Lesions: clear center with red margin − Causes only surface erosion of hair shafts − Macroscopically T. mentagrophytes ✓ colonies are cottony and white; − Typically forms perpendicular penetration pegs in the hair later will become velvety shafts − Microscopically ✓ contains clavateor peg- shaped microconidia VALENZUELA, ATASHA NICOLE DE JESUS UREASE TEST − Test used to differentiate T. mentagrophytes from T. rubrum is the 5-day urease test. − Tubes of Christensen Urea Agar are very lightly inoculated with the dermatophyte and held for 5 days at RT. T. rubrum − Isolates are negative or require more than 5 days to give a positive reaction. T. mentagrophytes − Urease production, resulting in a color change of the medium from peach to bright fuchsia. WOOD’S LAMP: (+) Microsporum and Epidermophyton (-) Trichophyton ADDITIONAL NOTES: ✓ Trichosporon spp. − Yellow or pale brown aggregations around hair shaft or axillary facial to genital scalp regions − Slimy, creamy and wrinkled ✓ Trichosporon asahii − Severe/frequently fatal disease − For immunocompromised patients ✓ Trichophyton tonsurans − macroscopic: Yellowish sunken center − microscopic: distorted shape (macroconidia), balloon shape appearance (microconidia) ✓ Microsporum spp. − Hair and skin − Large, rough-walled, multicellular, spindle-shaped − Macroconidia: produces spores ✓ Microsporum audouinii − Do not grow on rice agar but the rice grains (non- fortified rice) shows malted, velvety colonies and light to brown (tan) colonies. − Wood’s lamp: YELLOW to GREEN − Microscopically: racquet hyphae ✓ Epidermophyton floccosum − SDA + dichloromycetin = yellow to yellow tan, feathered edges and smaller in diameter − SDA + chloromycetin = velvety, powdery, greenish, yellow, and cottony center VALENZUELA, ATASHA NICOLE DE JESUS