MyCV 311 Lecture Notes on Dermatophytes (PDF)

HABITAT INFECTION MOT MICROSPORUM CANIS zoophilic – tinea capitis in humans animals to humans (ectothrix)...

HABITAT INFECTION MOT MICROSPORUM CANIS zoophilic – tinea capitis in humans animals to humans (ectothrix) – simple ringworm in pets MICROSPORUM geophilic – hair infection (ectothrix) GYPSEUM MICROSPORUM anthrophilic – non-inflammatory infections infected hairs on AUDOUINII of scalp and skin especially in – hats children – caps – upholstery combs – barbers clippers EPIDERMOPHYTON anthropophilic invades skin and nails but never may become epidemic among personnel FLOCCOSUM hair using common shower or gym facilities such – Tinea cruris (groin area) as athletic teams, troops, ship crews and – Tinea pedis (ringworm on inmates of institutions feet) – Onychomycosis (infection in nails) – Tinea corporis (mammary gland) TRICHOPHYTON anthropophilic – common cause of tinea RUBRUM ungium (nail) – skin, nail , rarely scalp infection – hair infection (endothrix or ectothrix) TRICHOPHYTON zoophilic – common cause of Tinea laboratory / domesticated animal hosts MENTAGROPHYTES worldwide pedis (athletes foot) including distribution – inflammatory skin or scalp – mice lesions in humans – guinea-pigs – hair infection (ectothrix) – kangaroos – cats – horses – sheep – rabbits TRICHOPHYTON common cause of Tinea capitis TONSURANS - “Black dot” (endothrix) TRICHOPHYTON zoophilic – ringworm in cattle VERRUCOSUM – infections in humans – direct contact with cattle or infected fomites – Tinea barbae – beard – hair infection (ectothrix) TRICHOPHYTON anthropophilic favus in humans SCHOENLEINII TRICHOPHYTON “black dot” tinea capitis VIOLACEUM (endothrix) ZOOPHILIC GEOPHILIC ANTHROPOPHILIC – Microsporum canis – Microsporum gypseum – Epidermophyton floccosum – Trichophyton mentagrophytes – Trichophyton rubrum – Trichophyton verrucosum – Trichophyton schoenleinii COMMON CAUSE OF TINEA UNGIUM (NAIL) Trichophyton rubrum COMMON CAUSE OF TINEA PEDIS (ATHLETES FOOT) Trichophyton mentagrophytes COMMON CAUSE OF TINEA CAPITIS Trichophyton tonsurans  HAIR INFECTION (ECTOTHRIX) HAIR INFECTION (ENDOTHRIX) HAIR INFECTION (ENDOTHRIX OR ECTOTHRIX) – Microsporum gypseum – Trichophyton tonsurans – Trichophyton rubrum – Trichophyton mentagrophytes – Trichophyton violaceum – Trichophyton verrucosum SURFACE PIGMENT REVERSE PIGMENT MICROSPORUM CANIS – white – golden-yellow to brownish yellow MICROSPORUM GYPSEUM – white – yellow brown – reddish-brown may be present in some strains MICROSPORUM AUDOUINII – white – reddish-brown – salmon or peach –pink – some strain has no reverse pigment EPIDERMOPHYTON FLOCCOSUM – greenish brown or khaki – deep yellowish brown TRICHOPHYTON RUBRUM – white – reddish rose purple – deep wine-red – no reverse pigment when grown on 1% peptone agar TRICHOPHYTON – white to cream – yellow-brown to pinkish brown MENTAGROPHYTES TRICHOPHYTON TONSURANS – white – yellow, the so-called “sulfureum” form to dark- brown – yellow-brown to reddish-brown to deep mahogany TRICHOPHYTON VERRUCOSUM – white – yellow TRICHOPHYTON SCHOENLEINII – cream colored to yellow – orange brown TRICHOPHYTON VIOLACEUM – deep violet some strain has no reverse pigment Microsporum audouinii no reverse pigment when grown on 1% peptone agar Trichophyton mentagrophytes  WOOD’S LAMP RICE AGAR TEST / IN VITRO HAIR NUTRITIONAL UREASE TEST HAIR PERFORATION PENETRATION TEST TEST MICROSPORUM CANIS bright greenish - POSITIVE yellow MICROSPORUM GYPSEUM MICROSPORUM apple green or NEGATIVE T1 POSITIVE AUDOUINII bright greenish - very poor or absent T4 POSITIVE yellow brown discoloration EPIDERMOPHYTON FLOCCOSUM TRICHOPHYTON do not fluoresce 28 days or 4 weeks NEGATIVE >5 days NONE, RUBRUM NEGATIVE WEAK OR DELAYED 7 days POSITIVE TRICHOPHYTON do not fluoresce 14 days POSITIVE 7 days MENTAGROPHYTES POSITIVE POSITIVE commonly 3 - 5 days ALREADY POSITIVE TRICHOPHYTON T1 NEGATIVE TONSURANS T4 POSITIVE TRICHOPHYTON fluorescence in T1 NEGATIVE VERRUCOSUM cattle but not in T4 POSITIVE humans TRICHOPHYTON pale greenish SCHOENLEINII yellow TRICHOPHYTON do not fluoresce T1 NEGATIVE VIOLACEUM T4 POSITIVE MANY STRAINS REQUIRE INOSITOL - Growth is enhanced at TRICHOPHYTON VERRUCOSUM 37OC ALL STRAINS OF T. VERRUCOSUM PRODUCE TYPICAL BRAIN HEART INFUSION BROTH WITH PARA-AMINO CHAINS OF CHLAMYDOCONIDIA WHEN GROWN AT THIS BENZOIC ACID (PAB) AND AGAR AT 37OC 10% KOH AND PARKER INK SOLUTION shows typical large spored T. violaceum REQUIRED THIAMINE FOR GROWTH – MICROSPORUM AUDOUINII – TRICHOPHYTON TONSURANS – TRICHOPHYTON VERRUCOSUM – TRICHOPHYTON VIOLACEUM SABOURAUD AGAR MICROSPORUM GYPSEUM – powdery – cinnamon brown color – some with white aerial mycelium at first and become matted SABOURAUD DEXTROSE AGAR MICROSPORUM AUDOUINII – malted – velvety – light tan to brown  MACROCONIDIA MICROCONIDIA MICROSPORUM CANIS – 3-15 celled – few pyriform to clavate – large – multi celled – spindle shaped – rough thick walled – terminal end: sometimes curved with a terminal knob MICROSPORUM GYPSEUM – symmetrical – singly or in clusters – ellipsoidal – numerous clavate shaped – thin – moderately thick walled – 4-6 celled – terminal or distal ends are thin slightly rounded and filamentous MICROSPORUM AUDOUINII – rarely produce – absent or bizarre, if present atypical vegetative hyphae with terminal chlamydospore, racquet hyphae and favic chandeliers EPIDERMOPHYTON – monotypic genus (cluster or single) FLOCCOSUM – often in clusters – 1-5 celled not formed – thin-walled – club shaped – greenish yellow TRICHOPHYTON RUBRUM – pencil-shaped – teardrop shaped occurring singly and in – slender or pyriform, pear shape clusters along hyphae – not usually present – slender clavate to pyriform – if present, thin wall, slender associated with cigar shape microconidia – slender or pyriform, pear shape TRICHOPHYTON – thin-walled – grape-like clusters - spherical and sub MENTAGROPHYTES – smooth spherical – cigar shaped – subspherical on terminal branches – multiseptate – spherical often forming in dense cluster – pear shape TRICHOPHYTON – various size and shapes, flattened base TONSURANS – aged microconidia: balloon forms absent or rare, distorted – long-clavate to broad-pyriform at right angles to the hypha – hyphae are relatively broad, irregular and much branched with numerous septa – older cultures: swollen giant forms TRICHOPHYTON – rare, if present have a characteristic of – large clavate, lateral VERRUCOSUM rat tail or string bean shape – clavate to pyriform / pear shape – 3-5 cells – thin-walled TRICHOPHYTON absent SCHOENLEINII TRICHOPHYTON absent VIOLACEUM  COLONY SURFACE COLONY MICROSPORUM CANIS MICROSPORUM GYPSEUM – central white downy umbo (dome) or a fluffy white tuft of mycelium – some also show a narrow , white periphery – like rays of sun MICROSPORUM AUDOUINII – thick-walled intercalary – flat, spreading, downy white surface chlamydoconidium EPIDERMOPHYTON FLOCCOSUM – yellow to yellow tan – greenish-brown or khaki coloured with – flat and feathery edges a suede-like surface – small diameter – thin in older culture TRICHOPHYTON RUBRUM – cottony and white – later become velvety TRICHOPHYTON MENTAGROPHYTES TRICHOPHYTON TONSURANS – slow growing – sunken center – wrinkled – may not grow w/o thiamine TRICHOPHYTON VERRUCOSUM – dry crusty layer TRICHOPHYTON SCHOENLEINII – very slow growers (30 days or – dry and waxy more) – small wrinkled waxy – favic chandeliers and chlamydospore formation TRICHOPHYTON VIOLACEUM – very slow growing – glabrous or waxy – heaped and folded – deep violet in colour TEST RICE AGAR TEST MATERIALS – rice grain – hair sample – agar PROCEDURE – cut an agar in square shape – place the hair sample on the agar – place the agar with the hair sample at the center of the rice grain EXAMINATION – remove hair every 4 days of 1 week – examine microscopically RESULT – POSITIVE – good surface growth – sporulation