MODULE-2-CUTANEOUS-MYCOSES-DERMATOPHYTOSES PDF

LESSON #2: MYCOSES CATEGORIES OF MYCOSES 1.CUTANEOUS SUPERFICIAL DERMATOPHYTOSES 2. SUBCUTANEOUS 3. SYSTEMIC 4. OPPORTUNISTIC  TOPIC OUTLINE: I Dermatophytoses II Classification of dermatophytes depending on their usual habitat: Anthropophilic, Geophilic, Zoophilic III Dermatophytosis...

LESSON #2: MYCOSES CATEGORIES OF MYCOSES 1.CUTANEOUS SUPERFICIAL DERMATOPHYTOSES 2. SUBCUTANEOUS 3. SYSTEMIC 4. OPPORTUNISTIC  TOPIC OUTLINE: I Dermatophytoses II Classification of dermatophytes depending on their usual habitat: Anthropophilic, Geophilic, Zoophilic III Dermatophytosis: Pathogenesis and Immunity Clinical Classification Tinea pedis, Tinea corporis, Tinea cruris, Tinea unguium, Tinea capitis (endothrix, ectothrix, kerion, favus) IV Three Anamorphic Genera involved in ringworm: Microsporum: Microsporum audouinii, Microsporum canis, Microsporum ferrugineum, Microsporum gypseum Epidermophyton: Epidermophyton floccosum Trichophyton: T. concentricum, T. mentagrophytes, T. rubrum, T. tonsurans, T. violaceum, T. verrucosum, T. schoenleinii  DERMATOPHYTOSES Affects the keratinized layers of the skin, hair, or nails. Symptoms: Itching Scaling Ring-like patches of the skin Brittle and Broken hair Thick discolored nails DERMATOPHYTOSES Dermatomycosis Dermatophytosis Dermatophytes are keratinophilic - "keratin loving" Ringworm - disease called ‘herpes' by the Greeks, and by the Romans ‘tinea' (which means small insect larvae)  CLASSIFICATION OF DERMATOPHYTES DEPENDING ON THEIR USUAL HABITAT 1. ANTHROPOPHILIC Keratin-utilizing on humans (M. audounii, T. tonsurans, Trichophyton rubrum) 2. GEOPHILIC Keratin-utilizing soil saprophytes (Microsporum gypseum) 3. ZOOPHILIC Keratin-utilizing on living animals Microsporum canis: cats and dogs, Trichophyton verrucosum: horse and swine, cows DERMATOPHYTOSIS: Pathogenesis and Immunity Contact and trauma Moisture Crowded living conditions Cellular immunodeficiency Chronic inflammation Re-infection is possible (but, larger inoculum is needed, the course is shorter) MAJOR SOURCES OF RINGWORM INFECTION ✓Schools ✓Military camps ✓Prisons ✓Warm damp areas ✓Animals MODE OF TRANSMISSION ✓Close human contact ✓Sharing clothes, combs, brushes, towels, bedsheets (fomites) ✓ Animal-to-human contact (Zoophilic) VARIOUS FORMS OF DERMATOPHYTOSES TYPES OF RINGWORM SITE AFFECTED Tinea capitis ringworm infection of the head, scalp, eyebrows, eyelashes Tinea facialis ringworm infection of the face Tinea corporis ringworm infection of the body Tinea cruris ringworm infection of groin (jock itch). Tinea unguium ringworm infection of the nails Tinea barbae ringworm infection of the beard Tinea manuum ringworm infection of the hand Tinea pedis ringworm infection of foot (athlete's foot) Tinea imbricata ringworm infection of the body (distinctive lesion) Tinea capitis Four types of clinical presentations: ✓Endothrix (black dot) ✓Ectothrix (gray patch) ✓Kerion ✓Favus Tinea capitis Tinea capitis  Tinea capitis 1. Endothrix: (Black Dot) Composed of fungal arthroconidia and hyphae, without cuticle destruction Causative organisms are Trichophyton spp. (T. tonsurans and T. violaceum)  Tinea capitis 1. Endothrix: (Black Dot) CLINICAL SYMPTOMS: The hair follicle is the initial site of infection, and fungal growth continues within the hair shaft, causing it to weaken. The brittle, infected hair shafts break off at the scalp, leaving the black dot stubs.  Tinea capitis 2. Ectothrix: (Gray Patch) The process of ectothrix invasion is similar to endothrix invasion, with the exception that the hyphae destroy hair cuticle, then converted into infectious arthroconidia Causative organisms are Microsporum (M. audouinii and M.canis) and Trichophyton.  Tinea capitis 2. Ectothrix: (Gray Patch) CLINICAL SYMPTOMS: The hair breaks close to the surface or a few millimeters above and there is scalp skin scaling. Small well-defined patches join together to form larger ones Tinea capitis Tinea capitis  Tinea capitis 3. Kerion A complication of scalp ringworm Speculated as an allergic reaction or an overzealous immunoresponse to the presence of tinea capitis  Tinea capitis 3. Kerion CLINICAL SYMPTOMS: Wet, purulent, inflamed & painful nodules & plaques; The most inflammatory form of tinea capitis (often of animal origin) Heals but there may be some scarring. Tinea capitis 4. Favus / Tinea favosa o A type of inflammatory tinea that is characterized by invasion of hair by hyphae o Severe form of tinea capitis oCausative organisms are: T. schoenleinii and T. violaceum  Tinea capitis 4. Favus / Tinea favosa CLINICAL SYMPTOMS: Patches of redness and scaling over which there are disc or cup shaped yellow crusts (scutula) pierced by 1 or 2 hairs which do not break; A foetid odour may be present. Tinea capitis Endothrix (Black Dot) Ectothrix (Gray Patch) Tinea corporis Generally restricted to stratum corneum of smooth skin Produces concentric or ring-like lesions on skin (annular plaques), and in severe cases these are raised and may become inflamed. *Trichophyton concentricum Causative organisms are: T. rubrum and T. tonsurans Tinea corporis CLINICAL SYMPTOMS: Symptoms result from fungi metabolites such as toxin/allergens. Tinea corporis Tinea cruris Lesions tend to be circinate and serpiginous with inflammatory, vesicular, enlarging margins Infection seen on scrotum and inner thigh, the penis is usually not infected. Causative organism is: E. floccosum Tinea cruris Predisposing factors include: opersistent perspiration, high humidity, tight clothing, diabetes and obesity, topical glucocorticoid application Tinea cruris  THREE ANAMORPHIC GENERA INVOLVED IN RINGWORM ✓Microsporum – infects hair and skin only ✓Epidermophyton – attacks skin and nails only ✓Trichophyton – attacks skin, hair or nails Tinea unguium Infection begins at the lateral or distal edges of the nail plate and results in paronychial inflammation Causative organisms are: T. rubrum, T. mentagrophytes, and E. flocossum Tinea unguium Tinea unguium  Tinea barbae Commonly found among farm workers Lesions tend to be inflammatory Causative organism: T. mentagrophytes Tinea barbae “Barber’s Itch”  Tinea manuum Dermatophyte infection of one or both hands This is most likely when a zoophilic or geophilic fungus is responsible The usual cause is an anthropophilic (human) fungus  Tinea manuum CLINICAL SYMPTOMS: An acute inflammatory rash like tinea corporis. There is usually a raised border and clearing in the middle (ringworm) Causes a slowly extending area of peeling, dryness and mild itching on the palm of one hand (hyperkeratotic tinea). Skin markings may be increased. Generally, both feet appear similar ("one hand, two-foot syndrome") Tinea manuum Tinea pedis Between toes or toe webs (releasing of clear fluid) o4th and 5th toes are most common sole. Commonly, patients describe pruritic, scaly soles and, often, painful fissures between the toes Causative organism: T. mentagrophytes, t. rubrum, and E. flocossum Tinea pedis DERMATOPHYTE IDENTIFICATION TABLE  THREE ANAMORPHIC GENERA INVOLVED IN RINGWORM Microsporum – infects hair and skin only Epidermophyton – attacks skin and nails only Trichophyton – attacks skin, hair or nails Microsporum Microsporum audouinii Microsporum canis Microsporum ferrugineum Microsporum gypseum Microsporum audoinii Macroconidia are often irregular or non-uniform in shape. Colonies on culture media are flat, silky in appearance. Favic chandeliers, pectinate bodies Microsporum audoinii Macroconidia are rarely seen, bizaar shaped Does not grow on Rice Medium Agar Gray-Patch Ringworm  Microsporum canis Causes sporadic outbreaks of ectothrix hair & skin infections Mainly zoophilic, erythema is common Colony is white and fluffy, sometimes canary yellow on the bottom Microscopically, characterized by large, thick-walled, echinulate or warty, spindle-shaped macroconidia, which contain 8-12 septa Microsporum canis Microsporum ferrugineum Common cause of tinea capitis and ectothrix infection Mainly anthropophilic Occurs in two colonial forms: o very slow growing, wrinkled suede-like, yellow to rust colored colony o rapid growing, flat, leathery and white Microscopically, the septate hyphae appear to have exceptionally thick septa Microsporum ferrugineum  Microsporum gypseum Causes tinea barbae, and ectothrix infection Infected hair does not fluoresce Colony is flat, light brown (cinnamon color) and with powdery appearance Throughout the colony, white tufts of hyphae appear (pleomorphic areas), which means that no spores are being formed on the hyphae. Microscopically, macroconidia are fusiform, thin-walled spindle- shaped spores containing 4-6 septa Microsporum gypseum  Epidermophyton floccosum Anthropophilic A common cause of infections of the groin, body, feet, and nails. Colony is yellow to greenish (olive drab) color with wrinkled or folded appearance Very fine, fuzzy texture like suede leather With areas of pleomorphism Epidermophyton floccosum Trichophyton Trichophyton concentricum Trichophyton mentagrophytes Trichophyton rubrum Trichophyton tonsurans Trichophyton violaceum Trichophyton verrucosum Trichophyton schoenleinii  Trichophyton concentricum Anthropophilic Infects skin and induces formation of circular lesions colony is slow growing, wrinkled or folded, velvety in appearance and white to orange to brown in color stimulated by the addition of thiamine Trichophyton concentricum  Trichophyton mentagrophytes Some are anthropophilic, some are zoophilic Worldwide cause of athlete’s foot Differentiated from T. rubrum by Hair Penetration Test It has several colony forms: a. “Downy”– culture is white, very fluffy b.“Granular” – very flat with aerial hyphae and has granulated appearance Trichophyton mentagrophytes  Trichophyton rubrum Anthropophilic Occurs worldwide Causes toenail infections, tinea corporis & tinea capitis Infected hairs do not fluoresce, and hair invasion is endothrix Skin lesions have red margin, with clear central portion May also exhibit two forms: o “Downy” – very fluffy, white with aerial hyphae o “Granular” – looks like a sugar sprinkled on the surface of the medium, undersurface is red, yellow to brown pigment Trichophyton rubrum  Hair Penetration Test 1. Preparation: The hair sample is typically taken from the scalp or affected area where fungal infection is suspected. The area should be cleaned to remove any debris or oils that may interfere with the test. 2. Collection of Hair Sample: A small number of hair strands (usually a few hairs) are collected from the affected area using clean tweezers. The hair should be plucked or cut as close to the scalp as possible. 3. Microscopic Examination: The hair sample is placed under a microscope to look for signs of fungal invasion. A KOH (potassium hydroxide) preparation is often used, where the hair is treated with a few drops of KOH solution and gently heated. 4. Interpretation of Results.  Hair Penetration Test Positive result: If fungal hyphae or conidia are seen penetrating inside the hair shaft, it indicates a fungal infection and suggests that the fungus has invaded the hair. Negative result: If no fungal elements are observed inside the hair shaft, it suggests that the infection is either not present or limited to the outer layers of the skin (not involving hair penetration). Hair Penetration Test  Hair Penetration Test T. mentagrophytes T. rubrum Culture Cultures burrow inside Cultures grow only on the hair, producing the outside of the hair V-shaped shafts in the hair Microscopic features Teardrop microconidia Clavate or peg shaped Hair Perforation Test (+) (-) Urease (+) (-) Trichophyton tonsurans Anthropophilic and occurs worldwide Causes endothrix infection, tinea capitis, tinea pedis and onychomycosis Etiologic agent of “adult ringworm of the scalp” Infected hairs do not fluoresce Colonies of T. tonsurans is powdery, suede-like with yellow to reddish brown in color with an underside of rich red to brown color Trichophyton tonsurans Trichophyton tonsurans Trichophyton violaceum Causes tinea favosa Colony deep violet in color, purplish pigment diffuses into media Colonies are waxy and grows better with thiamine Hyphae coarser in appearance than seen in other dermatophytes Hyphae are swollen containing granules Trichophyton violaceum  Trichophyton verrucosum Occasionally transmitted directly to man or via contaminated fomites Found on cattle Fungus forms large ectothrix spores All strains require thiamine and may need inositol Very slow growing, no pigment on reverse to yellow. Produces many small microconidia and occasionally macroconidia are produced. Large-spored ectothrix  Trichophyton verrucosum Macroconidia are thin-walled and may appear as “string beans” or “rat’s tails” Microconidia are clavate; teardrop shape Trichophyton schoenleinii Causes tinea favosa Endothrix infection of hair Demonstrate favic chandelier and chlamydospores Trichophyton schoenleinii