Mycology II: Cutaneous and Subcutaneous Mycoses
Cutaneous Mycoses: Causes of Dermatophytosis
Contact and trauma Moisture Crowded living conditions Cellular immunodeficiency -Chronic infection. Re-infection possible -Larger inoculum.
Cutaneous mycoses: Different types of this fungi
Infections of the keratinized surfaces TYPES: •Trichophyton, Microsporum and Epidermophyton ssp..............Tineas •Skin: Tinea corporis (body), Tinea cruris (jock), Tinea manuum (hands) and Tinea pedis (foot). •Hair: Tinea capitis (scalp) and Tinea barbae (facial hairs) •Nails: Tinea unguium (nail) -Some can cause fungemia in the immunocompromised.
Sporotrichosis: Diagnosis
1. Direct microscopic examination of pus or sputum. •Look for cigar shaped yeasts. 2. Histopathological examination of biopsy. •Yeast cells. •Asteroid body: =>Yeast cells surrounded by Splendore-Hoeppli material. =>Star shaped - deposition of antigen-antibody complexes.. SLIDE 78 PICTURES
Types of Sporotrichosis
1. Subcutaneous or **Lymphocutaneous -Primary lesion typically in distal upper extremities. •Cause minimal pain. •Typically afebrile and does not become systemic. 2. Pulmonary sporotrichosis -Patients with underlying COPD. -Subacute or chronic pneumonia.
Fungemia: Trichosporon species
-*Catheter-associated fungemia in neutropenic patients. •Individuals with malignancies. •Anti-fungal therapy usually inefficient: •high fatality rate =>Numerous Microconidia SLIDE 80
Fungemia: Candida albicans
-*Catheter-related blood infection is a serious side-effects due to Candida colonization. •Very High fatality rate •Often seen in cancer patients following surgery. •Ovoid cells with constricted buds and pseudohyphae. SLIDE 80
Lymphocutaneous Sporothrichosis: Pathogenesis & Clinical Findings
-Acquired through cutaneous inoculation. •Pricked on a thorn. -Rose Handler's disease. -*Initial* papules or nodules at site of inoculation: •Suppurating granuloma with centralized neutrophils surrounded by lymphocytes and plasma cells. -Ascending chain of nodules develop along skin lymphatic channel. SLIDE 76 + 77 PICTURES
Cutaneous Mycoses: Diagnosis of Dermatophytes
-Colony characteristics -Microscopic morphology •Presence of macroconidia and/or microconidia. -Physiological tests •Urea hydrolysis ....... Trichophyton ssp. (this would be a POS. test) •Vitamin requirements...also amino acids
Subcutaneous mycoses (Sporotrichosis: Sporothrix schenkii) background info and general features
-Environmental distribution: •Soil, bark of trees, shrubs and garden plants. -Thermally dimorphic. •37°C: Round/cigar-shaped yeast cells. •This is the human infection •25°C: Septate hyphae. GENERAL FEATURES: -Chronic infection involving subcutaneous and lymphatic tissues. -Frequently encountered in gardeners: •Predominantly males. •"Rose Handler's disease". -May develop in otherwise healthy individuals. SLIDE 73 PICTURE
Cutaneous mycoses: background info
-Fungal infection of the keratinized layer of skin, hair or nails. •Do not invade tissue. Clinical classification depends on body area involved....... -Caused by dermatophytic fungi called ***Dermatophytosis. -Differential: •Non-dermatophytic fungi are called: ***Dermatomycosis. =>Examples of fungi causing dermatomycoses is cutaneous candidiasis.
Cutaneous Mycoses: Dermatophytosis (background info and different types of Dermatophytosis)
-Infection of the skin, hair or nails. •Also called keratinophilic fungi: they Able to digest keratin by secreting the enzyme keratinase. -Etiologic agents are three common dermatophytes. •Microsporum •Epidermophyton •Trichophyton
Cutaneous Mycoses: Dermatophytes (Trichophytons) Where it infects and Clinical Signs
-Infects skin, hair and nails. •TRIchophyton •example: athlete's foot, ringworm, jock itch. -Numerous **MICROconidia •Variety of shapes: Teardrops, spheres, peg-shaped -Macroconidia rare. SLIDE 63 FOR PICTURES
Fungemia: Malassezia furfur
-Nosocomial infections related to the administration of IV lipid supplements through a *central venous catheter. •Infection subsides once lipid infusion stopped. •'Spaghetti & meatballs'. SLIDE 80
Treatment of Cutaneous Mycoses: TOPICAL and ORAL
-Topical ointment for mild skin disease. •Terbinafine cream or topical azoles. -Oral therapy for hair, nail or severe skin disease. •Terbinafine, Griseofulvin or Itraconazole.
Cutaneous Mycoses: Dermatophytes (Microsporum) Where it infects and Clinical Signs and Diagnosis
CLINICAL SIGNS -Infect skin and hair. •Rarely hair (no nails). •raised and scaly lesion. •pinpoint pustules. -Many, rough thick-walled ***MACROoconidia: •Spindle shaped and spiny. •*Rare to see microconidia. DIAGNOSIS -Microsporum fluoresce 'bright green' under Wood lamp (UV). SLIDE 61 KNOW PICTURES
Cutaneous Mycoses: Ecology of Dermatophytes
Classified into three groups depending on their usual habitat. -Anthropophilic •Usually associated with humans. •Person-to-person transmission. •Direct or indirect. -Geophilic •Found in soil. •Transmitted to person by direct exposure. -Zoophilic •Usually associated with animals. •Transmission to persons by close contact with animals or contaminated products.
Cutaneous Mycoses: Dermatophytes (Epidermophytons) Where it infects and Clinical Signs
Example: E. floccosum -Infects both skin and nails. -Form yellow-colored, cottony cultures. -Thick bifurcated hyphae with multiple smooth, club-shaped **MACROconidia (No microconidia.) SLIDE 62 PICTURES
Subcutaneous mycoses: Different types of this fungi
For Chronic, subcutaneous and lymphatic tissues: -Sporotrichosis: Sporothrix schenkii
Fungemia: Types of fungi species that do this
Fungemia- Fungi or yeasts in the blood 1. Malassezia furfur 2. Trichosporon species 3. Candida albicans
Cutaneous Mycoses: Types of Dermatophytes
Microsporum Epidermophyton Trichophyton
Sporotrichosis: Treatment
Spontaneous healing is possible. -Lymphocutaneous Sporotrichosis is treated with Oral itraconazole for 3 to 6 months. -Disseminated infection is treated with IV Amphotericin B: •Followed by Itraconazole for 1 year.
Examples of Cutaneous Mycoses (Tinea' species: A Colloquial term)
Tinea (or ringworm) is any of a variety of skin mycoses: -Tinea capitis = ringworm of the scalp (Refers to tineas of the scalp, eyebrows and eyelashes) -Tinea barbae = ringworm of the beard. -Tinea corporis = ringworm of glabrous skin -hairless skin -Tinea cruris = jock itch. Groin area. -Tinea pedis = athlete's foot. Between toes. -Tinea unguium = ringworm of the nails
Where it infects and Clinical presentation of: Tinea Cruris (Jock Itch) and Tinea Unguium (Onychomycosis) and Tinea Pedis - Athlete's Foot longgg
Tinea Cruris (Jock Itch) SLIDE 68 -Fungal infection of the groin and adjacent skin. -Manifests as a symmetric erythematous rash. •demarcated at the periphery. -Acute •Moist and exudative. -Chronic •Dry rashes, with a papular, annular or arciform border. •Advancing outer erythematous edge with a trailing (inner) scaly edge. •The rash may be itchy. and Tinea Unguium (Onychomycosis) SLIDE 69 -Fungal infection of nails: •More common in the toes than the fingers. •"Green Nail disease" -Begins as discoloration at a corner of the nail and slowly spreads toward the cuticle. -Nail eventually becomes thickened and flaky. and Tinea Pedis - Athlete's Foot SLIDE 70 Most common dermatophytosis. -Fungal infection of the soles of the feet and the interdigital spaces. -Pruritic, scaly soles. -Painful fissures between toes. -Less often vesicular or ulcerative lesions.
Where it infects and Clinical presentation of: Tinea capitis and Tinea Barbae and Tinea Corporis lonngggg
Tinea capitis SLIDE 65 PICTURES and Tinea Barbae SLIDE 66 -Limited to the bearded areas of the face and neck. -Inflammatory: •Deep, kerionlike plaques that appears as raised, spongy lesions. -Non-inflammatory superficial patches can also be seen. •Resembling tinea corporis or bacterial folliculitis. -Almost exclusively in older adolescent and adult males. and Tinea Corporis SLIDE 67 -Inflammatory or non-inflammatory lesions on the glabrous skin (no hair). -Excludes skin of the scalp, groin, palms and soles. -Pruritic, annular plaque: Burning sensation.
