cutaneous mycoses.ppt
TRANSCRIPT
INSTITUTE OF HEALTH TECHNOLOGY, DHAKADepartment of Laboratory Medicine
BSc in Health Technology (Laboratory)- 1st Year
MYCOLOGY Lecture No. 04 (Cutaneous Mycoses)
By
Sk. MIZANUR RAHMANLecturer, Mycology
MS in Biotechnology & Genetic Engineering (UODA)MS in Microbiology (SUB)
Cutaneous Mycoses
oDermatophytosis - "ringworm" disease of the nails, hair, and/or stratum corneum of the skin caused by fungi called dermatophytes. oDermatomycosis - more general name for any skin disease caused by a fungus.
Cutaneous mycoses
• Infection of the skin, hair or nails caused by a group of keratinophilic fungi, called dermatophytes
• DERMATOPHYTOSIS (=Tinea = Ringworm)
extend deeper into the epidermis, as well as invasive hair and nail diseases.
DERMATOPHYTES
• Digest keratin by their keratinases• Resistant to cycloheximide• Classified into three groups depending
on their usual habitat
Cutaneous mycoses
• Keratophilic – use keratin as subject to live ( parasites)
• Keratinases- invade only keratinized layers
DERMATOPHYTOSIS
ClassificationThree Groups/Types:• Clinical• Etiological• Ecological
Clinical DermatophytosisClinical Classification & Manifestations
• Infection is named according to the anatomic location involved:
- Tinea corporis: small lesions occurring anywhere on the body
- Tinea pedis :"athlete's foot". Infection of toe webs and soles of feet.
- Tinea unguium (onychomycosis) :nails. Clipped and used for culture
- Tinea capitis : head. Frequently found in children
Tinea barbae: ringworm of the bearded areas of the face and neck.
Cutaneous InfectionsInfections of skin and its appendages (nails, hair); 20 species of dermatophytes cause ringworm.
Etiology of Dermatophytes
Etiology (3 Genera) • Trichophyton• Microsporum• Epidermophyton
• Trichophyton - infections on skin, hair, and nails.
• Microsporum - infections on skin and hair (not the cause of TINEA UNGUIUM)
• Epidermophyton - infections on skin and nails (not the cause of TINEA CAPITIS)
Etiology (3 Genera)
Trichophyton (19 species)
• Hair • Skin• Nails
Trichophyton • For Trichophyton species - infections on hair follow one of
the 4 patterns. – Ectothrix - more or less parallel rows of arthrospores
produced on surface of hair. • 1. Small-spored ectothrix (arthrospores are < 5 mm
in diameter) - caused by T. mentagrophytes or T. rubrum (rare). Spores are about the same size as those produced by Aspergillus. • 2. Large-spored ectothrix (arthrospores are 5- 10
mm in diameter) - caused by T. verrucosum. – Endothrix - growth inside hair shaft only! • 3. "Black-dot" endothrix (hair stubs filled with
arthrospores) - caused by T. tonsurans or T. violaceum. • 4. "Favus hair" endothrix (honeycomb pattern
of damage seen on surface of hair shaft) - caused by T. schoenleinii.
Trichophyton species
Trichophyton rubrum
Causes a chronic infection in patients with a cell-mediated immune defect.
• Skin• Hair
Microsporum (13 species)
Microsporum species
Thick wall, spindle shape, multicellular
Microsporum canis
Most common etiologic agent of tinea
• Skin• Nails
Epidermophyton floccosum
Epidermophyton floccosum
Bifurcated hyphae with multiple, smooth, club shaped macroconidia (2-4 cells)
Ecology of Dermatophytes
To determine the source of infection
• Anthropophilic• Zoophilic• Geophilic
Anthropophilic
• Associated with humans only. Person -to-person transmission through contaminated objects (comb, hat, etc.) • e.g., M. audounii, T. tonsurans
Zoophilic
• Associated with animals. Direct transmission to humans by close contact with animals.• e.g., M. canis, T. verrucosum
Geophilic
• Usually found in soil (soil saprophytes). Transmitted to humans by direct exposure.•e.g., M. gypseum, T. ajelloi.
DERMATOPHYTOSISDiagnosis
I. ClinicalAppearanceWood’s lamp (UV, 365 nm) II. Lab A. Direct microscopic examination(10-25% KOH)
DERMATOPHYTOSISDiagnosis
B. Culture• Mycobiotic agar • Sabouraud dextrose agar • Selective media – containing cycloheximide and
chlorampenicolincubate at 25 C.• Identification based on the conidia
Diagnosis
• Diagnosis is based upon: 1. Anatomical site infected 2. Type of lesion 3. Examination with a Woods lamp (366 A°) 4. Examination of KOH-treated skin scales from the infected area 5. Culture of the organism (not too important)
Dermatophytes Culture
Dermatophyte Culture
Black collection card
Ringworm culture
General characteristics of Macroconidia and Microconidia of Dermatophytes
Genus Macroconidia Microconidia
Microsporum Numerous, thick walled,rough
Rare
Epidermophyton Numerous, smooth walled
Absent
Trichophyton Rare,thin walled, smooth
Abundant
Microsporum
Trichophyton
Epidermophyton floccusom