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Superficial mycoses
Pityriasis versicolor is a common superficial fungal infection of the skin caused by Malassezia furfur. It produces hypopigmented, hyperpigmented, or scaly macules on the trunk and neck. Diagnosis involves scraping skin lesions and examining under a microscope using potassium hydroxide, which reveals short hyphal fragments and clusters of yeast. Wood's lamp examination shows pale yellow-white fluorescence of lesions. M. furfur is normally present on human skin but overgrowth causes pityriasis versicolor. The fungus can be cultured using Sabouraud dextrose agar covered with oil, as M. furfur requires lipids for growth.
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Superficial mycoses
- 1. INSTITUTE OF HEALTHTECHNOLOGY, DHAKA Department of Laboratory Medicine BSc in Health Technology (Laboratory)- 1st Year MYCOLOGY Lecture No. 03 (Superficial Mycoses) By Sk. MIZANUR RAHMAN Lecturer, Mycology MS in Biotechnology & Genetic Engineering (UODA) MS in Microbiology (SUB)
- 2. Superficial mycoses pityriasis versicolor– causative fungus, lesion produce.
- 3. Anatomy of Skin Hairfollicle and sebaceous gland
- 4. Fungal Infections/ Mycoses •Superficial mycoses: – 2 types: surface and cutaneous mycoses – Skin, hair & nails. – Mild but chronic disease • Deep mycoses: – 2 types: subcutaneous & systemic mycoses – Caused by soil saprophytes – Infection is accidental – Range from a symptomatic infection to fatal disease
- 5. Superficial: Surface mycoses •Live exclusively on dead surfaces of skin and its appendages • No contact with living tissue, hence no inflammatory response 1. Tinea versicolor 2. Tinea nigra 3. Piedra
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- 7. Pityriasis (Tinea)Versicolor Fungal infectionof the skin This is a very common superficial mycoses caused by a lipophilic yeast Malassezia spp. It is seen in all countries but is particularly common in the tropics with more than 60 % of the population infected. The lesions are hypo or hyper pigmented. The etiologic agent is normal flora of man so the disease re-occurs. Multiple patchy lesions (oval shape c fine scales) either light in color or brown Typically occurs on the back, neck, chest, shoulders
- 8. Tinea Versicolor Recent evidencesuggest that seborrheic dermatitis is also caused, or triggered by, Malassezia yeast. There also is Malassezia folliculitis. This is seen in patients who are usually severely ill or in patients after sun exposure. Tx: Topical antifungal
- 9. General Morphology Tinea Versicolor •Numerous, well-marginated, oval-to-round macules (change in the color of the skin) with a fine white scale when scraped. • Pigmentary alteration uniform in each individual. – Red – Hypo pigmented – Hyperpigmented • Scattered over the trunk and neck. Seldom the face. • M. furfur – Normal flora of skin • Asymptomatic.
- 10. Tinea Versicolor Definition •Asymptomatic colonization Malasseziafurfur •Hypopigmentation •Hyperpigmentation •Seborrhoeic dermatitis •Dandruff •Fungaemia
- 11. Pityriasis versicolor • Conditions: –Health – Sweat – Greasy skin – Chronic bacterial infections – Steroids
- 12. Pityriasis versicolor • Clinicalmanifestations: – Maculae – White, cream, pink, red, brown – Scale/signs – Painless – Not itching
- 13. Superficial mycosis (Pityriasisversicolor)
- 14. Superficial mycosis (Pityriasisversicolor)
- 15. Pityriasis versicolor Laboratory diagnosis: •Sampling – Scalpel (sharp bladed instrument) – Wood ́s lamp (producing ultraviolet radiation) • Direct • Culture
- 16. Tinea Versicolor Diagnosis: •Scrape lightly– fine white scale •KOH Positive for short hyphae and spores (Spaghetti –hyphae and meatballs-yeasts) •Woods Light – pale yellow white fluoresce. •Culture rarely done.
- 17. Tinea Versicolor Direct exam. •Skinscraping •10% KOH preparation •Parker Ink Culture •Sabouraud Dextrose Agar •Lipophilic yeast •Flood with Olive oil
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- 19. Tinea Vesicolor –Woods Light Yellow White
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- 24. Culture Malassezia furfurcan be grown in a laboratory but only when one covers the culture with oil. This leads me to speculate that there is a genetic susceptibility to this disease resulting from qualitative or quantitative differences in the oil content of susceptible persons.