Mycology Lecture Notes: Superficial Mycoses

INSTITUTE OF HEALTH TECHNOLOGY, DHAKA Department of Laboratory Medicine BSc in Health Technology (Laboratory) - 1 st Year MYCOLOGY Lecture No. 03 (Superficial Mycoses) By Sk. MIZANUR RAHMAN Lecturer, Mycology MS in Biotechnology & Genetic Engineering (UODA) MS in Microbiology (SUB) Su...

INSTITUTE OF HEALTH TECHNOLOGY, DHAKA Department of Laboratory Medicine BSc in Health Technology (Laboratory) - 1 st Year MYCOLOGY Lecture No. 03 (Superficial Mycoses) By Sk. MIZANUR RAHMAN Lecturer, Mycology MS in Biotechnology & Genetic Engineering (UODA) MS in Microbiology (SUB) Superficial mycoses pityriasis versicolor – causative fungus, lesion produce. Anatomy of Skin Hair follicle and sebaceous gland 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 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 Superficial: Surface mycoses Pityriasis ( Tinea ) Versicolor Fungal infection of 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 Tinea Versicolor  Recent evidence suggest 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 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. Tinea Versicolor Definition • Asymptomatic colonization Malassezia furfur • Hypopigmentation • Hyperpigmentation • Seborrhoeic dermatitis • Dandruff • Fungaemia Pityriasis versicolor • Conditions: – Health – Sweat – Greasy skin – Chronic bacterial infections – Steroids Pityriasis versicolor • Clinical manifestations: – Maculae – White, cream, pink, red, brown – Scale/signs – Painless – Not itching Superficial mycosis ( Pityriasis versicolor ) Superficial mycosis ( Pityriasis versicolor ) Pityriasis versicolor Laboratory diagnosis: • Sampling – Scalpel (sharp bladed instrument) – Wood ́s lamp (producing ultraviolet radiation) • Direct • Culture 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. Tinea Versicolor Direct exam. • Skin scraping • 10 % KOH preparation • Parker Ink Culture • Sabouraud Dextrose Agar • Lipophilic yeast • Flood with Olive oil Tinea Versicolor Tinea Vesicolor – Woods Light Yellow White • Short fragments of hypha • cluster of yeast M.ovalae M.paraovalae M.furfur Malassezia Tinea Versicolor Microscope Culture  Malassezia furfur can 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.