Medical Mycology Lecture Notes PDF

Ministry of Higher Education and Scientific Research. Southern Technical University Colleges of Health and Medical Technology Basrah Department of Medical Laboratories Medical Mycology Thir...

Ministry of Higher Education and Scientific Research. Southern Technical University Colleges of Health and Medical Technology Basrah Department of Medical Laboratories Medical Mycology Third CLASS lecture no. 3 (2024 - 2025) Lecture : Dr.Shrouk Abdulrazak Hassan AL-Ibraheem dr.Shrouk Alibraheem 1  Superficial mycoses: These are superficial fungal infections of the Hair, dead skin and lipids secretions. Fungi which cause this kind of infection are living as saprophytes. No living tissue is invaded. Essentially no pathological changes. No immune system responed These infections are often so harmless that patients are often unaware of their condition dr.Shrouk Alibraheem 2  Superficial Mycoses  Limited to the outermost layer of the skin 1. Pityriasis versicolor 2. Tinea nigra 3. Black piedra 4. White piedra 5. Mycotic keratitis (Keratomcosis) 6.Otomycoses dr.Shrouk Alibraheem 3  Characteristics of mycoses  1- Superficial mycoses  A- Pityriasis versicolor  It is a chronic mild superficial infection of the stratum corneum caused by  Malassezia globosa  Malassezia furfur.  The term ‘pityriasis’ is used to describe skin conditions in which the scale appears similar to bran.  The multiple colours arising in the disorder give rise to the second part of the name, ‘versicolor’. dr.Shrouk Alibraheem 4  A- Pityriasis versicolor  Usually Malassezia grow sparsely in the seborrhoeic areas without causing a rash.  The yeasts induce enlarged melanosomes (pigment granules) within basal melanocytes in the brown type of pityriasis versicolor. .Pityriasis versicolor is characterized by hypopigmentation or hyperpigmentation of skin of the neck, shoulders, chest, and back.  Pityriasis versicolor usually presents as asymptomatic patches of hypo- or hyper-pigmented macules, varying in size, shape and color.  The most common sites are the chest, upper back, shoulders, upper arms and abdomen.  Hair shaft and nail are not infected.  Pityriasis versicolor is more common in hot, humid climates or in those who sweat heavily, so it may recur each summer. dr.Shrouk Alibraheem 5  Pityriasis versicolor infection* hypo pigmentation dr.Shrouk Al ibr ah ee m 6 hyperpigmentation  Laboratory diagnosis  Skin scraping & KoH (10%) exam. glycerol and Parker ink solution  Under microscope , thick-walled round, budding yeast-like cells and short angular hyphal forms up to 8um in diameter(spaghetti and meat balls).  Culture:  Media : Sabouraud's dextrose agar (SDA) (suppl.: containing cycloheximide (actidione) with olive oil )  Media is supplemented with fatty acids Malassezia furfur dr.Shrouk Alibraheem 7  Therapy  Tinea versicolor can be successfully treated with various agents. Effective topical agents include :  selenium sulfide  sodium sulfacetamide  as well as azole and allylamine antifungals.  Ketoconazole, fluconazole, and itraconazole are the preferred oral agents. dr.Shrouk Alibraheem 8  B-Tinea nigra  Tinea nigra ( or tinea nigra Palmaris ) is a superficial fungal infection of skin caused by the dematiaceous fungus  Exophiala werneckii.  characterised by brown to black macules which usually occur on the palmar aspects of hands and occasionally the plantar and other surfaces of the skin.  World-wide distribution, but more common in tropical regions of Central and South America, Africa, South-East Asia and Australia. dr.Shrouk Alibraheem 9  Tinea nigra dr.Shrouk Alibraheem 10  Diagnosis:  1- Direct Microscopy: Skin scrapings mounted in 10% KOH showing pigmented brown to dark olivaceous (dematiaceous) septate hyphal elements and yeast cells producing annello conidia typical of Hortaea werneckii.  2- Culture: Skin scrapings specimens should be inoculated onto Sabouraud's dextrose agar , showing appearance of dark (dematiaceous) septate hyphae. dr.Shrouk Alibraheem 11  Exophiala werneckii. dr.Shrouk Alibraheem 12  C- Piedra  Piedra originates from the Spanish word meaning stone.  Piedra refers to colonization of the hair shaft that results in firm, irregular nodules.  Piedra is an infection limited to hair shaft and is characterized by firm, irregular nodules composed of fungal elements.  Black piedra caused by Piedra hortae,  and white piedra which caused by Trichosporon beigelii are the only two recognized varieties of piedraThese nodules are a loose aggregate of hyphae and arthroconidia.  Multiple colonization of the same strand are common. The infection may affect hairs of the scalp, body and genital areas. dr.Shrouk Alibraheem 13  1. Black piedra:  Is usually found only on scalp hair. Although the infected hair appears normal in this case, the infected hair is rough, sandy, or granular to the touch.  Infection with this fungus is charactarized by asymptomatic nodules vary in size from microscopic to a few millimeters in diameter.  The thickness is usually greater one end, tapering at the opposite one.  Piedra hortai not penetrate the cortex of the hair shaft. dr.Shrouk Alibraheem 14  Diagnosis:  1- Direct Microscopy: Hairs should be examined using 10% KOH and Parker ink or calcofluor white.  Look for darkly pigmented nodules that may partially or completely surround the hair shaft.  Nodules are made up of a mass of pigmented with a stroma-like centre containing asci.  2- Culture: Hair fragments should be cultured on Sabouraud's dextrose agar. Colonies of Piedra hortae are dark, brown-black and take about 2-3 weeks to dr.Shrouakp Alibp rae hea emr. 15  diagnosis Black Piedra ❖ This is a culture of the fungus ❖ Piedraia hortai colony cultured on Sabourauds medium. ❖ The gross features in the center, is a dark brown-black to metallic green and is surrounded by a clear ring where the young growing mycelium has not yet produced the dark pigment. ❖ Microscopically, there are few characteristic features. The fungus produces dermatiaceous hyphae which may contain numerous chlamydospores. dr.Shrouk Alibraheem 16  Therapy of black piedra  Therapy includes shaving of affected areas , but this is often not considered acceptable,  and use topical application of salycylic acid,  2% formaldehyde  azole creams.  Oral therapy with either ketoconazole or  terbinafine has also been used. dr.Shrouk Alibraheem 17  White piedra:  White piedra is characterized by soft, mucilaginous, white greenish-yellow to light brown nodules seen more often on hairs of the genital area, beard, and mustache than on scalp, eyebrows or eyelashes.  The nodules are usually thickest at the center but may show variation in shape and size.  Unlike the nodules of black piedra the fungal mass of  Trichosporon beigelii can easily be pulled off the hair shaft.  The clinical growth of T. beigelii start beneath the cuticle of the hair shaft.  Therapy of White piedra : dr.ShroIutkrAalibcraohenemazole - 2% selenium - amp18hotericin B   Diagnosis White Piedra  hair with white piedra (Trichosporon beigelii).  Note that, when this module is compared with that seen in black piedra, it is not as discrete and lacks the dark coloration. Additionally, this fungus does not produce ascospores. dr.Shrouk Alibraheem 19  Trichosporon beigelii  This is a 4-5 week old culture of Trichosporon beigelii, grown on Sabourauds medium at room temperature.  This is the etiologic agent of white piedra. dr.Shrouk Alibraheem 20  Keratomycosis (Mycotic keratitis)  A fungal keratitis is an 'inflammation of the eye's cornea' (called keratitis) that results from infection by a fungal organism. Keratomycosis is the Greek terminology equivalent of fungal keratitis - it is the fungal infection of the cornea, the anterior part of the eye which covers the pupil.  Those experiencing these symptoms are typically advised to immediately visit the appropriate eye care professional.  Causes: Aspergillus fumigatus - Fusarium spp. -Candida spp.  Treatment:  Fluconazole ophthalmic solution for Candida infection dr.Shrouk Alibraheem 21  Amphotericin B eye drops  Otomycosis  is a fungal ear infection, a superficial mycotic infection of the outer ear canal. It is more common in tropical countries.  The infection may be either subacute or acute and is characterized by malodorous discharge, inflammation, pruritus, scaling, and severe discomfort.  Causes: Aspergillus sp - Mucor sp -Candida sp  Treatment:  Nystatin powder puffed into the ear  Imidazol dr.Shrouk Alibraheem 22 dr.Shrouk Alibraheem 23