Common Fungal Infections PDF
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Al Baha University
Hasan Alfahemi
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Summary
This document provides an overview of common fungal infections, including their characteristics, diagnosis, and treatment. It details various types like athlete's foot and ringworm, along with the role of keratin in infections. The epidemiology and laboratory diagnostic procedures are also outlined.
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Common Fungal infections Hasan H. Alfahemi Assistant Professor of Medical Microbiology Faculty of Medicine Department of Medical Microbiology Al-Baha University Cutaneous Mycoses • Also called dermatophytoses • Common diseases caused by a group of related fungi • Dermatophytes:- Microsporum – 3...
Common Fungal infections Hasan H. Alfahemi Assistant Professor of Medical Microbiology Faculty of Medicine Department of Medical Microbiology Al-Baha University Cutaneous Mycoses • Also called dermatophytoses • Common diseases caused by a group of related fungi • Dermatophytes:- Microsporum – 3 genera:- Trichophyton Epidermophyton Pathology • Defining characteristic of dermatophytes:– Ability to use keratin source of nutrition. – allows infection of keratinized tissues & structures:• Skin • Hair • Nails. Pathology • Some specificity of genera in infection site – All 3 genera attack skin – Microsporum not infect nails – Epidermophyton not infect hair – None invade underlying non-keratinized tissue. Epidemiology • The causative organisms of dermatophycoses are often distingushed according to their natural habitats. • Anthropophilic ( Residing on human skin). • Zoophilic ( Residing on the skin of domestic and farm animals). • Geophilic (Residing in the soil). • Most human infections are by anthrophilic and zoophilic organisms. • Transmission from human to human or animal to human is by infected skin scales. Tinea pedis (athlete's foot): Most often :Ø Trichophyton rubrum Ø Trichophyton mentagrophytes ØEpidermophyton floccosum. ØInfected tissue:ØInitially between toes ØCan spread to nails:ØBecome yellow & breakable. ØSkin fissures can lead to:Ø 2ndary bacterial infections, Ø consequent lymph node inflammation. Tinea corporis (ringworm): • Organisms most often isolated:– Epidermophyton floccosum. – Trichophyton – Microsporum. – Lesions appear as:- • advancing annular rings • with scaly centers • periphery of the ring which is the site of active fungal growth • Usually inflamed and vesiculated. – Any site on body can be affected – lesions most often on non-hairy areas of trunk. Tinea capitis (scalp ringworm): • Several species of:– Trichophyton – Microsporum – Predominant infecting species depending on the geographical location of the patient. – In USA predominant infecting specie is Trichophyton tonsurans. • Disease manifestations range:– Small scaling patches – Involvement of entire scalp – With extensive hair loss Tinea capitis (scalp ringworm) üHair shafts invaded by Microsporum hyphae üManifests by green fluorescence in long-wave ultraviolet light (Wood lamp). Tinea cruris (jock itch) • • • • Causative organisms:E. floccosum T. rubrum. Disease manifestations – similar to ringworm – Except lesions in moist groin area – Where they can spread from upper thighs to genitals. Tinea unguium (onychomycosis): • causative organism most often:– T. rubrum. • Nails:– thickened – Discolored – brittle. • Treatment must continue 34 months until all infected portions of nail grow out and are trimmed off Subcutaneous Mycoses • It is fungal infection of dermis, subcutaneous tissue, and bone. • Causative organisms often reside in the soil and decaying or live vegetation. Epidemiology of Subcutaneous Mycoses • Subcutaneous fungal infections are almost always acquired through traumatic lacerations or puncture wounds. • Sporotrichosis, for example, is often acquired from the prick of a thorn. • As expected, these infections are more common in individuals who have frequent contact with soil and vegetation and wear little protective clothing. • The subcutaneous mycoses are not transmissible from human to human under ordinary conditions. VAGINAL CANDIDIASIS Oral candidiasis • Oral candidiasis, also known as oral thrush is candidiasis that occurs in the mouth. • It is is a mycosis (yeast/fungal infection) of Candida species on the mucous membrane of the mouth. Laboratory diagnosis • Sample: scraping of:– scaly skin – affected nails – affected hair • Wet preparation of sample with 10-20% poattasium hydroxide • Direct examination under light microscope Laboratory diagnosis • • • • Isolation in a culture. KOH mount. Serology Molecular techniques: DNA hybridization, PCR. Treatment • Removal of infected skin • Followed by topical of antifungal:– Miconazole – Clotrimazole • Infections of hair and nails:– systemic (oral) therapy. • Terbinafine drug of choice for onychomycosis (fungal infection of the fingernails or toenails that causes discoloration, thickening, and separation from the nail bed). !"#"$"%&" • Harvey RA et al. Lippincott’s Illustrated Reviews: Microbiology Third Edition, 2013, Chapter 20, Page 203-206