Fungal Diseases - Mycoses

Superficial Fungi Pityriasis versicolora is a superficial mycosis which appears on the upper torso, arms, and abdomen as hyper/hypo pigmented macular lesions which scale leaving the area looking dry and chalky –Malassezia furfur is a lipophilic yeast which is part of the normal microflora of the skin; grows mostly a a yeast, but sometime produces a hyphal form. grow in the skin is activated by certain predilecting factors like exposure to sunlight, etc. organism is identified in KOH preparation of the white, chalky scales; organism appears a yeast cells among hypae

Cutaneous Fungi-Dermatophytes Dermatophyte Fungi - are mold fungi which grow in tissues containing keratin; Thus, they are limited to skin, hair and nails. –cellular immune response to the presence of fungi in the skin evokes an inflammatory response often described as “ ringworm” or “tinea” –infections are often classified by the area affected; such as tinea capitis, tinea pedis, tinea manus, tinea ungium, etc. –there are three main dermatophyte genera which infect humans Trichophyton Epidermophyton Microsporium –species within these genera are grouped based upon their source anthropophilichumans zoophilicanimals geophilicsoil –dermatophytes are diagnosed by finding septate hypha and asexual(anamorphic) spores in the scraping of infected tissue. specific identification of the fungi is made by culture

Subcutaneous Fungi-Mycosis Lymphocutaneous Sporotrichosisnodular and ulcerative lesions which develop along the lymph channels which drain the primary site of inoculation; when the lymph gland is infected, the fungus disseminates to other areas –Sporothrix schenckii - a dimorphic fungus fungus grow in soil and on plants and spores are inoculated into subcutaneous tissues by thorns and sharp needle of certain plants, like roses. Diagnosis is based upon finding yeast cells in lymphatic fluid from lesions In the laboratory at 25 C, characteristic colonies containing delicate branching hyphae with unique rosette conidia

Systemic Fungi -Systemic Mycoses Histoplamosis - acute necrotizing, caseous granuloma of the lungs; in immunocompromised people or those exposed to high infectious dose, the yeast cells invade the mediastinal and hilar lymph nodes and disseminate via macrophages to the liver and spleen; in immunocompetent people the cellular immune response limits the spread of the yeast and confines the infection to mild flu-like symptoms; most primary infections are asymptomatic; has many features similar to tuberculosis –Histophasma capsulatumdimorphic fungus found in nature; mutiplies extensively in area where bird feces accumulate Epidemiology -endemic geographical area; macroconidia(spores) are inhalated and taken into the lungs Blastomycosis - chronic granulomatous ans suppurative disease of the lungs resulting in small areas of pulmonary consolidation; when confined to the lungs resolution results in scarring; dissemiation involves the skin, bones, –Blastomyces dermatiditisdimorphic fungus found in nature –Epidemiologybroad geographic area with source unknown

Systemic Fungi- Systemic Mycoses Coccidioidomycosischronic, necrotizing mycotic infection of the lungs which pathologically resembles tuberculosis; begins as a bronchopneumonia with its inflammatory infiltrate; disseminates in immunocompromised people to many sites including skin, bones, meninges,liver, spleen.; symptoms range from asymptomatic to mild respiratory symptoms to diverse set of symptoms associated with the affected areas; another “great imitator” –Coccidioides immitisdimorhic fungus which grows in the soil of the S.W. United States; spores called arthrospores are inhaled into the alveoli and terminal bronchioles where they enlarge into “spherules”; spherules fill with endospores(yeast-like cells) which are released to form more spherules; Epidemiology Diagnosis

Systemic FungiSystemic Mycoses Cryptococcosis primary disease of the lungs with gramulomas and consolidation; readily spreads to the meninges and brain causing “meningoencephalitis” –Cryptococcus neoformans- only systemic fungus which is not dimorphic; its is a highly encapsulated yeast which accounts for its virulence Epidemiology Diagnosis

Opportunistic FungiMycoses Candidia albicans –a common unicelluar fungus which is part of the flora of the oral cavity, vagina, and gastrointestinal tract; in this setting in becomes an opportunist especially in immunocompromised people –in culture, it grow as blastospores, pseudohyphae, and septate hyphae –candidiasisthe collective term for infection involving Candida cutaneous vaginal systemic Aspergillus fumigatus/ A. flavus Pneumocystis carnii