PART 2. 20. THE "budding" doctors in the modern world of AIDS, organ transplantation, and modern chemotherapy, treat an unprecedented number of immunocompromised patients. With their lowered cell-mediated immunity, there is a dramatic increase in the incidence every fungal infection! You will commonly that used to be exceedingly rareFungi are eucaryotic cells, which lack chlorophyll, cannot generate energy through photosynthesisThey do require an aerobic environment. After discussing the following crucial terms, we will discuss of fungi pathogenic to humansYeast: Unicellular growth form of fungi. can appear spherical to ellipsoidal. Yeast reproduce by budding. When buds do not separate, they long chains of yeast cells, which are . Yeast reproduce at a slower rate : Threadlike, branching, cylindrical, of fungal cells attached end to end. by extending in length from the tips of the tubulesMolds (also called Mycelia): Multicellular of clumps of intertwined branching hyphaeMolds grow by longitudinal extension and : The reproducing bodies of molds. Spores seen in skin scrapingsDimorphic fungi: Fungi that can grow as either or mold, depending on environmental temperature (usually growing as a yeast at )Saprophytes: Fungi that live in and utilize (soil, rotten vegetation) as an energy wall: Surrounding the cell membrane is the , composed mostly of carbohydrate with some protein. Fungal cell walls are potent antigens to the systemCapsule: This is a polysaccharide coating that surrounds the cell wall. This antiphagocytic virulence factor is employed by Cryptococcus neoformans. can be visualized with the India ink stainFig. 20-1. It is helpful to organize the human by the depth of the skin that they FUNGAL INFECTIONSPityriasis versicolor and tinea nigra are extremely superficial fungus infections, whose primary manifestation is pigment change of the skinNeither of these cause symptoms and will only your attention because skin pigment change !!! Both are named for their respective versicolor ( multicolored).Tinea nigra (black colored)1) Pityriasis versicolor (also called tinea versicolor) is a chronic superficial fungal infection to hypopigmented or hyperpigmented the skin. With sunlight exposure the skin around will tan, but the patches will remain white. is caused by Malassezia furfur2) Tinea nigra is a superficial fungal infection dark brown to black painless patches on the the hands and feet. This infection is caused by Ex-FUNGAL MORPHOLOGYCertain morphologic characteristics serve as virulence factors as well as targets for antifungal antibioticsCell membrane: The bilayered cell membrane is layer around the fungal cytoplasm. It contains sterols (sterols are also found in the cell membranes of humans as well as the bacteria Mycoplasma)Ergosterol is the essential sterol in fungi, while cholesterol is the essential sterol in humans. The antibiotics amphotericin B and nystatin bind to punch holes in the fungal cell membrane, while ketoconazole inhibits ergosterol of both infections is based on of skin scrapings, mixed on a slide hydroxide (KOH). This will reveal spherical yeast, as the KOH digests . Malassezia can look like spaghetti (hyphae) (spherical yeast)Treatment of both consists of spreading containing selenium sulfide over the skinThis is an inexpensive and e
