tailieunhanh - Ebook BRS Microbiology & Immunology (6th edition): Part 2

(BQ) Part 2 book "BRS Microbiology & Immunolog" presents the following contents: Mycology, fungal diseases, parasitology, parasitic diseases, clues for distinguishing causative infectious agents (systems approach), immunology. | A. Fungi are eukaryotic organisms so they have many similarities to our cells. Differences targeted by antifungals include 1. Fungal cells have cell walls CWs . a. Fungal CWs protect cells from osmotic shock determine cell shapes and have components that are antigenic. b. Fungal CWs are composed primarily of complex carbohydrates such as chitin with glucans and mannose-proteins. The CW glucan not found in humans is the antifungal target of the echinocandins like caspofungin. 2. Ergosterol is the dominant fungal membrane sterol rather than cholesterol which is an important difference targeted by imidazoles triazoles and polyenes antifungals. B. Types. Fungi include organisms called molds mushrooms and yeasts. 1. Hyphae are filamentous tubelike cells of molds also known as the filamentous fungi and mushrooms. Hyphae grow at the tips apical growth . a. Septae or septations are cross walls of hyphae and occur in the hyphae of the great majority of the disease-causing fungi. They are referred to as septate Fig. . b. Nonseptate or aseptate hyphae lack regularly occurring cross walls. These cells are multinucleate and are also called coenocytic. They often are quite variable in width with broad branching angles Fig. . c. Hyphae may be dematiaceous dark colored or hyaline colorless . d. Fluffy surface masses of hyphae and their hidden growth into tissue or lab medium are called mycelia. 2. Yeasts are single-celled fungi generally round to oval shaped Fig. . They reproduce by budding blastoconidia . 3. Pseudohyphae hyphae with sausagelike constrictions at septations are formed by some yeasts when they elongate but remain attached to each other. Candida albicans is notable for developing into pseudohyphae and true hyphae when it invades tissues Fig. . 4. Thermally dimorphic fungi are fungi capable of converting from a yeast or yeastlike form to a filamentous form and vice versa. a. Environmental conditions such as temperature and nutrient availability trigger