tailieunhanh - Medical Microbiology made memorable - part 9

Nấm là những sinh vật có nhân điển hình và nhiều tính năng phổ biến trao đổi chất sinh học và chia sẻ với các tế bào của con người. Kết quả là, các tác nhân kháng nấm có khả năng gây độc cho tế bào của chúng ta trong phương thức hoạt động của họ. Điều này giới hạn số lượng các hợp chất có sẵn cho các điều trị của mycoses con người. | M E D I C A L MICROBIOLOGY Antifungal therapy Fungi are eukaryotic organisms and share many common biological and metabolic features with human cells. As a consequence antifungal agents are potentially toxic to our own cells in their mode of action. This limits the number of compounds available for the treatment of human mycoses. In addition many fungi also have detoxification mechanisms that remove the drugs. Fungal infections are termed mycoses and these may be either superficial localised to the epidermis hair and nails subcutaneous confined to the dermis and subcutaneous tissue or systemic deep infections of the internal organs . Superficial mycoses caused by dermatophytes are usually treated by application of creams or ointments to the infected area topical therapy . Subcutaneous and systemic mycoses require oral or intravenous administration systemic therapy . In vaginal candidiasis thrush treatment may be given using antifungal pessaries. Some antifungal agents are too toxic for systemic use but can be used safely in topical therapy of superficial mycoses. Antifungal agents are also used prophylactically in patients receiving immunosuppressive therapy to prevent infection by opportunistic fungi from the environment and the normal flora of the body. Examples are given below and their uses are summarised in Table . As with antibacterial drugs many antifungal agents are derived from the fermentation products of certain fungi . Streptomyces and Penicillium . The principal targets and mode of action of antifungal drugs are through the disruption or inhibition of fungal cell wall integrity cell wall biosynthesis RNA synthesis cell division and nucleic acid biosynthesis. Polyenes These bind to sterol components notably ergosterol of the fungal cell membrane causing increased permeability leakage of cellular components and cell death Nystatin is not absorbed by the gut and is too toxic for parenteral use. It is used as a topical preparation in the treatment .