Clostridium - دانلود رایگان
دانلود رایگان
دانلود رایگان لینک دانلود و خرید پایین توضیحاتدسته بندی : پاورپوینتنوع فایل : powerpoint (..ppt) ( قابل ويرايش و آماده پرينت )تعداد اسلاید : 30 اسلاید قسمتی از متن powerpoint (..ppt) : C. perfringens : gas gangrene; food poisoning C. tetani : tetanus C. botulinum : botulism C. difficile : pseudomembranous colitis Clostridium Anaerobic. Large gram-positive rods. The spores are usually wider than the rods, and are located terminally or subterminally . Most clostridia are motile by peritrichous flagella. Physiology and Structure C. perfringens Physiology and Structure Large gram-positive bacilli. Spores are rarely observed. Non-motile; capsulated. Hemolytic and metabolically active. S ubdivided into 5 types based on the four major lethal toxins they produce. Type A causes most of the human infections. C. perfringens Pathogenicity and Immunity Strains of C. perfringens are widely distributed in nature, and inhabit the intestine of humans and animals. They (type A strains are most commonly isolated from human infections) cause a spectrum of diseases primarily by producing toxins and enzymes: a -toxin : lecithinase (phospholipase C) that lyses a variety of cells. Lethal, necrotizing and hemolytic. Increases vascular permeability, resulting in massive hemolysis and bleeding, tissue destruction, hepatic toxicity, and myocardial dysfunction. Other necrotizing and hemolytic toxins DNase , hyaluronidase Enterotoxin : produced primarily by type A strains. C. perfringens Clinical Diseases Soft tissue infections Portal of entry: trauma or intestinal tract. Usually caused by mixed infection including toxigenic clostridia, proteolytic clostridia and various cocci and gram-negative organisms. Three types of infections with increasing severity: Cellulitis : gas formation in the soft tissue. Fasciitis or suppurative myositis : accumulation of gas in the muscle planes. Myonecrosis or gas gangrene: a life-threatening disease.