抗生素英文课件精品ANTIBIOTICS（39p）.ppt

Antibiotics First known use of antibiotic substances – 600 B.C. – moldy soybean curd Pasteur – 1877 – observed that anthrax bacilli were killed when grown in the presence of other bacteria Fleming – 1929 – antibacterial activity of penicillin discovered Florey and Chain – 1938 – First clinical use of penicillins What is an antibiotic? Definition: A product of metabolism of other organisms A synthetic product that is a structural analogue of a naturally occurring antibiotic Antagonizes the growth or survival of one or more species of microorganisms Effective in low concentrations Soil microorganisms are a rich source of antibiotics Antibiotics Attributes required of a useful antibiotic: Exhibit sufficient selective toxicity against the target microorganism to avoid serious recipient toxicity effects Sufficient chemical stability for isolation, processing, and storage for a sufficient period of time WITHOUT deterioration of potency Amenability of the antibiotic to provide active agent as a function of dosage form Rate of biotransformation and elimination should be sufficiently slow to allow for a convenient dosage schedule, but yet sufficiently rapid and complete to facilitate elimination of metabolites Commercial production: Fermentation Semi-synthetic or totally synthetic Pseudomembranous colitis A form of gastroenteritis which occurs when there is an over-growth of Clostridium difficile bacteria in the intestine. Occurs after long-term treatment with broad spectrum antibiotics. Commonly implicated antibiotics Clindamycin, ampicillin and other penicillins, and third-generation cephalosporins; however, some reports implicate nearly all antibiotics, including fluoroquinolones and some antineoplastic agents that have antibacterial activity. Clinical signs Diarrhea (mild and self-limited or severe with more than 20 stools per d) Leukocytosis (50-60% of patients) Fever (30-50% of patients) Abdominal pain or cramping (20-33% of patients) In the US: C. dif