Ch 20 Antimicrobial Drugs.pptx - Chapter 20 Antimicrobial...

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Chapter 20 Antimicrobial Drugs
Outline The spectrum of antimicrobial activity The action of antimicrobial drugs A survey of commonly used antimicrobial drugs Tests of chemotherapeutic agents Drug resistance Xiong MIC205A 2 8/4/20
Antimicrobial Drugs Chemotherapy : The use of drugs to treat a disease Antimicrobial drugs : Kill or interfere with the growth of microbes within a host Antibiotic : A substance produced by a microbe that, in small amounts, inhibits another microbe Selective toxicity : A drug that kills harmful microbes without damaging the host Xiong MIC205A 3 8/4/20
1910: Ehrlich speculated about a magic bullet and discovered salvarsan to treat syphilis. 1928 : Fleming discovered penicillin, produced by Penicillium 1940 : First clinical trials of penicillin Discovery of Antimicrobial Drugs Xiong MIC205A 4 8/4/20
Source of Antibiotics Sprinkling some soil on a plate Xiong MIC205A 5 8/4/20
Classification of Antimicrobial Drugs Narrow spectrum ( penicillin ) Broad spectrum ( tetracycline ) Superinfection may occur after the usage Bactericidal Kill microbes directly Bacteriostatic Prevent microbes from growing Xiong MIC205A 6 8/4/20
Spectrum of Antimicrobial Drugs 8/4/20 Xiong MIC205A 7
The Action of Antimicrobial Drugs Xiong MIC205A 8 8/4/20
Xiong MIC205A 9 ANIMATION Chemotherapeutic Agents: Modes of Action 8/4/20
Inhibitors of Cell Wall Synthesis Penicillins - inhibit transpeptidase Natural penicillins Penicillin G – against Gram +, requires injection Penicillin V – against Gram +, can be taken orally Semisynthetic penicillins Oxacillin – narrow spectrum, only gram-positives, but resistant to penicillinase Methicillin – resistant to penicillinase Ampicillin – extended spectrum, many gram-negatives Augmentin - Penicillins + -lactamase inhibitors Xiong MIC205A 10 8/4/20
Penicillinase attacks -lactam ring Xiong MIC205A 11 How do Microbes counter Penicillin?

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