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Ch 20: Antimicrobial Drugs

Ch 20: Antimicrobial Drugs. Chemotherapy The use of drugs to treat a disease Antimicrobial drugs Interfere with the growth of microbes within a host Antibiotic Substance produced by a microbe that, in small amounts, inhibits another microbe

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Ch 20: Antimicrobial Drugs

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  1. Ch 20: Antimicrobial Drugs • Chemotherapy The use of drugs to treat a disease • Antimicrobial drugs Interfere with the growth of microbes within a host • Antibiotic Substance produced by a microbe that, in small amounts, inhibits another microbe • Selective toxicity A drug that kills harmful microbes without damaging the host

  2. 1928 – Fleming discovered penicillin, produced by Penicillium. • 1940 – Howard Florey and Ernst Chain performed first clinical trials of penicillin. Figure 20.1

  3. Table 20.1

  4. Table 20.2

  5. The Action of Antimicrobial Drugs • Broad-spectrum • Superinfection • Bactericidal • Bacteriostatic

  6. The Action of Antimicrobial Drugs Figure 20.2

  7. The Action of Antimicrobial Drugs Figure 20.4

  8. Penicillins Figure 20.6

  9. Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis • Penicillin • Penicilinase-resistant penicillins • Extended-spectrum penicillins • Penicillins + -lactamase inhibitors • Carbapenems • Monobactam

  10. Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis Figure 20.8

  11. Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis • Cephalosporins • 2nd, 3rd, and 4th generations more effective against gram-negatives Figure 20.9

  12. Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis • Polypeptide antibiotics • Bacitracin • Topical application • Against gram-positives • Vancomycin • Glycopeptide • Important "last line" against antibiotic resistant S. aureus

  13. Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis • Antimycobacterium antibiotics • Isoniazid (INH) • Inhibits mycolic acid synthesis • Ethambutol • Inhibits incorporation of mycolic acid

  14. Antibacterial Antibiotics Inhibitors of Protein Synthesis • Chloramphenicol • Broad spectrum • Binds 50S subunit, inhibits peptide bond formation • Aminoglycosides • Streptomycin, neomycin, gentamycin • Broad spectrum • Changes shape of 30S subunit

  15. Antibacterial Antibiotics Inhibitors of Protein Synthesis • Tetracyclines • Broad spectrum • Interferes with tRNA attachment • Macrolides • Gram-positives • Binds 50S, prevents translocation • Erythromycin • Gram-positives • Binds 50S, prevents translocation

  16. Antibacterial Antibiotics Inhibitors of Protein Synthesis • Streptogramins • Gram-positives • Binds 50S subunit, inhibits translation • Synercid • Gram-positives • Binds 50S subunit, inhibits translation • Oxazolidinones • Linezolid • Gram-positives • Binds 50S subunit, prevents formation of 70S ribosome

  17. Antibacterial Antibiotics Injury to the Plasma Membrane • Polymyxin B • Topical • Combined with bacitracin and neomycin in over-the-counter preparation

  18. Antibacterial Antibiotics Inhibitors of Nucleic Acid Synthesis • Rifamycin • Inhibits RNA synthesis • Antituberculosis • Quinolones and fluoroquinolones • Ciprofloxacin • Inhibits DNA gyrase • Urinary tract infections

  19. Antibacterial Antibiotics Competitive Inhibitors • Sulfonamides (Sulfa drugs) • Inhibit folic acid synthesis • Broad spectrum Figure 5.7

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