Antibiotics

  1. Distribution of Common Agents
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  2. Basic steps for antimicrobial activity
    • Direct interaction between the antibacterial agent and the cell
    • Uptake (if activity is intracellular)
    • Agent reaches adequate intracellular concentration
    • Agent binds to target site
    • Disruption of cellular process leading to inhibition of cell growth (bacteriostatic) or cell death (bactericidal)
  3. Bactericidal v. Bacteriostatic
    • Bactericidal:
    • Kill bacteria
    • Used when the host defense mechanisms are impaired
    • Required in endocarditis, kidney infection, osteo, meningitis

    • Bacteriostatic:
    • Inhibit bacteria
    • Used when the host defense mechanisms are intact
    • Used in many infectious diseases
  4. Bacteriostatic v. Bactericidal Examples
    • Bacteriostatic:
    • Erythromycin
    • Clindamycin
    • Tetracyclines
    • Sulfonamides
    • Trimethoprim
    • Linezolid

    • Bactericidal:
    • Beta-lactams
    • Vancomycin
    • Aminoglycosides
    • Quinolones
    • Rifampin
    • Metronidazole
  5. 4 targets of antimicrobials
    • cell wall synthesis(Peptidoglycan) (i.e. penicillins, cephalosporins)
    • cell membrane (polymixin B)
    • protein synthesis l(Ribosomes)(i.e. tetracyclines, chloramphenicol, macrolides, Lingcosamides, aminoglycosides)
    • nucleic acid synthesis (sulfonamides, metronidazole, rifampin, fluoroquinolones
  6. Mechanisms of Bacterial Resistance
    • 1. Antibiotic Inactivation
    •               - Enzymatic modification of antimicrobial
    •               - Common Examples: Beta lactamase activity or aminoglycoside inactivation
    • 2. Alteration of the target site
    •               - Examples:
    •                    Alteration of penicillin binding proteins (MRSA)
    •                    DNA gyrase mutation results in fluoroquinolone resistance
    •                    RNA polymerase mutation results in rifampin resistance
    • 3. Interference with drug transport
    •               - The antimicrobial agent needs to first get inside the cell in order to have activity.
    •               - The bacteria’s own transport systems are used.
    • 4. Metabolic bypass
    •               - A different product is made that bypasses the antibacterial action
Author
csi_freak07
ID
327235
Card Set
Antibiotics
Description
Micro exam prep antibiotic lecture I, II, and III
Updated