Antimicrobial compounds Antiseptics and disinfectants Antibiotics

Bactericidal vs. bacteriostatic Bactericidal compounds - kill microorganisms Bacteriostatic compounds - inhibit or slow growth

Factors influencing effectiveness Metabolic rate of microorganism Distribution of drug in body Side effects

Antiseptics and disinfectants Most are bactericidal Too toxic for internal use

Antiseptics and disinfectants Antiseptics - applied to skin Disinfectants - applied to inanimate objects

Antibiotics Low molecular weight compounds ingested or injected into the body Produced by bacteria or fungi Some are synthetic

Antibiotics

Broad spectrum of activity Active against many different bacteria May also attack normal microbiota

Spectrum of activity

Antibiotics Targets of action Not present in eukaryotic cells Different from same molecule in eukaryotic cells “Magic bullets”

Targets of action

Classes of antibiotics and mechanisms of action Cell wall synthesis inhibitors Interfere with peptidoglycan synthesis

Classes of antibiotics and mechanisms of action Cell wall synthesis inhibitors Interfere with peptidoglycan synthesis  - lactam antibiotics (e.g. pencillins)

 - lactam antibiotics

Classes of antibiotics and mechanisms of action Cell wall synthesis inhibitors Interfere with peptidoglycan synthesis  - lactam antibiotics (e.g. pencillins) Glycopeptides (e.g. vancomycin)

Classes of antibiotics and mechanisms of action Cell wall synthesis inhibitors Interfere with peptidoglycan synthesis  - lactam antibiotics (e.g. pencillins) Glycopeptides (e.g. vancomycin) Phosphomycin and bacitracin (topical use)

Classes of antibiotics and mechanisms of action Protein synthesis inhibitors Aminogylcosides (e.g. streptomycin)

Classes of antibiotics and mechanisms of action Protein synthesis inhibitors Aminogylcosides (e.g. streptomycin) Tetracyclines (e.g. tetracycline)

Classes of antibiotics and mechanisms of action Protein synthesis inhibitors Aminogylcosides (e.g. streptomycin) Tetracyclines (e.g. tetracycline) Macrolides (e.g. erythromycin)

Classes of antibiotics and mechanisms of action Protein synthesis inhibitors Aminogylcosides (e.g. streptomycin) Tetracyclines (e.g. tetracycline) Macrolides (e.g. erythromycin) Lincosamides (e.g. clindamycin)

Classes of antibiotics and mechanisms of action Inhibition of nucleic acid synthesis Quinolones - inhibit DNA synthesis (e.g. ciprofloxacin)

Classes of antibiotics and mechanisms of action Inhibition of nucleic acid synthesis Quinolones - inhibit DNA synthesis (e.g. ciprofloxacin) Rifampin - inhibits RNA synthesis

Classes of antibiotics and mechanisms of action Inhibition of nucleic acid synthesis Quinolones - inhibit DNA synthesis (e.g. ciprofloxacin) Rifampin - inhibits RNA synthesis Trimethoprim and sulfonamides - inhibit enzymes in synthesis pathway

Classes of antibiotics and mechanisms of action Inhibition of nucleic acid synthesis Metronidazole - inhibits DNA synthesis Must be activated by bacterial protein

Newest antibiotics Glycyl-glycyl tetracycline Ketolides (macrolide derivative) Streptogramins - inhibit protein synthesis Oxazolidinones - inhibit protein synthesis