Antimicrobial compounds Antiseptics and disinfectants Antibiotics.

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

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