Mechanisms of action of antibiotics Flashcards
Pharmacokinetics
All the ways that the body manipulates a drug including absorption, distribution, metabolism, and excretion
Pharmacodynamics
Describes the biochemical and physiologic effects of the drug and its mechanism of action on the bacteria
Bacteriostatic
Antimicrobial agents that inhibit growth and/or reproduction of the infecting agent, but fail to actually kill the agent
Bacteriocidal
Antimicrobial agents that are capable of causing irreversible damage or death to the organism (eg B-lactams)
Five main mechanisms by which antibiotics inhibit or kill bacteria
- Interference with cell wall synthesis (most common)
- Interference with protein synthesis (second most common)
- Interference with cytoplasmic membrane function
- Interference with nucleic acid synthesis
- Interference with metabolic pathway
Bacteria that inhibit cell wall synthesis
- Beta lactams (penicillins, cephalosporins, carbapenems, monobactams)
- Vancomysin
- Bacitracin
Inhibition of cell wall synthesis general
-Interfere with peptidoglycan synthesis and murein assembly
Beta-Lactam antibiotics inhibition of cell wall synthesis mechanism
Binds at active site of transpeptidase enzyme that cross-links the peptidoglycan strands by mimicking the D-alanyl-D-alanine residues that would normally bind
-Irreversible, bacteriocidal
Four main B-lactam classes
- Penicillins
- Cephalosporins
- Monobactams
- Carbapenems
Penicillins
- Different classes
- Natural (penicillin G and penicillin)
- Penicillinase-resistant penicillins (methicillin, nafcillin, isoxazolyl penicillins)
- Aminopenicillins (ampicillin, amoxicillin)
- Carboxypenicillins (carbenicillin, ticarcillin)
- Acyl ureidopenicillins (azlocillin, mezlocillin, piperacillin)
Cephalosporins
- Categorized by generations
- Each generation exhibits increased spectrum of activity as well as increased resistance to destruction by B-lactamase enzymes
Monobactams
Active against aerobic gram-negative bacilli
Aztreonam
Carbapenems
Active against essentially all pathogenic organisms and resistance to destruction by the extended spectrum B-lactamses
Glycopeptides
Fosfomycin
MIC
minimal inhibitory concentration - represents the lowest concentration of the antibiotic which prevents the organisms from multiplying - not necessarily killing the organism.
MBC
minimal bacteriocidal concentration - represents the lowest concentration which kills the organism - not relevant with bacteriostatic agents.