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PCN MOA
- ● Bind transpeptidases (PBPs) and block catalysis of crosslinking of peptidoglycan residues resulting in weak cell walls and bacterial lysis if bacteria are actively growing
- ● Bactericidal
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β-lactamase Inhibitors MOA
- ● Contain b-lactam ring, which:
- → Act as decoy
- → Binding to and inhibit β-lactamases
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Vancomycin MOA
- ● Cell wall synthesis inhibitor
- → Binds to D-Ala-D-Ala building block of peptidoglycan
- → Blocks transpeptidase binding (peptidoglycan cross linking)
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Bacitracin MOA
- ● Bactoprenol transfers peptidoglycan subunits to the growing cell wall
- ● Bacitracin inhibits dephosphorylation in cycling of the lipid carrier
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Fosfomycin MOA
- ● Drug is transported to the bacterial cell by glycerolphosphate or glucose 6-phosphate transport system
- ● Inhibits the cytoplasmic enzyme enolpyruvate transferase and eventually inhibits synthesis of N-acetylmuramic acid (NAM)
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Daptomycin MOA
- ● Lipid portion (tail) of molecule inserts into bacterial cell membrane forming a channel
- → Depolarization of cell membrane
- → Potassium efflux
- → Rapid cell lysis
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Sulfonamides MOA
- ● Inhibits Dihydropteroate synthase from forming dihydrofolic acid
- ● Bacteriostatic
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Pyrimidines MOA
- ● Selectively inhibits bacterial dihydrofolate reductase, which converts dihydrofolic acid to tetrahydrofolic acid, a step leading to the synthesis of purines and ultimately to DNA
- ● Bacteriostatic
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Fluoroquinolones MOA
- ● Block bacterial DNA synthesis by inhibiting
- → Bacterial topoisomerase II (DNA gyrase- Inhibition of DNA gyrase prevents the relaxation of positively supercoiled DNA that is required for normal transcription and replication)
- → Topoisomerase IV (Inhibition of topoisomerase IV interferes with separation of replicated chromosomal DNA into the respective daughter cells during cell division)
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Aminoglycosides MOA
- ● Ribosomal protein synthesis inhibitor (irreversible binding to 30s ribosomal subunit)
- → Block the formation of the initiation complex
- → Miscoding of amino acids in the emerging peptide chain due to misreading of the mRNA
- → Block the translocation on mRNA
- ● Block of movement of the ribosome may occur after the formation of a single initiation complex, resulting in an mRNA chain with only a single ribosome on it, a so-called monosome
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Tetracyclines MOA
- ● Bind reversibly to 30S
- ● Bacteriostatic
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Macrolides MOA
Binding to 50S
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Oxazolidine MOA
Binds to the 23S ribosomal RNA of 50S
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Clindamycin MOA
Binding to 50S
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Metronidizole MOA
- ● Taken up by diffusion selectively absorbed by anaerobic bacteria and sensitive protozoa
- ● It is non-enzymatically reduced by pyruvate:ferredoxin oxido-reducatase system
- ● Reduced nitroso intermediates from linkages with cysteine bearing enzymes deactivating various cellular enzymes
- ● Metronidazole metabolites are taken up into bacterial DNA, strand breakage, destabilization
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Muporicin MOA
- ● Blocks the activity of isoleucyl-tRNA synthetase
- ● Blocks protein synthesis
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Nitrofurantoin MOA
Reduced by falvoproteins (nitrofurantoin redutase) to multiple reactive intermediates that attack ribosomal proteins, DNA, metabolic processes and other macromolecules
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Isoniazid MOA
- ● Inhibits synthesis of mycolic acids of the cell wall (FAS II)
- ● [Low] bacteriostatic
- ● [High] bactericidal
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Rifampicin MOA
- Inhibition of RNA synthesis by binding to the subunit of RNA polymerase (transcription)
- Bactericidal
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Ethambutol MOA
- ● Inhibits mycobacterial cell wall synthesis by inhibiting arabinosyl transferase
- ● Bacteriostatic
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Pyrazinamide MOA
- ● Inhibits fatty acid (FAS I) synthetase, involved in synthesis of short chain mycolic acid
- ● Bacteriostatic and bactericidal
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Ethionamide MOA
Blocks synthesis of mycolic acid (FAS II)
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Capreomycin MOA
Inhibition of protein synthesis (blocking translation)
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Aminosalicylic Acid (PAS) MOA
Inhibit folate synthesis (Dihydropteroate synthase preventing synthesis of dihydrofolic acid from PABA)
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