Lecture | Antimicrobial & Resistance Flashcards
the capacity to kill or suppress the growth of microorganisms
ANTIMICROBIAL AGENTS
Sources of Antibiotics :
1. Streptomyces spp.
2. Bacitracin and polymyxin - Bacillus species
Microorganisms (natural)
Sources of Antibiotics : Chloramphenicol
Synthetic
Sources of Antibiotics : produced by the fermentation process
Semi-synthetic
Sources of Antibiotics : penicillins and cephalosporin
Semi-synthetic
Inhibit bacterial growth but generally do not kill the organism
Bacteriostatic Agents
kill target organism
Bactericidal
Classification of antimicrobial agent : penicillins & cephalosporins
β-Lactam antibiotics
Act by binding PBPs (penicillin-binding
proteins)
β-Lactam antibiotics
Inhibit cell wall synthesis
β-Lactam antibiotics
enzymes anchored in the cell membrane and necessary in the production and maintenance of the peptidoglycan layer
PBPs
core of the structure of our beta lactam antibiotics is
Beta-lactam ring
Classification of antimicrobial agent : Vancomycin
Glycopeptides
Also inhibit bacterial cell wall synthesis and Binds to the end of peptidoglycan
Glycopeptides
directly binds to the terminal D-Ala of the pentapeptidyl-glycosyl peptidoglycan intermediates
Vancomycin
blocks the transpeptidation
Glycopeptides/vancomycin
binds to the substrate of the enzyme
glycopeptides
drawback of glycopeptide
cannot penetrate to the outer membrane of most of gram negatives due to large size
Binds to and disrupts the cell membrane and inserts its hydrophobic tail into the membrane, disrupting the cell membrane and increasing its permeability, which results in cell death
Lipopeptide
Daptomycin - gram “?”
gram+
Polymyxins - Gram “?”
Gram -
are cyclic lipopeptide agents that disrupt bacterial cell membranes.
Polymyxins (polymyxin B and colistin)
act as detergents, interacting with phospholipids in the cell membranes to increase permeability.
Polymyxins