Lecture 6 - Antibacterial Agents Flashcards
What was the compound that Paul Ehrlich came up with?
Compound 606 aka Salvarsan
What was the first real antibiotic?
Penicillin (1928)
What is the definition of an antibiotic?
Chemical that is able to kill or inhibit the growth of bacterial cells
What is the definition of antimicrobial?
All agents that kill all types of microorganisms
What are the two very basic actions carried out by antibiotics?
Bacteriostatic + Bacteriocidal
What is bacteriostatic?
Inhibits the growth of bacteria
What is bacteriocidal?
Kills bacteria
What are the three categories in regards to spectrum of activity?
Narrow - Broad - Moderate
What is the major goal of antibiotic development (what should be one of the most important?
Selective toxicity
What is selective toxicity?
AB is more toxic to the bacterial cells than it is the host cells
What are some basic targets for antibiotics to ensure that they have selective toxicity?
Cell wall + Ribosomes + Bacterial enzymes
What does it mean to use antibiotics in a non-therapeutic manner?
Commonly seen in food animal medicine. This is the practice of using AB to prevent an infection from occurring before it is even present in the animal.
What is bad about the non-therapeutic use of AB’s?
This helps increase the rate in which bacterias become resistant to various antibiotics
What are the five classes of antibiotics?
Inhibition of cell wall synthesis Disruption of cell membrane function Inhibition of protein synthesis Inhibition of nucleic acid synthesis Action as antimetabolite
What are the three AB’s that are inhibitors of cell wall synthesis?
Beta-Lactam
Glycopeptides
Bacitracin
What is the spectrum of activity of beta-lactam?
Varies
Is beta-lactam a -cidal or a -static?
Bactericidal
What is the mechanism of beta-lactam?
Binds/blocks transpeptidase
Prevents peptidoglycan cross-linking
Cell lysis
What is another name for transpeptidase?
Penicillin binding protein
What is the spectrum of activity for glycopeptides?
Narrow - Gram(+) only
Is glycopeptide -cidal or -static?
Bactericidal
What is the mechanism of glycopeptides?
Binds to the pentapeptide chains of NAM
Blocks transglycosylation + transpeptidation of peptidoglycan syn.
Cell lysis
What is the spectrum of activity for Bacitracin?
Broad
What is crucial to know clinically about Bacitracin?
Topical use only, too toxic for systemic use
Is Bacitracin -cidal or -static?
Bactericidal
What is the mechanism for Bacitracin?
Prevents dephosphorylation of bactoprenol
Prevents transport of NAG-NAM monomers
Cell lysis
What antibiotic works through disruption of the cell membrane?
Polymyxins
What is the spectrum for Polymyxins?
Moderate