1.6 Introduction To Antibiotics Flashcards
Define: Broad-Spectrum
A drug that is active on a wide range of bacteria, viruses, fungi or parasites
Define: Narrow-Spectrum
A drug that is active on a limited number of bacteria, viruses, fungi or parasites
Define: Bactericidal
An antibacterial that will kill the bacteria
Define: Bacteriostatic
An antibacterial that inhibits the growth of bacteria
What is meant by “selective toxicity”?
The antibacterials have specific targets in the bacterial cell so won’t have an effect on human cells.
What five features of bacteria does the selective toxicity of antibiotics target?
Cell Wall synthesis Protein synthesis DNA synthesis RNA synthesis Folic acid synthesis
What two classes of drugs target cell wall synthesis? Give examples of each
Beta-lactam antibiotics: Penicillin, Flucloxacillin, Amoxycillin, Cephalosporins
Glycopeptides: Vancomycin
What is the mechanism of action of beta-lactam antibiotics?
They prevent the formation of peptide bridges between adjacent strands of peptidoglycan by inhibiting the transpeptidase activity of Penicillin Binding Proteins (PBPs)
What changes does chemical modification of antibiotics result in?
Spectrum of activity
Toxicity
Stability
Describe Cephalosporins and provide some examples
Broader spectrum. Often given to patients with penicillin allergies. Cephalexin, Cefepine
What mechanisms of resistance do bacterium have to beta-lactams?
They acquire a gene encoding beta-lactam inactivating enzyme called beta-lactamase
What solution do we have to bacterial resistance through beta-lactamase?
Co-administer beta-lactams with beta-lactamase inhibitors such as clavulanate.
What is the mechanism of action of Glycopeptide antibiotics? And what group of bacteria do they work on? Provide examples
Bind to “D-Ala D-Ala” of the peptide NAM complex in peptidoglycan which prevents cell wall synthesis. Is only effective in gram positive bacteria. Vancomycin.
Name the 7 classes of drugs that inhibit bacterial protein synthesis.
Aminoglycosides Tetracyclines Streptogramins Macrolides Chloramphenicol Lincosamides Oxazolidinones
Describe and provide examples of Aminoglycosides.
Bind to 30S subunit of ribosome and block the initiation of translation and causes the misreading of mRNA Broad spectrum Aerobic, gram negative bacteria IV only Gentamycin