Mechanism of action of antibiotics.docx

Beta Lactam Inhibits transpeptidase (PBP) which recognises the terminal sequence to form cross bridges in the cell wall. Irreversibly binds. The Quinolones Synthetic antibacterial compound DNA gyrase inhibitor Found within all bacteria (gram positive and gram negative) Derivates of nalidixic acid. Q...

Beta Lactam Inhibits transpeptidase (PBP) which recognises the terminal sequence to form cross bridges in the cell wall. Irreversibly binds. The Quinolones Synthetic antibacterial compound DNA gyrase inhibitor Found within all bacteria (gram positive and gram negative) Derivates of nalidixic acid. Quinoline backbone. Used for UTI Mechanism of action of Quinolones Interferes with changes in DNA supercoiling by binding to DNA gyrase. DNA gyrase is important for controlled unwinding of DNA during replication. Quinolones prevents the controlled unwinding of supercoiled DNA. Causes cell death and breaks in the double strand. The macrolides Natural antibiotic Isolated from organism. Most active against gram positive cocci. Contains lactone rings bonded to sugars (EI) Mechanism of action of macrolides Protein synthesis inhibitors Reversible binding to P site on 50S subunit Disruption of proteome leading to cell death. The Aminoglycosides Natural products- amino acid bonded by glycosidic bond. Bactericidal Mechanism of action of Aminoglycosides Protein synthesis inhibitors Binds to aminoacyl site of 16S rRNA in 30S subunit of the ribosome. Causes cell death. Causes mis-incorporation of amino acids into elongating peptides= incorporation of these misfolded peptides in the membrane can increase drug uptake. The Tetracyclines Natural products Bactericidal Has 4 rings Better against gram positive. Mechanism of action of Tetracyclines Protein synthesis inhibitors Stalls protein synthesis Causes disruption to proteome leading to bacteriostasis.