Microbio antibiotics general Flashcards
Trimethoprim resistance
Plasmid-coded, trimethoprim-resistant dihydrofolate reductase.
Penicilllin resistance
Hydrolysis of ß-lactam ring by ß-lactamase enzyme; decreased Cephalosporins permeability of bacteria to the antibiotic; altered penicillin binding proteins
Methicillin resistance
Altered penicillin binding proteins (not in ß-lactamase). (a ß-lactamase-resistant penicillin).
Aminoglycosides resistance
Enzymatic modification of drug by plasmid-coded enzyme; decreased permeability of bacteria to the antibiotic; mutation alters site to which antibiotic normally binds (e.g. S12 ribosomal protein for streptomycin).
Tetracyclines resistance
Interference with transport of drug into cell.
Chloramphenicol resistance
Detoxification of drug by acetylation of hydroxyl.
Erythromycin resistance
Enzymatic methylation of 23S ribosomal RNA.
Ciprofloxacin, Rifampin resistance
Altered target enzymes (gyrase, RNAP)
Vancomycin resistance
Alteration of cell wall precursor target.
antimetabolites (sulfonamides, trimethoprim) mechanism of action
Inhibit synthesis of dihydrofolate, ultimately nucleic acid synthesis.
Antimetabolite (flucytosine) mechanism of action
inhibits thmidylate synthetase and ultimately DNA synthesis
Isoniazid mechanism of action
Inhibits synthesis of mycolic acid (specific for Mycobacteria).
b-Lactams (penicillins, cephalosporins) mechanism of action
Interfere with cell wall biosynthesis. Inhibition of transpeptidation weakens cell wall. Autolytic enzymes of bacteria then promote lysis.
Glycopeptides (cycloserine, bacitracin, vancomycin, teichoplanin, caspofungin) mechanism of action
Interfere with cell wall biosynthesis.
Polymyxins and polyenes (nystatin, amphotericin B daptomycin) mechanism of action
Disrupt membrane integrity.
Aminoglycosides (streptomycin) mechanism of action
Inhibit protein synthesis by binding to a specific protein of 30S ribosomal subunit.
Aminoglycosides (gentamicin, kanamycin neomycin, amikacin tobramycin) mechanism of action
Bind to 30S ribosomal subunit at multiple sites. Inhibit protein synthesis.
tetracyclines mechanism of action
Block protein synthesis by inhibiting binding of amino-acyl t-RNA to 30S subunit.
Macrolides (Erythromycin, azithromycin), clindamycin, chloramphenicol mechanism of action
bind to 50S ribosomal subunit. Inhibit protein synthesis at chain
elongation step.
Oxazolidinones (linezolid) mechanism of action
Bind rRNA on both ribosomal subunits (new)
Streptogramins (dalfopristin, quinupristin) mechanism of action
Bind to 50S ribosomal subunit (new)
Mupirocin mechanism of action
Binds isoleucyl tRNA synthetase, preventing charging of Ile-tRNA and thus affecting protein synthesis.
Fluoroquinolones ciprofloxacin mechanism of action
Inhibit bacterial DNA gyrase.
Nitroimidazoles mechanism of action
fragments DNA
