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32 Cards in this Set
- Front
- Back
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Which transpeptidase is involved in peptidoglycan synthesis?
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PBP1a and PBP1b
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Which transpeptidase is involved in septum formation?
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PBP3
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PBP2 is responsible for..
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Maintaining the rod shape of bacilli
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PBP 4, 5, 6 are responsible for
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hydrolysis of D-ala-D-ala terminal peptide bones of the cross-linking peptides.
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Where are transpeptidases found on gram negative bacteria?
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Inner membrane
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How is degradation of the Beta lactam ring catalyzed?
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Low pH
Alkaline pH Primary amine groups in drugs (aminoglycosides other beta lactam antibiotics) B-lactamase Endogenous peptidase |
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What is the major mechanisms of resistance to B-lactam antibiotics?
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Expression of B-lactamase
Mutation of porins Mutation of PBPs |
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List the semisynthetic penicillinase resistant parenteral penicillins...
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Methicillin
Nafcillin |
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List the semisynthetic penicillinase resistant oral penicillins
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Oxacillin
Cloxacillin Dicloxacillin |
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List the semi-synthetic, penicillinase sensitive, broad spectrum, oral penicillin
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Ampicillin
Amoxicillin |
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List the semi-synthetic, penicillinase sensitive, broad spectrum, parenteral penicillin
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Carbenizillin
Carbenicillin phenyl Carbenicillin indanyl Ticarcillin Azlocillin Mezolcillin Piperacillin |
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What is the function of the "goat" structure on some beta lactams?
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The extensive steric hindrance caused by the goat prevents degradation of beta lactamases.
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Which part of beta-lactam antibiotics are most important for antibiotic activity?
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B-lactam ring
2-carboxylate group B to the lactam nitrogen |
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What are the effects of an electron withdrawing group (electron deficient aromatic rings or protonated rings) on the activity of beta lactams?
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Electron withdrawing groups increases acid stability, leading to better oral availability
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What is the significance of zwitter ion type penicillins?
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They are substrates of intestinal dipeptide transporters, which increase thir oral absorption.
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Why are hydrophobic ester prodrugs of beta lactams used?
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They improve oral bioavailability of the parent drug.
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How does hydrophilicity on the acyl side chain contribute to activity against gram negative bacteria?
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Better binding of PBPs of G- bacteria and/oe
Better permeation through porins |
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Generic name for Augmentin
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Amoxicillin-clavulanate
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Brand name for ticarcillin-clavulanate?
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Timentin
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Generic name for Unasyn
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Ampicillin-sulbactam
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What is the benefit of a leaving group on C3-CH2 of a cephalosporin?
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More resistant to degradation by many B-lactamases.
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What are the drawbacks of a leaving group on C3-CH2 of a cephalosporin?
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Facilitates non-enzymatic hydrolysis of the B-lactam ring.
Acetyloxy leaving group can undergo hydrolysis and lactonization which prohits oral activity. |
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What is the drawback of a MTT leaving group on the C3-CH2 of a cephalosporin?
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Higher incidence of clotting difficulties
Acute alcohol intolerance |
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Which agents carry MTT as a leaving group?
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Cefotetan
Cefamandole Celmetazole Cefoperazone Moxalactam |
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What are the first generation parenteral cephalosporins?
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Cephapirin
Cefazolin |
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What are the first generation oral cephalosporins?
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Cephalexin
Cefadroxil |
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What are the second generation parenteral cephalosporins?
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Cefamandole
Cefonicid Cefuroxime Cefoxitin Cefotetan |
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What are the second generation oral cephalosporins?
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Cefaclor
Loracarbacef Cefprozil |
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What are the third generation parenteral cephalosporins?
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Cefotaxime
Ceftizoxime Ceftriaxone Ceftazidime Cefoperazone |
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What are the third generation oral cephalosporins?
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Cefixime
Ceftibuten Cefpodoxime proxetil Cefdinir |
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What is the significance of the syn-alkoximine group on cephalosporins?
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The -OR group and beta-lactam on the same side of C=N double bond hinders hydrolysis by B-lactamase.
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What structural features contribute to the resistance of cephalosporins against inactivation by B-lactamases?
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Leaving group on the CH2 at C3 of the cephem nucleus.
Methoxy substitution at 7 position of the cephem nucleus. Syn-alkoximine function in the aminoacyl side chain. |
