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What are the 4 classes of beta-lactams?
- 1- Penicillins
- 2- Cephalosporins
- 3- Carbapenems
- 4- Monobactams
All beta-lactams have _________ in their chemical structures
4-membered lactam ring
What are the 4 mechanisims of resistace to beta-lactams?
- 1- inactivation via beta-lactamases
- 2- modification of target PBPs
- 3- impared penetration of the antibiotic
- 4- active efflux
Which mechanisim of bacterial resistance to beta-lactams is the most important?
inactivation of the antibiotic via beta-lactamases
True or false, impared penetration of beta-lactams into the cell can only occur in gram positive bacteria.
False, it only occurs in gram negative bacteria
Active efflux pumps are _______ which causes resistance to beta-lactams
Reistant strains produce PBPs that have ____ affinity for binding to beta-lactams
- (Modification of target PBPs)
synthesis is R-factor mediated or induced by the presence of beta-lactams
True or false, beta-lactamases can be narrow or broad in their substrate specificity
How do beta-lactamases inactivate beta-lactam antibiotics?
The lactamase cleaves the lactam ring rendering it inactive
What are the Class I beta-lactamase inhibitors? (3)
- 1- clavulanic acid
- 2- sulbactam
- 3- tazobactam
What are the Class II beta-lactamase inhibitors? (1)
weak inhibitors of beta-lactamases
potent inhibitors of PBPs
Class II Inhibitors of beta-lactamases
potent inhibitors of beta-lactamases
weak inhibitors of PBPs
Class I Inhibitors of beta-lactamases
What is the major difference in Class I and Class II beta-lactamase inhibitors?
Class II is NOT used in combination with antibiotics
Carbapenems are hydrolyzed by what 2 enzymes?
- 1- carbapenemases
- 2- metallo-beta-lactamases
What are the 3 carbapenem drugs on the market?
- 1- imipenem
- 2- meropenem
- 3- doripenem
Amoxicillin + K-Clavulanate
Ticarcillin + K-Clavulanate
Ampicillin + Sulbactam Na
Piperacillin + Tazobactam Na
True or false, Class II is more electronegative than Class I.
False, it is less electronegative
Which class of beta-lactamase inhibitors binds to beta-lactamase and causes prolonged inactivation?
Class I ONLY
Why can you not physically mix an aminoglycoside and a beta-lactam?
The aminoglycoside will cleave the amide bond in the beta-lactam ring rendering them both inactive
True or false, the aminoglycoside/beta-lactam combination antibiotic is antagonistic.
False, it is synergistic---the 2 drugs must be administered separately but they work together in vivo
True or false, beta-lactamases travel into the periplasmic space of gram negative bacteria