Chapter 176 - Beta-lactam antimicrobials Flashcards
Name three drug classes that are referred to as B-lactam antimicrobials.
Penicillins, cephalosporins, carbapenems
How do B-lactams work (general)?
Interfering with bacterial cell wall synthesis
On a cellular level, how do B-lactams interfere with cell wall synthesis?
Binding and inhibiting transpeptidases and peptidoglycan-active enzymes (penicillin binding proteins) that catalyze the cross-linking of the glycopeptides that form the cell wall
Are B lactams bactericidal or bacteriostatic?
Bactericidal
Are B lactams lipid soluble or insoluble?
Insoluble- they do not enter living cells well
T/F: B-lactams do a good job of crossing biologic membranes.
False
As a general rule, cephalosporins become more gram positive or gram negative with increasing generation?
Negative, among the first three generations
Name two ways in which bacterial resistance is achieved with regards to cephalosporins?
Production of B-lactamase usually via plasmids and changes in cell wall permeability (by altering their penicillin binding proteins).
What is the most important penicillin binding protein mutation?
Acquisition of Staph of a gene known as mecA that codes for PBP-2a (causes methicillin resistance)
T/F: Penicillin G is synergistic with aminoglycosides.
True
What is Pen G the drug of choice for?
Strep (necrotizing fasciitis?), clostridial infections and actinomycosis
Antipseudomonal penicillins exhibit greater activity against what organisms?
Pseudomonas and Proteus
Name some examples of antipseudomonal penicillins.
Ticarcillin, piperacillin
Which generation of cephalosporins are considered TOC for empiric therapy for infections located within the CNS?
Third
T/F: Methicillin resistant staph are resistant to treatment with carbapenems.
True
