Cephalosporins Flashcards
How do cephalosporins compare chemically and structurally to penicillins?
Chemically and structurally similar to penicillins
What two drugs are included in the cephalosporin class but technically cephamycins?
Cefoxitin and cefotetan
What is the MOA of cephalosporins?
inhibit mucopeptide synthesis in the bacterial cell wall, making the bacterium osmotically unstable. Like penicillins, cephalosporins inhibit PBPs involved in cross-linking peptidoglycans in the cell wall
What are Penicillin Binding Proteins (PBPs)?
subgroup of enzymes of transpeptidases. Essential for bacterial cell wall synthesis. involved in the final stages of synthesizing peptidoglycan.
Inhibition of PBPs leads to defects in cell wall structure and irregularities in cell shape
What are cephalosporins most effective against?
They are most effective against rapidly growing organisms forming cell walls and when antibiotic concentrations exceed the pathogen’s MIC for at least 50% of the dosing interval
What is the only intravenous first-generation cephalosporin?
Cefazolin
What are the most commonly used first-generation cephalosporins?
cephalexin & cefadroxil
What species are intrinsically resistant to cephalosporins?
Enterococcus species
Do 1st gen cephalosporins readily enter the CSF?
No
What are the three 2nd gen. cephalosporins?
cefaclor, cefprozil, and cefuroxime
2nd gen cephalosporins are active against?
active against the same organisms as the first generation but with increased activity against H. influenzae
Cephamycins are included in what generation of cephalosporins?
2nd generation
What are the two cephamycins?
cefotetan and cefoxitin
What needs to be performed before ordering a second gen. cephalosporin?
2nd gens have variable activity, so susceptibility tests need to be performed
What are three 3rd gen. cephalosporin abx?
Cefotaxime, Cefpodoxime, and Ceftriaxone
Ceftazidime is what generation of cephalosporin, and what bacteria does it have increased activity against?
3rd generation. increased gram-negative activity such as Pseudomonas aeruginosa