Cephalosporins Flashcards
What kind of antibiotics are cephalosporins?
Semisynthetic beta lactam antibiotics. Their beta lactam ring connected to a 6 membered ring allows greater stability against B-lactamase enzymes.
Cephalosporins Mechanism of Action
Bind PBPs to inhibit the final transpeptidation step of peptidoglycan cell wall synthesis
Cephalosporins
Cidal or Static?
Bactericidal
Which generation of cephalosporins is most stable against beta-lactamase enzymes?
4th Gen
Cephalosporins
Mechanisms of Resistance
- Production of Beta-lactamase enzyme
- Alteration in PBPs
- Alter outer membrane to decrease permeability
Cephalosporins Elimination
Primarily by kidneys, except for ceftriaxone (biliary) and cefoperazone (liver)
Cephalosporins Elimination Half Life
Most are about 2 hrs, but ceftriaxone is longer at 8 hrs
First Gen Cephalosporins
Spectrum of Activity
Best against Gram Positive aerobes
MSSA, PSSP
Group and viridians strep
Gram negative aerobes (PEK)
Proteus mirabilis
E coli
Klebsiella
2nd Gen Cephalosporins
Spectrum of Activity
Less active against Gram Positive aerobes
MSSA, PSSP, group and viridians strep
More active against Gram Negative aerobes (HENPEK) Haemophilus E coli Neisseria Proteus Enterobacter Klebsiella
Subgroup of 2nd Gen Cephalosporins has special activity against what bacteria?
Cephamycins have activity against anaerobes (like Bacteroides)
3rd Gen Cephalosporins
Spectrum of Activity
Much better against Gram Negative aerobes (HENPECKSSS +P) Haemophilus E coli Neisseria Proteus Enterobacter Citrobacter Klebsiella Serratia Shigella Salmonella Pseudomonas (only ceftazidime)
4th Gen Cephalosporins
Spectrum of Activity
Stable against B-lactamases. Gram positive activity similar to ceftriaxone.
Gram Negatives - Pseudomonas aeruginosa, B-lactamase producing Enterobacter spp.
5th Gen Cephalosporins
Spectrum of Activity
Respiratory pathogens: Haemophilus influenzae, Strep pneumoniae, Moraxella, Staph aureus
SSSI: Strep pneumoniae, MRSA
Cephalosporins Absorption
Oral is well absorbed, but achieves lower serum concentration than parenteral
Cephalosporins
Distribution
Widely distributed to tissues and fluids.
Good CSF penetration with 3rd and 4th gen cephalosporins