Cephalosporins

Why are they used?

Alternative to Penicillin due to allergies and resistance

Stability against B lactamases

MOA?

Same as penicillins

What is it made from?

Penicillin N by C.fungi and Streptomyces bacteria

Semi synthetic?

Can use acylase to remove side chain from penicillin N to produce Cephem core

Via chemical acylation

Biosynthesis

Same steps to make penicillin N

Take 5 membered saturated ring

Break bond between central carbon atom and sulphur reforming with only one methyl group

Introducing double bond

Flattening the compound

Other enzymes introduce hydroxyl which allows further modification

Turning either a amide or acetyl group

2nd generation?

Cefuroxime most commonly used

3rd generation?

Ceftriaxone → meningitis

Ceftazidime

Variability?

due to the R groups

1 → antimicrobial

2 → Pk

Double bond only if between 2nd and 3rd carbon starting at sulphur going east

Cephalosporinases?

Catalyse hydrolysis

Move double bond if leaving group

producing conjugate base

Specturm

Gram +/-