mode of action

Last reviewed 01/2018

The penicillins interfere with cell wall synthesis and are bactericidal. They cause inhibition of bacterial cell wall synthesis through the inhibition of a membrane-bound transpeptidase.

The weakened cell wall results in lysis and cell wall death.

Bacterial resistance occurs as a result of bacterial production of beta-lactimase (penicillinase) that splits the beta-lactam ring of the penicillin nucleus.

The principle organisms that produce penicillinase are:

  • Staph aureus
  • E. coli
  • Proteus mirabilis
  • Pseudomonas aeruginosa