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Beta-lactam antibiotics and S. aureus

Antibiotics inhibit bacterial growth by interfering with one or more cellular processes. Beta-lactams are a large group of cell wall active antibiotics used to treat a wide variety of infections.

S. aureus cell wall synthesis is dependent on the proper functioning of a number of enzymes. The beta-lactam antibiotics exert their effect by binding with one specific type of enzyme, transpeptidase, thus interfering with its ability to catalyze the final stage of peptidoglycan synthesis, resulting in defective cell wall formation.

The beta-lactams comprise four main groups of antibiotics; all have the beta-lactam ring as their basic chemical structure:

  • Penicillins (penicillin, oxacillin/methicillin, ampicillin and piperacillin)
  • Cephalosporins
  • Carbapenems
  • Monobactams

The spectrum of antimicrobial activity is dependent upon the particular structural modification of the beta-lactam ring.

The transpeptidases are commonly referred to as penicillin-binding proteins (PBPs). Different bacterial species have distinct PBPs, resulting in very specific drug interactions.