Amoxicillin inhibits bacterial cell wall synthesis. Specifically, it targets penicillin-binding proteins (PBPs), enzymes crucial for the final stages of peptidoglycan synthesis. Peptidoglycan forms the rigid bacterial cell wall, providing structural support and protecting the cell from osmotic lysis.
Interference with Transpeptidation
Amoxicillin’s action is similar to that of other beta-lactam antibiotics. It binds to the active site of PBPs, preventing the transpeptidation reaction. This reaction is responsible for cross-linking peptidoglycan strands, creating the strong, mesh-like structure of the bacterial cell wall. Without this cross-linking, the cell wall remains weak and unstable.
Cell Wall Weakening and Lysis
The resulting weakened cell wall renders bacteria susceptible to osmotic pressure. Water rushes into the bacterium, causing it to swell and eventually burst – a process called cell lysis. This leads to bacterial death.
Spectrum of Activity
Amoxicillin is effective against a range of Gram-positive and some Gram-negative bacteria. Its effectiveness varies depending on the bacterial species and its susceptibility to the antibiotic. Certain bacteria possess mechanisms to inactivate amoxicillin, such as beta-lactamases, enzymes that break down the antibiotic molecule. This limits the antibiotic’s efficacy against those bacteria.
