From the Guidelines
Penicillins work by inhibiting bacterial cell wall synthesis, which ultimately leads to bacterial cell death, and this mechanism is accomplished through the binding of the antimicrobial to the various PBPs in the cell wall, as stated in the study by 1. The mechanism of action of penicillins involves binding to and inactivating penicillin-binding proteins (PBPs), which are enzymes responsible for cross-linking peptidoglycan chains during bacterial cell wall formation.
- Without proper cross-linking, the cell wall becomes structurally weak and unstable.
- As bacteria continue to grow and divide, the compromised cell wall cannot withstand osmotic pressure, causing the bacterial cells to rupture and die. This mechanism makes penicillins bactericidal rather than bacteriostatic, and they are effective primarily against gram-positive bacteria because these organisms have cell walls with exposed peptidoglycan layers that are easily accessible to the antibiotic, as noted in the study by 1.
- Common penicillins include penicillin G, penicillin V, ampicillin, amoxicillin, and piperacillin. However, the effectiveness of penicillins has diminished over time due to bacterial resistance mechanisms, particularly the production of beta-lactamase enzymes that can break down the beta-lactam ring structure that is essential to penicillin's activity, as discussed in the study by 1.
- This has led to the development of beta-lactamase inhibitors (like clavulanic acid) that are often combined with penicillins to overcome this resistance mechanism. It's also worth noting that the prevalence of penicillin-resistant Streptococcus pneumoniae (PRSP) and multidrug-resistant SP varies between regions, as reported in the study by 1.
- The use of certain antibiotics, such as cefuroxime, in cases of bacteraemic pneumococcal pneumonia caused by penicillin non-susceptible strains has been linked to an increased mortality, highlighting the importance of choosing the appropriate antibiotic, as stated in the study by 1.
From the FDA Drug Label
Amoxicillin is similar to penicillin in its bactericidal action against susceptible bacteria during the stage of active multiplication. It acts through the inhibition of cell wall biosynthesis that leads to the death of the bacteria Penicillinase-resistant penicillins exert a bactericidal action against penicillin-susceptible microorganisms during the state of active multiplication. All penicillins inhibit the biosynthesis of the bacterial cell wall
The mechanism of action (MOA) of penicillins is through the inhibition of cell wall biosynthesis, which leads to the death of the bacteria. This occurs during the stage of active multiplication of susceptible bacteria.
- The penicillins are bactericidal, meaning they kill bacteria directly.
- They work by inhibiting the formation of the bacterial cell wall.
- This action is effective against a wide range of gram-positive and gram-negative bacteria 2, 3.
From the Research
Mechanism of Action of Penicillins
The mechanism of action (MOA) of penicillins involves:
- Inhibition of bacterial cell wall synthesis, which is essential for bacterial growth and multiplication 4
- Interaction with penicillin-binding proteins (PBPs), leading to bacterial lysis 4, 5
- Inhibition of transpeptidase activity, which is necessary for the formation of peptide cross-links in the cell wall 5, 6, 7
Key Targets of Penicillins
The key targets of penicillins are:
- Penicillin-binding proteins (PBPs), which are involved in the synthesis of the bacterial cell wall 5, 6, 7
- Transpeptidases, which are responsible for forming peptide cross-links in the cell wall 5, 6, 7
- Glycosyltransferases, which are involved in the synthesis of peptidoglycan, a key component of the bacterial cell wall 6
Resistance to Penicillins
Resistance to penicillins can occur through: