Β-Lactam

Β-Lactam is a class of antibiotics that includes four major groups: penicillins, cephalosporins, carbapenems, and monobactams. The name "β-lactam" is derived from the structure of these antibiotics, which all contain a β-lactam ring, a structure that is essential for their antibacterial activity.

Structure and Mechanism of Action

The β-lactam ring is a four-membered cyclic amide, which is highly strained and therefore reactive. This reactivity is crucial for the antibiotic activity of β-lactam drugs. The β-lactam antibiotics work by inhibiting the formation of the peptidoglycan layer in bacterial cell walls. They do this by binding to penicillin-binding proteins (PBPs), which are enzymes that cross-link the peptidoglycan polymers in the cell wall. By inhibiting these enzymes, β-lactam antibiotics prevent the bacteria from forming a complete cell wall, which is necessary for their survival.

Resistance to Β-Lactam Antibiotics

Resistance to β-lactam antibiotics is a significant clinical problem. There are two main mechanisms by which bacteria can become resistant to these drugs: modification of the PBPs, and production of β-lactamases. In the first mechanism, the bacteria alter the structure of their PBPs so that the β-lactam antibiotics can no longer bind to them effectively. In the second mechanism, the bacteria produce enzymes called β-lactamases that can break open the β-lactam ring, rendering the antibiotic ineffective.

Clinical Use

Β-Lactam antibiotics are widely used in clinical practice due to their broad spectrum of activity and low toxicity. They are effective against a wide range of bacteria, including both Gram-positive and Gram-negative species. However, the increasing prevalence of β-lactam resistance has led to the development of new β-lactam antibiotics and β-lactamase inhibitors.

See Also

• Antibiotic resistance
• Penicillin-binding protein
• Peptidoglycan
• Penicillin
• Cephalosporin
• Carbapenem
• Monobactam