- β-Lactam antibiotics are a major class of antibiotics defined by their distinctive β-lactam ring structure. These medications have revolutionized the treatment of bacterial infections since the discovery of penicillin.
- The core mechanism of action involves binding to penicillin-binding proteins (PBPs), which disrupts bacterial cell wall synthesis. This interference prevents proper cross-linking of peptidoglycan, an essential component of bacterial cell walls. As a result, the cell wall becomes structurally weak, leading to bacterial cell lysis and death. This mechanism makes β-lactams bactericidal rather than bacteriostatic.
- The β-lactam family includes several important subgroups: penicillins (such as amoxicillin and ampicillin), cephalosporins (categorized into generations, from first to fifth), carbapenems (like meropenem and imipenem), and monobactams (such as aztreonam). Each subgroup has specific advantages and spectrum of activity, with newer generations generally offering broader coverage and better resistance to β-lactamase enzymes.
- Bacterial resistance to β-lactams primarily occurs through β-lactamase production, which breaks down the β-lactam ring, rendering the antibiotic ineffective. To counter this, β-lactamase inhibitors like clavulanic acid are often combined with β-lactam antibiotics. Other resistance mechanisms include altered PBPs, reduced membrane permeability, and efflux pumps.
- Common side effects include allergic reactions (particularly with penicillins), gastrointestinal disturbances, and the risk of Clostridioides difficile infection. Cross-reactivity between different β-lactams can occur, though it’s less common between different subgroups. These antibiotics are generally considered safe during pregnancy and are widely used due to their excellent safety profile and effectiveness.
