6laktami

6-lactams are a class of β-lactam antibiotics characterized by a four-membered β-lactam ring fused to a six-membered lactam ring. This structural feature distinguishes them from other β-lactam antibiotics, such as penicillins (which have a five-membered thiazolidine ring fused to the β-lactam) and monobactams (which lack the fused ring system). The 6-lactam core is found in several important antibiotic families, including cephalosporins, carbapenems, and oxacephems.

The β-lactam ring in 6-lactams is responsible for their antibacterial mechanism of action. These compounds inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), enzymes essential for cross-linking peptidoglycan chains in the bacterial cell wall. By disrupting this process, 6-lactams weaken the cell wall, leading to osmotic instability and bacterial lysis.

Cephalosporins are the most well-known subclass of 6-lactams, with generations categorized based on their spectrum of activity and resistance profiles. First-generation cephalosporins, such as cefazolin, are effective against Gram-positive bacteria and some Gram-negative organisms, while later generations exhibit broader activity, including against Pseudomonas aeruginosa. Carbapenems, such as imipenem and meropenem, are highly potent β-lactams with broad-spectrum activity, often used as last-resort treatments for multidrug-resistant infections. Oxacephems, like moxalactam, are less common but structurally similar to cephalosporins.

Resistance to 6-lactams can arise through various mechanisms, including the production of β-lactamases—enzymes that hydrolyze the β-lactam ring—and alterations in PBPs. To combat resistance, β-lactamase inhibitors, such as clavulanate or avibactam, are often co-administered with 6-lactams to extend their efficacy. The development of new 6-lactam derivatives remains an active area of research to address emerging bacterial resistance.