Β-Lactam antibiotic

Class of broad-spectrum antibiotics

Examples of β-lactam antibiotics

β-Lactam antibiotics are a class of broad-spectrum antibiotics that contain a β-lactam ring in their molecular structures. This class includes penicillins, cephalosporins, monobactams, and carbapenems, which are among the most widely used antibiotics in the world.

Mechanism of action

Mechanism of action of penicillin

β-Lactam antibiotics work by inhibiting the synthesis of the bacterial cell wall. They target the penicillin-binding proteins (PBPs) that are essential for the cross-linking of the peptidoglycan layer, which provides structural integrity to the bacterial cell wall. By binding to these proteins, β-lactam antibiotics prevent the bacteria from forming a stable cell wall, leading to cell lysis and death.

Types of β-lactam antibiotics

Penicillins

Penicillins are the first discovered β-lactam antibiotics and include natural penicillins like penicillin G and penicillin V, as well as semisynthetic derivatives such as amoxicillin and ampicillin. These antibiotics are effective against a wide range of Gram-positive bacteria and some Gram-negative bacteria.

Structure of amoxicillin

Cephalosporins

Cephalosporins are similar to penicillins but have a broader spectrum of activity. They are classified into generations, with each subsequent generation having increased activity against Gram-negative bacteria and better resistance to β-lactamases.

Monobactams

Monobactams, such as aztreonam, are effective primarily against Gram-negative bacteria. They are unique among β-lactams in that they contain a single β-lactam ring without the additional fused ring structure found in other β-lactams.

Carbapenems

Carbapenems, including imipenem and meropenem, are highly resistant to β-lactamases and have a very broad spectrum of activity, covering most Gram-positive and Gram-negative bacteria.

Resistance

Bacterial resistance to β-lactam antibiotics is a significant clinical problem. The most common mechanism of resistance is the production of β-lactamase enzymes, which hydrolyze the β-lactam ring, rendering the antibiotic ineffective. Other mechanisms include alterations in PBPs and reduced permeability of the bacterial cell wall.

β-Lactamase inhibitors

Structure of clavulanic acid

To overcome resistance, β-lactam antibiotics are often combined with β-lactamase inhibitors such as clavulanic acid, sulbactam, and tazobactam. These inhibitors bind to β-lactamases and prevent them from inactivating the antibiotic.

Clinical uses

β-Lactam antibiotics are used to treat a wide variety of infections, including pneumonia, meningitis, sepsis, and urinary tract infections. They are often the first-line treatment for many bacterial infections due to their efficacy and safety profile.

Adverse effects

Common adverse effects of β-lactam antibiotics include allergic reactions, ranging from mild rashes to severe anaphylaxis. Other side effects may include gastrointestinal disturbances such as diarrhea and nausea.

Related pages

• Antibiotic resistance
• Penicillin
• Cephalosporin
• Carbapenem
• Monobactam