Cephamycin

Cephamycin

Core structure of cephamycin

Cephamycins are a group of beta-lactam antibiotics that are structurally and functionally related to cephalosporins. They are characterized by the presence of a methoxy group at the 7-alpha position of the beta-lactam ring, which confers resistance to certain beta-lactamases produced by bacteria. This makes cephamycins particularly useful in treating infections caused by beta-lactamase-producing organisms.

Structure and Mechanism of Action

Cephamycins share a core structure with cephalosporins, which includes a beta-lactam ring fused to a dihydrothiazine ring. The distinguishing feature of cephamycins is the methoxy group at the 7-alpha position. This structural modification enhances their stability against beta-lactamase enzymes.

The mechanism of action of cephamycins, like other beta-lactam antibiotics, involves the inhibition of bacterial cell wall synthesis. They achieve this by binding to and inactivating penicillin-binding proteins (PBPs), which are essential for the cross-linking of the peptidoglycan layer of the bacterial cell wall. This leads to cell lysis and death of the bacterium.

Clinical Uses

Cephamycins are used to treat a variety of bacterial infections, particularly those caused by anaerobic bacteria and Gram-negative organisms. They are effective against organisms such as Escherichia coli, Klebsiella pneumoniae, and Bacteroides fragilis.

Commonly used cephamycins include:

• Cefoxitin
• Cefotetan

These antibiotics are often used in surgical prophylaxis and in the treatment of intra-abdominal and pelvic infections.

Resistance

While cephamycins are resistant to many beta-lactamases, resistance can still occur through other mechanisms. Bacteria may acquire resistance through the production of extended-spectrum beta-lactamases (ESBLs) or through alterations in penicillin-binding proteins. Additionally, efflux pumps and changes in porin channels can contribute to resistance.

Related Pages

• Beta-lactam antibiotic
• Cephalosporin
• Antibiotic resistance