cephalosporinlactamase

Cephalosporinlactamase, commonly referred to as cephalosporinase, is a beta-lactamase enzyme that hydrolyzes cephalosporin antibiotics, thereby inactivating them. It broadly describes enzymes with a high activity against cephalosporins, most notably AmpC beta-lactamases, which belong to Ambler class C and can be encoded chromosomally or plasmid-borne. AmpC producers may be constitutive or inducible and can spread via plasmids among Gram-negative bacteria.

Mechanism and classification: Beta-lactamases are grouped into Ambler classes A, B, C, D. Cephalosporinases include serine beta-lactamases (classes A, C, D) and metallo-beta-lactamases (class B). AmpC enzymes hydrolyze a wide range of cephalosporins and cephamycins, are less susceptible to inhibition by clavulanic acid, sulbactam, or tazobactam, and may be inhibited by newer inhibitors such as avibactam in some contexts. Plasmid-mediated AmpCs (pAmpC) such as CMY-2 and DHA-type variants contribute to disseminated resistance.

Clinical relevance: Production of cephalosporinases narrows therapeutic options. Infections caused by cephalosporinase-producing bacteria may require carbapenems or newer beta-lactamase inhibitor combinations; therapy decisions depend on susceptibility testing.

Epidemiology: Cephalosporinases are found in Enterobacterales and other Gram-negative pathogens. Chromosomal AmpC is common in organisms like Enterobacter, Citrobacter, and Serratia; plasmid-mediated AmpCs are increasingly reported worldwide.

Note: The term cephalosporinlactamase is conceptually overlapping with beta-lactamase activity against cephalosporins and is often used to describe AmpC-type enzymes.