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Class C Beta Lactamases

This class includes:

AmpC-type β-lactamases

AmpC type β-lactamases are commonly isolated from extended-spectrum cephalosporin-resistant Gram-negative bacteria. AmpC β-lactamases (also termed class C or group 1) are typically encoded on the chromosome of many Gram-negative bacteria including Citrobacter, Serratia and Enterobacter species where its expression is usually inducible; it may also occur on Escherichia coli but is not usually inducible, although it can be hyperexpressed. AmpC type β-lactamases may also be carried on plasmids. AmpC β-lactamases, in contrast to ESBLs, hydrolyse broad and extended-spectrum cephalosporins (cephamycins as well as to oxyimino-β-lactams) but are not inhibited by β-lactamase inhibitors such as clavulanic acid.


The first class C carbapenemase was described in 2006 and was isolated from a virulent strain of Enterobacter aerogenes.It is carried on a plasmid, pYMG-1, and is therefore transmissible to other bacterial strains