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.
CMY
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
