ESBL (CTX-M) variant + reduced permeability of the cell membrane.
Upregulated AmpC production + reduced permeability
Intrinsic chromosomal resistance in certain organisms
Various carbapenemases found in class A, B and D.
All carbapenems are resistant.
Ertapenem is resistant but imipenem appears sensitive.
Carbapenems appear sensitive but are ineffective in vivo.
Ertapenem appears more resistant than imipenem.
All can be used with equal accuracy