Carbapenemases: molecular diversity and clinical consequences

Future Microbiol. 2007 Oct;2(5):501-12. doi: 10.2217/17460913.2.5.501.


Carbapenemases are beta-lactamases that hydrolyze most beta-lactams including carbapenems. Carbapenemases are classified in four molecular classes; those belonging to class A are the chromosomally-encoded and clavulanic acid-inhibited IMI, NMC-A and SME, identified in Enterobacter cloacae and Serratia marcescens; the plasmid-encoded KPC enzymes identified in Enterobacteriaceae (and rarely in Pseudomonas aeruginosa); and the GES-type enzymes identified in Enterobacteriaceae and P. aeruginosa. The class B enzymes are the most clinically-significant carbapenemases; they are metallo-beta-lactamases, mostly of the IMP and the VIM series. They have been reported worldwide and their genes are plasmid- and integron-located, hydrolyzing all beta-lactams with the exception of aztreonam. One single plasmid-mediated AmpC beta-lactamase, CMY-10, identified in an Enterobacter aerogenes isolate, has been shown to be a cephaslosporinase with some carbapenemase properties. Finally, the class D carbapenemases are being increasingly reported, mostly in Acinetobacter baumannii, and they compromise the efficacy of imipenem and meropenem significantly.

Publication types

  • Review

MeSH terms

  • Bacterial Proteins / classification*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Carbapenems / metabolism
  • Carbapenems / pharmacology*
  • Drug Resistance, Bacterial
  • Gram-Negative Bacteria / enzymology
  • Gram-Negative Bacteria / genetics
  • Gram-Negative Bacterial Infections / microbiology
  • Humans
  • beta-Lactamases / classification*
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism


  • Bacterial Proteins
  • Carbapenems
  • beta-Lactamases
  • carbapenemase