[Carbapenemases of gram-negative bacteria]

Carbapenems are often antibiotics of last resort for the treatment of severe infections. They are stable to most beta-lactamases produced by gram-negative bacteria. However, bacterial enzymes named carbapenemases can efficiently hydrolyze carbapenems. They are produced most frequently by Enterobacteriaceae and non-fermentative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannnii. They belong to group A (KPC, SME, IMI, NMC), B (VIM, IMP, SPM, GIM, NDM, SIM, DIM, AIM) and D (OXA-23, OXA-24, OXA-48, OXA-58, OXA-143). The accurate and rapid laboratory identification of carbapenem-resistant isolates is important to prevent spread of such multidrug resistant strains and to avoid therapeutic failures. Therapeutic options are often limited because carbapenemases are encoded on mobile genetic elements which often harbour resistance genes to other groups of antibiotics. Thus, colistin is often the only therapeutic option.