• Metallo-betalactamases have potent carbapenemase activity
  • inhibition to resistance by beta-lactam / ase inhibitors
  • carbapenemases can’t hydrolyze aztreonam. but same bug making carbapenemase is often also making an ESBL
  • Bugs we worry about are PsA, Acinetobacter, Enterobacteraciae. Call these Carbapenemase producing gram negative bacilli, to include serine and metallo-producing oranisms, where this has happened and made us all so nervous
  • Growing family of carbapenemases: non-metallo (serine active target, KPC). Oxa-48, and imipenem
  • Metallo (zinc at active site). VIM = class B,  New Dehli Metallo-Blase (Class B)


Carbapenem resistance mediated by β-lactamases, or carbapenemases, has become widespread

reports of Klebsiella pneumoniae carbapenemases, New Delhi metallo-β-lactamase-1, and recently OXA-48 (oxacillinase-48) have become more common


(i) hyperproduction or derepression of Ambler class C β-lactamases (AmpC β-lactamases) or ESBLs (e.g., sulfhydryl variable (SHV), temoneira (TEM), cefotaxime (CTX-M) type β-lactamases) with loss or alteration in outer membrane porins;

(ii) augmented drug efflux;

(iii) alterations in penicillin binding proteins (PBPs);

(iv) carbapenemase production

Carbapenemases belong to three molecular classes of β-lactamases, Ambler class A, B, and D

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