CRE Resistance Mechanisms

Several mechanisms are responsible for carbapenem resistance among Enterobacteriaceae. One important mechanism is the production of a carbapenemase, an enzyme that efficiently breaks down carbapenem antibiotics. 

Carbapenemases reported in the United States include:

Klebsiella pneumoniae carbapenemase (KPC)

• Currently, KPC is the most common carbapenemase found in the United States.
  • Guidance for Control of Infections with Carbapenem-Resistant or Carbapenemase-Producing Enterobacteriaceae in Acute Care Facilities: CDC
    CDC and HICPAC Recommendations. MMWR March 20, 2010 / 58(10);256-260.

Metallo-β-lactamases (MBLs)

New Delhi metallo-β-lactamase (NDM-1)

• CDC has identified Enterobacteriaceae isolates carrying a newly described resistance mechanism, New Delhi metallo-β-lactamase (NDM). Carriage of these organisms is closely linked to recent receipt of medical care in India or Pakistan.
  • Detection of Enterobacteriaceae Isolates Carrying Metallo-Beta-Lactamase - United States, 2010: CDC
    MMWR June 25, 2010 / 59(24);750.
• Clinicians should call MDH Infectious Disease Epidemiology, Prevention and Control (IDEPC) at 651-201-5414 or toll free 1-877-676-5414 if treating a patient in which a CRE is detected and who has received medical care in India or Pakistan within the past 6 months.

Verona integron-encoded metallo-β-lactamase (VIM)

• In July 2010, CDC was notified of a patient with a carbapenem-resistant Klebsiella pneumoniae strain that produced a Verona integron-encoded metallo-β-lactamase (VIM) carbapenemase.
  • Detection of a Verona Integron-Encoded Metallo-Beta-Lactamase (VIM) in Klebsiella pneumoniae - United States, 2010: CDC
    MMWR September 24, 2010 / 59(37);1212.

Imipenemase metallo-β-lactamase (IMP)

• CDC has also identified a CRE isolate caused by the IMP enzyme.