Guideline for phenotypic screening and confirmation of carbapenemases in Enterobacteriaceae

Int J Antimicrob Agents. 2010 Sep;36(3):205-10. doi: 10.1016/j.ijantimicag.2010.05.014. Epub 2010 Jul 3.


Adequate detection of carbapenemase-producing Enterobacteriaceae is crucial for infection control measures and appropriate choice of antimicrobial therapy. This guideline aims to improve the detection of carbapenemase-producing Enterobacteriaceae in the routine setting of clinical microbiology laboratories. Detection of carbapenemases in Enterobacteriaceae includes a screening step followed by a genotypic and optional phenotypic confirmatory step. For all Enterobacteriaceae, the meropenem screening breakpoint to detect carbapenemases is set at >or=0.5mg/L or a zone diameter of <or=23 mm (10 microg disk loading). For Escherichia coli, Klebsiella spp., Salmonella spp., Enterobacter spp. and Citrobacter spp., the imipenem screening breakpoint is set at >or=2mg/L or a zone diameter <or=21 mm. Ertapenem is not advised as an indicator carbapenem as it has a lower specificity compared with imipenem and meropenem. On the first isolate from a patient with a positive carbapenemase screen test, a polymerase chain reaction (PCR)-based test should be performed to detect carbapenemase genes. However, if genotypic confirmation is not immediately available, phenotypic confirmation tests should be performed to avoid delayed reporting of carbapenemase-producers to the clinic. Recommended phenotypic confirmation tests are the modified Hodge test as well as carbapenemase inhibition tests with boronic acid for Ambler class A carbapenemases and with ethylene diamine tetra-acetic acid (EDTA) or dipicolinic acid for metallo-carbapenemases.

Publication types

  • Practice Guideline
  • Review

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / analysis*
  • Bacterial Proteins / genetics
  • Carbapenems / pharmacology
  • DNA, Bacterial / genetics
  • Enterobacteriaceae / drug effects
  • Enterobacteriaceae / enzymology*
  • Enterobacteriaceae / genetics
  • Humans
  • Mass Screening / methods*
  • Microbial Sensitivity Tests / methods
  • Polymerase Chain Reaction
  • beta-Lactamases / analysis*
  • beta-Lactamases / genetics


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Carbapenems
  • DNA, Bacterial
  • beta-Lactamases
  • carbapenemase