Guideline for phenotypic screening and confirmation of carbapenemases in Enterobacteriaceae
A b s t r a c t
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 ≥0.5 mg/L or a zone diameter of ≤23mm (10ug disk loading).
For Escherichia coli, Klebsiella spp., Salmonella spp., Enterobacter spp. and Citrobacter spp., the imipenem screening breakpoint is set at ≥2 mg/L or a zone diameter ≤21mm. 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 classAcarbapenemases and with ethylene diamine tetra-acetic acid (EDTA) or dipicolinic acid for metallo-carbapenemases.
© 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.
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