Carbapenemase-producing Enterobacteriaceae: now that the storm is finally here, how will timely detection help us fight back?

Acquired carbapenemases of the Ambler Classes A, B and D have gradually disseminated over the past decade among isolates of the Enterobacteriaceae family. Located on highly mobile genetic elements, these enzymes have established their presence in successful bacterial clones, signaling the prelude to a novel endemic era in the hospital setting. In such a context, prompt detection of carbapenemase-producing microorganisms seems warranted, not only for the selection of an appropriate antibiotic regimen, but also for organizing and implementing effective surveillance and infection control measures. However, issues regarding detection, confirmatory testing and characterization persist. Determination of carbapenemase production via susceptibility pattern interpretation may not always be feasible, confirmatory testing remains debatable and precise characterization is a challenge for the clinical laboratory. We aim to review the current situation from a laboratory point of view, highlighting the tools that have been proposed in an effort to help outline reliable screening and detection procedures, with inhibitor-based phenotypic testing as the cornerstone of these strategies, and discuss the necessity for implementing identification of possible producers in the everyday workflow.