9.2.3 Carbapenemases in practice

  • From what you have learned about carbapenemases in the module, how might EDTA, a potent zinc chelating agent, be useful for identifying carbapenemases?

  • EDTA can be used to identify metallo-β-lactamases as the EDTA will remove the zinc and inactivate the enzymes. It is usually included in interpretative panels. See Section 3.1.1.

Activity 11 Identifying carbapenemases

Timing: Allow 5 minutes
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Discussion

Note that meropenem is the best antimicrobial to screen as false positives are much less likely than with other carbapenems. For example, ertapenem could be used in Enterobacterales as it is very sensitive but might over-detect resistance leading to wasting resources in unnecessary confirmatory tests.

9.2.1 Carbapenemases in non-Enterobacterales

9.3 Confirming mechanisms in Gram-positive organisms