Our results indicate that the zinc
concentration in MH agar of the medium
is crucial for efficient detection of VIM and
NDM-type carbapenemases. These results
are similar to those obtained with
the modified Hodge test, for which
higher sensitivity can be obtained using
zinc-supplemented plates. However, with
the Carba NP test, the IMP enzymes were
always detected regardless of the zinc
content of the MH agar used. The higher
catalytic activity of IMP-1 compared with
NDM-1 and VIM-2 (Yong et al., 2009),
coupled with its active site plasticity,
might explain these results (Horton et al.,
2012).