TABLE 1.

Modified carbapenem inactivation method testing results from 100 carbapenem-resistant Pseudomonas aeruginosa clinical isolates (31 carbapenemase producers by PCR) upon initial testing and after retesting of 22 isolates with indeterminate or discrepant results^a

Result^b	No. of isolates at indicated test broth vol
	Upon testing	After retesting
	2 ml	2 ml	400 μl
mCIM
Positive	27	27	29
Indeterminate	16
Negative	57	73	71
Concordant
mCIM⁺/PCR⁺	24	25	27
mCIM⁻/PCR⁻	54	67	67
Discrepant
mCIM⁺/PCR⁻	3	2	2
mCIM⁻/PCR⁺	3	6	4

PCR-based detection included the following carbapenemases: KPC, GES, IMP, VIM, NDM, OXA-48, and NMC/IMI.

mCIM, modified carbapenem inactivation method; indeterminate, no carbapenemase detected (n = 12) or GES-5 detected (n = 4).