TABLE 2.

Ability of commercial systems to infer carbapenemase production in isolates of Enterobacteriaceae with defined carbapenem resistance mechanisms^a

Mechanism	No. of isolates
	Phoenix		MicroScan NM36		MicroScan NBC39		Vitek 2
	Positive	Negative	Positive	Negative	Positive	Negative	Positive	Negative
KPC (n = 8)	8	0	8	0	8	0	8	0
MBL (IMP, VIM, or NDM; n = 20)	20	0	19	1b	20	0	16	4b
OXA-48 (n = 11)	11	0	6	5	4	7	5	6
E. coli/Klebsiella spp., ESBL, porin loss (n = 10)	10	0	10	0	8	2	8	2
Enterobacter spp., AmpC/ESBL, porin loss (n = 6)	6	0	5	1	5	1	2	4

^aThere were 55 test isolates. Phoenix flagged likely carbapenemase producers as potentially having an MBL, whereas the MicroScan flagged them as potentially having KPC enzymes. These inferences were taken to mean carbapenemase positive.

^bAll IMP types.