Table 4.

Effect of the A172V mutation in KPC-2 on resistance of KPC-Kp to CAZ–AVI and IMI–REL

Transformed plasmid	Strain	MIC value of CAZ–AVI (mg/L)	MIC fold change (WT was used as control)	MIC value of CAZ (mg/L)	MIC fold change (WT was used as control)	MIC value of IMI–REL (mg/L)	MIC fold change (WT was used as control)	MIC value of IMI (mg/L)	MIC fold change (WT was used as control)
None	DH5α	< 0.03	< 0.5	< 2	< 0.06	< 0.03	< 0.25	< 0.03	< 0.03
pACYC184		< 0.03	< 0.5	< 2	< 0.06	< 0.03	< 0.25	< 0.03	< 0.03
pACKPCWT		0.06	1	32	1	0.125	1	4	1
pACKPCA172V		1	16	64	2	0.125	1	2	0.5

The lowest detection limit of concentrations of CAZ–AVI, CAZ, IMI–REL and IMI in antimicrobial susceptibility testing were 0.03 mg/L, 2 mg/L, 0.03 mg/L and 0.03 mg/L, respectively. The MIC values of these four antimicrobials to the parent strain DH5α and the strain DH5α carrying the plasmid pACYC184 are all below the lowest detect limitation. Therefore, the accurate fold changes of MIC values could not be calculated between these two strains and the control strain (DH5α carrying the plasmid pACKPCWT), respectively

WT wild type