TABLE 1.
Strain | Genotypea |
MIC of imipenem (mg/liter) on Mueller-Hinton agar supplemented with zeocin at the indicated concn (mg/liter)b |
Specific activities (mU/mg of protein) using imipenem as the substrate after induction with zeocin at the indicated concn (mg/liter)c |
|||||||
---|---|---|---|---|---|---|---|---|---|---|
blaNDM−1 | bleMBL | 0 | 10 | 50 | 100 | 500 | 0 | 10 | 50 | |
E. coli TOP10 (pCR2.1) | − | − | 0.12 | − | − | − | − | ND | ND | ND |
E. coli TOP10 (pCR2.1 PNDM-blaNDM-1-bleMBL) | + | + | >32 | >32 | >32 | >32 | 16 | 2.92 ± 0.26 | 3.07 ± 0.14ns | 2.84 ± 0.21ns |
E. coli 271 | + | + | 6 | 6 | 6 | 4 | 2 | 4.67 ± 1.33 | 7.17 ± 1.15ns | 5.24 ± 0.65ns |
K. pneumoniae 419 | + | + | 1.5 | 1 | 1 | 1 | 0.5 | 1.31 ± 0.73 | 2.09 ± 0.52ns | 3.27 ± 0.88ns |
K. pneumoniae DIN | + | + | 4 | 2 | 2 | 1.5 | 1.5 | 6.21 ± 1.08 | 3.88 ± 1.26ns | 7.91 ± 1.45ns |
−, absence of the corresponding gene; +, presence and expression of the corresponding gene.
−, no growth.
ND, not determined; ns, not significant. Statistical analysis was performed on the results of 3 independent experiments using Student's t test. P values of <0.05 were considered significantly different.