Table 4

Detection of IMP in CNS-Enterobacteriaceae by four different methods

Strain groupIMP typeSpeciesNo. testedMIC (μg/ml) of:No. (%) of isolates with positive resultNo. (%) of indeterminate tests for Etest
IPMMEM
RangeNo. (%) of:RangeNo. (%) of:
Isolates of > 4Isolates of > 1Isolates of > 4Isolates of > 1IC assayDDSTMHAEtest
IMP-producing EnterobacteriaceaeIMP-1C. freundii24 to 81 (50)2 (100)162 (100)2 (100)2 (100)2 (100)2 (100)0 (0)2 (100)
E. cloacae152 to 82 (4)15 (100)2 to 169 (60)15 (100)15 (100)12 (80)14 (93)0 (0)15 (100)
E. coli52 to 161 (20)5 (100)4 to 324 (80)5 (100)5 (100)5 (100)5 (100)1 (20)4 (80)
K. oxytoca181 (100)1 (100)161 (100)1 (100)1 (100)1 (100)1 (100)0 (0)1 (100)
K. pneumoniae122 to 322 (16)12 (100)4 to 3210 (83)12 (100)12 (100)12 (100)12 (100)1 (8)12 (91)
P. rettgeri1>641 (100)1 (100)321 (100)1 (100)1 (100)1 (100)1 (100)0 (0)1 (100)
S. marcescens1316 to >6413 (100)13 (100)16 to >6413 (100)13 (100)13 (100)13 (100)12 (92)13 (100)0 (0)
IMP-1 total492 to >6421 (42)49 (100)2 to >6440 (81)49 (100)49 (100)46 (93)47 (95)15 (30)34 (69)
IMP-6E. cloacae140 (0)1 (100)81 (100)1 (100)1 (100)1 (100)1 (100)0 (0)1 (100)
E. coli4≤1 to 20 (0)1 (25)8 to 164 (100)4 (100)4 (100)4 (100)4 (100)0 (0)4 (100)
K. pneumoniae3≤1 to 20 (0)1 (33)163 (100)3 (100)3 (100)3 (100)3 (100)0 (0)3 (100)
P. rettgeri1>641 (100)1 (100)>641 (100)1 (100)1 (100)1 (100)1 (100)1 (100)0 (0)
S. marcescens1641 (100)1 (100)>641 (100)1 (100)1 (100)1 (100)1 (100)1 (100)0 (0)
IMP-6 total10≤1 to >642 (20)5 (50)8 to >6410 (100)10 (100)10 (100)10 (100)10 (100)2 (20)8 (80)
IMP-11K. pneumoniae22 to 40 (0)2 (100)8 to 162 (100)2 (100)2 (100)2 (100)2 (100)0 (0)2 (100)
S. marcescens1>641 (100)1 (100)>641 (100)1 (100)1 (100)1 (100)1 (100)1 (100)0 (0)
IMP-11 total32 to >641 (33)3 (100)8 to >643 (100)3 (100)3 (100)3 (100)3 (100)1 (33)2 (66)
IMP-19S. marcescens1641 (100)1 (100)321 (100)1 (100)1 (100)1 (100)1 (100)1 (100)0 (0)
IMP-22P. rettgeri1321 (100)1 (100)321 (100)1 (100)1 (100)1 (100)1 (100)1 (100)0 (0)
IMP total64≤1 to >6426 (40)59 (92)4 to >6455 (85)64 (100)64 (100)61 (95)62 (96)20 (31)44 (68)
Non-IMP-producing EnterobacteriaceaeNoneE. cloacae34 to 81 (33)3 (100)2 to 40 (0)3 (100)0 (0)2 (66)0 (0)0 (0)3 (100)
NoneE. aerogenes44 to 162 (50)4 (100)2 to 81 (25)4 (100)0 (0)0 (0)0 (0)0 (0)2 (50)
NoneP. rettgeri140 (0)1 (100)≤10 (0)0 (0)0 (0)0 (0)0 (0)0 (0)0 (0)
NoneP. stuartii220 (0)2 (100)≤10 (0)0 (0)0 (0)0 (0)0 (0)0 (0)2 (100)
Non-IMP total102 to 163 (30)10 (100)≤1 to 161 (10)7 (70)0 (0)2 (20)0 (0)0 (0)7 (70)
Sensitivity (%)4093851001009596NAa
Specificity (%)700903010080100NA
  • a NA, not applicable because data included indeterminate results.