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Table 1 Minimum inhibitory concentrations (MICs) and fractional inhibitory concentration (FIC) index of blaIMP-1 or blaIMP-6 positive Enterobacteriaceae isolates

From: Bactericidal efficacy of meropenem in combination with cefmetazole against IMP-producing carbapenem-resistant Enterobacteriaceae

 Isolates MIC (μg/mL)MEM MIC reductionFIC indexEvaluation
MEMCMZ
IMP-1 producing isolatesTUM10695E. hormaechei25121/4, 1/80.27, 0.19Synergy
TUM11051E. hormaechei820481/4, 1/40.50, 0.50Synergy
TUM11052E. hormaechei810241/4, 1/40.28, 0.27Synergy
TUM11134E. hormaechei210241/4, 1/40.31, 0.50Synergy
TUM11259E. coli85121/8, 1/80.25, 0.38Synergy
TUM13773E. coli42561/4, 1/80.50, 0.37Synergy
TUM14683E. coli45121/16, 1/80.19, 0.19Synergy
TUM14697E. coli2641/4, 1/80.38, 0.19Synergy
TUM14759E. coli45121/8, 1/40.25, 0.28Synergy
TUM13774K. pneumoniae82561/8, 1/80.25, 0.38Synergy
TUM13775K. pneumoniae85121/8, 1/80.25, 0.25Synergy
TUM14366K. pneumoniae82561/8, 1/40.25, 0.31Synergy
TUM14380K. pneumoniae25121/4, 1/40.50, 0.38Synergy
IMP-6 producing isolatesE015E. coli162561/8, 1/160.16, 0.13Synergy
E020E. coli162561/8, 1/160.13, 0.19Synergy
E030E. coli325121/16, 1/160.09, 0.08Synergy
E038E. coli165121/32, 1/160.05, 0.14Synergy
E046E. coli3210241/8, 1/80.14, 0.14Synergy
E070E. coli162561/32, 1/320.19, 0.06Synergy
E109E. coli16641/32, 1/320.28, 0.28Synergy
E138E. coli6410241/8, 1/80.19, 0.19Synergy
E039K. pneumoniae322561/16, 1/160.13, 0.13Synergy
E045K. pneumoniae322561/8, 1/160.16, 0.09Synergy
E065K. pneumoniae322561/32, 1/320.09, 0.06Synergy
E085K. pneumoniae325121/8, 1/80.19, 0.16Synergy
E139K. pneumoniae3210241/8, 1/40.25, 0.27Synergy
  1. CMZ cefmetazole, MEM meropenem
  2. FIC index was measured in duplication. FIC index was calculated in following formula; FIC index = (MIC of MEM measured in combination with CMZ)/(MIC of MEM only) + (MIC of CMZ measured in combination with MEM)/(MIC of CMZ only). FIC index ≤ 0.5 was defined as synergy, > 0.5 to ≤ 4.0 as indifferent, and > 4.0 as antagonistic. MEM MIC fold-reduction by CMZ was calculated at the lowest FIC index