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. 2018 Apr;24(4):741–745. doi: 10.3201/eid2404.170095

Table 1. Susceptibility of Clostridium difficile RT017 imipenem-resistant isolates from hospital A and imipenem-susceptible isolates from hospital B to 11 antimicrobial drugs, Portugal*.

Hospital
 Resistance breakpoint†
 Antimicrobial drug, MIC breakpoints, mg/L
IMP‡ ETP‡ MRP‡ MXF†§ MTZ†§ VAN†§ CLI‡ CHL‡ RIF† TGC† TET‡
>16
 >16
 >16
 >4
 >2
 >2
 >8
 >32
 >0.004
 >0.25
 >16
A, 22 isolates
 MIC range >32 3–16 1.5–4 >32 <0.016–1 0.38–2 >256 2–6 >32 <0.016–0.094 16–32
GM MIC 32 7.56 2.31 32 0.12 0.73 256 3.29 32 0.025 18.08
MIC90 32 12 3 >32 0.38 2 256 4 32 0.032 32
MIC50 32 6 2 >32 0.19 0.75 256 3 32 0.023 16
% Resistant
 100
 4.5
 0
 100
 0
 0
 100
 0
 100
 0
 100
B, 3 isolates
 MIC range 1.5–3 1.5–2 0.5–1.5 1.5 <0.016–0.25 0.38–0.75 >256 3–4 >32 <0.016–0.023 16
GM MIC 2.08 1.82 0.83 1.5 0.072 0.60 256 3.30 32 0.020 16
MIC90 3 2 1.5 1.5 0.25 0.75 256 4 32 0.023 16
MIC50 2 2 0.75 1.5 0.094 0.75 256 3 32 0.023 16
% Resistant
 0
 0
 0
 0
 0
 0
 100
 0
 100
 0
 100
p value <0.0001 <0.0001 <0.0001 <0.0001 0.45 0.56 ND 0.98 ND 0.41 0.51

*CHL, chloramphenicol; CLI, clindamycin; ETP, ertapenem; GM, geometric mean; IMP, imipenem; MIC50, minimal inhibitory concentration for 50% of strains; MIC90, minimal inhibitory concentration for 90% of strains; MRP, meropenem; MTZ, metronidazole; MXF, moxifloxacin; ND, not done; RIF, rifampin; TGC, tigecycline; VAN, vancomycin.
†European Committee on Antimicrobial Susceptibility Testing breakpoint.
‡Clinical and Laboratory Standards Institute breakpoint.
§Previously determined (9).