TABLE 1

MICs and resistance rates of S-649266 and other antimicrobial agents against 617 clinical isolates of Enterobacteriaceaea

Species (no. of isolates)Test compoundMIC (μg/ml)
RangeMIC50MIC90R%b
Total, 6 species (617)S-649266≤0.063 to >64≤0.0630.5
Cefepime≤0.125 to >32≤0.12589.2
Ceftazidime≤0.125 to >320. 25>3224.5
Meropenem≤0.063 to >16≤0.0630.1252.6
Levofloxacin≤0.031 to >80.125>813.3
Escherichia coli (106)S-649266≤0.063–40.1251
Cefepime≤0.125 to >32≤0.12588.5
Ceftazidime≤0.125 to >320.2529.4
Meropenem≤0.063–0.125≤0.063≤0.0630
Levofloxacin≤0.031 to >80.063>826.4
Klebsiella pneumoniae (105)S-649266≤0.063–2≤0.0630.125
Cefepime≤0.125 to >32≤0.125>3217.1
Ceftazidime≤0.125 to >320.25>3219.0
Meropenem≤0.063 to >16≤0.0630.1256.7
Levofloxacin0.063 to >80.125>821.0
Serratia marcescens (103)S-649266≤0.063 to >64≤0.063≤0.063
Cefepime≤0.125 to >32≤0.12515.8
Ceftazidime≤0.125 to >32≤0.12518.7
Meropenem≤0.063 to >16≤0.06324.9
Levofloxacin≤0.031 to >80.2527.8
Citrobacter freundii (100)S-649266≤0.063 to >64≤0.0630.125
Cefepime≤0.125 to >32≤0.12589.0
Ceftazidime≤0.125 to >321>3236.0
Meropenem≤0.063 to >16≤0.063≤0.0631.0
Levofloxacin≤0.031 to >80.125812.0
Enterobacter aerogenes (100)S-649266≤0.063–8≤0.0630.5
Cefepime≤0.125 to >32≤0.12545.0
Ceftazidime≤0.125 to >321>3243.0
Meropenem≤0.063–8≤0.063≤0.0633.0
Levofloxacin≤0.031 to >80.0630.56.0
Enterobacter cloacae (103)S-649266≤0.063–160.1251
Cefepime≤0.125 to >32≤0.12589.4
Ceftazidime≤0.125 to >320.5>3232.0
Meropenem≤0.063–1≤0.0630.1250
Levofloxacin≤0.031 to >80.06345.8
  • a Cation-adjusted Mueller-Hinton broth was used as a medium but was supplemented with 20 μM human apo-transferrin for S-649266 to obtain free iron-deficient condition.

  • b Resistance rate (%) based on CLSI resistance breakpoints: 16 μg/ml for cefepime and ceftazidime, 4 μg/ml for meropenem, and 8 μg/ml for levofloxacin (23).