TABLE 3.

Antimicrobial susceptibility of 102 E. faecium isolatesa

Isolate typeAgentRectal isolatesClinical isolates
MIC (mg/liter)No. of isolatesMIC (mg/liter)No. of isolates
Range50%90%SIRRange50%90%SIR
Ampicillin resistantAmpicillin24-25664128586->256326423
Ciprofloxacin0.75->32>32>3265473->32>32>320122
Linezolid0.75-211.558000.5-1.511.52300
Quinupristin/dalfopristin0.25-640.51.550440.19-0.50.50.52300
Vancomycin0.5-21258000.5-21.51.52300
Teicoplanin0.094-20.251.558000.064-1.50.190.52300
Gentamicin2->10248125532-1648230
Ampicillin susceptibleAmpicillin0.75-43480.064-81813
Ciprofloxacin0.38->320.75>325310.38->321.5>32544
Linezolid1-1.511.58000.75-1.511.51300
Quinupristin/dalfopristin0.38-21.528000.38-20.521300
Vancomycin1-2228000.5-2121300
Teicoplanin1.5-3338000.032-20.1921300
Gentamicin3-646800.19-848130
  • a 50% and 90%, MIC for 50 and 90% of isolates, respectively. S, sensitive; I, intermediate; R, resistant, breakpoints defined by NCCLS. For gentamicin, high-level aminoglycoside resistance = MIC ≥ 512 mg/liter. There were 58 ampicillin-resistant and 8 ampicillin-susceptible rectal isolates and 23 ampicillin-resistant and 13 ampicillin-susceptible clinical isolates. —, no value possible (for ampicillin) or no criteria established by NCCLS (for gentamicin).