TABLE 2.

Distributions of disk diffusion zones of 951 fecal isolates to 12 antimicrobial agents

AgentOverallLower peakUpper peakCLSI breakpointa
MeanMedianRangeMedianRangeMedian
Neomycin17.716.36.0-18.715.419.0-26.222.012
Streptomycin15.214.53.2-16.713.517.0-26.020.017
Tetracycline18.621.76.0-13.96.015.0-35.023.714
Ampicillinb19.319.013
TMP/SMZc26.726.16.0-29.924.530.0-38.033.010
Cephalothin17.616.16.0-17.914.418.0-32.022.014
Sulfisoxazole20.622.16.0-7.86.012.0-35.022.812
Gentamicin21.019.66.0-20.918.321.0-30.025.012
Chloramphenicol25.625.46.0-26.924.327.0-35.028.012
Ofloxacinb29.329.412
Nalidixic acid24.222.96.0-25.921.026.0-36.029.013
Nitrofurantoin21.019.56.0-20.818.121.0-30.025.014
  • a Maximum diffusion zone (mm) breakpoint for the determination of antimicrobial resistance (17).

  • b Not bimodally distributed; lower and upper peak ranges and medians not reported.

  • c TMP/SMZ, trimethoprim-sulfamethoxazole.