TABLE 1.

Model-fitted parameter estimatesa for vancomycin versus S. aureus strains displaying the normal and SCV phenotypes

ParameterValue for S. aureus strain:
COLIa48NewmanIII33A20780 IA20780 II
Log ratio area parameters
E0−0.060 (70.0)0.018−0.016 (>100)−0.057 (57.8)0.014 (>100)0.00 (>100)
Emax3.12 (1.57)1.943.25 (1.05)1.99 (1.91)2.61 (3.36)2.00 (1.40)
H8.97 (39.8)15.0b8.29 (12.29)5.82 (8.52)17.2 (>100)6.08 (7.91)
EC500.840 (7.14)0.6180.787 (3.12)0.699 (3.14)0.902 (>100)1.50 (>100)
R20.9990.9950.9990.9980.9990.999
Log ratio change parameters
E02.77 (15.87)1.93 (11.5)2.60 (10.5)1.75 (1.95)2.00 (2.62)1.81 (2.35)
Emax6.21 (8.83)3.14 (8.23)6.97 (4.73)3.59 (1.14)4.34 (1.49)3.67 (1.60)
H2.11 (28.91)6.16 (85.9)4.33 (30.45)4.29 (7.05)6.89 (34.4)17.56 (>100)
EC501.07 (16.1)0.839 (16.9)0.991 (5.65)0.895 (1.56)0.955 (2.02)1.97 (6.59)
R20.9740.9710.9910.9990.9990.995
  • a Data are reported as maximum-likelihood parameter estimates (percent standard errors are shown in parentheses). E0, effect at concentration-to-MIC ratio of 0; Emax, maximal effect (values expressed as log10 numbers of CFU per milliliter); H, Hill's constant; EC50, concentration-to-MIC ratio for which there is 50% maximal effect.

  • b Hill's constant was fixed at 15.0, and the percent standard error is not shown.