Dose (mg/mL) Parameter Parameter Estimate Standard error P valuea
0 β0b 8.543 0.126 <0.0001
0 β1c 0.249 0.024 <0.0001
0 β2d -0.007 0.001 <0.0001
  Time to maxe 18.6    
  Value at maxf 10.9    
0.3 β0 8.358 0.130 <0.0001
0.3 β1 0.242 0.025 <0.0001
0.3 β2 -0.008 0.001 <0.0001
  Time to max 14.07    
  Value at max 10.06    
0.6 β0 8.285 0.139 <0.0001
0.6 β1 0.211 0.027 <0.0001
0.6 β2 -0.007 0.001 <0.0001
  Time to max 13.31    
  Value at max 9.69    
1.2 β0 8.280 0.181 <0.0001
1.2 β1 0.091 0.036 0.0136
1.2 β2 -0.004 0.001 0.0049
  Time to max 10.68    
  Value at max 8.76    
2.4 β0 8.690 0.549 <0.0001
2.4 β1 -0.188 0.107 0.1053
2.4 β2 -0.005 0.004 0.2034
  Time to maxg -16.9    
  Value at maxg 10.28    
a Significance of parameter estimates represents appropriate fit of model (Y = β0 + β1 x +β2 x2 + ε1) to data. b β0 represents y-intercept at time of inoculation; c β1 represents the rate of bacterial growth over time; d β2 represents point of inflection where growth reached its maximum at a specific time; ε1 represents the random error; e Time to max = time (h) when maximal growth was achieved; f Value at max = amount of growth (estimated log CFU) at the time when maximal growth was achieved; g for 2.4mg/mL dose, the time to maximum growth and its value for this treatment should be interpreted with caution due to the lack of fit indicating that the reduced model did not fit the data for 2.4 mg/mL PGF treatment. The lack of fit at this specific concentration relates to the continuous decrease in bacterial growth associated with the bactericidal effects of 2.4 mg/mL PGF treatment.
Table 1: Parameter estimates, standard errors, and the associated P–values for the reduced regression models of S. aureus treated with various concentrations of PGF.