TABLE 2.

Pharmacological descriptors, goodness of fit, and statistical analysis of studies of the dose-response of ceftobiprole against MSSA, HA-MRSA, and CA-MRSA strains^a

Data plot function and resistance pattern	Pharmacological descriptorb				Goodness of fit (R2)
	E0c (95% CId)	Emaxe (95% CI)	EC50f (95% CI)	Csg
Data plotted as a function of the MIC measured at pH 5.5
MSSA	3.06 (2.49 to 3.64) AC,a	−1.04 (−1.27 to −0.81) A,a	0.41 (0.23 to 0.70) AC,a	1.19	0.93
HA-MRSA	2.63 (2.27 to 2.98) B,a	−1.01 (−1.20 to −0.82) A,a	0.77 (0.51 to 1.17) B,a	1.97	0.91
CA-MRSA	2.78 (2.34 to 3.211) BC,a	−1.02 (−1.27 to −0.77) A,a	0.54 (0.33 to 0.88) C,a	1.45	0.87
Data plotted as a function of the MIC measured at pH 7.4
MSSA	3.06 (2.49 to 3.64) AC,a	−1.04 (−1.27 to −0.81) A,a	0.20 (0.12 to 0.35) A,b	0.60	0.92
HA-MRSA	2.60 (2.19 to 3.01) B,a	−0.99 (−1.21 to −0.77) A,a	0.28 (0.17 to 0.45) AB,b	0.74	0.88
CA-MRSA	2.74 (2.27 to 3.21) BC,a	−1.01 (−1.29 to −0.73) A,a	0.33 (0.19 to 0.56) BC,b	0.91	0.84

^aData are for 24 h of incubation and are from Fig. 1.

^bThe equation for the sigmoidal dose-response is as follows: , where x is the concentration (in mg/liter). Statistical analyses were performed as follows: (i) data for the parameters (E₀, E_max, and EC₅₀) between MSSA, HA-MRSA, and CA-MRSA for pH 5.5 (upper half of table) or 7.4 (lower half of table) were compared by one-way analysis of variance with the Tukey-Kramer multiple-comparisons test (data with different uppercase letters were significantly different from each other [P < 0.05]) and (ii) data for the same parameters but between values observed at pH 5.5 (upper half of table) and with those observed at pH 7.4 (lower half of table) were compared by unpaired t test, two tailed (data with different lowercase letters are significantly different from each other [P<0.05]).

^cChange in log₁₀ CFU per mg of cell protein from the original postphagocytosis inoculum for an infinitely low ceftobiprole extracellular concentration.

^dCI, confidence interval.

^eChange in log₁₀ CFU per mg of cell protein from the original postphagocytosis inoculum for an infinitely large ceftobiprole extracellular concentration.

^fCeftobiprole concentration (in multiples of the MIC [Table 1; for strains for which two different values were obtained, the mean value was used]) giving a response halfway between E₀ and E_max.

^gApparent static concentration (in multiples of the MIC [Table 1; for strains for which two different values were obtained, the mean value was used]), as determined by graphical intrapolation of the corresponding function.