TABLE 3.

Population parameter estimates for meropenem against P. aeruginosa 1280

Parameter	Term	U	Estimate (SE)d
Growth parameters
Log10 initial inoculum	LogCFU0	Log10 CFU/ml	6.97 (1.5)
Mean generation time
Susceptible population	k12,S−1	min	49.3 (9.5)
Intermediate population	k12,I−1	min	683 (19)
Resistant population	k12,R−1	min	78.5 (10.4)
Replication rate constant	k21	h−1	50 (fixed)a
Log10 (maximum population size)	LogCFUmax	Log10 CFU/ml	9.98 (0.9)
Log10 (mutation frequencies)
Intermediate population	LogMFI		−3.66 (5.2)
Resistant population	LogMFR		−6.28 (6.9)
Inhibition of probability of successful replication by meropenem
Maximum inhibition
Susceptible population	Imax Rep,S		1.0 (fixed)b
Intermediate population	Imax Rep,I		0.673 (56.3)
Resistant population	Imax Rep,R		0.956 (25.0)
Concn causing 50% of inhibition
Susceptible population	IC50 Rep,S	mg/liter	0.648 (39.8)
Intermediate population	IC50 Rep,I	mg/liter	2.96 (45.3)
Resistant population	IC50 Rep,R	mg/liter	6.09 (23.3)
Hill coefficient
Susceptible population	Hill,S		1.0 (fixed)c
Intermediate population	Hill,I		7.14 (23.9)
Resistant population	Hill,R		2.19 (62.3)
SD of additive residual error on log10 scale	SDCFU	Log10 CFU/ml	0.493

^aBacterial replication was assumed to be fast, as previously described (14, 54, 67).

^bThe I_max Rep,S was estimated at 0.999 and therefore was eventually fixed to 1.0.

^cHill,S was estimated at 1.03 and therefore was eventually fixed to 1.0.

^dStandard errors (in parentheses) are expressed as percentages.