TABLE 3.

CIs and relative fitnesses of PR-39-resistant strains in LB, M9 medium, and mice

Strains	CIa				Relative fitnessc
	LB	M9 medium + glycerol	Miceb		LB	M9 medium + glycerol	Miceb
			Spleen	Liver			Spleen	Liver
DA10898	0.96	0.43	ND	ND	1.00	0.99	ND	ND
DA10899	2.48	1.02	5.08	4.47	1.01	1.01	1.22	1.20
DA10905	2.56	0.28	1.08	1.25	1.01	0.99	1.01	1.03
DA10914	1.19	0.29	1.26	0.88	1.00	1.00	1.03	0.98
DA12088	2.20	0.50	1.20	0.77	1.01	0.99	1.02	0.96

^aMeasured after 130 generations of growth in laboratory media and after 10 generations of growth in mice (end point of experiments) as the number of mutant colonies divided by the number of wild-type colonies. For each in vitro competition experiment, the CI was measured at regular intervals and plotted against the number of generations of growth. A selection coefficient (s) was calculated from the following regression model: s = [lnR(t)/R(0)]/[t × ln(2)], where R is the CI and t equals the number of generations of growth. For the in vivo competitions, the equation used to calculate s was s = ln(CI)/10 ln(2).

^bND, not determined.

^cFitness of the wild-type parental strain was set to 1, and relative fitness of the mutants was calculated as 1 + s_mutant (the selection coefficient of each mutant).