TABLE 3.

Mutants of S. aureus RP 13 selected in cardiac vegetations after a 4-day treatment with Q-D in nine rabbits with aortic endocarditis^a

Selective mediumb	No. of animals with mutants	No. of mutants in the vegetations	Stability of the mutants	MIC (μg/ml) of:
				Q	D	Q-D
D	9	1 × 10−2	Unstable	8	>128	1
Q	5	2.8 × 10−3	Unstable	64	>128	2
Q-D	1	1 × 10−2	Stable	64	>256	8

^aQ, quinupristin; D, dalfopristin. 

^bDrugs were used at two times the MIC.