TABLE 3.

Rifabutin resistance of variants after serial passage of H. pylori ATCC 43504 as donor strains and after transformation of H. pylori 2802A and H. pylori 26695 (12) for confirmation of unexpected results^a

Mutation	Rifabutin MIC (μg/ml) (agar dilution) for H. pylori strain:
	ATCC 43504	2802A	26695
None	0.002	0.008	0.008
L525P	0.25	0.5
Q527K	32	32
Q527R	64	64
D530V	16	16
D530N	8	0.5	0.125
H540Y	32	16
H540N	0.5–1	2
S545L	64	32
I586N	0.25	2	2
I586L	0.064	0.25	0.25

^aRifampin MICs were 32 to 64 μg/ml for all transformed strains.