TABLE 2.

MICs of metronidazole before and after exposure to subinhibitory concentrations of metronidazole for three passages and after three additional passages without metronidazole

Strain	Species	Locus	MIC (μg/ml) preinduction	Induced-resistance MIC (μg/ml) after 3 passages with metronidazole	Stability of MIC (μg/ml) after 3 additional passages without metronidazole	IS element upstream of nim gene
ATCC 25285	B. fragilis		0.5	2.0	2.0
CCGU 29741	B. thetaiotaomicron		1.0	2.0	1.0
AUT41	B. fragilis		0.064	0.064	0.064
FRA01	B. ovatus		0.064	0.064	0.064
CZE58	B. thetaiotaomicron		1.0	1.0	1.0
HUN31	B. fragilis	nimA	1.0	>256	32	+
FRA35	B. fragilis	nimA	8.0	256	256	+
CZE16	B. fragilis	nimB	1.0	>256	8.0	+
AUT91	B. fragilis	nimB	2.0	>256	16	+
GBR32	B. fragilis	nimB	4.0	>256	256	+
FRA100	B. fragilis	nimC	4.0	>256	4.0	+
FRA2	B. fragilis	nimD	8.0	64	8.0	+
DNK5	B. fragilis	nimE	8.0	256	8.0
AUT85	B. ovatus	nimA	4.0	256	8.0
FRA90	B. thetaiotaomicron	nimD	0.25	256	16	+
SWE94	B. thetaiotaomicron	nimD	4.0	256	16	+
HUN19	B. vulgatus	nimF	1.0	1.0	1.0