TABLE 2.

MICs for various H. pylori strains as determined by E-test

Antibiotic	MIC (μg/ml)a for H. pylori
	Tetr strain 181	Reference strain 26695	Tetr transformant of strain 26695
Tetracycline	8	0.19	8
Doxycycline	12	0.19	12
Minocycline	8	0.125	6
Amoxicillin	<0.016	<0.016	<0.016
Clarithromycin	<0.016	<0.016	<0.016
Metronidazole	0.19	0.016	0.064

^aData shown are the averages of three independent experiments. The isolates were considered resistant when the MICs of the tetracyclines (tetracycline, doxycycline, and minocycline), amoxicillin, clarithromycin, and metronidazole were ≥4, ≥8, ≥2, and ≥8 μg/ml, respectively (5, 13).