TABLE 3.

Induction of the croRp-lacZ fusion in E. faecalis JH2-2 by various antibiotics^a

Antibiotic	Tested range (μg/ml)	Drug concn (μg/ml) for maximum induction	Induction ratio
Cephalothin	1-100	20	8.6
Cefuroxime	50-1,000	1,000	7.3
Ceftriaxone	20-1,000	1,000	6.0
Cefepime	100-800	200	7.8
Ampicillin	0.01-2	0.5	6.4
Amdinocillin	50-1,000	500	17.2
Imipenem	0.01-0.5	0.2	6.2
Oxacillin	1-300	100	8.0
Fosfomycin	0.01-40	40	12.9
d-Cycloserine	50-200	200	26.6
Moenomycin	0.01-0.4	0.3	8.9
Bacitracin	1-64	32	12.5
Ramoplanin	0.01-20	20	10.5
Vancomycin	0.01-5	2	4.7
Gentamicin	4-32	4	1.2
Ofloxacin	0.2-8	4	1.2
Trimethoprim	0.001-10	5	3.9

^aBacteria were grown to an OD₆₀₀ of 0.55 in broth containing erythromycin (10 μg/ml) in addition to the drug tested for induction. A minimum of three concentrations were tested, and the induction ratio was calculated for the concentration leading to the highest activity.