TABLE 5.

Effect of the phenyl-thiazolylurea-sulfonamides on the susceptibility of a relA⁺ strain and its isogenic strain carrying a relA mutation^legend

Compound or drug	MIC (μg/ml)
	E. coli CP78	E. coli CP79
1	0.78	0.05
2	0.39	0.1
3	0.2	0.003
4	0.39	0.05
5	0.78	0.2
6	0.2	0.012
7	0.2	0.006
Mupirocin	0.2	0.05
Chloramphenicol	0.1	0.1
Kanamycin	0.05	0.05
Erythromycin	0.003	0.003
Tetracycline	0.05	0.05
Rifampicin	0.0008	0.0008
Cerulenin	0.05	0.05

^legendaMICs were compared for the relA⁺ strain E. coli CP78, which is able to induce the stringent response cascade, versus the isogenic relA CP79, which is not. The culture broth was supplemented with polymyxin B nonapeptide to facilitate passage of the compounds across the outer membrane. In the absence of polymyxin B nonapeptide, no activity was detected for the phenyl-thiazolylurea-sulfonamides.