TABLE 3.

Antimicrobial activity of selected phenyl-thiazolylurea-sulfonamides against major respiratory tract pathogens

Compound or drug	MIC (μg/ml)a
	S. aureus 133		S. pneumoniae G9A		H. influenzae Spain 7		M. catarrhalis 489
	−Phe	+50 μM Phe	−Phe	+50 μM Phe	−Phe	+50 μM Phe	−Phe	+50 μM Phe
1	0.39	3.13	6.25	6.25	0.39	1.56	0.39	1.56
2	1.56	12.5	12.5	12.5	0.39	1.56	1.56	3.13
3	0.78	25	12.5	12.5	0.39	1.56	3.13	6.25
4	0.39	3.13	0.78	1.56	0.39	0.78	0.39	0.78
5	0.78	3.13	0.39	0.78	0.39	0.78	0.39	0.78
6	1.56	12.5	6.25	12.5	0.2	0.78	0.78	1.56
7	3.13	25	6.25	12.5	0.2	0.78	0.39	1.56
Mupirocin	0.1	0.1	0.1	0.1	0.024	0.024	1.56	1.56
Chloramphenicol	6.25	6.25	6.25	6.25	0.78	0.78	0.78	0.78
Methicillin	NT	NT	0.39	0.39	6.25	6.25	6.25	6.25

^aMICs were determined in a synthetic medium either without Phe or supplemented with 50 μM Phe. NT, not tested. For comparison with the IC₅₀ data presented above, the molecular mass values were in the range of 500 g/mol (Fig. 1). Thus, 1 μg/ml corresponds to approximately 2 μM.