In Vitro Bactericidal Activity of 4- and 5-Chloro-2-hydroxy-N-[1-oxo-1-(phenylamino)alkan-2-yl]benzamides against MRSA

Table 2

Extent of bacterial killing exerted by 5-chloro-2-hydroxy-N-[(2S)-3-methyl-1-oxo-1-{[4-(trifluoromethyl)-phenyl]amino}butan-2-yl]benzamide (1f), N-{(2S)-1-[(4-bromophenyl)amino]-3-methyl-1-oxobutan-2-yl}-4-chloro-2-hydroxybenzamide (1g), and 4-chloro-N-{(2S)-1-[(3,4-dichlorophenyl)amino]-3-methyl-1-oxobutan-2-yl}-2-hydroxybenzamide (1h) over time against four staphylococci strains.

Drug and concentration (multiplicity of MIC)	Number of strains showing the following log10 CFU/mL decrease^a at the designated incubation time
	4 h			6 h			8 h			24 h
	−1	−2	−3	−1	−2	−3	−1	−2	−3	−1	−2	−3
Comp. 1f
4× MIC	2	1	1	4	3	2	4	4	2	4	4	4
2× MIC	1	1	1	1	1	1	3	1	1	4	3	0
1× MIC	0	0	0	0	0	0	0	0	0	0	0	0
Comp. 1g
4× MIC	2	1	1	2	1	1	4	2	1	4	4	2
2× MIC	1	1	0	1	1	1	2	1	1	0	0	0
1× MIC	0	0	0	0	0	0	0	0	0	0	0	0
Comp. 1h
4× MIC	2	2	0	4	2	2	4	3	2	4	4	2
2× MIC	1	0	0	2	1	0	2	0	0	1	0	0
1× MIC	0	0	0	1	0	0	0	0	0	0	0	0

CFU: colony-forming units.
 CFU/mL) values of −1, −2, and − 3  CFU/mL correspond to 90% (bacteriostatic), 99% (bacteriostatic), and 99.9% (bactericidal) of killing, respectively.