The experiment was performed by the method of National Committee for Clinical Laboratory Standards (NCCLS 2008) with some modification. Agar microdilution was performed by using two-fold decrements of the compounds in DMSO and The plates were incubated, minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) were determined in the usual manner.
The MICs were defined as the lowest concentration of the compound to inhibit the growth of microorganisms and the MBCs or MFCs were defined as the lowest concentration of the compound to kill the microorganisms.