4) Preliminary susceptibility test
The disc diffusion method (Acar and Goldstein, 1996) was used to screen the antimicrobial activity. Sterile disks (6mm) were impregnated with 10 µl of crude extract at concentration of 200 µg/ml. For bacteria, the microbes were placed on the surface of MHA, whereas SDA was used for fungi. The extract was tested in triplicate; control discs contained 10 µl of dimethyl sulfoxide (DMSO). The standard antibiotics consisted of tetracycline (30 µg/disc) for the Gram-positive bacteria, norfloxacin (10 µg/disc) for the Gram-negative bacteria, amphotericin B (10 µg/disc) for the yeast and ketoconazole (25 µg/disc) for the dermatophytes.The plates were incubated at 35oC for 18 h and 48 h for the bacteria and yeast, respectively. Plates with dermatophyteswere incubated at 30oC for 4 days and the inhibition zonediameters were then measured.