Technical grade 95% ethanol, analytical grade
chloroform, ethyl acetate (RCI Labscan Ltd., Thailand)
and p-iodonitrotetrazolium chloride (Sigma-Aldrich
Chemical Co., Singapore) were purchased from Belman
Laboratories. Mueller Hinton agar (MHA) were obtained from
Becton Dickinson, Heidelberg. The reference antibiotic
susceptibility discs gentamicin and tetracycline (mastdiscsTM
AST, Mast Group Ltd., UK) were purchased from Medical Test
Systems, Inc.