title: Antibacterial Activities and Possible Modes of Action of Acacia nilotica (L.) Del. against Multidrug-Resistant Escherichia coli and Salmonella.
abstract: Medicinal plants are frequently used for the treatment of various infectious diseases. The objective of this study was to evaluate the antibacterial activity and mode of action ofAcacia niloticaand the antibiogram patterns of foodborne and clinical strains ofEscherichia coliandSalmonella. The mechanism of action of acacia extracts againstE. coliandSalmonellawas elucidated by observing morphological damages including cell integrity and cell membrane permeability, as well as changes in cell structures and growth patterns in kill-time experiments. The clinical isolates ofE. coliandSalmonellawere found resistant to more of the tested antibiotics, compared to food isolates. Minimum inhibitory concentration and minimum bactericidal concentration of acacia leaf extracts were in the ranges of 1.56-3.12 mg/mL and 3.12-6.25 mg/mL, respectively, whereas pods and bark extracts showed somewhat higher values of 3.12-6.25 mg/mL and 6.25-12.5 mg/mL, respectively, against all tested pathogens. The release of electrolytes and essential cellular constituents (proteins and nucleic acids) indicated that acacia extracts damaged the cellular membrane of the pathogens. These changes corresponded to simultaneous reduction in the growth of viable bacteria. This study indicates thatA. niloticacan be a potential source of new antimicrobials, effective against antibiotic-resistant strains of pathogens.
authors.affiliation: Food Engineering and Bioprocess Technology, Asian Institute of Technology, Bangkok 12120, Thailand. m.bilalsadiq@hotmail.com.
authors.forename: Muhammad Bilal
authors.initials: MB
authors.lastname: Sadiq
authors.affiliation: Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand. joel@tropmedres.ac.|Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7FZ, UK. joel@tropmedres.ac.
authors.forename: Joel
authors.initials: J
authors.lastname: Tarning
authors.affiliation: Food Engineering and Bioprocess Technology, Asian Institute of Technology, Bangkok 12120, Thailand. actayxar@gmail.com.
authors.forename: Tay Zar
authors.initials: TZ
authors.lastname: Aye Cho
authors.affiliation: Food Engineering and Bioprocess Technology, Asian Institute of Technology, Bangkok 12120, Thailand. anilkumar@ait.ac.th.
authors.forename: Anil Kumar
authors.initials: AK
authors.lastname: Anal
mesh_terms: D000045:Acacia / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000819:agonists* / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D004269:DNA, Bacterial / Q000819:agonists* / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D012475:Salmonella / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D010936:Plant Extracts
keywords: SEM; antibacterial activity; antibiogram; bacterial membrane permeability; kill-time analysis