Synergistic antimicrobial activity of Camellia sinensis and Juglans regia against multidrug-resistant bacteria

• Published in: PloS one 2015-02, Vol.10 (2), p.e0118431-e0118431
• Main Authors: Farooqui, Amber, Khan, Adnan, Borghetto, Ilaria, Kazmi, Shahana U, Rubino, Salvatore, Paglietti, Bianca
• Format: Article
• Language: English
• Subjects: Agar; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Antibacterial agents; Antimicrobial activity; Antimicrobial agents; Bacteria; Camellia sinensis; Camellia sinensis - chemistry; Catechin; Cell morphology; Cell walls; Cytology; Dilution; Drug resistance; Drug Synergism; Electron microscopy; Escherichia coli; Gram-positive bacteria; Health aspects; Juglans - chemistry; Juglans regia; Kinetics; Laboratories; Methicillin; Methicillin-Resistant Staphylococcus aureus - drug effects; Microbial drug resistance; Multidrug resistance; Multidrug resistant organisms; Nalidixic acid; Nalidixic Acid - pharmacology; Oxacillin; Oxacillin - pharmacology; Pathogens; Plant extracts; Plant Extracts - pharmacology; Salmonella; Salmonella enterica; Shigella; Staphylococcus aureus; Staphylococcus infections; Strains (organisms); Tea; Titration; Transmission electron microscopy
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0118431

Synergistic combinations of antimicrobial agents with different mechanisms of action have been introduced as more successful strategies to combat infections involving multidrug resistant (MDR) bacteria. In this study, we investigated synergistic antimicrobial activity of Camellia sinensis and Juglans regia which are commonly used plants with different antimicrobial agents. Antimicrobial susceptibility of 350 Gram-positive and Gram-negative strains belonging to 10 different bacterial species, was tested against Camellia sinensis and Juglans regia extracts. Minimum inhibitory concentrations (MICs) were determined by agar dilution and microbroth dilution assays. Plant extracts were tested for synergistic antimicrobial activity with different antimicrobial agents by checkerboard titration, Etest/agar incorporation assays, and time kill kinetics. Extract treated and untreated bacteria were subjected to transmission electron microscopy to see the effect on bacterial cell morphology. Camellia sinensis extract showed higher antibacterial activity against MDR S. Typhi, alone and in combination with nalidixic acid, than to susceptible isolates." We further explore anti-staphylococcal activity of Juglans regia that lead to the changes in bacterial cell morphology indicating the cell wall of Gram-positive bacteria as possible target of action. The synergistic combination of Juglans regia and oxacillin reverted oxacillin resistance of methicillin resistant Staphylococcus aureus (MRSA) strains in vitro. This study provides novel information about antimicrobial and synergistic activity of Camellia sinensis and Juglans regia against MDR pathogens.