In vitroactivity of a combination of bacteriophages and antimicrobial plant extracts

Abstract

Significance and Impact of Study: This preliminary study provides insights into the potential combination of bacteriophages and antimicrobial plant bulk extracts to target bacterial pathogens. It is to our knowledge the first time in which virulent bacteriophages have been combined with antimicrobial plant extracts. AbstractThe continuing threat of antimicrobial resistance presents a considerable challenge to researchers to develop novel strategies ensuring that bacterial infections remain treatable. Many plant extracts have been shown to have antibacterial properties and could potentially be combined with other antibacterial agents to create more effective formulations. In this study, the antibacterial activity of three plant extracts and virulent bacteriophages have been assessed as individual components and in combination. When assessed with a modified suspension test, these plant extracts also exhibit antiviral activity at bacterial inhibitory concentrations. Hence, to investigate any potential additive effects between the extracts and virulent phages, the extracts were tested at subantiviral concentrations. Phages alone and in combination with plant extracts significantly reduced (P < 0Á05) the bacterial concentration compared to untreated and extract treated controls up to 6 h (2-3log 10 ), but this reduction did not extend to 24 h. In most cases, the phage and extract combinations did not significantly reduce bacterial content compared to phages alone. Additionally, there was little impact on the ability of the phages to reproduce within their bacterial hosts. To our knowledge, this study represents the first of its kind, in which antimicrobial plant extracts have been combined with virulent phages and has highlighted the necessity for plant extracts to be functionally characterized prior to the design of combinatorial therapies.

Wide‐scale evaluation of Origanum munzurense Kit Tan & Sorger using different extraction techniques: Antioxidant capacity, chemical compounds, trace element content, total phenolic content, antibacterial activity and genotoxic effect

“…In the last decade, the overuse and misuse of antibiotics or chemical antimicrobial agents in the treatment of bacterial infections have increased the incidence of multiple drug resistance which pose a serious threat to public health 23,24 . Similarly, the extensive use of antibiotics in the treatment of infections causing significant economic losses in animal husbandry results in resistance in some pathogenic bacterial strains and their resistance genes are transferred to bacteria causing disease in humans 25,26 . Furthermore, a wide range of synthetic preservatives is commonly used in the food industry to prevent the foodborne diseases associated with bacterial contamination and to extend the shelf life of foods 27 .…”

Enhancing Whole Phage Therapy and Their Derived Antimicrobial Enzymes through Complex Formulation

“…Once the initial characterization of the phage or antimicrobial enzyme had been performed, and prior to assessing the overall effects of a finished formulation, it would be necessary to know the impact of any potential adverse or additive effects that adjunct compounds provide to the phages or the derived antimicrobial enzymes themselves, as well as the impact upon the bacterial host [ 59 , 60 ]. Perhaps the most obvious concern would be a decrease in the stability or activity of the phages or their derived antimicrobial enzymes.…”

“…Perhaps the most obvious concern would be a decrease in the stability or activity of the phages or their derived antimicrobial enzymes. In the case of whole phages, this is likely to arise as the result of broad-spectrum antimicrobial activity which may potentially inactivate the phage along with the bacterial host [ 59 , 60 , 61 ], while in the case of phage-derived antimicrobial enzymes, this could be achieved through the modification of protein domains as the result of residue oxidation [ 62 ]. Therefore, in order to counteract these potentially harmful effects, it would be necessary to optimize the concentrations of these compounds in order to minimize the damage that they could cause to the active component without completely losing any beneficial effects they provide, using standardized test regimes, such as fractional inhibitory concentration (FIC) or checkerboard testing [ 63 , 64 ].…”

“…The risk of broad spectrum antimicrobial activity when combined with bulk antimicrobial plant extracts is also seen in Pimchan et al [ 59 ]. This study compared the antibacterial effects of three different bulk plant extracts from plants with known antibacterial properties in combination with two different E. coli phages.…”

“…As the plant extracts were diluted to reduce the potential adverse effects on the viability of the phages, a loss of phage titer of approximately 1log 10 was only observed for one of the conditions tested. However, this also reduced the overall antibacterial activity compared to the phage alone [ 59 ].…”