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SAN DIEGO, OCTOBER 20, 2017 - Employing the xCELLigence® technology from ACEA Biosciences, a team of Spanish scientists have developed a real-time assay for screening anti-biofilm treatments and quantifying their efficacy. Biofilms are surface-attached communities of bacterial or fungal cells that are enmeshed in an extensive extracellular matrix which makes them more resistant to both antibiotics and the immune system. With biofilms estimated to be responsible for >60% of microbial infections, and 80% of chronic infections in humans, finding ways to disrupt established biofilms is of critical importance. In recent years there has been a growing interest in exploiting bacteriophages, or the lytic proteins that they encode, to treat biofilms.
Citing that the techniques currently used to identify anti-biofilm activities in phage-derived proteins have the “important shortcomings” of being laborious endpoint assays that suffer from poor reproducibility, in the recent issue of Frontiers in Microbiology a team of scientists lead by Diana Gutierrez report a proof of concept study using an xCELLigence Real-Time Cell Analysis instrument to monitor the disruption of clinically important Staphylococcus aureus biofilms. Within the proprietary xCELLigence microtiter plates that contain gold biosensors, biofilms of S. aureus were established and then exposed to different bacteriophage-derived proteins that catalyze degradation of the key biofilm extracellular polymers peptidoglycan or exopolysaccharide. The authors demonstrated that the degradation of these polymers, and the concomitant dissipation of the biofilm, causes a decrease in the xCELLigence biosensor signal that is both time- and dose-dependent. Importantly, this real-time biofilm disruption data correlated well with the data from traditional end point assays such as the labor intensive crystal violet staining technique.
Because each well of an xCELLigence microtiter plate can acquire thousands of data points, each individual well yields a complete time course for biofilm deposition or dissipation, greatly reducing the number of wells/plates needed and the total workload. Because of this, the authors were able to easily screen multiple S. aureus strains and four different lytic enzymes over a range of concentrations. The dose-response curves generated by this approach made it possible to accurately calculate key parameters such as the MBEC50 (the minimum biofilm eradicating concentration that removes 50% of the biofilm) for each treatment. In the ongoing effort to develop better biofilm therapeutics, Gutierrez and colleagues suggested that the synergistic effects of combining phage enzymes with different substrate specificities should be a key area of focus. With this in mind, they concluded that the reduced workload, improved efficiency, and higher reproducibility of the xCELLigence assay will make it possible to “quickly assess and compare by standardized parameters the disaggregating activity of phage anti-biofilm proteins.”. See the original Frontiers in Microbiology publication here.
About xCELLigence RTCA
xCELLigence Real Time Cell Analysis (RTCA) instruments utilize gold microelectrodes embedded in the bottom of microtiter wells to non-invasively monitor the status of adherent cells using the principle of cellular impedance. In short, cells act as insulators – impeding the flow of a miniscule electric current between electrodes. This impedance signal is measured automatically, at an interval defined by the user, and provides an extremely sensitive readout of cell number, cell size, and cell-substrate attachment strength. xCELLigence RTCA instruments are being used in both academia and industry for basic and applied applications ranging from cancer immunotherapy and cardiotoxicity to drug discovery and bacterial biofilm research. To date xCELLigence has been used in more than 1,400 publications, which can be viewed in a searchable library. Read more
About ACEA Biosciences
Founded in 2002, ACEA Biosciences is a pioneer in the development and commercialization of high performance, cutting edge cell analysis platforms for life science research. ACEA’s xCELLigence impedance-based, label-free, real-time cell analysis instruments and NovoCyte flow cytometer are used in pre-clinical drug discovery and development, toxicology, safety pharmacology, and basic academic research. More than 2,000 instruments have been placed globally. Read more