MicrobiologySymcel, the company behind the revolutionary cell-based assay tool, calScreener, providing real-time cellular bioenergetics measurements, has developed the groundbreaking technique to address the critical industry challenge of antibiotic resistance – at a time of mounting healthcare costs in the face of the growth in multi-resistant bacteria.

The company’s novel solution for antibiotic development and monitoring utilizes calorimetry in the form of a sensitive label-free cell-based assay that brings the capability to measure bacterial activity in a range of complex settings in real-time. Moreover, minimum effort is required to apply the technique.

Magnus Jansson, Chief Scientific Officer at Symcel, commented: “The properties of calorimetry based cell monitoring, and the data it produces, are uniquely well suited to the development of novel antibiotics. Indeed, the technique has the distinct advantage of being a label-free and non-destructive measurement, making post-experimental analysis possible whilst being totally independent of sample morphology.”

“Consequently, assays can be performed on bacteria in solution as well as on solid media, including three-dimensional matrixes such as bone biopsies, surgical and dental implant materials, whilst being totally indifferent to turbid or fluorescent properties of the system. The 3D factor is especially significant as it addresses the serious problem with normal assays that can’t give representative samples of bacteria colonizing three dimensional surfaces, rendering microscopy, fluorescence and molecular methods prone to large deviations,” he added.

Calorimetry measures the power produced in a cell culture at any given time as Joules/second (W). The heat generated, which is a measurement of the metabolic processes in cells, provides a true phenotype fingerprint of organisms. Different bacteria and different treatments give rise to unique heat profiles that reveal significant information about the system being tested. A growth curve, creating by integrating the metabolic power over time to accumulate heat over time (in Joules), provides data that enables both the lag-time and the maximal growth rate of the cell culture to be calculated. This serves as the basis for determining  the effect of antibiotic treatment.

Magnus Jannson continued: “One of the unique properties of calorimetry based metabolic monitoring of bacterial growth is that the pattern of energy expenditure is both species- as well as strain-specific. Consequently, each bacteria gives rise to a specific growth pattern as heat production with time and, as a result, the metabolic output assay becomes both quantitative as well as qualitative. Even minor changes in growth behaviour, such as metabolic pathway mutations, biofilm formation and antimicrobial sensitivity are all detected.”

The approach has a range of other significant advantages. As calorimetry measures the total metabolism, bioavailability becomes a non-issue as it is accounted for in the measurement. Moreover, bacterial growth assays can be performed in both liquid and solid media, enabling the investigation of different properties during colonization, such as dental and surgical implant materials. The technique also has the benefit of only accounting for the actual number of metabolic, live cells. DNA or protein based assays, by contrast, lack this advantage with the effect that misrepresentations of clustered cells as single colonies leads to incorrect quantifications of cell numbers.

Calorimetry also enables the easy and continuous monitoring of the metabolic activity during prolonged periods, with the typical assay running from a couple of hours up to days or even weeks. This has the benefit of enabling the monitoring of persister-cells, or cells that are derived with antibiotic resistance by the pressure of natural selection, giving rise to metabolic activity at a lower but constant rate during a prolonged period of time – with the cells distinguishable in the assay.

Christer Wallin, CEO of Symcel, added: “Calorimetry is an easy to use technique for the accurate and reliable monitoring of multiple modes of action of combined therapies and the use of potentiating compounds, with no inherent antibiotic properties. The co-operative effects of two or more compounds are readily followed and there is the clear benefit of unbiased phenotype screening as it is not necessary to know the mechanism of action prior to the experiment, Moreover, the technique is a very ‘open’ type of cell-based assay that is not limited to a specific cell type or setting. It serves as a highly useful tool for testing the toxicity of novel chemical entities on mammalian cell systems using the same equipment used for testing the antibacterial potency and, as a consequence, it is a good value proposition for the healthcare sector.”