Point-of-care-testing: from disc to diagnosis

Interview with Dr. Konstantinos Mitsakakis, Coordinator of the EU project DiscoGnosis, Department of Microsystems Engineering - IMTEK, University of Freiburg

Easy solutions that deliver results quickly are a great asset in medicine: patients receive their diagnosis faster and physicians have more time to treat them. Such tools also work without sophisticated resources and trained personal. A device currently developed in a project funded by the European Commission could bring all of this to point-of-care-testing for infectious diseases.


Photo: Smiling young man with glasses and dark hair - Dr. Mitsakakis Konstantinos; Copyright: IMTEK & Hahn-Schickard

Dr. Mitsakakis Konstantinos; ©IMTEK & Hahn-Schickard

Dr. Konstantinos Mitsakakis talks with MEDICA-tradefair.com about a disc-shaped point-of-care-test, how to shrink lab analyses to the size of a CD and what this will achieve for patients.

Dr. Mitsakakis, we are talking about the LabDisk device developed in the EU project DiscoGnosis. Which problem does this device actually address?

Dr. Konstantinos Mitsakakis: The device is a diagnostic tool to identify the causative agent of fever and guide the physician to the proper treatment. We do this by differentiating the genetic profile of the pathogen. Our panel includes malaria, dengue, salmonellosis and pneumonia. The panel can be expanded depending on the endemic/epidemic needs.

For example, malaria causes fever, but there are also other infections that cause fever but have a different pathogenic origin: viruses or bacteria for example. So, these infections need different treatment. Physicians who only look at the clinical symptom of fever will come to wrong conclusions and choose the wrong treatment.

This causes two main problems: patient mortality is higher under the wrong treatment. Furthermore, choosing general antimicrobial drugs instead of specific ones can lead to increased resistance in pathogens.

How does the analysis work?

Mitsakakis: Our device basically integrates all the steps required to analyze a pathogen in the lab, to a disc that is roughly CD-sized. Normally, the analysis in a microbiological laboratory would require special buffer fluids that extract the DNA of the pathogen from a sample. It would also require purification and amplification of the DNA in order to detect it. All these tasks are time-consuming if we would do them by hand, they would require a lot of reagents and trained personal.

Our LabDisk device automates these steps. The disc contains microfluidic chambers and channels for handling the liquids, and stored reagents for performing the biochemical analysis. We just need to insert a small blood sample, press a button and wait for the result to show.

Also, the time in which we receive results is very short. Standard culturing methods take up to two or three days. Our time to results currently is between one and two hours. This is already very quick, but I think it can become even less through some technical optimizations that we try.

Is there a special idea behind this disc form?

Mitsakakis: The system is driven by centrifugal force, meaning by spinning the disc in various frequencies. We avoid some typical problems that occur in microfluidic platforms that are pressure-driven, like microbubbles and clogging of the fluidic microchannels. The device also functions without pumps or valves. The platform works in a modular way, meaning that its components are interfaced like "puzzle pieces". Therefore, it is adaptable to the end-users' needs, for example a quick change in the diagnostic panel.

Photo: Researcher is looking at microfluidic LabDisc; Copyright: Hahn-Schickard/Bernd Müller Fotografie

The LabDisc contains microfluidic chambers and channels for handling liquids, and stored reagents for performing biochemical analysis; ©Hahn-Schickard/ Bernd Müller Fotografie

Can you estimate how expensive this device will be?

Mitsakakis: If we assume that a few hundred thousands of discs are produced, which is a reasonable amount of patients who are in need of a test like this, the plastic of the disc and the reagents would cost no more than eight to ten Euros per disc. Although there are rapid malaria tests costing 1 Euro or less, they only detect malaria. Thus, in the case of a negative malaria result, the physician needs to use several additional methods to identify the cause of fever, which adds to cost. The multiplicity offered by our test, meaning that several diseases screened in a single run, justifies its cost. The reader device currently is a prototype. But if we assume that around 1.000 pieces of it are produced per year, it would most likely cost between 5.000-7.000 Euros apiece.

Does it require special training to use?

Mitsakakis: I think one day of training will be enough to handle it. The interface will be quite intuitive and guide the user through all steps of the analysis. The results will also be presented in a straight-forward way. Training will be needed for the handling of the disc and how to inset the sample.

How far along are you in the testing?

Mitsakakis: The project is planned to end at the end of April. Until then, we have some plans to test the device in the field. Currently, we collaborate with the Institute Pasteur in Dakar, Senegal. And there are also partners who prepare a site in Sudan and Congo by collecting samples and building up a biobank. And we are looking for other sites as well who want to work at the validation of the device with us.

We are evaluating the isothermal amplification method used "in tube" with hundred patient samples that came from Congo. The next step will be to test them on disc. We are also looking into biobank samples that have been characterized with polymerase chain-reaction (PCR) to use as a reference.

We are currently finalizing the microfluidics to achieve higher sensitivity by improving the DNA extraction and purification method. One of our partners is testing the long-term stability of some reagents in areas with high temperature and humidity with promising results.

How do you plan to continue work at the project?

Mitsakakis: We look for follow-up funding to continue this project beyond April, yet even without this, all partners involved have expressed their motivation to continue work on their own resources for some clinical testing in the field.

Photo: Timo Roth; Copyright: B. Frommann

© B. Frommann

The interview was conducted by Timo Roth and translated from German by Elena O'Meara.