Flexible monitoring system for automated detection of bacterial growth in a commercial specimen processing platform

Diagnosing the presence of bacteria in a biological sample is a task to accomplish as early as possible, since bacterial infections still represent a serious threat to human health. In the market, there are commercial systems carrying out pre-analytical tests on biological specimens. An example is provided by the WASPLab, by COPAN Italia S.p.A., which monitors bacterial growth on Petri dishes that contain the samples, by taking and processing images of one dish at a time in a completely automated way. In this paper, we propose a newly monitoring sensor system for all the Petri dishes at the same time for the detection of bacterial growth with the aim of integrating it directly in the WASPLab. It could permit to obtain quantitative information about bacterial activity in real time directly inside the incubator, offering a more rapid and complete diagnosis response and avoiding the movement of the samples. In addition, the user can set measurement parameters according to his/her needs. This allows the system reaching a great level of flexibility. We tested our solution in two ways. First, we analyzed the behavior of the proposed solution comparing the output signals with the data obtained using an impedance analyzer (HP4194A) as reference. We obtained an average deviation equal to 0.768 Ω in magnitude and 0.059 ° in phase angle. Second, we carried out a 24-hour test to monitor the activity of Staphylococcus Aureus AT C 6538 in a climate chamber. We found that our system succeeded in observing bacterial growth, with an early detection time of 4 hours. Research is undergoing to integrate the proposed system in the WASPLab.