Real time monitoring of the impedance characteristics of Staphylococcal bacterial biofilm cultures with a modified CDC reactor system.

Detection of device-associated infectious processes is still an important clinical challenge. Bacteria grow adhered to the device surfaces creating biofilms that are resistant to antimicrobial agents, increasing mortality and morbidity. Thus there is need of a surgical procedure to remove the indwelling infected device. The elevated cost of these procedures, besides patients discomfort and increased risks, highlights the need to develop more efficient, accurate and rapid detection methods. Biosensors integrated with implantable devices will provide an effective diagnostic tool. In vivo, rapid and sensitive detection of bacteria attached to the device surfaces will allow efficient treatments. Impedance spectroscopy technique would be an adequate tool to detect the adherence and the growth of the microorganism by monitoring the impedance characteristics. In this work a label-free interdigitated microelectrode (IDAM) biosensor has been developed to be integrated with implantable devices. Impedance characterization of Staphylococcus epidermidis biofilms has been performed achieving electrical monitoring of the bacterial growths in a few hours from the onset of the infection. This pathogen represents the most common microorganism related to intravascular catheters associated infections. The experimental setup presented in this work, a modified CDC biofilm reactor, simulates the natural environment conditions for bacterial biofilm development. The results prove that the low range of frequency is the most suitable setting for monitoring biofilm development. Our findings prove the effectiveness of this technique which shows variations of 59% in the equivalent serial capacitance component of the impedance.