Study of Real-Time Spatial and Temporal Behavior of Bacterial Biofilms Using 2-D Impedance Spectroscopy.

OBJECTIVE: The purpose of this paper is to demonstrate the use of 2-D impedance spectroscopy to identify areas of biofilm growth on a CMOS biosensor microelectrode-array. METHODS: This paper presents the design and use of a novel multichannel impedance spectroscopy instrument to allow 2-D spatial and temporal evaluation of biofilm growth. The custom-designed circuits can provide a wide range of frequencies (1 Hz-100 kHz) to allow customization of impedance measurements, as the frequency of interest varies based on the type and state of biofilm under measurement. The device is capable of taking measurements as fast as once per second on the entire set of impedance sensors, allowing real-time observation. It also supports adjustable stimulus voltages. The distance between neighboring sensors is 220 micrometers which provides reasonable spatial resolution for biofilm study. RESULTS: Biofilm was grown on the surface of the chip, occupancy was measured using the new tool, and the results were validated optically using fluorescent staining. The results show that the developed tool can be used to determine the bacterial biofilm presence at a given location. CONCLUSION: This paper confirms that 2-D impedance spectroscopy can be used to measure biofilm occupancy. The new tool developed to perform the measurements was able to display real-time results, and determine biofilm coverage of the array electrodes. SIGNIFICANCE: The system presented in this report is the first fully integrated 2-D EIS measurement system with full software support for capturing biofilm growth dynamics in real-time. Due to its ability to nondestructively monitor biofilms over time, 2-D impedance spectroscopy using a microelectrode-array is a useful tool for studying biofilms.

A mouse model of pulmonary Mycobacteroides abscessus infection.

There is no preclinical mouse model to investigate pulmonary Mycobacteroides abscessus (formerly Mycobacterium abscessus) infection in an immunocompetent mouse strain, especially in the context of antibiotic testing and regimen development. We developed a mouse model of pulmonary M. abscessus infection using the aerosolized route of infection that leads to an increase in bacterial burden post- implantation and develops pathology as a result. In this mouse model, treatment with corticosteroid allows for initial proliferation and sustained M. abscessus pulmonary infection and permits evaluation of efficacies of antibiotics. Administration of corticosteroids that permitted higher levels of bacterial burden in the lungs were more likely to have pathology. Treatment of mice with antibiotics administered intranasally or subcutaneously significantly reduced lung M. abscessus burden. In addition to the reference strain, independent clinical isolates of M. abscessus also readily establish infection and proliferate in the lungs of mice in this model.