Fig. 2

Experimental set-up for determining TTD of mycobacteria. Two sets of similar samples are prepared by inoculating with mycobacteria and incubated at 37 °C. One set is sent to the hospital microbiology lab for detection using MGIT 960 automated culture-based system while the other set of sample is tested using our technique. For our technique, at regular intervals of time, small aliquots of sample are drawn and its impedance is tested using impedance analyzer. The data is fitted to an equivalent circuit to generate a Nyquist plot [48] and thereby estimates the values of the desired circuit parameters. We show on the graph three sets of data: those obtained at 2, 8, and 12 h for a culture of M. smegmatis (large, medium, and small semi-circles). The inset shows the software output for circuit parameters obtained by fitting the data at 12 h to the circuit