A system for determining the presence or absence of microbes in a specimen, said system comprising: a sealed blood culture bottle for holding a specimen suspected of containing one or more microbes comprising a growth media and an interior volume for holding a specimen; a test device capable of monitoring changes in the specimen caused by metabolic processes of the one or more microbes; and a circuit comprising: two electrodes (102, 104), the electrodes located in contact with or in proximity to the bottle such that the two electrodes (102, 104) are adjacent to, but not in contact with, the specimen upon collection thereof wherein the bottle is cylindrical or comprises a cylindrical portion and wherein the two electrodes are disposed circumferentially around the bottle, and wherein the two electrodes are interdigitated, and wherein the first of the two interdigitated conductive electrodes is a sensor electrode and a second of the two interdigitated conductive electrodes is a ground reference electrode; wherein the circuit further comprises a signal generator configured to produce a sine wave and wherein the signal to the sensor electrode is 180 degrees out of phase with the signal to the ground reference electrode thereby providing current from the sensor electrode to the ground reference electrode through an intercapacitance between the sensor electrode and the ground reference electrode wherein the circumferentially disposed electrodes form an electrodynamic field over at least a portion of the volume; and wherein the test device is configured to measure a value of the electrodynamic field wherein the changes in the electrodynamic field are capacitance changes indicative of changes in the dielectric constant of the specimen. a sealed blood culture bottle for holding a specimen suspected of containing one or more microbes comprising a growth media and an interior volume for holding a specimen; a test device capable of monitoring changes in the specimen caused by metabolic processes of the one or more microbes; and a circuit comprising: two electrodes (102, 104), the electrodes located in contact with or in proximity to the bottle such that the two electrodes (102, 104) are adjacent to, but not in contact with, the specimen upon collection thereof wherein the bottle is cylindrical or comprises a cylindrical portion and wherein the two electrodes are disposed circumferentially around the bottle, and wherein the two electrodes are interdigitated, and wherein the first of the two interdigitated conductive electrodes is a sensor electrode and a second of the two interdigitated conductive electrodes is a ground reference electrode; wherein the circuit further comprises a signal generator configured to produce a sine wave and wherein the signal to the sensor electrode is 180 degrees out of phase with the signal to the ground reference electrode thereby providing current from the sensor electrode to the ground reference electrode through an intercapacitance between the sensor electrode and the ground reference electrode wherein the circumferentially disposed electrodes form an electrodynamic field over at least a portion of the volume; and wherein the test device is configured to measure a value of the electrodynamic field wherein the changes in the electrodynamic field are capacitance changes indicative of changes in the dielectric constant of the specimen. two electrodes (102, 104), the electrodes located in contact with or in proximity to the bottle such that the two electrodes (102, 104) are adjacent to, but not in contact with, the specimen upon collection thereof wherein the bottle is cylindrical or comprises a cylindrical portion and wherein the two electrodes are disposed circumferentially around the bottle, and wherein the two electrodes are interdigitated, and wherein the first of the two interdigitated conductive electrodes is a sensor electrode and a second of the two interdigitated conductive electrodes is a ground reference electrode; wherein the circuit further comprises a signal generator configured to produce a sine wave and wherein the signal to the sensor electrode is 180 degrees out of phase with the signal to the ground reference electrode thereby providing current from the sensor electrode to the ground reference electrode through an intercapacitance between the sensor electrode and the ground reference electrode wherein the circumferentially disposed electrodes form an electrodynamic field over at least a portion of the volume; and wherein the test device is configured to measure a value of the electrodynamic field wherein the changes in the electrodynamic field are capacitance changes indicative of changes in the dielectric constant of the specimen.