Methods for detection and identification of bacteria within a sample include the step of inserting a pair of electrodes into the sample. A first impedance across the electrodes is established with a first AC voltage source having a first frequency. A phage is introduced into the sample, and impedance fluctuations that are caused by ion release by the bacteria due to the phage introduction are measured. The use of impedance fluctuations instead of voltage fluctuations to detect and identify bacteria minimizes 1/f noise effects and increases system sensitivity. To further increase system sensitivity by eliminating thermal noise, a second impedance across the electrodes can be established using a second AC voltage source at a second frequency. Second impedance fluctuations are cross-correlated to the first impedance fluctuations, and the cross-correlation results are analyzed to determine whether or not bacteria are present in the sample based on phage electrical activity.