A method for bacteria detection and the assessment of the antimicrobial susceptibility profile uses a bacterial viability assay based on combining a highly efficient affinity bacteria enrichment/ separation with an electrochemical redox interrogation measurement. The method comprises: the affinity enrichment/ separation of bacteria from a liquid sample by using ligands-modified paramagnetic or superparamagnetic particles; the subsequent introduction of the bacteria isolate together with a solution containing a metabolic redox marker into a container for incubation; transferring the solution containing the metabolic redox marker and bacteria complexes to an electrochemical cell containing electrodes with magnets outside the reservoir so as to form a bacteria isolate (super)paramagnetic agglutinate on or close to the detection electrode, and the electrochemical detection of the change of the oxidation state of the metabolic redox marker inside the bacteria isolate (super)paramagnetic agglutinate as a direct measure of bacterial metabolic activity. Antimicrobial susceptibility testing (AST) is performed by adding an antibiotic to the sample at any stage, such as before the affinity enrichment/ separation.