Polymer Electrochromism Driven by Metabolic Activity Facilitates Rapid and Facile Bacterial Detection and Susceptibility Evaluation

Abstract The electrochromism of a water‐soluble naturally oxidized electrochromic polymer, ox‐PPE, is harnessed for rapid and facile bacterial detection, discrimination, and susceptibility testing. The ox‐PPE solution shows distinct colorimetric and spectroscopic changes within 30 min when mixed with live bacteria. For the underlying mechanism, it is found that ox‐PPE responds to the reducing species (e.g., cysteine and glutathione) released by metabolically active bacteria. This reduction reaction is ubiquitous among various bacterial strains, with a noticeable difference that enables discrimination of Gram‐negative and Gram‐positive bacterial strains. Combining ox‐PPE with antibiotics, methicillin‐susceptible and methicillin‐resistant Staphylococcus aureus can be differentiated within 2.5 h. Proof‐of‐concept demonstration of ox‐PPE for antimicrobial susceptibility testing is carried out by incubating Escherichia coli with various antibiotics. The obtained minimum inhibition concentrations are consistent with the conventional culture‐based methods, but with the procedure time significantly shortened to 3 h.