LAUSR

The dissemination of antimicrobial resistance around the world is one of the biggest threats to global public health. The acquisition and expression of extended‐spectrum β‐lactamases (ESBLs) in pathogenic bacterial are mainly responsible for bacterial resistance to third‐generation cephalosporins. Reported herein is a ratiometric fluorescent probe for the detection of the activity of ESBLs. This imaging reagent adopts the core structure of cefotaxime as an enzymatic recognition moiety, and exhibits excellent selectivity to ESBLs over other β‐lactamases. The specific activation of this sensor by ESBLs can lead to over 2500‐fold changes in the fluorescent ratio, which is independent of the concentration of the probe and environmental conditions. Further experiments have demonstrated that this ratiometric fluorescent probe can distinguish bacteria with extended‐spectrum antibiotic resistance from a group of clinically important pathogens within a short period of time.