Sensitive Detection of <i>Escherichia coli</i> <i>O157:H7</i> Using Allosteric Probe and Hairpin Switches-Based Isothermal Transcription Amplification

Pathogens pose a serious threat to public and population health, leading to serious outbreak and spread of diseases irrespective of the region. The capability to directly, sensitively, and specifically detect viable pathogens in low numbers in food and clinical samples is very desirable but remains a challenge. In this work, we present a novel assay of a combination of an aptamer-based allosteric probe and hairpin switch-controlled T7 RNA polymerase-based isothermal transcription amplification, which enables rapid, ultrasensitive, label-free detection of direct pathogens. It can detect <i>Escherichia coli</i> as low as 73.2 CFU/mL. Moreover, with the usage of the proposed assay, sensitive quantification of <i>E. coli</i><i>O157:H7</i> in milk samples has been achieved, showing significant potential as a simple and sensitive tool to quantify pathogens in milk and other foods.