Bacterial Diagnosis

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Science  11 Apr 2014:
Vol. 344, Issue 6180, pp. 131
DOI: 10.1126/science.344.6180.131-b

You've read about the enormous community of microbes that live in the guts of humans and other animals. But what if we could train some of them to perform non-invasive but reliable diagnostic procedures deep inside the body? Kotula et al. report experiments showing that such a strategy is not at all farfetched. Bacteria were engineered to contain a stable genetic switch that would record exposure to a chemical while the bacteria were living in the gut of a mouse. The switch was then rigged to be activated if the bacteria were exposed to a certain chemical, low concentrations of which regulated a repressor element built into the trigger mechanism for the sensor. The modified bacteria could then be fed to mice. When the bacteria were later collected from fecal samples, they accurately “remembered’ whether or not the host animal had been exposed to the chemical more than a week earlier. Given these results, one can imagine similar programming of bacteria that would report the presence of diagnostically sensitive chemicals indicative of cancer, inflammation, or other conditions within the gut of the host animal.

Proc. Natl. Acad. Sci. U.S.A. 111, 10.1073/pnas.1321321111 (2014).

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