Two research teams said they have used Escherichia coli (E. coli) as diagnostic tools to detect liver cancer and diabetes.
In the first study, researchers at the Massachusetts Institute of Technology (MIT) and the University of California at San Diego used a harmless strain of E. coli called Nissle 1917, which is marketed as a promoter of gastrointestinal health, Xinhua news agency reported.
The researchers engineered the bacteria to produce a luminescent signal when they encounter a tumor, which will then be detected with a simple urine test.
When fed to mice by mouth, the bacteria do not accumulate in tumors all over the body, but predictably zero in on liver tumors, the researchers found. That's because the hepatic portal vein carries them from the digestive tract to the liver.
The animals that were given the engineered bacteria did not exhibit any harmful side effects, the researchers said.
With the E. coli test, the researchers said they were able to detect liver tumors larger than about one cubic millimetre, offering more sensitivity than existing imaging methods.
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This kind of diagnostic could be most useful for monitoring patients after they have had a colon tumor removed because they are at risk for recurrence in the liver, according to study author Sangeeta Bhatia, a professor of health sciences and electrical engineering and computer science at the MIT.
In the second study, researchers engineered E. coli to detect biological signals in urine and, at a specific threshold, generate a visible colour change.
The researchers demonstrated their so-called bactosensors in urine samples from diabetic patients and found that they accurately and reliably detected abnormal glucose levels in urine, performing almost as well as current standard urine dipsticks.
Both papers were published in the US journal Science Translational Medicine.