(University of California, Santa Barbara)
21 September 2018. A system for identifying bacterial infections shows the system’s smartphone app and accompanying lab kit can detect urinary tract infections, including those with sepsis, in about an hour. The system developed by researchers at University of California in Santa Barbara and Stanford University is described in yesterday’s issue of the journal EBio Medicine.
The team led by UC-Santa Barbara bacteriologist Michael Mahan and Stanford bioengineering professor Tom Soh is seeking faster, less expensive, and more readily available tests for infections conducted at the point of care. Among commonly diagnosed infections are urinary tract infections, which occur most often in women, in the bladder and urethra. If left untreated, these infections can spread to the kidneys or beyond with serious consequences. National Kidney Foundation says urinary tract infections are responsible for some 10 million doctor visits a year in the U.S., with at least 1 in 5 women likely to have an infection in her lifetime.
To meet this need, Mahan, Soh, and colleagues developed their smaRT-LAMP system, short for smartphone-based real-time loop-mediated isothermal amplification. In the paper, the researchers used the system with urine samples, although its developers say it can also detect infectious bacteria in blood and feces samples. The samples are captured in vials, warmed with a hot-plate, and treated with sodium hydroxide, containing lye and caustic soda, then reactants that generate fluorescent signals indicating unique amplified copy numbers of bacterial DNA.
The smartphone app, written for the Android operating system and Samsung Galaxy S7, uses the phone’s camera to capture the fluorescent signals, recording images every 10 seconds over a 50-minute period. Built-in algorithms then analyze the signals to determine the type of bacteria present in the sample and calculate the bacterial burden quantity. The results are then matched against statistical curves for standard bacterial concentrations. The free app, called Bacticount, includes a step-by-step tutorial.
The team evaluated the test kit and app in the lab with 8 different bacteria and strains within those bacteria, followed by lab tests with whole blood, urine, and feces from mice, including bacteria associated with sepsis. The researchers then assessed urine samples from 10 patients at a Santa Barbara hospital with urinary tract infections. The smaRT-LAMP system successfully detected the infections in the patients, including patients who developed sepsis, when compared to hospital lab assessments of blood samples from those individuals. However, the smaRT-LAMP tests returned results in about an hour, while the hospital lab needed 18 to 28 hours.
The team says the test kit costs less than $100 to produce, which with the smartphone app offers a faster and inexpensive bacterial testing method for detecting a wide range of pathogens for point-of-care clinics. Mahan says in a UC-Santa Barbara statement, “We believe that this lab test holds exciting potential to bring state-of-the-art diagnostics within easy reach of non-expert users.” Soh adds, “We hope technologies like this offer new ways of providing better health care around the globe.”
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