The diagnostic spinner in action.
Urinary tract infections have been referred to as the "canary in the coal mine" of global antibiotic resistance. With more than half of all women having a urinary tract infection in their lives and men becoming more vulnerable with age, urinary tract infections are one of the most common bacterial infections in the world.
Because it is not always possible to test a urine sample for a bacterial infection, patients often receive antibiotics only because of the symptoms – a practice that contributes to the growing resistance of many UTIs to the most common treatments.
We could be saved by an unexpected hero: the fidgety spinner. In an article in Nature Biomedical Engineering earlier this week, researchers in South Korea and India describe a new test for urinary tract infections that only requires a few turns of a spinner-like device by hand. The results that anyone can read will be ready in about an hour.
Laboratory on a CD
Currently UTIs are best diagnosed using urine culture tests that are slow and resource intensive. Test strip tests, in which only a treated paper strip has to be immersed in a urine sample, are cheaper and immediately available, but not as reliable.
The ideal test would not only be quick and accurate, but also resource-saving like an oil dipstick – usable in environments without electricity, with limited money and with few trained specialists. This is where the fidgety spinner comes into play.
A research team led by Yoon-Kyoung Cho built a device that works on the same principles as a fidgety spinner. Like the toy, it has small "wings" that rotate around a central point. and like the toy, it can spin forever after just one or two hand thrusts. In contrast to the three rags of the usual fidget spinner toy, this "laboratory on a disc" is rectangular. This is made up for by much more interesting content.
The tester takes only 1 ml of urine in a central chamber. When the device is rotated, the centrifugal force pushes the sample through a membrane that collects all bacteria from the sample while the liquid filters into a reservoir. When a dye is added, it filters through this bacterial sample and changes color to indicate how high the bacterial load is. It takes less than an hour for the results to be visible to the naked eye.
To test the device on the road, the researchers took it to a clinic in Tiruchirappalli, India, where patients are usually given antibiotics only because of their symptoms. They collected samples from 39 UTI patients and then tested them using conventional urine culture tests and the new device. The two methods had comparable results, although the spinner found some additional patients who tested negative using conventional methods.
The team also used the device to test antibiotic resistance. They exposed bacterial samples to various drugs in the test and then compared them to samples that had not been treated. The samples that remained heavily stained by the dye were considered resistant. While this would not compete with gold standard tests for microbial resistance, it could help doctors make a quick decision about which antibiotic to prescribe.
Another test confirmed that the spinner can be used by anyone, regardless of hand size. The researchers checked the differences in spin speed between ten different test spinners, five men and five women. Anyone could make the device fling the entire urine sample through the filter, although some of them will take more than one turn to do this.
Of these 39 patients in Tiruchirappalli, all would have been prescribed antibiotics based on their symptoms. With the spinner, that number dropped to 18, which would save 21 people from unnecessary prescriptions – and the associated personal and global risks.
Nature Biomedical Engineering, 2020. DOI: 10.1038 / s41551-020-0557-2 (About DOIs).