Researchers at the University of Bath have developed a test that could help medics quickly diagnose urinary tract infections (UTIs), using a smartphone camera.
Similar in principle to a pregnancy test, the process can identify the presence of harmful E. coli bacteria in a urine sample in just 25 minutes. In addition to faster testing, the procedure could make accurate UTI testing more widely available in developing nations and remote regions, thanks to its potential to be made portable, and it is far cheaper than existing lab-based tests.
According to the article, E. coli is present in 80% of bacterial UTIs, so if it is found it tells medical professionals that an antibiotic treatment is needed.
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Described in the journal Biosensors and Bioelectronics, the test uses antibodies to capture bacterial cells in very thin capillaries within a plastic strip, detecting and identifying the cells optically, rather than through the microbiological methods currently used.
Dr. Nuno Reis, from Bath's Department of Chemical Engineering, who led the development of the test, said, "The test is small and portable, so it has major potential for use in primary care settings and in developing countries.
"Currently, bacterial infections in UTIs are confirmed via microbiological testing of a urine sample. That is accurate, but time-consuming, taking several days. We hope that giving medical professionals the ability to quickly rule in or rule out certain conditions will allow them to treat patients more quickly and help them make better decisions about the prescription of antibiotics."
Scientists note that the lack of rapid diagnostics for UTIs has in many cases led to a catch-all prescription of potentially unnecessary antibiotics, which increases the risk of bacteria becoming resistant to treatment.
The test is carried out by passing a urine sample over a ridged plastic micro-capillary strip, containing an immobilizing antibody able to recognize E. coli bacterial cells. If E. coli is present in the sample, antibodies in the reagents will bind with it, stopping it from passing through the section of plastic strip. Finally, an enzyme is added that causes a change in color that can be picked up by a smartphone camera.
The system also measures the concentration of E. coli in the sample by analyzing an image taken by the camera. The procedure is simple and could be manually operated or fully automated without any need for a mains power supply.
While the test has merit, regulatory concerns could pose an obstacle. To date, bodies such as the United States Food & Drug Administration (FDA) have not granted approval to techniques that use smartphones—citing the potential for both non-lab conditions and software updates to the phone to make tests unscientific. But Dr. Reis hopes that the way the test uses a variable scale to digitally compare the pixels within an image will convince regulators to allow the test to move toward eventual production.
Dr. Reis adds that wealthier nations could also benefit from adopting the methodology, as it could make testing within primary care facilities more viable, reducing the need to send samples to central labs for testing.
"Driving more of this will bring better outcomes to patients in terms of speeding up the process, but will also lower the cost to healthcare providers. We are not talking about replacing centralized diagnostics services but providing the first point of contact with affordable and rapid tools to support prescription of antibiotics and avoid their overuse."