Researchers from the University of Southampton in the UK have used laser technology to create a paper-based test that can identify bacteria in a urine sample and tell whether the species is showing antibiotic resistance.
Urinary tract infections (UTIs) are the most commonly diagnosed infections worldwide and are typically caused by bacteria such as Escherichia coli.
The infections are currently diagnosed by growing the bacteria on agar plates for two-to-three days and then testing them for antibiotic resistance, which takes a further 24 hours. During this time, patients are often prescribed broad-action antibiotics, which can be less effective than selective antibiotics and contribute to antibiotic resistance.
In a paper published in the journal Biosensors and Bioelectronics, Peijun He and colleagues from the University of Southampton presented their novel point-of-care detection device that can cut this detection time down to about 10 hours by identifying the bacterial strain and its antibiotic susceptibility at the same time.
The device consists of three layers: a top layer that contains four common antibiotics – amoxicillin, ciprofloxacin, gentamicin, and nitrofurantoin – which are placed in wells created by lasers, an absorbent middle layer to which the sample is added, and an agar gel-containing base layer that provides the nutrients to allow the bacteria to grow.
The agar contains a dye that turns blue if E. coli is present in the sample. If the bacteria are susceptible to the antibiotics, they will not grow in the areas immediately surrounding the wells.
Study group leader Collin Sones told me that he thinks the test could be used at home by people with symptoms of a UTI before they even see a doctor. They could perform the test, leave it somewhere warm, and then take a photo of the result and send it to the doctor.
By the time you see the doctor, they “will be able to advise what antibiotics should be used rather than giving a broad-spectrum antibiotic, so it’s more focused towards antimicrobial resistance,” Sones said.
Peijun He told me that early preclinical trials have shown “the device works very well and the feedback from our pathologist is very positive.”
He added that one of the next steps in the research, which has been funded by the Engineering and Physical Sciences Research Council, is to carry out a field trial in Uganda, where access to laboratory facilities can be limited.
If successful, the researchers hope to commercialize the test through their start-up company, Highfield Diagnostics.
Images from Shutterstock and the University of Southampton