Researchers have developed a new device which can detect bacterial species that cause urinary tract infections – a major cause of sepsis – within 70 minutes. Untreated urinary tract infections may trigger sepsis, which occurs when the immune system, in an attempt to fight off the infection, inadvertently activates body-wide inflammation that can cause blood clots and leaky blood vessels. Sepsis is a major killer and accounts for about half of the hospital deaths in the US by some estimates.
Hospital patients often acquire urinary tract infections via infected catheters and so untreated infections are a huge problem faced by healthcare providers around the world. Early diagnosis could save lives and reduce healthcare costs.
A team of researchers in Germany and Ireland set out to speed up the detection process for bacteria that cause urinary tract infections.
In the journal Biomicrofluidics, the team described creating a Lab-on-a-Disc platform that combines microfluidics and Raman microscopy, a modern optical detection method.
Their medical diagnostics device is designed to harness centrifugal force – akin to the circular swing of a “Chair-o-Plane” carnival ride, in which a fast rotation creates a force that causes the seats to drift radially away from the ride’s centre – to capture the tiny bacteria directly from patients’ samples of bodily fluids in this case, urine.
The work involves extremely small sample sizes, on the scale of a small raindrop, so the device needed to be a microfluidic one.
“Our device works by loading a few microlitres of a patient’s urine sample into a tiny chip, which is then rotated with a high angular velocity so that any bacteria is guided by centrifugal force through microfluidic channels to a small chamber where ‘V-cup capture units’ collect it for optical investigation,” said Ulrich-Christian Schroder, a PhD student at the Jena University Hospital and Leibniz Institute of Technology in Germany.
The team’s concept then adds Raman spectroscopy to its centrifugal microfluidic platform.
“Raman spectroscopy uses the way light interacts with matter to produce ‘unique scattering,’ the equivalent of a molecular fingerprint, which can then be used to identify the types of bacteria present,” said Ute Neugebauer, group leader at the Jena University Hospital and Leibniz Institute of Technology.
“In our pilot study, we were able to identify Escherichia coli (more commonly known as E coli) and Enterococcus faecalis – two species known to cause urinary tract infections – within 70 minutes, directly from patients’ urine samples,” said Schroder.
The speedy diagnosis marks a tremendous reduction in the wait time compared to the lengthy lag – often 24 hours or more – associated with methods routinely used to identify bacteria and diagnose urinary tract infections today.