Rapid Test Uses Bacteria-Infecting Viruses to Accurately Identify UTI-Causing Pathogens

By LabMedica International staff writers
Posted on 31 Jul 2023

New rapid test uses bacteriophages to quickly and accurately identify UTI-causing pathogens (Photo courtesy of ETH Zurich)

Cystitis affects approximately 50% of women at some point in their lives, with many experiencing recurring urinary tract infections. These bladder infections not only cause pain and potential complications but also present a significant challenge to healthcare providers. The rampant spread of antibiotic resistance in urinary tract infections often forces physicians to prescribe antibiotics indiscriminately without awareness of their effectiveness against the infection-causing pathogen. This is largely due to the lengthy period taken by conventional diagnostic methods to identify specific pathogens. Now, scientists have developed a rapid test that uses bacteriophages, viruses that naturally prey on bacteria, and have also altered them genetically to further increase their effectiveness in destroying pathogenic bacteria.

Bacteriophages, or simply phages, are highly specialized viruses. Each phage species infects only a particular bacterial type or strain. Scientists at ETH Zurich (Zurich, Switzerland) have harnessed this unique feature to develop a rapid test and a new therapeutic approach for urinary tract infections. Their initial step was identifying the most potent phages against the three primary bacteria types associated with urinary tract infections: Escherichia coli, Klebsiella, and Enterococci. The researchers then altered these naturally occurring phages in order to trigger the bacteria they recognize and infect to emit an easily detectable light signal. Using this technique, the researchers could reliably identify the disease-causing bacteria directly from a urine sample within four hours. This novel method could enable immediate prescription of the appropriate antibiotic after diagnosis, minimizing resistance development and promoting better antibiotic management.

The new method offers another advantage: it enables physicians to determine which patients might particularly benefit from personalized phage therapy, as the light signal strength in the assay indicates the phages' effectiveness in attacking the bacteria – the brighter the sample, the better the response to therapy. In a proof of concept study, the researchers enhanced the phages' efficacy by genetically modifying them. The altered phages not only generate new phages inside the host bacterium but also bacteriocins. These bacteria-killing proteins are especially potent against bacterial strains that have modified their surface parts to evade phage recognition, offering a two-pronged attack for enhanced treatment efficacy.

Nonetheless, the widespread application of such therapies in Western countries still has considerable obstacles to overcome. Aside from comprehensive clinical trials, regulatory amendments acknowledging phages as evolving biological entities that co-evolve with their bacterial hosts would be beneficial. The researchers' next step will involve testing the newly-developed phage therapy's efficacy in a clinical trial involving selected patients.

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ETH Zurich