About one in two women are affected by cystitis during her lifetime, and many suffer from recurrent urinary tract infections. Bladder infections are not only painful and potentially dangerous, but they also pose a significant dilemma for physicians. With antibiotic resistance becoming widespread in urinary tract infections and continually increasing, physicians are often forced to blindly prescribe antibiotics without knowing their effectiveness against the pathogen causing the infection. This is because it takes several days to identify a specific pathogen using conventional diagnostics.
Researchers at ETH Zurich, in collaboration with Balgrist University Hospital, have now developed a rapid test that employs the natural viral predators of bacteria, bacteriophages. The researchers also genetically modified the phages to make them more efficient at destroying the pathogenic bacteria.
Fast and reliable diagnosis
Phages are highly specialised viruses. Each species of phage infects only one particular type or strain of bacteria. ETH Zurich scientists from the Food Microbiology research group led by Professor Martin Loessner are now taking advantage of this unique characteristic. The first step was to identify the phages that are effective against the three main types of bacteria implicated in urinary tract infections, namely Escherichia coli, Klebsiella and Enterococci. These natural phages were then modified in such a way that any bacteria they recognize and infect are propelled to produce an easy-to-measure light signal.
Using this method, the researchers were able to reliably detect the pathogenic bacteria directly from a urine sample in less than four hours. In the future, the method could make it possible to prescribe a suitable antibiotic immediately after diagnosis and thus minimize resistance development and improve antibiotic stewardship.
The method also has another advantage: it allows physicians to predict which patients are likely to respond particularly well to a tailored phage therapy, as the strength of the light signal produced in the assay already indicates how efficient the phages are in attacking the bacterium – the more the sample glows, the better the bacterium will respond to the therapy.
