Urinary tract infection tests: results in less than 4 hours?

Normally, a person suffering from a urinary tract infection (UTI) has to wait between 24 and 48 hours to obtain the results of a test to identify the bacteria responsible for the UTI. In addition to having to endure the symptoms of UTIs during this time and ingesting broad-spectrum antibiotics, patients put themselves at risk of developing antibiotic-resistant bacteria. “Rapid and accurate detection of bacterial infection is essential to provide appropriate antibiotic therapy to patients and avoid the emergence of drug-resistant pathogens,” wrote a team of researchers from Laval University in Quebec City, who have been working for several years on the development of a rapid test to identify and quantify the bacterial strain responsible for UTI.“We propose a culture-free workflow, enabling bacterial identification and quantification in less than four hours using 1 ml of urine,” said the authors in an article published in the journal Molecular & Cellular Proteomics. They describe their approach, combining proteomics and artificial intelligence.A new workflow adapted to clinical laboratoriesClinical laboratories have completely revised the identification method to make it more efficient. Firstly, the initial urine volume was reduced from 10 ml to just one, to make sample preparation fully automated.Next, the researchers used a new workflow, LC-SRM-ML (capillary flow liquid chromatography coupled with selected reaction monitoring), suitable for routine analysis in clinical laboratories.The workflow consists of four steps: “sample preparation” to isolate bacterial cells from urine, extract and digest their proteins into peptides; “LC-SRM analysis” to monitor urine signature peptides; “identification” to predict bacterial species using a machine learning model; and “quantification” to estimate the bacterial quantity in urine using the SRM peptide signal with standard curves.This workflow has been validated on 45 inoculated samples (15 bacterial species inoculated at three concentrations in the urine of healthy volunteers) and with 84 UTI-positive urine samples from patients collected at Centre Hospitalier Universitaire de Québec in Quebec City.“The LC gradient was reduced from 90 to 10 minutes, allowing analysis of up to 75 samples per day,” with 99.2% accuracy on bacterial inoculations of healthy urine, the authors said. They also improved classification by machine learning to avoid prediction errors and defined calibration curves for each of the 15 bacterial species that cause 84% of UTIs to distinguish simple sample contamination from a true infection requiring antibiotic therapy.As reliable as the current test, without bacterial culture By monitoring the signature of urinary tract infections—the abundance of 82 peptides for each of 15 species—using a mass spectrometer, and then comparing these signatures with those of the bacteria present in a patient's urine, the team led by Dr. Arnaud Droit, professor at Laval University's faculty of medicine, can determine the bacteria responsible for UTI in less than four hours, without the need for bacterial culture. The rapid test was carried out on 70 UTI sufferers, and the diagnosis produced was compared with the method currently used in Quebec. Result: 93.3% of inoculated urine was correctly identified with the new test, compared with 97.8% with the reference method. What's more, results on UTI-positive urine matched in 87% of cases.“This performance would be high enough to consider using the rapid test in a clinical setting. What's more, its effectiveness could be improved by adding more peptides to the signature of each bacterium,” said Dr. Droit. However, the researchers have developed this test using instruments that are inaccessible in clinics and hospitals. They are collaborating with a scientific instrument manufacturer to adapt the method to instruments that can be used in clinical settings. The full study is published in Molecular & Cellular Proteomics.

Urinary tract infection tests: results in less than 4 hours?

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