A new test developed by scientists in the United Kingdom could provide urinary tract infection (UTI) patients with quicker antibiotic treatment, according to a study today in JAC-Antimicrobial Resistance.
The rapid microcapillary direct-from-urine antibiotic susceptibility test (RMD AST), developed by researchers at the University of Reading and the University of Southampton, uses “dip and test” technology to provide antibiotic susceptibility results directly from urine samples in just under six hours. The device contains thin tubes that are loaded with different antibiotics and dipped directly into urine samples. Optical imaging detects whether the bacterial growth in the urine continues or is halted.
The standard process for testing antibiotic susceptibility from urine samples involves growing bacteria from the samples in cultures and then exposing the bacteria to antibiotics, a process that takes two to three days to produce results. That means UTI patients are typically treated with empiric antibiotics before the clinicians knows whether the bacteria are resistant to the selected antibiotic.
“By the time the laboratory delivers the result under current methods, a patient may already have finished their antibiotics, or been given ones that do not work,” study co-author Oliver Hancox, PhD, of the University of Reading’s School of Pharmacy, said in a university press release. Hancox is also CEO of Astratus Limited, a company established by the team that developed the test.
Getting the right treatment sooner
To evaluate the accuracy of the test, the researchers used 352 diagnostic remnant urine samples from the Hampshire Hospitals National Health Service (NHS) Foundation Trust one to five days after they arrived at the hospital’s microbiologic lab. They tested for resistance to seven antibiotics used as first-line treatments for UTIs and compared the RMD AST results to those from the standard method, which was used as a reference point.
The RMD AST results agreed with the reference method in 96.5% of urine samples containing a single organism (either Escherichia coli or Staphylococcus aureus). Susceptibility results came back in two to 10 hours, with a mean time of 5.85 hours.
But the researchers were concerned that boric acid, which inhibits bacterial growth and is typically added to urine samples to stabilize them for microbiologic testing, might interfere with the results. This was the first study of a direct-from-urine AST test to examine the impact of the compound, they noted.
Being able to tell a doctor the same day which antibiotic to use means the patient gets the right treatment sooner, reducing the risk of resistance developing and their infection turning into potentially lethal sepsis.
To do so, they collected 90 fresh urine samples and split them into two duplicate samples, with boric acid added to one set. They found RMD AST results in the split samples agreed with the reference method in 98.8% of cases.
“There was no indication that the presence of boric acid led to false negatives for growth detection that would indicate interference with growth detection by the bacteriostatic agent,” the study authors wrote.
Important results for often-resistant infections
Although the researchers say more evaluation of RMD AST at other hospitals with different antibiotic-resistance profiles is needed, the test could improve initial antibiotic treatment of UTIs, which have become increasingly resistant to first-line antibiotics. The latest report from the World Health Organization’s Global Antimicrobial Resistance and Use Surveillance System, published in October, found that one in three UTIs globally were resistant to first-line antibiotics.
Resistant UTIs can lead to treatment failure and more severe outcomes. Data from the NHS show that more than 800,000 people were admitted to UK hospitals because of a UTI from 2018 to 2023.
“Being able to tell a doctor the same day which antibiotic to use means the patient gets the right treatment sooner, reducing the risk of resistance developing and their infection turning into potentially lethal sepsis,” Hancox said.
The study was funded by the UK’s National Institute for Health and Care Research.
