Up to 20% of Clostridium difficile infections are being missed by standard testing while thousands more are being falsely diagnosed, according to research.
A study by St George's, University of London, and St George's Healthcare NHS Trust found that the six most commonly used tests for the hospital bug gave inaccurate results in a number of cases.
The study, which will be published on the Lancet's Infectious Diseases website and in the journal, found that as many as 20% of positive results for C difficile may be false – meaning around 11,000 patients may have been falsely diagnosed with the infection in the past year.
Two-stage testing is now being recommended to avoid misdiagnosis.
Tests were also found to be missing up to 20% of real C difficile cases, leading to infected patients not receiving the right treatment and potentially passing the infection on to others.
C difficile is a potentially fatal hospital-acquired infection that can lead to diarrhoea and severe inflammation of the bowel.
Currently, patients across the NHS are diagnosed with a single test, based on the level of a toxin produced by the bacteria in stool samples. St George's Hospital has now been piloting a two-stage testing process over the past six months.