Research aims for two-minute diagnosis of CDI with laser spectroscopy

Clostridium difficile (CDI) is a hospital-acquired infection causing severe diarrhoea, which can prove fatal in vulnerable individuals, particularly the elderly. Tackling hospital-acquired infections such as CDI is a government priority.

In an EPSRC-funded project due to begin later this year, researchers at Cranfield University plan to develop a diagnostic tool for detecting CDI on hospital wards, without the need to send samples to the laboratory for analysis.

The point-of-care device will use laser spectroscopy to identify specific chemical biomarkers for CDI in volatile organic compounds (VOCs) emitted by patient’s stool samples, according to Dr Jane Hodgkinson at Cranfield, a researcher involved in the project.

Current tests for CDI involve the use of expensive laboratory equipment, and can mean a wait of up to 24 hours for a result. Furthermore, the tests can only detect the presence or absence of the bacteria, which can be carried in a proportion of the population without causing symptoms, potentially leading to misdiagnosis in patients who carry C. difficile but have unrelated diarrhoea.

Misdiagnosis can lead to patients being unnecessarily isolated from wards or treated unnecessarily with antibiotics, contributing to the development of antimicrobial resistance.

In contrast, the new technique can measure the virulence of an infection, by detecting levels of the biomarker. It can also potentially produce a result in just two minutes.

The technology takes advantage of the fact that different chemicals absorb mid-infrared light at different wavelengths, generating a unique signature.

Previous studies by researchers at Cranfield have identified several biomarkers in samples from patients with CDI that appear to be connected with the bacterial infection.

So by tuning the lasers to measure at the specific wavelength that these biomarkers absorb light, the researchers hope to detect the presence of CDI, said Hodgkinson.

“You can detect these chemicals with really exquisite precision, in terms of being able to selectively isolate a particular compound and measure its concentration,” she said.

To use the instrument, a member of staff at the hospital would first place the sample in a holder. Clean air would then be passed over the sample, causing it to emit VOCs.

These compounds would then pass into the spectrometer, where they would be analysed for the presence of the identified biomarkers.