What is the problem?

Most bacterial infections can be treated with antibiotics. However, with the increase of antimicrobial resistance, limiting the use of antibiotics by first identifying the cause of the infection is vital. At present, in order to identify the bacteria causing an infection for UTIs (urinary tract infections) a culture from the patient’s urine sample has to be grown in the laboratory. This process can take up to 18 hours or more, by which time clinicians may already have made prescribing decisions, possibly including antibiotics.

A device which can detect the presence of bacteria and identify the species rapidly would help clinicians to diagnose the cause of infection. This would enable them to administer the most appropriate antbiotic, thereby reducing the need to prescribe broad spectrum antibiotics unnecessarily.

A potential solution

Prof M. Carmen Galan (School of Chemistry) and Prof Jim Spencer (School of Cellular and Molecular Medicine) are developing such a device which can be used in patient samples to detect and correctly identify bacteria. Their research is based on E. coli bacteria in UTIs.

The team are combining a novel series of chemical probes, Fluorescent Carbon Dots (FCDs), that can attach to bacteria to make them fluorescent, with an ultra-sensitive Quantum Photonic Sensor (QPS) which is able to detect the fluorescent bacteria in samples. The QPS is being developed by the team's industrial partner, FluoretiQ Ltd.

In order to correctly identify the bacteria, specific sugar molecules (glycans) will be attached to the surface of the FCDs (glycan-FCDs) to see if specific bacteria bind to them. This imitates the process by which different bacteria attach to human cells.

Alongside this, the researchers will see if glycan-FCDs can be used as a basis for new treatments. Initial tests have shown that FCDs can kill bacteria in a light–dependent process. The team will see if these modified glycan-FCDs retain this feature and investigate whether it is glycan and bacteria–specific. Finally, antibiotics will be attached to FCDs to test their ability to kill bacteria as many antibiotics have been rendered ineffective due to their inability to enter the bacterial cell.

Next steps

Dr Charlotte Colenso (School of Cellular and Molecular Medicine), a computational chemist, has been awarded a BBSRC Flexible Talent Mobility Account (FTMA) in partnership with FluoretiQ. Her tasks will be to apply computational approaches to identify and validate new glycan targets.

A longer term goal of the project is to extend the methodology to additional pathogens and infections. One aim is to create a rapid diagnostic method capable of identifying infectious Tuberculosis (TB) for use in resource-poor settings i.e. low and middle income countries (LMICs) where TB is most prevalent and medical infrastructure is limited. With the expertise of colleagues at Kenya Medical Research Institute (KEMRI), access to clinical samples will allow the team to assess the success of this approach and identify routes towards its implementation.