Colorimetric point-of-care diagnostic to monitor Enterococcus faecalis causing urinary tract infection

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Clinical Diagnostics

Background:

• Urinary tract infections (UTIs) are common, with diagnosis relying on slow culture methods.
• Point-of-care (POC) devices offer potential for rapid UTI diagnosis and improved treatment.
• Current diagnostic methods for UTIs are time-consuming and costly.

Purpose of the Study:

• To develop a fast, specific, and accurate colorimetric sensor for detecting *Enterococcus faecalis* in urine.
• To indirectly detect *E. faecalis* by targeting its metabolite, L-lactate.
• To create a sensor for both qualitative and quantitative UTI diagnosis.

Main Methods:

• Developed a sensing probe using silica nanoparticles (SNP) loaded with MnO2 (MnSNP) and functionalized with lactate oxidase (Lac@MnSNP).
• Characterized probe morphology and composition at each synthesis step.
• Evaluated sensor responsiveness to L-lactate and detection of *E. faecalis* in various urine samples.

Main Results:

• The Lac@MnSNP probe showed a linear decrease in signal up to 50 μM L-lactate, with a limit of detection of 31 μM.
• Successfully detected *E. faecalis* in artificial and complex urine samples at concentrations as low as 10^3 CFU mL^-1 within 5 hours.
• Confirmed that nanoparticle morphology was unaffected by MnO2 incorporation and enzyme functionalization.

Conclusions:

• The developed Lac@MnSNP probe enables fast, accurate, and lactate-specific detection of *E. faecalis*.
• This sensor shows significant potential for point-of-care UTI diagnostics.
• The probe offers a promising alternative to traditional, time-consuming culture-based methods.