On-Body Monitoring of E. coli in Catheter Bags for Early Detection of Urinary Tract Infections

Catheter-associated urinary tract infections (CAUTIs) are one of the most commonly acquired healthcare-associated infections. Current clinical practice for diagnosis is based on urine culture, which is highly accurate but time-consuming, leading to delays in treatment decisions. Here, we present a low-cost, on-bag, reusable, and wearable fluorescence sensor that adheres to standard catheter bags for automated monitoring of E. coli growth for an early alert of infection [1]. It works in conjunction with an E. coli-specific reagent pre-loaded into the catheter bag, which uses 4-methylumbelliferyl-β-D-glucuronide (MUG) to cleave a bright fluorophore using the endogenous enzyme of E.coli, β-glucuronidase. The wearable device utilizes a flexible T-shaped PCB with 8 UV LEDs and a multi-channel spectral sensor for synchronized excitation/emission sampling. It monitors the total-contrast metric between channels, suppressing ambient light, bag geometry, and motion artifacts. The integrated Raspberry Pi on the device coordinates LED timing and wireless data transfer to a mobile app for on-site automated analysis without requiring a cloud service. With a prototyping cost of ~$47 and weight of 72 g, a single charge of the battery supports ~10 h of device operation. The device performance was tested using spiked urine samples with a range of ~100–105 CFU/mL, time-to-positivity decreased from ~9 h to ~3.5 h, and followed a strong relation between bacteria concentration and detection time (R²≈0.9996). Assay specificity was assessed against common UTI bacteria- Staphylococcus epidermidis, Pseudomonas aeruginosa, and Klebsiella pneumoniae- none of which produced positive fluorescence. Practicality was evaluated in an in-vitro bladder model, using E. coli-spiked human urine, confirming the detection kinetics match the bench results. This platform can facilitate early detection of E. coli-associated CAUTIs at the point of care and has the potential to transform clinical practice.