In vivo imaging of infection using a bacteria-targeting optical nanoprobe

Wound and device-associated infection is a leading cause for morbidity and mortality. As such, rapid and early diagnosis of bacterial colonization is critical to infection treatment. The current diagnostic methods however, are not able to meet this requirement. Therefore, there is a practical need for the development of a new method to rapidly identify colonized bacteria. This study aims to develop optical nanoprobes that can detect and quantify the number of colonized bacteria in real time. To this end, we have synthesized an imaging nanoprobe with three elements: Concanavalin A (Con A) as a bacterial targeting ligand, a nanoparticle carrier, and a near infrared fluorescent dye. An MTS assay revealed that the bacteria nanoprobe is cell compatible. In vitro testing further showed that the bacteria nanoprobe had a very high specificity and affinity to bacteria. Using a murine wound and catheter infection model, we found that the bacteria nanoprobes can rapidly detect and quantify the extent of bacterial colonization on wounds and catheters in real time.