A family of highly sensitive contrast agents that enable in vivo imaging of bacterial infections in rats is presented in a study published online this week in Nature Materials. Such contrast agents could aid in the early clinical detection of bacterial infections, which could help people to avoid medical complications such as tissue damage or sepsis.

Bacteria are an important cause of various illnesses and sometimes death worldwide. The main challenge in imaging bacterial infections is in developing contrast agents that enter bacteria specifically and quickly.

Niren Murthy and colleagues achieved this by chemically attaching a fluorescent side group, the part of the molecule that creates the imaging contrast, to a specific type of carbohydrates that plays an important role in the metabolism of many bacteria. The researchers found that Escherichia coli and other species rapidly take up these metabolic fluorescent imaging probes, and that infections could be imaged with 100-fold improved sensitivity compared with previous contrast agents.