Radiolabeled Sweetener Helps Image Bacterial Infections In Mice

Hospital-acquired infections in the U.S. hover at the 2 million mark annually, putting clinicians under pressure to identify and locate causative bacteria quickly. Noninvasive imaging techniques such as positron emission tomography use radiotracers to illuminate regions deep within the body. However, the standard tracer, ¹⁸F-fluorodeoxy­glucose, can’t distinguish between a tumor, inflammation, and infection. Sanjay K. Jain and colleagues at Johns Hopkins University report that ¹⁸F-fluorodeoxysorbitol, which is derived from the glucose tracer, is a sensitive, specific probe for gram-negative bacteria in mice (Sci. Transl. Med. 2014, DOI: 10.1126/scitranslmed.3009815). Gram-negative pathogens such as Escherichia coli readily metabolize sorbitol, and they take up the tracer far more efficiently than do healthy cells, tumor cells, and gram-positive bacteria such as Staphylococcus aureus. Jain’s team used its patented tracer to monitor the effectiveness of antibiotic treatment in mice. An accompanying commentary from Niren Murthy of the University of California, Berkeley, cautions that this tracer and two others for bacterial infections have yet to be evaluated in biofilms, which tend not to internalize tracers quickly but represent a major type of infection.