11CPABA: A PET tracer targeting bacteria-specific metabolism

摘要

Imaging studies are frequently used to support the clinical diagnosis of infection. These techniques include computed tomography (CT) and magnetic resonance imaging (MRI) for structural information, and single photon emission computed tomography (SPECT) or positron emission tomography (PET) for metabolic data. However, frequently there is significant overlap in the imaging appearance of infectious and non-infectious entities using these tools. To address this concern, recent approaches have targeted bacteria-specific metabolic pathways. For example, radiolabelled sugars derived from sorbitol and maltose have been investigated as PET radiotracers, since these are efficiently incorporated into bacteria but are poor substrates for mammalian cells. We have previously shown that para-aminobenzoic acid (PABA) is an excellent candidate for development as a bacteria-specific imaging tracer as it is rapidly accumulated by a wide range of pathogenic bacteria, including metabolically quiescent bacteria and clinical strains, but not by mammalian cells. Therefore, in this study we developed an efficient radiosynthesis for [¹¹C]PABA, investigated its accumulation into Escherichia coli and Staphylococcus aureus laboratory strains in vitro, and shown that it can distinguish between infection and sterile inflammation in a murine model of acute bacterial infection.