[Ga]Ga-Schizokinen, a Potential Radiotracer for Selective Bacterial Infection Imaging.

Gallium-68-labeled siderophores as radiotracers have gained interest for the development of infection-specific imaging diagnostics. Here, we report radiolabeling, screening, and pharmacokinetics (PK) of gallium-68-labeled schizokinen ([Ga]Ga-SKN) as a new potential radiotracer for imaging bacterial infections. We radiolabeled SKN with ≥95% radiochemical purity. Our studies demonstrated its hydrophilic characteristics, neutral pH stability, and short-term stability in human serum and toward transchelation. uptake of [Ga]Ga-SKN by , , , and , but no uptake by , , or , demonstrated its specificity to bacterial species. Whole-body [Ga]Ga-SKN positron emission tomography (PET) combined with computerized tomography (CT) in healthy mice showed rapid renal excretion with no or minimal organ uptake. The subsequent biodistribution resembled this fast PK with rapid renal excretion with minimal blood retention and no major organ uptake and showed some dissociation of the tracer in the urine after 60 min postinjection. These findings warrant further evaluation of [Ga]Ga-SKN as a bacteria-specific radiotracer for infection imaging.