Evaluation of [sup.99m]]Tc-ceftazidime as bacterial infection imaging agent

Although our understanding of microorganisms has advanced significantly and antimicrobial therapy has become increasingly available, infection remains a major cause of patient morbidity and mortality. The use of radiopharmaceuticals for diagnosis of infection is increasing due to their ability to distinguish between septic and aseptic inflammation. A wide range of radiopharmaceuticals have been proposed to visualize infection and inflammation scintigraphically. Ceftazidime a cephalosporin antibiotic used to treat bacterial infections was investigated to label with [sup.99m]Tc. Labeling was performed using sodium dithionite as reducing agent at 100°C for 10 min and radiochemical analysis involved ITLC and HPLC methods. The stability of labeled antibiotic was checked in the presence of human serum at 37°C up to 24 h. The maximum radiolabeling yield was 95.4 ± 2.0% corresponding to a specific activity of 178 GBq/mmol. Bacterial binding assay was performed with S. aureus and the in vivo distribution was studied in mice. Images showed minimal accumulation in nontarget tissues, with an average target/nontarget ratio of% 1.4 ± 0.2. Keywords [sup.99m]Tc * Ceftazidime * Radiolabeling * Infection imaging