99mTc-Labeled Erythrocin and Biological Evaluation in Mice for Detection of Bacterial Infection

Nuclear medicine is a powerful diagnostic technique capable of detecting inflammatory points in human disease by using radiolabeled compounds. The ideal compound for imaging infection should be specific for an infected site with minimal side effects, low marrow, gut and renal uptake, be safe and easy to synthesize. The goal of this work was labelling of erythrocin with Technetiun-99m using stannous chloride as a reducing agent. Dependence of the yield of the 99mTc-erythrocin complex on the amount of Erythrocin, reducing agent, pH of the reaction mixture, reaction time and reaction temperature were studied. Under best conditions, the labelling yield of 99mTc-erythrocin complex was (85 ±1.1%) and was achieved using 5 mg of erythrocin, 5 µg of Sn (ΙΙ), pH 10 and 30 minute reaction time at room temperature (25ºC). 99mTc- erythrocin complex was stable for 1 hour after labelling, then the yield decreased gradually until reaching 47.3 ±1.1% after 24 hours. Biodistribution studies were achieved in mice with left thigh infection using a bacterial effect such as Staphylococcus aureus. The biochemical parameters were done before and after inflammation process. The ratio of the bacterially infected thigh to normal thigh was evaluated. The time for the maximum accumulation of 99mTc- erythrocin at the site of infection was 1 hour after administration of the labelled compound. The ratio of abscess-to-muscle for 99mTc- erythrocin is (4.12 ± 0.15%) while in the commercially available 99mTc-Ciprofloxacin is (3.8 ± 0.5 %) under the same conditions. The results suggest that 99mTc- erythrocin could be used as infection imaging.