Radiosynthesis and biodistribution of 99mTc-rifampicin: A novel radiotracer for in-vivo infection imaging

99mTc–rifampicin (99mTc–RMP) a new radioantibiotic complex was synthesized specifically for the infection localization caused by methicillin-resistant Staphylococcus aureus (MRSA). The in-vitro radiochemical purity (RCP) yield, in-vivo biodistribution behavior in artificially infected rats (AIT) and scintigraphic accuracy in artificially infected rabbit (AIB) of the 99mTc–RMP complex was investigated using different concentration of the RMP, sodium pertechnetate (Na99mTcO4), stannous chloride dihydrate (SnCl2·2H2O) at different pH ranges 5–6. The best RCP yield observed at 30, 60, 90 and 120 min after labeling was; 98.95±0.20, 98.15±0.24, 96.50±0.27 and 91.55±0.22%, respectively, using 1.5 mg RMP, 175 μL of SnCl2·2H2O (1 μg/μL in 0.01 N HCl), 3 mCi of Na99mTcO4, at pH 5.6. Initially in the infected muscle (INM) of the AIT the activity was lower but after 90 min it went up to 18.35±0.20% from 5.95±0.25%. The activity in the inflamed muscle (IMM), normal (NM) muscle, blood, liver and spleen was initially high that decreased with time. The ratios of the INM/NM and IMM/NM were 7.34±0.74 and 1.20±0.85, respectively. The whole body static (WBS) imaging of the MRSA infected rabbit confirmed the usefulness of the 99mTc-RMP as a precise radiotracer for MRSA infection imaging. On the basis of in-vitro RCP, in-vivo biodistribution and scintigraphic precision, we recommend the 99mTc–RMP complex prepared aseptically for in-vivo assessment of MRSA infection.