Evaluation of 99mTc-sulfadiazine as Bacillus microorganisms infection imaging agent using animal model.

Bacterial infection is one of the vital sources of morbidity and mortality. The development of single photon emission computed tomography (SPECT) radiotracer agents using antibiotics, for targeting in-vivo bacteria, helps in antibiotic dose calibration, targeted infection therapy and reduction in mortality rate. The aim of this study was to appraised 99mTc-labeling sulfadiazine as a radiopharmaceutical for bacillus infections imaging. Radiolabeling of sulfadiazine with technetium-99m was carried out by subsequent addition of 1.5 mL aqueous solution of sulfadiazine (1mg/mL), 120µg stannous tartrate, gentistic acid as stabilizing agent and 185 MBq normal saline solution of 99mTcO4-1 (pertechnetate) at pH = 5. The reaction mixture was incubated for 40 min at room temperature with light stirring. The quality control analysis (ITLC-SG and paper chromatography analysis) revealed ~ 98% labeling yield. Biodistribution and scintigraphic study was carried using bacillus bacterial infection induced New Zealand white rabbits. Due to the ease of 99mTc-sulfadiazine conjugation method, high labeling efficiency, shelf stability (>95% up to 6h), blood serum stability (~90% up to 6h) and high uptake in the infected muscle (T/NT =2.21 at 1H), 99mTc-SDZ could be used as radiopharmaceutical of choice for further pre-clinical and clinical studies.

Radiolabeling of benzylpenicillin with lutetium-177: Quality control and biodistribution study to develop theranostic infection imaging agent.

Benzylpenicillin acts through binding with beta-lactamase enzyme and inhibiting the bacterial cell wall biosynthesis. Therefore, the radiolabeling of benzylpenicillin with lutetium-177 is expected to serve as a theranostic agent for deep-seated bacterial infections. The radiolabeling of benzylpenicillin resulted ~93% radiochemical yield at optimized reaction conditions. Radiochemical purity analysis was tested with the help of Whatman No. 2 paper and instant thin layer chromatography. Biodistribution study with healthy New Zeeland white rabbit revealed moderate accumulation in different organs. Kidneys are the major organs, showed not more than 4.57±0.89% injected dose per gram organ (ID/gm organ) at 1 h time point and 3.48±1.11% ID/gm organ at 6 h time point. The accumulation of tracer agent in liver was found in the range of 7.42±2.42% to 9.09±2.76 ID/gm organ. The glomerular filtration rate studies revealed rapid clearance - omitting the chance of nephrotoxicity. The radiolabeling yield, biodistribution and glomerular filtration rate results revealed 177Lu-benzylpencillin could be a potential candidate to diagnose the deep-seated bacterial infection.

Technetium-99m-Labeled Sulfadiazine: a Targeting Radiopharmaceutical for Scintigraphic Imaging of Infectious Foci Due To Escherichia coli in Mouse and Rabbit Models.

Bacterial infection is one of the vital reasons of morbidity and mortality, especially in developing countries. It appears silently without bothering the geological borders and imposes a grave threat to humanity. Nuclear medicine technique has an important role in helping early diagnosis of deep-seated infections. The aim of this study was to develop a new radiopharmaceutical 99mTc-labeling sulfadiazine as an infection imaging agent. Radiolabeling of sulfadiazine with technetium-99m (99mTc) was carried out using stannous tartrate as a reducing agent in the presence of gentistic acid at pH = 5. The quality control tests revealed ~98% labeling efficiency. Paper chromatographic (PC) and instant thin-layer chromatographic (ITLC) techniques were used to analyze radiochemical yield. Biodistribution and infection specificity of the radiotracer were performed with Escherichia coli (E. coli) infection-induced rats. Scintigraphy and glomerular filtration rate (GFR) study was performed in E. coli-infected rabbits. Scintigraphy indicated E. coli infection targeting potential of 99mTc-SDZ, while biodistribution study showed minimal uptake of 99mTc-SDZ in non-targeted tissues. The uptake in the kidneys was found 2.56 ± 0.06, 2.09 ± 0.10, and 1.68 ± 0.09% at 30 min, 1 h, and 4 h, respectively. The infected muscle (target) to non-infected muscle (non-target) ratio (T/NT) was found 4.49 ± 0.04, 6.78 ± 0.07, and 5.59 ± 0.08 at 30 min, 1 h, and 4 h, respectively.