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Spoelstra GB, Blok SN, Reali Nazario L, Noord L, Fu Y, Simeth NA, IJpma FFA, van Oosten M, van Dijl JM, Feringa BL, Szymanski W, Elsinga PH. Synthesis and preclinical evaluation of novel 18F-vancomycin-based tracers for the detection of bacterial infections using positron emission tomography. Eur J Nucl Med Mol Imaging 2024:10.1007/s00259-024-06717-7. [PMID: 38644432 DOI: 10.1007/s00259-024-06717-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 04/14/2024] [Indexed: 04/23/2024]
Abstract
INTRODUCTION Bacterial infections are a major problem in medicine, and the rapid and accurate detection of such infections is essential for optimal patient outcome. Bacterial infections can be diagnosed by nuclear imaging, but most currently available modalities are unable to discriminate infection from sterile inflammation. Bacteria-targeted positron emission tomography (PET) tracers have the potential to overcome this hurdle. In the present study, we compared three 18F-labelled PET tracers based on the clinically applied antibiotic vancomycin for targeted imaging of Gram-positive bacteria. METHODS [18F]FB-NHS and [18F]BODIPY-FL-NHS were conjugated to vancomycin. The resulting conjugates, together with our previously developed [18F]PQ-VE1-vancomycin, were tested for stability, lipophilicity, selective binding to Gram-positive bacteria, antimicrobial activity and biodistribution. For the first time, the pharmacokinetic properties of all three tracers were compared in healthy animals to identify potential binding sites. RESULTS [18F]FB-vancomycin, [18F]BODIPY-FL-vancomycin, and [18F]PQ-VE1-vancomycin were successfully synthesized with radiochemical yields of 11.7%, 2.6%, and 0.8%, respectively. [18F]FB-vancomycin exhibited poor in vitro and in vivo stability and, accordingly, no bacterial binding. In contrast, [18F]BODIPY-FL-vancomycin and [18F]PQ-VE1-vancomycin showed strong and specific binding to Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), which was outcompeted by unlabeled vancomycin only at concentrations exceeding clinically relevant vancomycin blood levels. Biodistribution showed renal clearance of [18F]PQ-VE1-vancomycin and [18F]BODIPY-FL-vancomycin with low non-specific accumulation in muscles, fat and bones. CONCLUSION Here we present the synthesis and first evaluation of the vancomycin-based PET tracers [18F]BODIPY-FL-vancomycin and [18F]PQ-VE1-vancomycin for image-guided detection of Gram-positive bacteria. Our study paves the way towards real-time bacteria-targeted diagnosis of soft tissue and implant-associated infections that are oftentimes caused by Gram-positive bacteria, even after prophylactic treatment with vancomycin.
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Affiliation(s)
- G B Spoelstra
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713GZ, The Netherlands
| | - S N Blok
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713GZ, The Netherlands
| | - L Reali Nazario
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713GZ, The Netherlands
| | - L Noord
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713GZ, The Netherlands
| | - Y Fu
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 7, Groningen, 9747AG, The Netherlands
| | - N A Simeth
- Institute for Organic and Biomolecular Chemistry, Department of Chemistry, University of Göttingen, Tammannstraβe 2, 37077, Göttingen, Germany
| | - F F A IJpma
- Department of Trauma Surgery, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713GZ, The Netherlands
| | - M van Oosten
- Department of Medical Microbiology and Infection Prevention, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713GZ, The Netherlands
| | - J M van Dijl
- Department of Medical Microbiology and Infection Prevention, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713GZ, The Netherlands
| | - B L Feringa
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 7, Groningen, 9747AG, The Netherlands
| | - W Szymanski
- Department of Radiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713GZ, The Netherlands
- Department of Medicinal Chemistry, Photopharmacology and Imaging, University of Groningen, Groningen Research Institute of Pharmacy, Antonius Deusinglaan 1, Groningen, 9713AV, The Netherlands
| | - P H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713GZ, The Netherlands.
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