A systematic approach for developing bacteria-specific imaging tracers

Academic Article

Abstract

  • © COPYRIGHT 2017 by the Society of Nuclear Medicine and Molecular Imaging. The modern patient is increasingly susceptible to bacterial infections including those due to multidrug-resistant organisms (MDROs). Noninvasive whole-body analysis with pathogen-specific imaging technologies can significantly improve patient outcomes by rapidly identifying a source of infection and monitoring the response to treatment, but no such technology exists clinically. Methods: We systematically screened 961 random radiolabeled molecules in silico as substrates for essential metabolic pathways in bacteria, followed by in vitro uptake in representative bacteria-Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and mycobacteria. Fluorine-labeled analogs, that could be developed as PET-based imaging tracers, were evaluated in a murine myositis model. Results: We identified 3 novel, nontoxic molecules demonstrating selective bacterial uptake: para-Aminobenzoic acid (PABA), with uptake in all representative bacteria including Mycobacterium tuberculosis; mannitol, with selective uptake in S. aureus and E. coli; and sorbitol, accumulating only in E. coli. None accumulated in mammalian cells or heat-killed bacteria, suggesting metabolism-derived specificity. In addition to an extended bacterial panel of laboratory strains, all 3 molecules rapidly accumulated in respective clinical isolates of interest including MDROs such as methicillin-resistant S. aureus, extended-spectrum b-lactamase-producing, and carbapenem-resistant Enterobacteriaceae. In a murine myositis model, fluorine-labeled analogs of all 3 molecules could rapidly detect and differentiate infection sites from sterile inflammation in mice (P 5 0.03). Finally, 2-deoxy-2-[F-18]fluoro-D-sorbitol (18F-FDS) can be easily synthesized from 18F-FDG. PET, with 18F-FDS synthesized using current good manufacturing practice, could rapidly differentiate true infection from sterile inflammation to selectively localize E. coli infection in mice. Conclusion: We have developed a systematic approach that exploits unique biochemical pathways in bacteria to develop novel pathogen-specific imaging tracers. These tracers have significant potential for clinical translation to specifically detect and localize a broad range of bacteria, including MDROs.
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    Author List

  • Ordonez AA; Weinstein EA; Bambarger LE; Saini V; Chang YS; DeMarco VP; Klunk MH; Urbanowski ME; Moulton KL; Murawski AM
  • Start Page

  • 144
  • End Page

  • 150
  • Volume

  • 58
  • Issue

  • 1