Rationale: Infectious disease remains the main cause of morbidity and mortality throughout the world. Of growing concern is the rising incidence of multidrug-resistant bacteria, derived from various selection pressures. Many of these bacterial infections are hospital-acquired and have prompted the Center for Disease Control and Prevention (CDC) in 2019 to reclassify several pathogens as urgent threats, its most perilous assignment. Consequently, there is an urgent need to improve the clinical management of bacterial infection, via new methods to specifically identify bacteria and monitor antibiotic efficacy in vivo. In this report, we developed a novel radiopharmaceutical, [¹⁸F]fluoromannitol ([¹⁸F]FMtl), which we show is specifically accumulated in both gram-positive and gram-negative bacteria but not in mammalian cells in vitro or in vivo. Methods: Clinical isolates of bacteria were serially obtained from wounds of combat service members for all in vitro and in vivo studies. The quantification of bacterial infection in vivo was performed using Positron Emission Tomography (PET)/CT imaging, and infected tissue was excised to confirm radioactivity counts ex vivo. These same tissues were used to confirm the presence of bacteria by extracting and correlating radioactive counts with CFU of bacteria. Results: [¹⁸F]FMtl was able to differentiate sterile inflammation from S. aureus and E. coli infections in vivo in a murine myositis model using PET imaging. Our study was extended to a laceration wound model infected with A. baumannii, an important pathogen in the nosocomial and battlefield setting. [¹⁸F]FMtl PET could rapidly and specifically detect infections caused by A. baumannii and several other important ESKAPE pathogens. Importantly, [¹⁸F]FMtl PET was able to monitor therapeutic efficacy of vancomycin against S. aureus in vivo. Principal Conclusions: The ease of production of [¹⁸F]FMtl is anticipated to facilitate wide radiopharmaceutical dissemination. Furthermore, the broad sensitivity of [¹⁸F]FMtl for bacterial infection in vivo suggests that it is an ideal imaging agent for clinical translation to detect and monitor infections and warrants further studies in the clinical setting.

Alexandria E. Kesterson

Publications