Visualization of Abscess Formation in a Murine Thigh Infection Model of Staphylococcus aureus by 19F-Magnetic Resonance Imaging (MRI)

Abstract

BackgroundDuring the last years, 19F-MRI and perfluorocarbon nanoemulsion (PFC) emerged as a powerful contrast agent based MRI methodology to track cells and to visualize inflammation. We applied this new modality to visualize deep tissue abscesses during acute and chronic phase of inflammation caused by Staphylococcus aureus infection.Methodology and Principal FindingsIn this study, a murine thigh infection model was used to induce abscess formation and PFC or CLIO (cross linked ironoxides) was administered during acute or chronic phase of inflammation. 24 h after inoculation, the contrast agent accumulation was imaged at the site of infection by MRI. Measurements revealed a strong accumulation of PFC at the abscess rim at acute and chronic phase of infection. The pattern was similar to CLIO accumulation at chronic phase and formed a hollow sphere around the edema area. Histology revealed strong influx of neutrophils at the site of infection and to a smaller extend macrophages during acute phase and strong influx of macrophages at chronic phase of inflammation.Conclusion and SignificanceWe introduce 19F-MRI in combination with PFC nanoemulsions as a new platform to visualize abscess formation in a murine thigh infection model of S. aureus. The possibility to track immune cells in vivo by this modality offers new opportunities to investigate host immune response, the efficacy of antibacterial therapies and the influence of virulence factors for pathogenesis.

Noninvasive Imaging of Early Venous Thrombosis by 19 F Magnetic Resonance Imaging With Targeted Perfluorocarbon Nanoemulsions

“…Until now, 19 F MRI has been used predominantly for immune cell tracking in a variety of clinically relevant inflammation models. [21][22][23][24][25][26][27][28][29] This approach is based on the rapid uptake of intravenously injected PFCs by circulating monocytes that subsequently migrate into the inflamed area, resulting in a local accumulation of 19 F-loaded immune cells. In the present study, we report a novel procedure for the generation of targeted PFCs that makes use of a sterol-based postinsertion technique (SPIT) to generate α2-antiplasminlabeled PFCs (α2 AP -PFCs).…”

In vivo MR detection of fluorine-labeled human MSC using the bSSFP sequence

“…[32][33][34][35][36] However, these studies used a chemical shift imaging (CSI) approach with bSSFP to allow for visualization of the different spatial distributions of chemically shifted PFC compounds. Overall, the vast majority of studies that perform cell tracking with 19 F MRI have employed spin echo sequences.…”

Bioluminescence and 19 F Magnetic Resonance Imaging Visualize the Efficacy of Lysostaphin Alone and in Combination with Oxacillin against Staphylococcus aureus in Murine Thigh and Catheter-Associated Infection Models

“…The aims of the present study were (i) to assess the in vivo activity of a novel recombinant form of lysostaphin using a murine model of S. aureus central venous catheter-associated infection (12) and a deep tissue infection model (13) and (ii) to evaluate two in vivo imaging modalities, bioluminescence imaging (BLI) and 19 F magnetic resonance imaging (MRI) with perfluorocarbons (PFC), as markers to study the dynamics of antibiotic action during disease progression. Currently, determination of CFU after recovery of infected organs at the end of the experiment represents the gold standard in vivo preclinical testing method for the evaluation of antibacterial agents, but this procedure delivers no information on the dynamics of the infection and the hostpathogen interaction.…”