Molecular Imaging of Bacterial Infections

Molecular imaging of bacterial infections harnesses targeted probes to visualise pathogens in vivo with high specificity, complementing conventional anatomical techniques. By exploiting unique aspects of microbial metabolism or structure—such as cell‐wall biosynthesis, sugar uptake pathways and iron acquisition systems—clinicians can distinguish live bacteria from sterile inflammation and monitor treatment response in real time. Positron emission tomography (PET) and optical modalities each offer distinct advantages: PET tracers provide deep‐tissue sensitivity and quantification, while fluorescence and bioluminescent probes enable rapid intraoperative or endoscopic detection. Progress in radiochemistry and probe design has yielded agents that bind directly to peptidoglycan precursors, D‐amino acids or siderophores, thereby ensuring pathogen specificity. Such innovations promise earlier diagnosis, tailored antibiotic selection and reduced reliance on broad‐spectrum therapy, addressing the growing threat of antimicrobial resistance on a global scale.

Research from Nature Portfolio

Recent studies have demonstrated that D‐amino acid–derived PET tracers can selectively incorporate into bacterial peptidoglycan, providing clear discrimination between active infection and sterile inflammation. One foundational work developed a radio-labelled D-methionine analogue that rapidly accumulates in Escherichia coli and Staphylococcus aureus in vivo, enabling sensitive detection of occult foci. A complementary investigation leveraged the siderophore pyoverdine from Pseudomonas aeruginosa, chelated to gallium-68, to achieve pathogen-specific PET imaging with low background uptake and superior contrast relative to conventional tracers. Together, these advances highlight the power of metabolic targeting to improve diagnostic accuracy and guide personalised therapy.

Molecular Imaging of Bacterial Infections publication trend

The graph below shows the total number of articles in molecular imaging of bacterial infections across all publications each year (not limited to Nature Index journals).

Technical terms

Positron Emission Tomography (PET): A nuclear imaging technique that detects γ-rays emitted by positron-emitting radiotracers to produce three-dimensional images of tracer distribution.

Radiotracer: A biologically active molecule labelled with a radioactive isotope, used to visualise physiological processes in vivo.

Siderophore: A low-molecular-weight compound secreted by bacteria to chelate and import iron, which can be hijacked for targeted imaging.

Peptidoglycan: A polymeric meshwork forming the bacterial cell wall, composed of sugar chains crosslinked by peptides.

D-amino acid: The enantiomeric form of natural L-amino acids; some bacteria incorporate D-amino acids into their cell wall, providing a unique imaging target.

Fluorine-18: A positron-emitting radioisotope with a half-life of approximately 110 minutes, widely used in PET radiotracer synthesis.

References

1. Chemoenzymatic Syntheses of Fluorine-18-Labeled Disaccharides from [18F] FDG Yield Potent Sensors of Living Bacteria In Vivo. Journal of the American Chemical Society (2023).
2. Imaging the Bacterial Cell Wall Using N‑Acetyl Muramic Acid-Derived Positron Emission Tomography Radiotracers. ACS Sensors (2023).
3. Peptidoglycan-Targeted [18F]3,3,3-Trifluoro‑d‑alanine Tracer for Imaging Bacterial Infection. JACS Au (2024).
4. Imaging Active Infection in vivo Using D-Amino Acid Derived PET Radiotracers. Scientific Reports (2017).
5. Imaging of Pseudomonas aeruginosa infection with Ga-68 labelled pyoverdine for positron emission tomography. Scientific Reports (2018).
6. Optical imaging of bacterial infections. Clinical and Translational Imaging (2016).