Aspergillus infection monitored by multimodal imaging in a rat model

Area of Science:

• Medical imaging
• Mycology
• Analytical chemistry

Background:

• Current Aspergillus diagnostics lack early, noninvasive tools with high sensitivity and specificity.
• Fungal burden assessment in lung infections requires improved detection methods.

Purpose of the Study:

• To develop and validate a multimodal imaging approach for early detection of Aspergillus fungal burden in rat lungs.
• To investigate the utility of elemental imaging, specifically silver and gold, for sensitive fungal infection tracking.

Main Methods:

• Multimodal imaging combining positron emission tomography and light microscopy (Grocott's stain, eosin counterstain).
• Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) imaging for elemental analysis.
• Energy dispersive X-ray scattering (EDX) and scanning electron microscopy (SEM) for submicron imaging.

Main Results:

• LA-ICP-MS imaging revealed increased iron in fungal-infected areas, attributed to microbial siderophores.
• Silver (Ag) and gold (Au) were identified as excellent elements for sensitive Aspergillus tracking.
• Low limits of detection (0.03 μg/g for Ag and Au) were achieved with a 5 μm laser focus.
• Selective incorporation of Ag and Au into fungal cells with low background noise confirmed by EDX/SEM.

Conclusions:

• Multimodal imaging, particularly LA-ICP-MS with silver and gold, provides a sensitive and specific method for early Aspergillus infection detection.
• This elemental imaging approach offers a viable alternative to current optical diagnostic methods in clinical settings.