Molecular Detection of Gram-positive Bacteria in the Human Lung through an Optical Fiber Based Endoscope

# Purpose # The relentless rise in antimicrobial resistance is a major societal challenge and requires, as part of its solution, a better understanding of bacterial colonization and infection. To facilitate this, we developed a highly efficient no-wash red optical molecular imaging agent that enables the rapid, selective and specific visualization of Gram-positive bacteria through a bespoke optical fiber based delivery/imaging endoscopic device. # Methods # We rationally designed a no-wash, red, Gram-positive specific molecular imaging agent based on vancomycin and an environmental merocyanine dye. We demonstrated the specificity and utility of the imaging agent in escalating in vitro and ex vivo whole human lung models (n=3), utilizing a bespoke fiber-based delivery and imaging device, coupled to a wide-field, two-color endomicroscopy system. # Results # The imaging agent was specific to Gram-positive bacteria and enabled no-wash imaging of Gram-positive bacteria within the alveolar space of whole ex vivo human lungs within 60s of administration into the field-of-view. # Conclusion # This platform enables the rapid and specific detection of Gram-positive bacteria in the human lung.