Molecular detection of Gram-positive bacteria in the human lung through an optical fiber\u2013based endoscope

Bethany Mills,Jonathan C Knight,Harry A C Wood,Nikola Krstajić,Helen E Parker,James M Stone,Tushar R Choudhary,Kevin Dhaliwal,Thomas J Quinn ,Christopher Haslett,Emma Scholefield,Mark Bradley,Irene Young,Ahsan R Akram,Muhammed Üçüncü ,Annya Bruce ,Sheelagh Duncan,Dominic Norberg,T A Birks ,Alicia Megia‐Fernandez ,G Williams ,Adam Marshall,Michael G Tanner,Kerrianne Harrington

doi:10.1007/s00259-020-05021-4

Abstract

PurposeThe 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.MethodsWe rationally designed a no-wash, red, Gram-positive-specific molecular imaging agent (Merocy-Van) 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.ResultsThe imaging agent (Merocy-Van) was specific to Gram-positive bacteria and enabled no-wash imaging of S. aureus within the alveolar space of whole ex vivo human lungs within 60 s of delivery into the field-of-view, using the novel imaging/delivery endomicroscopy device.ConclusionThis platform enables the rapid and specific detection of Gram-positive bacteria in the human lung.

Highlights

Gram-positive bacteria are responsible for a vast range of serious clinical pathologies, including infections of wounds, colonization of indwelling medical devices including catheters and prosthetic joints, and ventilator-associated pneumonia (VAP) [1,2,3]
We describe the rational development and characterization of a highly specific, selective, rapidly reporting fluorescent glycopeptide-based imaging agent that has no requirement for a wash or processing step, and demonstrate its utility in detecting Gram-positive bacteria within seconds in a whole explanted human lung
A benzaldehyde-modified merocyanine was synthesized in three steps (Supporting Information Scheme S1) starting from commercially available 2,3,3-trimethyl-3H-indolenine, which was alkylated with 4-(chloromethyl)benzyl alcohol

Summary

Introduction

Gram-positive bacteria are responsible for a vast range of serious clinical pathologies, including infections of wounds, colonization of indwelling medical devices including catheters and prosthetic joints, and ventilator-associated pneumonia (VAP) [1,2,3]. Such infections result in significant morbidity, mortality and healthcare costs meaning that accurate and rapid diagnosis of these infections is critical for the initiation of appropriate treatment [4]. A VAP diagnostic strategy could benefit from technological advances offered by optical endomicroscopy and suitable molecular imaging agents [12, 13]

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Discussion

Conclusion