Toward Point-of-Care Detection of Mycobacterium tuberculosis: A Brighter Solvatochromic Probe Detects Mycobacteria within Minutes.

Mireille Kamariza,Ashley Utz,Teresia Chen,Benjamin D Knapp,Kerwyn Casey Huang,Carolyn R Bertozzi,Samantha G L Keyser,Bavesh Kana,Green Ahn,C J Cambier,Christopher Ealand

doi:10.1021/jacsau.1c00173

Abstract

There is an urgent need for point-of-care tuberculosis (TB) diagnostic methods that are fast, inexpensive, and operationally simple. Here, we report on a bright solvatochromic dye trehalose conjugate that specifically detects Mycobacterium tuberculosis (Mtb) in minutes. 3-Hydroxychromone (3HC) dyes, known for having high fluorescence quantum yields, exhibit shifts in fluorescence intensity in response to changes in environmental polarity. We synthesized two analogs of 3HC-trehalose conjugates (3HC-2-Tre and 3HC-3-Tre) and determined that 3HC-3-Tre has exceptionally favorable properties for Mtb detection. 3HC-3-Tre-labeled mycobacterial cells displayed a 10-fold increase in fluorescence intensity compared to our previous reports on the dye 4,4-N,N-dimethylaminonapthalimide (DMN-Tre). Excitingly, we detected fluorescent Mtb cells within 10 min of probe treatment. Thus, 3HC-3-Tre permits rapid visualization of mycobacteria that ultimately could empower improved Mtb detection at the point-of-care in low-resource settings.

Highlights

With 1.2 million deaths and 10 million new cases in 2018, tuberculosis (TB) is the most lethal infectious disease in the world.[1]
Poor detection methods have contributed to millions of missed TB diagnoses in high-burden, endemic countries.[1,2]
Because of the lack of accurate detection at the point-of-care, TB transmission rates have been sustained in low-income countries

Summary

Introduction

With 1.2 million deaths and 10 million new cases in 2018, tuberculosis (TB) is the most lethal infectious disease in the world.[1] Early detection of the bacterium Mycobacterium tuberculosis (Mtb), the causative agent of TB, followed by appropriate treatment could prevent most deaths.[2] The gold standard for TB diagnosis remains a labor-intensive culture test that requires weeks of incubation time in specialized facilities. PCR-based tests are expensive and require skilled technicians. Microscopy-based methods are attractive in low-resource settings as they are low-cost, have fast turnaround times and report on people at greatest risk of transmission and death.[3] As a result, the sputum smear microscopy test is the most widely used technique for TB diagnosis. The century-old smear test is based on the propensity of fluorescent auramine dye or colored Ziehl-Neelson (ZN)

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