Research ArticleTuberculosis

Rapid detection of Mycobacterium tuberculosis in sputum with a solvatochromic trehalose probe

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Science Translational Medicine  28 Feb 2018:
Vol. 10, Issue 430, eaam6310
DOI: 10.1126/scitranslmed.aam6310

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A trehalose tool for tuberculosis

Tuberculosis (TB) is the leading infectious killer worldwide. The prevalence of drug- and multidrug-resistant Mycobacterium tuberculosis necessitates more rapid and specific diagnostics. Kamariza et al. designed a color-changing dye based on trehalose, a sugar that makes up the outer membrane of M. tuberculosis. The dye stained live bacteria within minutes, emitting fluorescence upon incorporation into the hydrophobic mycobacterial membrane. Heat-inactivated bacteria did not fluoresce, and drug-treated bacteria emitted reduced fluorescence. Fluorescence intensity was similar between trehalose analog– and Auramine O–stained human sputum samples from patients with TB. This trehalose-based dye does not require sample washing and emits minimal background fluorescence, which could make it particularly useful for the rapid detection of metabolically active M. tuberculosis in resource-limited environments.

Abstract

Tuberculosis (TB) is the leading cause of death from an infectious bacterial disease. Poor diagnostic tools to detect active disease plague TB control programs and affect patient care. Accurate detection of live Mycobacterium tuberculosis (Mtb), the causative agent of TB, could improve TB diagnosis and patient treatment. We report that mycobacteria and other corynebacteria can be specifically detected with a fluorogenic trehalose analog. We designed a 4-N,N-dimethylamino-1,8-naphthalimide–conjugated trehalose (DMN-Tre) probe that undergoes >700-fold increase in fluorescence intensity when transitioned from aqueous to hydrophobic environments. This enhancement occurs upon metabolic conversion of DMN-Tre to trehalose monomycolate and incorporation into the mycomembrane of Actinobacteria. DMN-Tre labeling enabled the rapid, no-wash visualization of mycobacterial and corynebacterial species without nonspecific labeling of Gram-positive or Gram-negative bacteria. DMN-Tre labeling was detected within minutes and was inhibited by heat killing of mycobacteria. Furthermore, DMN-Tre labeling was reduced by treatment with TB drugs, unlike the clinically used auramine stain. Lastly, DMN-Tre labeled Mtb in TB-positive human sputum samples comparably to auramine staining, suggesting that this operationally simple method may be deployable for TB diagnosis.

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