Abstract
Tuberculosis (TB) remains a leading cause of death worldwide. Lipid rich, phenotypically antibiotic tolerant, bacteria are more resistant to antibiotics and may be responsible for relapse and the need for long-term TB treatment. We present a microfluidic system that acoustically traps live mycobacteria, M. smegmatis, a model organism for M. tuberculosis. We then perform optical analysis in the form of wavelength modulated Raman spectroscopy (WMRS) on the trapped M. smegmatis for up to eight hours, and also in the presence of isoniazid (INH). The Raman fingerprints of M. smegmatis exposed to INH change substantially in comparison to the unstressed condition. Our work provides a real-time assessment of the impact of INH on the increase of lipids in these mycobacteria, which could render the cells more tolerant to antibiotics. This microfluidic platform may be used to study any microorganism and to dynamically monitor its response to different conditions and stimuli.
Highlights
Tuberculosis (TB) remains a leading cause of death worldwide
We have shown that wavelength modulated Raman (WMR) spectroscopy is a promising non-destructive methodology to study mycobacterial cell content for cells plated onto coverslips[9]
The system presented in this study integrates both Raman spectroscopy and acoustic trapping, and permits us to make continuous measurement, using a non-destructive and label-free method over a period of many hours
Summary
Tuberculosis (TB) remains a leading cause of death worldwide. Lipid rich, phenotypically antibiotic tolerant, bacteria are more resistant to antibiotics and may be responsible for relapse and the need for long-term TB treatment. Our work provides a real-time assessment of the impact of INH on the increase of lipids in these mycobacteria, which could render the cells more tolerant to antibiotics This microfluidic platform may be used to study any microorganism and to dynamically monitor its response to different conditions and stimuli. Examples of current state of the art in technologies for realtime monitoring of bacterial populations include a fluorescent oxygen sensor in BACTEC MGIT1, electrical sensors[2] and continuous measurement of the biomass[3] These surrogate markers only give a limited view of changes in a complex cell content. Acoustic trapping can produce and maintain suspended clusters of bacteria (recently demonstrated with E. coli[6]) This creates the possibility of monitoring a viable population of suspended bacteria over time, and to probe their response to stresses, including drugs and a changing environment. It may be implemented using piezoelectric transducers, operating typically at megahertz frequencies
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