Identification of mycolic acid forms using surface-enhanced Raman scattering as a fast detection method for tuberculosis

Abstract

BackgroundTuberculosis (TB) is the ninth leading cause of death worldwide and the leading cause from a single infectious agent, based on the WHO Global Tuberculosis Report in 2017. TB causes massive health care burdens in many parts of the world, specifically in the resource constrained developing world. Most deaths from TB could be prevented with cost effective early diagnosis and appropriate treatment.PurposeConventional TB detection methods are either too slow as it takes a few weeks for diagnosis or they lack the specificity and accuracy. Thus the objective of this study was to develop a fast and efficient detection for TB using surface enhanced Raman scattering (SERS) technique.MethodsSERS spectra for different forms of mycolic acids (MAs) that are both synthetic origin and actual extracts from the mycobacteria species were obtained by label-free direct detection mode. Similarly, we collected SERS spectra for γ-irradiated whole bacteria (WB). Measurements were done using silver (Ag) coated silicon nanopillar (Ag SNP) as SERS substrate.ResultsWe report the SERS based detection of MA, which is a biomarker for mycobacteria species including Mycobacterium tuberculosis. For the first time, we also establish the SERS spectral characterization of the three major forms of MA – αMA, methoxy-MA, and keto-MA, in bacterial extracts and also in γ-irradiated WB. We validated our findings by mass spectrometry. SERS detection of these three forms of MA could be useful in differentiating pathogenic and nonpathogenic Mycobacterium spp.ConclusionsWe have demonstrated the direct detection of three major forms of MA – αMA, methoxy-MA, and keto-MA, in two different types of MA extracts from MTB bacteria, namely delipidated MA and undelipidated MA and finally in γ-irradiated WB. In the near future, this study could pave the way for a fast and efficient detection method for TB, which is of high clinical significance.

Biofilms of the non-tuberculous Mycobacterium chelonae form an extracellular matrix and display distinct expression patterns

“…RS has been widely used to study bacterial biofilms ( Kelestemur et al, 2018 ). It has also been used to study the biology of mycobacteria ( Buijtels et al, 2008 , Kumar et al, 2020 , Perumal et al, 2018 , Stöckel et al, 2017 , Stöckel et al, 2015 , Verma et al, 2019 ). Raman spectroscopy also has potential as a diagnostic tool, as it allows the identification of mycobacteria to the species level ( Buijtels et al, 2008 , Stöckel et al, 2017 , Stöckel et al, 2015 , Verma et al, 2019 ), and even to determine the viability of the identified bacilli ( Kumar et al, 2020 ).…”

Tuberculosis Presenting as Isolated Wrist Swelling: A Case Report and Review of Literature

“…For the fast and efficient detection of TB, the use of mycolic acids of tuberculin bacilli was also described. This was reported by the use of surface-enhanced Raman scattering (SERS) technique to detect three major forms of mycolic acids which were expressed by mycobacteria [24]. The detection rate of the diseases by the use of small quantity of samples is of paramount importance in cases with TB where the amount of tissue is limited for sampling.…”

Dual-Approach Electrochemical Surface-Enhanced Raman Scattering Detection of Mycobacterium tuberculosis in Patient-Derived Biological Specimens: Proof of Concept for a Generalizable Method to Detect and Identify Bacterial Pathogens

“…Interestingly, the spectral pattern for all the prominent peaks seen within the 800−1600 cm −1 frequency range of the fingerprint region obtained for wtBCG from the biosensor based studies strongly resembles the SERS spectral pattern typically reported for cell-wall bound mycolic acid lipid profiles, as seen for intact whole cell TB-affiliated mycobacteria. 13 ■ CONCLUSIONS…”