Quantum chemical calculations helped to identify antibiotic resistant bacteria by their cell walls
June 17th, 2025
Scientists from Immanuel Kant Baltic Federal University with the help of quantum chemical calculations suggested the approach for detecting key spectral markers, that differentiate antibiotic resistant strains of agent of tuberculosis from sensible variants. The obtained theoretical data enabled to confirm results of experimental investigations, that is important for elaboration of new methos of express-diagnostics of dangerous strains in clinical practice. Results of the research are published in Journal of Molecular Structure.
According to World Health Organization more than 1,2 million people in the world die from infections, caused by antibiotic resistant microorganisms. The most dangerous is agent of tuberculosis—bacterium Mycobacterium tuberculosis—with multiple drug resistance. Thus, in 2022 about 410 thousand of new disease cases were registered. By this the efficiency of treatment of tuberculosis with multiple drug resistance is approximately 63%, and the average cost of therapy is much more higher, than that of the common tuberculosis.
Existing methods of diagnostics of resistant strains of Mycobacterium tuberculosis are time-consuming, they take 2-8 weeks or expensive equipment, and so are not always convenient and available in regions with high incidence of disease. The use of Raman spectroscopy for that aim represents crucially new approach—analysis of "molecular fingerprints" of bacteria. Such method takes only several hours and easy to realize, however obtained "fingerprints"—spectra of light dispersion by bacterial cells—are hard to interpret. That's why Raman spectroscopy isn't used in clinical practice yet.
Scientists from Immanuel Kant Baltic Federal University (Kaliningrad) with the help of Raman spectroscopy obtained spectra of light dispersion of antibiotic resistant and sensible strains of Mycobacterium tuberculosis that were isolated from patients with tuberculosis. These spectra enabled to trace peculiarities of chemical composition of microorganisms' walls, in particular abundance and types of mycolic acids, phosphatides and other components.
The analysis showed that in spectra of dispersion there was a range of important markers that helped to distinguish resistant strains from sensible ones more precisely. These are signals on wave numbers 822 cm-1, 1437 cm-1, 1295 cm-1 and 1061 cm-1, that respectively correspond lines of arabinogalactan and alpha-mycolic acids. Wave numbers reflect frequency of vibration of molecular bonds, and so enable to trace differences in certain classes of chemical compounds. Authors stress that discovered markers help to detect antibiotic resistant strains with precision of 92%.
These results are especially important because they enable to pass from simple observation of spectral differences to their precise molecular explanation. The understanding of nature of each marker opens the opportunity for creating more perfect algorithms of automatic diagnostics, where every signal will be not simply a statistic marker, but a concrete direction at certain structural changes in a bacterial cell.
"Obtained results open the way for creation of new generation of diagnostic systems, that enable to reduce time of diagnostics of tuberculosis with multiple drug resistance from several weeks to one day, that is especially critical for countries where this illness is widespread, for example, states of Africa and South-East Asia. We are planning to conduct further researches in the sphere of application of theoretical methods connected with calculation of vibrational lines of spectra for complex objects: proteins, receptors, cell walls. Such methods are very useful for confirmation of experimental data",—tells Andrey Zyubin, Ph.D. (Physics and Mathematics), head of the laboratory of mathematical modelling of optical properties of nanomaterials, chief scientific researcher of SEC "Fundamental add applied Photonics. Nanophotonics" Immanuel Kant Baltic Federal University.
More information:
Anna Kundalevich et al, Raman spectra DFT simulation of M.Tuberculosis cell wall components, Journal of Molecular Structure (2024). DOI: 10.1016/j.molstruc.2024.141051
Provided by Immanuel Kant Baltic Federal University