Two-dimensional low resolution raman spectroscopy applied to fast discrimination of clinically relevant microorganisms: a whole-organism fingerprinting approach

Abstract

A diferenciação de bactérias causadoras de gastrenterites através de métodos microbiológicos clássicos é muito eficiente, na maior parte dos casos. Todavia, o elevado custo dos reagentes e o tempo necessário para tais determinações, cerca de 4 dias, podem causar sérias conseqüências, quando os pacientes são crianças, idosos ou adultos com baixa resistência imunológica. Assim, a pesquisa por métodos espectroscópicos de baixo custo, que permitam tais determinações com pouco uso de reagentes e em curtos intervalos de tempo é extremamente relevante. Neste trabalho os principais microrganismos causadores de gastrenterites, E. coli, S. chroleraesuis, S. flexneri foram avaliados. Foram preparadas sessenta dispersões para cada um dos microrganismos, usando solução fisiológica como solvente, e seus espectros adquiridos. Os espectros obtidos foram muito similares, tornando muito difícil a diferenciação dos microrganismos. Entretanto, aplicando a teoria de correlação generalizada em 2D, foi possível diferenciar os microrganismos avaliados usando o espectro síncrono como "impressão digital do organismo" em um curto intervalo de tempo (~10h).The discrimination of the bacteria that cause gastroenteritis through classical microbiological methods is very efficient in the great majority of the cases. However, the high cost of chemicals and the time spent for such identifications, about four days, could generate serious consequences for the patients. Thus, the search for low cost spectroscopic methods which would allow a fast and reagentless discrimination of these microorganisms is extremely relevant. In this work the main microorganisms that cause gastroenteritis: E. coli, S. chroleraesuis, S. flexneri were studied. For each of the microorganisms sixty different dispersions were prepared using physiological solution as solvent and its Raman spectra recorded. The 1D spectra obtained were similar, making it very difficult to differentiate the microorganisms. However, applying the 2D correlation method, it was possible to identify the microorganisms evaluated using the synchronous spectrum as "whole-organism fingerprinting" in a reduced time interval (~10 h).

Vibrational spectroscopy—A powerful tool for the rapid identification of microbial cells at the single‐cell level

“…In another study using 2D‐correlation spectroscopy it was possible to identify microorganisms responsible for gastroenteritis. In this work, the external factor responsible for characteristic spectral changes is the increase of the bacterial concentration that are dispersed in a physiological solution resulting in a solvation‐induced shift of the amide I mode (67).…”

Two‐dimensional correlation Raman spectroscopy for characterizing protein structure and dynamics

“…Recently, 2D correlation analysis of Raman data of bacteria has been utilized to differentiate various microorganisms based on small differences in amide I Raman bands of their proteins. [41] The researchers in Ref. [41] used 2D Raman spectroscopy for the rapid qualitative identification of gastroenteritis causing bacteria, such as E. coli, S. chroleraesuis and S. flexneri, using low-resolution Raman spectroscopy based on dilution effect.…”

“…[41] The researchers in Ref. [41] used 2D Raman spectroscopy for the rapid qualitative identification of gastroenteritis causing bacteria, such as E. coli, S. chroleraesuis and S. flexneri, using low-resolution Raman spectroscopy based on dilution effect. López-Díez et al [11] used 2D UV resonance Raman spectroscopy combined with discriminant analysis, a supervised classification technique, and partial least squares regression to model the concentration of amikacin in bacterial cells.…”

IR and Raman Spectroscopy for Pathogen Detection

“…The change in the relative concentration of different amino acids, nucleic acids, fatty acids, and components of the main metabolic pathway such as coenzyme A could be calculated. In another study, Mello et al [68] used 2D correlation spectroscopy from samples with increased bacterial concentrations in order to obtain more detailed Raman information of the amide I band. Both the synchronous and the asynchronous plots for three species of different genera causing gastroenteritis could be used to differentiate between the bacteria.…”