Surface-enhanced Raman spectroscopy for monitoring antibacterial activity of imidazole derivative (1-benzyl-3-(sec‑butyl)-1H-imidazole-3-ium bromide) against Bacillus subtilis and Escherichia coli.

BACKGROUND

Bacterial resistance against antibiotics remains a challenge and Raman Spectroscopy (SERS) may provide critical information concerning this.

OBJECTIVES

In the current study, surface enhances Raman spectroscopy (SERS) has been used to determine the biochemical changes induced during the antibacterial activity of the in house synthesized imidazole derivative (1-benzyl-3-(sec‑butyl)-1H-imidazole-3-ium bromide) in comparison to commercially available drugs (fasygien) against both gram-positive and gram-negative bacteria.

METHODS

For this purpose, the antibacterial activity of this compound was assessed on Bacillus subtilis and Escherichia coli. The SERS spectral changes are detected which can be associated with the biochemical changes in the bacterial cells as a result of the application of both drugs, including fasygien and the imidazole derivative drug demonstrating the technique's potential for analyzing the antibacterial activities of drug candidates.

RESULTS

The chemometric techniques such as Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) were performed for the differentiation of SERS spectral data sets of unexposed, exposed with imidazole derivative and commercially available antibacterial drugs for two different bacteria including E. coli and Bacillus.

CONCLUSIONS

PCA was found helpful for the qualitative differentiation of all drug-treated E. coli and Bacillus in the form of separate clusters of spectral data sets and PLS-DA discriminated the unexposed and the exposed bacteria with imidazole derivative and commercially available drug with 93% sensitivity and 96% specificity for Bacillus and with 90% sensitivity and 89% specificity for E. coli.