Antimicrobial Resistance Studies Using Raman Spectroscopy on Clinically Relevant Bacterial Strains

Abstract

There has been a steep rise in the emergence of antibiotic-resistant bacteria in the past few years. A timely diagnosis can help in initiating appropriate antibiotic therapy. However, conventional techniques for diagnosing antibiotic resistance are time-consuming and labor-intensive. Therefore, we investigated the potential of Raman spectroscopy as a rapid surveillance technology for tracking the emergence of antibiotic resistance. In this study, we used Raman spectroscopy to differentiate clinical isolates of antibiotic-resistant and -sensitive bacteria of Escherichia coli, Acinetobacter baumannii, and Enterobacter species. The spectra were collected with or without exposure to various antibiotics (ciprofloxacin, gentamicin, meropenem, and nitrofurantoin), each having a distinct mechanism of action. Ciprofloxacin- and meropenem-treated sensitive strains showed a decrease in the intensity of Raman bands associated with DNA (667, 724, 785, 1378, 1480, and 1575 cm–1) and proteins (640 and 1662 cm–1), coupled with an increase in the intensity of lipid bands (891, 960, and 1445 cm–1). Gentamicin- and nitrofurantoin-treated sensitive strains showed an increase in the intensity of nucleic acid bands (668, 724, 780, 810, 1378, 1480, and 1575 cm–1) while a decrease in the intensity of protein bands (640, 1003, 1606, and 1662 cm–1) and the lipid band (1445 cm–1). The Raman spectral changes observed in the antibiotic-resistant strains were opposite to that of antibiotic-sensitive strains. The Raman spectral data correlated well with the antimicrobial susceptibility test results. The Raman spectral dataset was used for partial least-squares (PLS) analysis to validate the biomarkers obtained from the univariate analysis. Overall, this study showcases the potential of Raman spectroscopy for detecting antibiotic-resistant and -sensitive bacteria.

V2CTx-Au Nanostructures for Rapid Surface-Enhanced Raman Scattering Detection of Bacteria and Synergistic Photothermal/Photodynamic Therapy

“…In Figure c, the characteristic peaks located at 733 and 753 cm –1 represent the nucleic acids and proteins of ESBL-E. coli, respectively . As shown in the figure, the intensity of the characteristic peak at 733 cm –1 decreases and gradually becomes wider as the concentration of ESBL-E.…”