Towards Raman‐based epidemiological typing of Pseudomonas aeruginosa

Abstract

Raman spectra of bacteria can be used as highly specific fingerprints, enabling discrimination at strain level. Pseudomonas aeruginosa strains can be strongly pigmented, making it difficult to obtain high quality spectra of such isolates due to high fluorescent spectral backgrounds. Furthermore, the spectra that could be measured with acceptable quality often showed large spectral variations limiting the reproducibility required for strain level discrimination. P. aeruginosa produces a characteristic yellowish green fluorescent pigment, called pyoverdin. Applying a washing procedure to reduce the amount of fluorescent pigment, enabled the highly pigmented isolates to be measured with sufficient spectral quality. Isolation of the pigment/pyoverdin spectral features, together with spectral scaling methods improved reproducibility. It will be important to analyze the range of the spectral variations that can occur and ensure the correction of all of these factors to obtain the highest reproducibility required for strain level typing.

Culture-free diagnostics of Pseudomonas aeruginosa infection by silver nanorod array based SERS from clinical sputum samples

“…Despite high accuracy (95%) in sample differentiation, low sensitivity and significant interference from background florescence were observed. Spectral interference from sample matrix was also reported in other studies on Raman spectroscopic identification of P. aeruginosa 6, 7 . These studies all adopted the strategy to detect whole bacterial cells.…”

The application of Raman spectroscopy for the detection and identification of microorganisms

“…The pigment was detectable in very low amounts and was used to dynamically monitor P. aeruginosa pigment excretion during its growth . Strain‐level discrimination of P. aeruginosa was implemented by applying a washing procedure to reduce the amount of the fluorescing pigment . Also, without the presence of pigments, a sensitive and specific discrimination of pathogenic and non‐pathogenic E. coli strains was accomplished on the basis of spectral differences, and two statistical analysis methods were compared.…”

“…Thus, Raman spectroscopy could find applications for screening variability within a collection of isolates. Clinical and epidemiological studies could benefit from a fast, high‐throughput analysis of multiple colonies per patient …”

Rapid Typing of Extended-Spectrum β-Lactamase- and Carbapenemase-Producing Escherichia coli and Klebsiella pneumoniae Isolates by Use of SpectraCell RA

“…In recent years, Raman spectroscopic analysis (RA) has been validated for the bacterial typing of different species (12,25,26). RA is a label-free, optical technology based on the inelastic scattering of light by molecules.…”