Rapid urinary tract infection diagnostics by surface-enhanced Raman spectroscopy (SERS): identification and antibiotic susceptibilities

Abstract

SERS spectra of 12 bacterial strains of urinary tract infection (UTI) clinical isolates grown and enriched from urine are reported. A partial least squares-discriminant analysis (PLS-DA) classification treatment of these SERS spectra results in strain level identification with >95% sensitivity and >99% specificity. The classification model successfully identified the SERS spectra of a urine-cultured strain not used to build this statistical model. Enrichment was accomplished by a filtration and centrifugation protocol. The predetermined drug susceptibility profiles of these clinical isolates thus allowed the SERS methodology to provide appropriate UTI antibiotic information in less than 1 h. Most of this time was used for sample preparation procedures (enrichment and washing) for this proof of principle study. SERS spectra of the enriched bacterial samples are dominated by nucleotide degradation metabolites: adenine, hypoxanthine, xanthine, guanine, uric acid, AMP, and guanosine. Strain-specific specificity is due to the different relative amounts of these purines contributing to the corresponding SERS spectra of these clinical isolates. All measurements were made at the minimal bacterial concentration in urine for UTI diagnosis (10 cfu/mL). Graphical abstract The relative contribution of each of the seven purines found to contribute to the bacterial SERS spectra are summarized in this bar graph. Although strain specific differences are evident, it can be see how the pattern of contributing purines is more different between the four species than between strains of a given species.

Strain-level typing and identification of bacteria – a novel approach for SERS active plasmonic nanostructures

“…However, slight changes of the dominant SERS bands may be caused by the presence of the additional proteins/enzymes produced by bacterial cells, which can be concluded from the SERS experiments performed with E. coli strains. Premasiri et al claimed that the SERS spectrum of E. coli 6757, which has the most different drug resistance profile from the other five measured E. coli strains, has also the most different SERS spectrum [17]. …”

“…Previous experiments showing the possibility of SERS-based bacteria identification did not consider what the molecular resistance mechanism of strains under study was. Hypothetically, this could be the reason for the inability of differentiation of all bacteria strains [17]. …”

“…The identification of different strains belonging to single bacterial species was performed also for Vibrio parahemolyticus [16]. Additionally, it was shown that SERS-based strain level identification is suitable for differentiation of E. coli , Klebsiella pneumoniae , Staphylococcus saprophyticus , and Enterococcus faecalis because of the differences in their antibiotic susceptibility profile [17]. In this paper, we demonstrate that SERS coupled with PCA (principal component analysis) is also suitable for discrimination of L. monocytogenes – it allows the identification of L. monocytogenes at the genoserotype level and the detection of some membrane proteins within a single L. monocytogens genoserogroup.…”

The biochemical origins of the surface-enhanced Raman spectra of bacteria: a metabolomics profiling by SERS

“…Preliminary data acquired in our lab point to the ability of these SERS to provide strain specificity classification within some well-defined bacterial classes. [32, 67, 68]…”

Raman spectroscopy and density functional theory study of energetically closely separated C2′‐endo and C3′‐endo pentose forms in purine nucleoside analogue drug‐gold conjugates

“…Several studies have been carried out to investigate the adsorption of adenine on metal nanoparticles (NPs) . Despite the large number of previous synthesized DNA base analogues, there is no study for the binding modes of the nucleoside on Au in connection with its amino and imino tautomeric isomers and C 2 ′‐endo and C 3 ′‐endo conformers.…”