title: Combined dielectrophoresis-Raman setup for the classification of pathogens recovered from the urinary tract.
abstract: Rapid and effective methods of pathogen identifications are of major interest in clinical microbiological analysis to administer timely tailored antibiotic therapy. Raman spectroscopy as a label-free, culture-independent optical method is suitable to identify even single bacteria. However, the low bacteria concentration in body fluids makes it difficult to detect their characteristic molecular fingerprint directly in suspension. Therefore, in this study, Raman spectroscopy is combined with dielectrophoresis, which enables the direct translational manipulation of bacteria in suspensions with spatial nonuniform electrical fields so as to perform specific Raman spectroscopic characterization. A quadrupole electrode design is used to capture bacteria directly from fluids in well-defined microsized regions. With live/dead fluorescence viability staining, it is verified, that the bacteria survive this procedure for the relevant range of field strengths. The dielectrophoretic enrichment of bacteria allows for obtaining high quality Raman spectra in dilute suspensions with an integration time of only one second. As proof-of-principle study, the setup was tested with Escherichia coli and Enterococcus faecalis, two bacterial strains that are commonly encountered in urinary tract infections. Furthermore, to verify the potential for dealing with real world samples, pathogens from patients' urine have been analyzed. With the additional help of multivariate statistical analysis, a robust classification model could be built and allowed the classification of those two strains within a few minutes. In contrast, the standard microbiological diagnostics are based on very time-consuming cultivation tests. This setup holds the potential to reduce the crucial parameter diagnosis time by orders of magnitude.
authors.affiliation: Institute of Photonic Technology , Albert-Einstein-Straße 9, Jena, Thuringia, 07745 Germany.
authors.forename: Ulrich-Christian
authors.initials: UC
authors.lastname: Schröder
authors.forename: Anuradha
authors.initials: A
authors.lastname: Ramoji
authors.forename: Uwe
authors.initials: U
authors.lastname: Glaser
authors.forename: Svea
authors.initials: S
authors.lastname: Sachse
authors.forename: Christian
authors.initials: C
authors.lastname: Leiterer
authors.forename: Andrea
authors.initials: A
authors.lastname: Csaki
authors.forename: Uwe
authors.initials: U
authors.lastname: Hübner
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Fritzsche
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Pfister
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer
authors.forename: Jürgen
authors.initials: J
authors.lastname: Popp
authors.forename: Ute
authors.initials: U
authors.lastname: Neugebauer
mesh_terms: D004586:Electrophoresis / Q000379:methods*; D013293:Enterococcus faecalis / Q000302:isolation & purification* / Q000472:pathogenicity; D004926:Escherichia coli / Q000302:isolation & purification* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology / Q000652:urine; D005453:Fluorescence; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology / Q000652:urine; D006801:Humans; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014552:Urinary Tract Infections / Q000145:classification* / Q000382:microbiology* / Q000652:urine