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Journal of Biomedical Optics • Open Access

Direct identification of clinically relevant bacterial and yeast microcolonies and macrocolonies on solid culture media by Raman spectroscopy
Author(s): Isabelle Espagnon; Denis Ostrovskii; Raphael Mathey; Mathieu G. Dupoy; Pierre Joly; Armelle Novelli-Rousseau; Fredric Pinston; Olivier Gal; Frédéric Mallard; Denis F. Leroux

Paper Abstract

Decreasing turnaround time is a paramount objective in clinical diagnosis. We evaluated the discrimination power of Raman spectroscopy when analyzing colonies from 80 strains belonging to nine bacterial and one yeast species directly on solid culture medium after 24-h (macrocolonies) and 6-h (microcolonies) incubation. This approach, that minimizes sample preparation and culture time, would allow resuming culture after identification to perform downstream antibiotic susceptibility testing. Correct identification rates measured for macrocolonies and microcolonies reached 94.1% and 91.5%, respectively, in a leave-one-strain-out cross-validation mode without any correction for possible medium interference. Large spectral differences were observed between macrocolonies and microcolonies, that were attributed to true biological differences. Our results, conducted on a very diversified panel of species and strains, were obtained by using simple and robust sample preparation and preprocessing procedures, while still confirming published results obtained by using more complex elaborated protocols. Instrumentation is simplified by the use of 532-nm laser excitation yielding a Raman signal in the visible range. It is, to our knowledge, the first side-by-side full classification study of microorganisms in the exponential and stationary phases confirming the excellent performance of Raman spectroscopy for early species-level identification of microorganisms directly from an agar culture.

Paper Details

Date Published: 12 February 2014
PDF: 14 pages
J. Biomed. Opt. 19(2) 027004 doi: 10.1117/1.JBO.19.2.027004
Published in: Journal of Biomedical Optics Volume 19, Issue 2
Show Author Affiliations
Isabelle Espagnon, Commissariat à l'Énergie Atomique (France)
Denis Ostrovskii, bioMérieux SA (France)
Raphael Mathey, bioMérieux SA (France)
Mathieu G. Dupoy, CEA-LETI (France)
Pierre Joly, CEA-LETI (France)
Armelle Novelli-Rousseau, bioMérieux SA (France)
Fredric Pinston, bioMérieux SA (France)
Olivier Gal, Commissariat à l'Énergie Atomique (France)
Frédéric Mallard, bioMérieux SA (France)
Denis F. Leroux, bioMérieux SA (France)

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