Article Figures & Data
Figures
- FIG. 1.
Typical Raman (a) and FT-IR (b) spectra of four microorganisms included in the reference database used for the identification of pathogens isolated from blood. The spectra have been displaced vertically on the intensity axis. Some marked spectral differences between the species have been highlighted. a.u., arbitrary units.
- FIG. 2.
Sequential identification schemes used for the identification of bacteria. (a) Sequential LDA model used for identification of microorganisms on the basis of their Raman spectra. (b) Schematic diagram of the hierarchical network used to identify bacteria on the basis of their IR spectra. See the text for details.
Tables
- TABLE 1.
Results of leave-one-out evaluation of the Raman and infrared prediction models on the basis of strains in the reference databases
Organism(s) Raman spectroscopy IR spectroscopy No. (%) identified correctly Misidentification (no. of strains) No. (%) identified correctly Misidentification (no. of strains) S. aureus 9 (100) 13 (100) CNSa 25 (96.2) S. aureus (1) 17 (94.4) S. aureus (1) E. coli 16 (97.3) E. cloacae (1) 12 (100) E. cloacae 9 (81.8) E. aerogenes (2) 6 (100) E. aerogenes 7 (77.8) E. cloacae (2) 6 (100) P. aeruginosa 9 (100) 5 (100) E. faecalis groupa 8 (100) 9 (100) E. faecium groupa 8 (100) 9 (100) Streptococcus spp.a 8 (88.9) E. faecalis (1) 9 (82) E. faecalis group (1) Candida albicans 6 (85.7) C. kefyr (1) 7 (87.5) C. dubliniensis (1) Candida dubliniensis 5 (100) Candida glabrata 5 (100) 5 (100) Candida kefyr 7 (100) 4 (100) Candida krusei 7 (100) 4 (100) Candida tropicalis 8 (100) 5 (83.3) C. albicans (1) ↵ a In the different species groups, the following species were included (number of strains in Raman database/number in IR database): CNS, S. epidermidis (10/6), S. schleiferi (3/2), S. saprophyticus (3/2), S. haemolyticus (3/2), S. capitis (3/2), S. lugdunensis (2/0), S. warneri (2/2), and S. hominis (0/2); Streptococcus spp., S. agalactiae (1/0), S. oralis (2/3), S. salivarus (2/2), S. pneumoniae (1/2), S. pyogenes (3/3), and Streptococcus variant Gr. A (0/1); Enterococcus faecium group, E. faecium (6/5), E. hirae (1/2), and E. durans (1/2); Enterococcus faecalis group (identified as such for IR analysis only), E. faecalis (6), E. casseliflavus (1), and E. gallinarum (2).
- TABLE 2.
Comparison of phenotypic and vibrational spectroscopic identifications of patient samples included in the prospective studya
Organism(s) Raman spectroscopy IR spectroscopy No. (%) identified correctly Misidentification(s) (no. of strains) No. (%) identified correctly Misidentification (no. of strains) S. aureus 19 (100) 27 (96.4) S. aureus (1) CNS 37 (97.4) Streptococcus sp. (1) 52 (98.1) CNS (1) E. coli 22 (91.7) E. aerogenes (2) 12 (100) E. cloacae 2 (40) E. aerogenes (3) 2 (100) E. aerogenes 3 (100) P. aeruginosa 5 (100) 1 (100) E. faecalis group 3 (100) 6 (100) E. faecium group 1 (100) 5 (100) Streptococcus spp. 8 (72.7) E. faecalis (2), E. aerogens (1) 7 (100) Candida albicans 6 (100) 5 (100) Candida glabrata 1 (100) Candida tropicalis 1 (100) ↵ a For Raman spectroscopy, 115 samples were included, and for IR spectroscopy, 121 samples were included.
