Discrimination of selected species of pathogenic bacteria using near-infrared Raman spectroscopy and principal components analysis.
ABSTRACT. A method, based on Raman spectroscopy, for identification of different microorganisms involved in bacterial urinary tract infections has been proposed. Spectra were collected from different bacterial colonies (Gram-negative: Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa and Enterobacter cloacae, and Gram-positive: Staphylococcus aureus and Enterococcus spp.), grown on culture medium (agar), using a Raman spectrometer with a fiber Raman probe (830 nm). Colonies were scraped from the agar surface and placed on an aluminum foil for Raman measurements. After preprocessing, spectra were submitted to a principal component analysis and Mahalanobis distance (PCA/MD) discrimination algorithm. We found that the mean Raman spectra of different bacterial species show similar bands, and S. aureus was well characterized by strong bands related to carotenoids. PCA/MD could discriminate Gram-positive bacteria with sensitivity and specificity of 100% and Gram-negative bacteria with sensitivity ranging from 58 to 88% and specificity ranging from 87% to 99%.
Universidade Paulista-UNIP, Instituto de Ciências e Saúde, Rod. Pres. Dutra, km 157, São José dos Campos, SP, Brazil 12240-420.
Fernanda SantAna
FS
de Siqueira e Oliveira
Hector Enrique
HE
Giana
Landulfo
L
Silveira
D000465:Algorithms; D001419:Bacteria / Q000737:chemistry* / Q000145:classification*; D025341:Principal Component Analysis / Q000379:methods*; D012680:Sensitivity and Specificity; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*